Ideas of Gottfried Leibniz, by Theme

[German, 1646 - 1716, Born at Leipzig. Widely travelled. For a long time at the court of the Elector of Hanover. Died at Hanover.]

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1. Philosophy / A. Wisdom / 1. Nature of Wisdom
Wisdom is the science of happiness
     Full Idea: Wisdom is the science of happiness.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1690.03.23)
     A reaction: That probably comes down to common sense, or Aristotle's 'phronesis'. I take wisdom to involve understanding, as well as the quest for happiness.
Wisdom is knowing all of the sciences, and their application
     Full Idea: Wisdom is a perfect knowledge of the principles of all the sciences and of the art of applying them.
     From: Gottfried Leibniz (On Wisdom [1693], 0)
     A reaction: 'Sciences' should be understood fairly broadly here (e.g. of architecture, agriculture, grammar). This is a scholar's vision of wisdom, very different from the notion of the wisest person in a village full of illiterate people.
Wisdom involves the desire to achieve perfection
     Full Idea: The wiser one is, the more one is determined to do that which is most perfect.
     From: Gottfried Leibniz (On the Ultimate Origination of Things [1697], p.151)
     A reaction: Debatable. 'Perfectionism' is a well-known vice in many areas of life. Life is short, and the demands on us are many. Skilled shortcuts and compromises are one hallmark of genius, and presumably also of wisdom.
1. Philosophy / A. Wisdom / 2. Wise People
Wise people have fewer acts of will, because such acts are linked together
     Full Idea: The wiser one is, the fewer separate acts of will one has and the more one's views and acts of will are comprehensive and linked together.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.04.12)
     A reaction: [letter to Landgrave, about Arnauld] It is unusual to find a philosopher who actually tries to analyse the nature of wisdom, instead of just paying lipservice to it. I take Leibniz to be entirely right here. He equates wisdom with rational behaviour.
1. Philosophy / C. History of Philosophy / 4. Later European Philosophy / b. Seventeenth century philosophy
Leibniz aims to give coherent rational support for empiricism
     Full Idea: Leibniz's philosophy largely serves to justify and enable a coherent empirical account of the world.
     From: report of Gottfried Leibniz (works [1690]) by Franklin Perkins - Leibniz: Guide for the Perplexed 4.I
     A reaction: A nice counter to the simplistic idea of Locke as empiricist and Leibniz as rationalist. Leibniz is explicit that science needs a separate 'metaphysics' to underpin it. Perkins says Locke constructs experience, and Leibniz analyses it.
1. Philosophy / D. Nature of Philosophy / 2. Invocation to Philosophy
All other human gifts can harm us, but not correct reasoning
     Full Idea: Although people can be made worse off by all other gifts, correct reasoning alone can only be for the good.
     From: Gottfried Leibniz (Preface to Universal Characteristic [1679])
     A reaction: How about a kind heart? Not everyone would agree with the remark, but philosophers should.
Philosophy is sanctified, because it flows from God
     Full Idea: Philosophy is sanctified by having its streams flow from the fountain of God's attributes.
     From: Gottfried Leibniz (A General Principle to Explain Laws of Nature [1687], p.69)
1. Philosophy / E. Nature of Metaphysics / 1. Nature of Metaphysics
Metaphysics is a science of the intelligible nature of being
     Full Idea: For Leibniz, metaphysics is above all a science of the intelligible nature of being.
     From: report of Gottfried Leibniz (works [1690]) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 4.3.1
     A reaction: [Their footnote gives two quotes in support] I could take this as my motto. We are not studying the 'nature of being', because we can't. We are studying what is 'intelligible' about it; my thesis is that the need for intelligibility imposes an order.
1. Philosophy / E. Nature of Metaphysics / 4. Metaphysics as Science
Leibniz tried to combine mechanistic physics with scholastic metaphysics
     Full Idea: Leibniz made a sustained attempt to combine a mechanistic physics with something like a scholastic metaphysics.
     From: report of Gottfried Leibniz (works [1690]) by Robert Pasnau - Metaphysical Themes 1274-1671 20.1
     A reaction: This seems to me clear enough, and a lot of current philosophers seem to underestimate how Aristotelian Leibniz was.
1. Philosophy / E. Nature of Metaphysics / 5. Metaphysics beyond Science
Metaphysics is geometrical, resting on non-contradiction and sufficient reason
     Full Idea: I claim to give metaphysics geometric demonstrations, assuming only the principle of contradiction (or else all reasoning becomes futile), and that nothing exists without a reason, or that every truth has an a priori proof, from the concept of terms.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 XI)
     A reaction: For the last bit, see Idea 12910. This idea is the kind of huge optimism about metaphysic which got it a bad name after Kant, and in modern times. I'm optimistic about metaphysics, but certainly not about 'geometrical demonstrations' of it.
We can grasp the wisdom of God a priori
     Full Idea: We can grasp the wisdom of God a priori, and not from the order of the phenomena alone. ... For the senses put nothing forward concerning metaphysical matters.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: Nice instance of the aspirations of big metaphysics, before Kant cut it down to size. The claim is not far off Plato's, that by dialectic we can work out the necessities of the Forms, to which even the gods must bow. Are necessities really kept from us?
1. Philosophy / F. Analytic Philosophy / 1. Nature of Analysis
An idea is analysed perfectly when it is shown a priori that it is possible
     Full Idea: Every idea is analysed perfectly only when it is demonstrated a priori that it is possible.
     From: Gottfried Leibniz (Of Organum or Ars Magna of Thinking [1679], p.3)
     A reaction: I take it he means metaphysical possibility, rather than natural, or we can't think about pigs flying. He probably has maths in mind. Seeing the possibility of something may well amount to understanding its truth conditions.
Analysis is the art of finding the middle term
     Full Idea: The art of finding intermediate terms (the 'middle term') is the art of 'analysis'.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.02)
     A reaction: This proposal is straight out of Aristotle's 'Posterior Analytics'. Nowadays we would say there was much more to analysis, the finding of necessary and sufficient conditions being the most obvious way of putting it.
1. Philosophy / F. Analytic Philosophy / 2. Analysis by Division
Analysing right down to primitive concepts seems beyond our powers
     Full Idea: An analysis of concepts such that we can reach primitive concepts...does not seem to be within human power.
     From: Gottfried Leibniz (Introduction to a Secret Encyclopaedia [1679], C513-14), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz
     A reaction: Leibniz is nevertheless fully committed, I think, to the existence of such primitives, and is in the grip of the rationalist dream that thoughts can become completely clear, and completely well-founded.
2. Reason / A. Nature of Reason / 1. On Reason
Reason is the faculty for grasping apriori necessary truths
     Full Idea: Leibniz actually characterises reason as the faculty for apprehending priori, necessary truths.
     From: report of Gottfried Leibniz (works [1690]) by Tyler Burge - Frege on Apriority (with ps) 2
     A reaction: No wonder it is called the Age of Reason when the claims are this grandiose.
A reason is a known truth which leads to assent to some further truth
     Full Idea: A reason is a known truth whose connection with some less well-known truth leads us to give our assent to the latter.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.17)
     A reaction: This is plainly false, because you can have a reason for believing something, but still not give your assent to it, presumably because of counter-reasons. And a false belief could also be a reason, even to believe a truth. Tut tut.
2. Reason / A. Nature of Reason / 3. Pure Reason
Reasonings have a natural ordering in God's understanding, but only a temporal order in ours
     Full Idea: All reasonings are eminent in God, and they preserve an order among themselves in his understanding as well as in ours; but for him this is just an order and a priority of nature, whereas for us there is a priority of time.
     From: Gottfried Leibniz (The Theodicy [1710], p.192), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.III
     A reaction: This view is found in Frege, and seems to be the hallmark of rationalist philosophy. There is an apriori assumption that reality has a rational order, so that pure reason is a tool for grasping it. Lewis's 'mosaic' of experiences has no order.
2. Reason / A. Nature of Reason / 4. Aims of Reason
The two basics of reasoning are contradiction and sufficient reason
     Full Idea: The two first principles of reasoning are: the principle of contradiction, and the principle of the need for giving a reason.
     From: Gottfried Leibniz (A Specimen of Discoveries [1686], p.75)
     A reaction: Could animals have any reasoning ability (say, in solving a physical problem)? Leibniz's criteria both require language. Note the overlapping of the principle of sufficient reason (there IS a reason) with the contractual idea of GIVING reasons.
For Leibniz rationality is based on non-contradiction and the principle of sufficient reason
     Full Idea: Leibniz distinguished two fundamental principles of rationality - the principle of non-contradiction and the principle of sufficient reason.
     From: report of Gottfried Leibniz (works [1690]) by José A. Benardete - Metaphysics: the logical approach Ch.18
2. Reason / A. Nature of Reason / 7. Status of Reason
Opposing reason is opposing truth, since reason is a chain of truths
     Full Idea: To speak against reason is to speak against truth, for reason is a chain of truths.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: Truth has a talismanic quality here (which it didn't always have). This is a lovely slogan for defenders of the Enlightenment. It forces modern critics of the Enlightenment (Adorno etc) to launch an attack on truth, which is a doomed line.
2. Reason / A. Nature of Reason / 9. Limits of Reason
The universe is infinitely varied, so the Buridan's Ass dilemma could never happen
     Full Idea: The Buridan's Ass case of perfect equilibrium is chimerical. ...The universe has no centre and its parts are infinitely varied; thus it will never happen that all will be perfectly equal and will strike equally from one side or the other.
     From: Gottfried Leibniz (Letters to Coste [1707], 1707)
     A reaction: Can the great Leibniz have missed the point? Surely all that matters is that the ass cannot distinguish the two options - not that they actually are identical in every detail? If the ass is short-sighted, that should be easy to set up.
2. Reason / B. Laws of Thought / 1. Laws of Thought
Necessities rest on contradiction, and contingencies on sufficient reason
     Full Idea: The principle of contradiction is the principle of necessity, and the principle that a sufficient reason must be given is the principle of contingency.
     From: Gottfried Leibniz (On Sufficient Reason [1686], p.95)
     A reaction: [this paragraph is actually undated] Contradictions occur in concrete actuality, as well as in theories and formal systems. If so, then there are necessities in nature. Are they discoverable a posteriori? Leibniz says not.
General principles, even if unconscious, are indispensable for thinking
     Full Idea: General principles enter into our thoughts, serving as their inner core and their mortar. Even if we give no thought to them, they are necessary for thought, as muscles and tendons are for walking.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01.20)
     A reaction: Famously, Leibniz identified sufficient reason and non-contradiction as the two foundational principles. Modern logicians seem less keen on this idea, but then they have less interest in how we actually think.
2. Reason / B. Laws of Thought / 2. Sufficient Reason
For every event it is possible for an omniscient being to give a reason for its occurrence
     Full Idea: Nothing ever takes place without its being possible for one who knew everything to give some reason why it should have happened rather than not.
     From: Gottfried Leibniz (Letter on Freedom [1689], p.112)
     A reaction: Presumably there will be GOOD reason why genocide occurs. Note that there is a reason for every 'event'. Is there a reason for every truth? Presumably not, or there would have to be reasons for self-evident truths.
Leibniz said the principle of sufficient reason is synthetic a priori, since its denial is not illogical
     Full Idea: Leibniz assigns synthetic a priori status to the principle of sufficient reason, readily conceding that one can deny it without fear of inconsistency.
     From: report of Gottfried Leibniz (works [1690]) by José A. Benardete - Metaphysics: the logical approach Ch.18
No fact can be real and no proposition true unless there is a Sufficient Reason (even if we can't know it)
     Full Idea: The principle of sufficient reason says no fact can be real or existing and no proposition can be true unless there is a sufficient reason why it should be thus and not otherwise, even though in most cases these reasons cannot be known to us.
     From: Gottfried Leibniz (Monadology [1716], §32)
     A reaction: I think of this as my earliest philosophical perception, a childish rebellion against being told that there was 'no reason' for something. My intuition tells me that it is correct, and the foundation of ontology and truth. Don't ask me to justify it!
The principle of sufficient reason is needed if we are to proceed from maths to physics
     Full Idea: In order to proceed from mathematics to physics the principle of sufficient reason is necessary, that nothing happens without there being a reason why it should be thus rather than otherwise.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], §2)
There is always a reason why things are thus rather than otherwise
     Full Idea: Nothing happens without a sufficient reason why it should be thus rather than otherwise.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 3.2)
No reason could limit the quantity of matter, so there is no limit
     Full Idea: There is no possible reason which could limit the quantity of matter; therefore there cannot in fact be any such limitation.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 4.21)
2. Reason / B. Laws of Thought / 6. Ockham's Razor
Reason avoids multiplying hypotheses or principles
     Full Idea: Reason requires that we avoid multiplying hypotheses or principles, in somewhat the same way that the simplest system is always preferred in astronomy.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], 5)
     A reaction: He offers this principle without mentioning Ockham, as if it were self-evident.
2. Reason / D. Definition / 1. Definitions
'Nominal' definitions just list distinguishing characteristics
     Full Idea: A 'nominal' definition is nothing more than an enumeration of the sufficient distinguishing characteristics.
     From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.284)
     A reaction: Not wholly clear. Are these actual distinguishing characteristics, or potential ones? Could DNA be part of a human's nominal definition (for an unidentified corpse, perhaps).
2. Reason / D. Definition / 3. Types of Definition
A nominal definition is of the qualities, but the real definition is of the essential inner structure
     Full Idea: The essence of gold is what constitutes it and gives it the sensible qualities which let us recognize it and which make its nominal definition; but if we could explain this structure or inner constitution we would possess the real, causal definition.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.03)
     A reaction: This is the view which I am championing, particularly in the role of explanation in the whole game. Explanation and understanding are the hallmarks of the discovery of a real essence. However, a falsehood may explain things well. Tricky.
2. Reason / D. Definition / 4. Real Definition
Definitions can only be real if the item is possible
     Full Idea: Definitions to my mind are real, when one knows that the thing defined is possible; otherwise they are only nominal, and one must not rely on them.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 XI)
     A reaction: It is interesting that things do not have to actual to have real definitions. For Leibniz, what is possible will exist in the mind of God. For me what is possible will exist in the potentialities of the powers of what is actual.
One essence can be expressed by several definitions
     Full Idea: Although a thing has only one essence, this can be expressed by several definitions.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.03)
     A reaction: See Idea 12976 and Idea 12977 for a view which seems to conflict with this. He seemed to imply that once you identify the essence, the definitions converge, with multiple definitions being symptomatic of imperfect ideas of things.
If our ideas of a thing are imperfect, the thing can have several unconnected definitions
     Full Idea: The result of having an imperfect idea of something is that the same subject admits of several mutually independent definitions: we shall sometimes be unable to derive one from another, or see in advance that they must belong to a single subject.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.31)
     A reaction: See Idea 12975 for imperfect ideas of things. Obviously the idea is that perfect knowledge will converge on a single definition, which will pinpoint the essence of a thing, and then all explanations will flow. A nice addition to the Aristotelian view.
Real definitions, unlike nominal definitions, display possibilities
     Full Idea: The real definition displays the possibility of the definiendum, and the nominal definition does not.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.03)
     A reaction: This, I take it, is because the real definition indicates the actual powers of the thing, and not just the superficial characteristics. Is knowledge of powers identical with knowledge of possibilities?
2. Reason / D. Definition / 5. Genus and Differentia
Genus and differentia might be swapped, and 'rational animal' become 'animable rational'
     Full Idea: The genus can very often be turned into the differentia, ...so that in place of saying that man is a 'reasonable animal' we could, if language permitted, say that man is an 'animable rational', a rational substance with animal nature.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.03)
     A reaction: This is a very telling point which rather undermines any dogmatic approach to what Aristotle says about these sorts of definitions. I don't find this account of definitions very helpful anyway. Leibniz links it to the order of cataloguing.
2. Reason / E. Argument / 6. Conclusive Proof
Leibniz is inclined to regard all truths as provable
     Full Idea: Leibniz has an inclination to regard all truths as provable.
     From: report of Gottfried Leibniz (works [1690]) by Gottlob Frege - Grundlagen der Arithmetik (Foundations) §15
     A reaction: Leibniz sounds like the epitome of Enlightenment optimism about the powers of reason. Could God prove every truth? It's a nice thought.
3. Truth / A. Truth Problems / 1. Truth
A truth is just a proposition in which the predicate is contained within the subject
     Full Idea: In every true affirmative proposition, necessary or contingent, universal or particular, the concept of the predicate is in a sense included in that of the subject; the predicate is present in the subject; or else I do not know what truth is.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14)
     A reaction: Why did he qualify this with "in a sense"? This is referred to as the 'concept containment theory of truth'. This is an odd view of the subject. If the truth is 'Peter fell down stairs', we don't usually think the concept of Peter contains such things.
The predicate is in the subject of a true proposition
     Full Idea: In a true proposition the concept of the predicate is always present in the subject.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 X)
     A reaction: This sounds very like the Kantian notion of an analytic truth, but Leibniz is applying it to all truths. So Socrates must contain the predicate of running as part of his nature (or essence?), if 'Socrates runs' is to be true.
3. Truth / A. Truth Problems / 5. Truth Bearers
Truth is a characteristic of possible thoughts
     Full Idea: Truth really belongs to the class of thoughts which are possible.
     From: Gottfried Leibniz (Dialogue on Things and Words [1677], p.7)
     A reaction: I like the fact that this ties truth to 'thoughts', rather than peculiar abstract unthought entities called 'propositions', but I take it that thoughts which are possible but not thought will thereby not exist, so they can't be true.
True and false seem to pertain to thoughts, yet unthought propositions seem to be true or false
     Full Idea: B: I concede that truth and falsity both pertain to thoughts and not to things. A: But this contradicts your previous opinion that a proposition remains true even when you are not thinking about it.
     From: Gottfried Leibniz (Dialogue on Things and Words [1677], p.7)
     A reaction: I don't trigger the truth of a proposition by thinking about it - I see that it is true. But I dislike the idea that reality is full of propositions, which seems to be mad metaphysics. So I deny unthought propositions are true, because there aren't any.
3. Truth / A. Truth Problems / 8. Subjective Truth
We hold a proposition true if we are ready to follow it, and can't see any objections
     Full Idea: A proposition is held to be true by us when our mind is ready to follow it and no reason for doubting it can be found.
     From: Gottfried Leibniz (Introduction to a Secret Encyclopaedia [1679], p.7)
     A reaction: This follows on from Descartes' view, but it now sounds more like psychology than metaphysics. Clearly a false proposition could fit this desciption. Personally I follow propositions to which I can see no objection, without actually holding them true.
Choose the true hypothesis, which is the most intelligible one
     Full Idea: One should choose the more intelligible hypothesis, and the truth is nothing but its intelligibility.
     From: Gottfried Leibniz (On Copernicanism and Relativity of Motion [1689], p.91)
     A reaction: This apparently simple observation strikes me as being rather profound. Our picture of the world is shaped entirely by what is intelligible to us. An odd notion of truth, though. The age of reason. See Idea 13158.
3. Truth / C. Correspondence Truth / 1. Correspondence Truth
Truth is correspondence between mental propositions and what they are about
     Full Idea: Let us be content with looking for truth in the correspondence between the propositions which are in the mind and the things which they are about.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.05)
     A reaction: In an age when the nature of truth was hardly debated, and theories such as coherence and pragmatism, never mind semantic accounts, were unthought of, it is interesting to see that correspondence seems obvious to Leibniz. Correct!
3. Truth / D. Coherence Truth / 1. Coherence Truth
Everything in the universe is interconnected, so potentially a mind could know everything
     Full Idea: Every body is sensitive to everything in the universe, so that one who saw everything could read in each body what is happening everywhere, and even what has happened and will happen.
     From: Gottfried Leibniz (Monadology [1716], §61)
5. Theory of Logic / A. Overview of Logic / 3. Value of Logic
Logic teaches us how to order and connect our thoughts
     Full Idea: Logic teaches us how to order and connect our thoughts.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.10)
     A reaction: Leibniz had a higher opinion of logic than contemporaries like Locke. The question is whether logic can actually teach us better order than we could otherwise manage, or whether it just describes what most thinkers do.
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
'Blind thought' is reasoning without recognition of the ingredients of the reasoning
     Full Idea: Leibniz invented the concept of 'blind thought' - reasoning by a manipulation of characters without being able to recognise what each character stands for.
     From: report of Gottfried Leibniz (Towards a Universal Characteristic [1677]) by Richard T.W. Arthur - Leibniz
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
At bottom eternal truths are all conditional
     Full Idea: At bottom eternal truths are all conditional, saying 'granted such a thing, such another thing is'.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.11.14), quoted by Alan Musgrave - Logicism Revisited §4
     A reaction: Thus showing Leibniz to have sympathy with the if-thenist view. He cites geometry as his illustration.
5. Theory of Logic / D. Assumptions for Logic / 3. Contradiction
Falsehood involves a contradiction, and truth is contradictory of falsehood
     Full Idea: We judge to be false that which involves a contradiction, and true that which is opposed or contradictory to the false.
     From: Gottfried Leibniz (Monadology [1716], §31)
5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names
People who can't apply names usually don't understand the thing to which it applies
     Full Idea: Someone who goes wrong in relating an idea to a name will usually go wrong about the thing he wants the name to stand for.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.29)
     A reaction: This seems to give tentative support to a Millian account of names, whose only content is just the thing which is named. Leibniz's observation certainly seems to be right.
5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
It is always good to reduce the number of axioms
     Full Idea: To reduce the number of axioms is always something gained.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.06)
     A reaction: This is rather revealing about the nature of axioms. They don't have any huge metaphysical status - in fact one might say that their status is epistemological, or even pedagogic. They enable us to get out minds round things.
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
We can assign a characteristic number to every single object
     Full Idea: The true principle is that we can assign to every object its determined characteristic number.
     From: Gottfried Leibniz (Towards a Universal Characteristic [1677], p.18)
     A reaction: I add this as a predecessor of Gödel numbering. It is part of Leibniz's huge plan for a Universal Characteristic, to map reality numerically, and then calculate the truths about it. Gödel seems to allow metaphysics to be done mathematically.
6. Mathematics / A. Nature of Mathematics / 2. Geometry
Circles must be bounded, so cannot be infinite
     Full Idea: An infinite circle is impossible, since any circle is bounded by its circumference.
     From: Gottfried Leibniz (Dialogue on human freedom and origin of evil [1695], p.114)
     A reaction: This is interesting if one is asking what the essence of a circle must be. If is tempting to say merely that the radii must be equal, but can they have the length of some vast transfinite number? The circumference must be 2π bigger.
Geometry, unlike sensation, lets us glimpse eternal truths and their necessity
     Full Idea: What I value most in geometry, considered as a contemplative study, is its letting us glimpse the true source of eternal truths and of the way in which we can come to grasp their necessity, which is something confused sensory images cannot reveal.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.12)
     A reaction: This is strikingly straight out of Plato. We should not underestimate this idea, though nowadays it is with us, but with geometry replaced by mathematical logic.
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / a. Units
There is no multiplicity without true units
     Full Idea: There is no multiplicity without true units.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.04.30)
     A reaction: Hence real numbers do not embody 'multiplicity'. So either they don't 'embody' anything, or they embody 'magnitudes'. Does this give two entirely different notions, of measure of multiplicity and measures of magnitude?
Number cannot be defined as addition of ones, since that needs the number; it is a single act of abstraction
     Full Idea: Leibniz's talk of the addition of ones cannot define number, since it cannot be specified how often they are added without using the number itself. Number must be an organic unity of ones, achieved by a single act of abstraction.
     From: comment on Gottfried Leibniz (works [1690]) by Kit Fine - Cantorian Abstraction: Recon. and Defence §1
     A reaction: I doubt whether 'abstraction' is the right word for this part of the process. It seems more like a 'gestalt'. The first point is clearly right, that it is the wrong way round if you try to define number by means of addition.
Only whole numbers are multitudes of units
     Full Idea: The definition of 'number' as a multitude of units is appropriate only for whole numbers.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.15)
     A reaction: One can also define rational numbers by making use of units, but the strategy breaks down with irrational numbers like root-2 and pi. I still say the concept of a unit is the basis of numbers. Without whole numbers, we wouldn't call the real 'numbers'.
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / g. Applying mathematics
Everything is subsumed under number, which is a metaphysical statics of the universe, revealing powers
     Full Idea: There is nothing which is not subsumable under number; number is therefore a fundamental metaphysical form, and arithmetic a sort of statics of the universe, in which the powers of things are revealed.
     From: Gottfried Leibniz (Towards a Universal Characteristic [1677], p.17)
     A reaction: I take numbers to be a highly generalised and idealised description of an aspect of reality (seen as mainly constituted by countable substances). Seeing reality as processes doesn't lead us to number. So I like this idea.
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / d. Actual infinite
I strongly believe in the actual infinite, which indicates the perfections of its author
     Full Idea: I am so much for the actual infinite that instead of admitting that nature abhors it, as is commonly said, I hold that it affects nature everywhere in order to indicate the perfections of its author.
     From: Gottfried Leibniz (Reply to Foucher [1693], p.99)
     A reaction: I would have thought that, for Leibniz, while infinities indicate the perfections of their author, that is not the reason why they exist. God wasn't, presumably, showing off. Leibniz does not think we can actually know these infinities.
I don't admit infinite numbers, and consider infinitesimals to be useful fictions
     Full Idea: Notwithstanding my infinitesimal calculus, I do not admit any real infinite numbers, even though I confess that the multitude of things surpasses any finite number, or rather any number. ..I consider infinitesimal quantities to be useful fictions.
     From: Gottfried Leibniz (Letters to Samuel Masson [1716], 1716)
     A reaction: With the phrase 'useful fictions' we seem to have jumped straight into Harty Field. I'm with Leibniz on this one. The history of mathematics is a series of ingenious inventions, whenever they seem to make further exciting proofs possible.
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / j. Infinite divisibility
The continuum is not divided like sand, but folded like paper
     Full Idea: Leibniz said the division of the continuum should not be conceived 'to be like the division of sand into grains, but like that of a tunic or a sheet of paper into folds'.
     From: report of Gottfried Leibniz (works [1690], A VI iii 555) by Richard T.W. Arthur - Leibniz
     A reaction: This from the man who invented calculus. This thought might apply well to the modern physicist's concept of a 'field'.
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / k. Infinitesimals
Nature uses the infinite everywhere
     Full Idea: Nature uses the infinite in everything it does.
     From: Gottfried Leibniz (works [1690]), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.1
     A reaction: [The quote can be tracked through Kitcher's footnote] He seems to have had in mind the infinitely small.
A tangent is a line connecting two points on a curve that are infinitely close together
     Full Idea: We have only to keep in mind that to find a tangent means to draw a line that connects two points of a curve at an infinitely small distance.
     From: Gottfried Leibniz (works [1690]), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.1
     A reaction: [The quote can be tracked through Kitcher's footnote]
6. Mathematics / B. Foundations for Mathematics / 3. Axioms for Geometry
We shouldn't just accept Euclid's axioms, but try to demonstrate them
     Full Idea: Far from approving the acceptance of doubtful principles, I want to see an attempt to demonstrate even Euclid's axioms, as some of the ancients tried to do.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.02)
     A reaction: This is the old idea of axioms, as a bunch of basic self-evident truths, rather than the modern idea of an economical set of propositions from which to make deductions. Demonstration has to stop somewhere.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / a. Axioms for numbers
We know mathematical axioms, such as subtracting equals from equals leaves equals, by a natural light
     Full Idea: It is by the natural light that the axioms of mathematics are recognised. If we take away the same quantity from two equal things, …a thing we can easily predict without having experienced it.
     From: Gottfried Leibniz (Letters to Queen Charlotte [1702], p.189)
     A reaction: He also says two equal weights will keep a balance level. Plato thinks his slave boy understands halving an area by the natural light, but that is just as likely to be experience. It is too easy to attribut thoughts to a 'natural light'.
7. Existence / A. Nature of Existence / 3. Being / g. Particular being
What is not truly one being is not truly a being either
     Full Idea: What is not truly one being is not truly a being either.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.04.30), quoted by Alain Badiou - Briefings on Existence 1
     A reaction: Badiou quotes this as identifying Being with the One. I say Leibniz had no concept of 'gunk', and thought everything must have a 'this' identity in order to exist, which is just the sort of thing a logician would come up with.
7. Existence / A. Nature of Existence / 3. Being / h. Dasein (being human)
The idea of being must come from our own existence
     Full Idea: I would like to know how we could have the idea of being if we did not, as beings ourselves, find being within us.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01)
     A reaction: I could envisage a creature with an entirely 'externa' mind, that just focused on environment, and took its own place in it unthinkingly for granted. I suppose he's right, though.
7. Existence / A. Nature of Existence / 5. Reason for Existence
Possibles demand existence, so as many of them as possible must actually exist
     Full Idea: From the conflict of all the possibles demanding existence, this at once follows, that there exists that series of things by which as many of them as possible exist.
     From: Gottfried Leibniz (Exigency to Exist in Essences [1690], p.91)
     A reaction: I'm in tune with a lot of Leibniz, but my head swims with this one. He seems to be a Lewisian about possible worlds - that they are concrete existing entities (with appetites!). Could Lewis include Leibniz's idea in his system?
God's sufficient reason for choosing reality is in the fitness or perfection of possibilities
     Full Idea: The sufficient reason for God's choice can be found only in the fitness (convenance) or in the degree of perfection that the several worlds possess.
     From: Gottfried Leibniz (Exigency to Exist in Essences [1690], p.92)
     A reaction: The 'fitness' of a world and its 'perfection' seem very different things. A piece of a jigsaw can have wonderful fitness, without perfection. Occasionally you get that sinking feeling with metaphysicians that they just make it up.
Leibniz first asked 'why is there something rather than nothing?'
     Full Idea: The historical honour of having first raised the question "Why is there something rather than nothing?" belongs to Leibniz.
     From: report of Gottfried Leibniz (On the Ultimate Origination of Things [1697]) by Dale Jacquette - Ontology Ch.3
     A reaction: I presume that people before Leibniz may well have had the thought, but not bothered to even articulate it, because there seemed nothing to say by way of answer, other than some reference to the inscrutable will of God.
There must be a straining towards existence in the essence of all possible things
     Full Idea: Since something rather than nothing exists, there is a certain urge for existence, or (so to speak) a straining toward existence in possible things or in possibility or essence itself; in a word, essence in and of itself strives for existence.
     From: Gottfried Leibniz (On the Ultimate Origination of Things [1697], p.150)
     A reaction: Thus 'essence precedes existence'. Not sure I understand this, but at least it places an active power at the root of everything (though Leibniz probably sees that as divine). The Big Bang triggered by a 'quantum fluctuation'?
Because something does exist, there must be a drive in possible things towards existence
     Full Idea: From the very fact that something exists rather than nothing, we recognise that there is in possible things, that is, in the very possibility or essence, a certain exigent need of existence, and, so to speak, some claim to existence.
     From: Gottfried Leibniz (On the Ultimate Origination of Things [1697], p.347)
     A reaction: I love the fact that Leibniz tried to explain why there is something rather than nothing. Bede Rundle and Dale Jacquette are similar heroes. As Leibniz tells us, contradictions have no claim to existence, but non-contradictions do.
First: there must be reasons; Second: why anything at all?; Third: why this?
     Full Idea: We rise to metaphysics by saying 'nothing takes place without a reason', then asking 'why is there something rather than nothing?, and then 'why do things exist as they do?'
     From: Gottfried Leibniz (Principles of Nature and Grace based on Reason [1714], §7)
     A reaction: Wonderful. This is what we pay philosophers for - to attempt to go to the heart of the mystery, and then start formulating the appropriate questions. The question of 'why this?' is the sweetest question. The first one seems a little intractable.
7. Existence / A. Nature of Existence / 6. Criterion for Existence
What is not active is nothing
     Full Idea: We can now show from the inner truths of metaphysics that what is not active is nothing.
     From: Gottfried Leibniz (True Method in Philosophy and Theology [1686], p.64)
     A reaction: This is Leibniz's rebellion against the Cartesian idea that all that matters for natural existence is spatial extension. I agree (tentatively) with Leibniz's vision of nature here. Modern physics reveals a seething turmoil beneath the placid exterior.
7. Existence / C. Structure of Existence / 5. Supervenience / a. Nature of supervenience
A thing 'expresses' another if they have a constant and fixed relationship
     Full Idea: One thing 'expresses' another (in my terminology) when there exists a constant and fixed relationship between what can be said of one and of the other. This is the way that a perspectival projection expresses its ground-plan.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.10.09)
     A reaction: Arnauld was puzzled by what Leibniz might mean by 'express', and it occurs to me that Leibniz was fishing for the modern concept of 'supervenience'. It also sounds a bit like the idea of 'covariance' between mind and world. Maybe he means 'function'.
7. Existence / C. Structure of Existence / 6. Fundamentals / c. Monads
Substances are in harmony, because they each express the one reality in themselves
     Full Idea: Every substance expresses the whole sequence of the universe in accordance with its own viewpoint or relationship to the rest, so that all are in perfect correspondence with one another.
     From: Gottfried Leibniz (Identity in Substances and True Propositions [1686], p.98)
     A reaction: Thus 'expression' (something like mapping what is exterior) is the mechanism through which God achieves harmony in the universe. Instants of time are said to be successive moments of perfect harmony.
Leibniz proposes monads, since there must be basic things, which are immaterial in order to have unity
     Full Idea: Leibniz believes in monads because it would be contrary to reason or divine wisdom if everything was compounds, down to infinity; there must be ultimate unified building-blocks; they cannot be material, for material things lack genuine unity.
     From: report of Gottfried Leibniz (works [1690]) by Nicholas Jolley - Leibniz Ch.3
     A reaction: It is hard to discern the basis for the claim that only immaterial things can have unity. The Greeks proposed atoms, and we have no reason to think that electrons lack unity.
Reality must be made of basic unities, which will be animated, substantial points
     Full Idea: A multiplicity can only be made up of true unities, ..so I had recourse to the idea of a real and animated point, or an atom of substance which must embrace some element of form or of activity in order to make a complete being.
     From: Gottfried Leibniz (New System and Explanation of New System [1696], p.116)
     A reaction: This seems to be a combination of logical atomism and panpsychism. It has a certain charm, but looks like another example of these rationalist speculators overreaching themselves.
A piece of flint contains something resembling perceptions and appetites
     Full Idea: I don't say that bodies like flint, which are commonly called inanimate, have perceptions and appetition; rather they have something of that sort in them, like worms are in cheese.
     From: Gottfried Leibniz (Letters to Johann Bernoulli [1699], 1698.12.17)
     A reaction: Leibniz is caricatured as thinking that stones are full of little active minds, but he nearly always says that what he is proposing is 'like' or 'analogous to' that. His only real point is that nature is active, as seen in the appetites of animals.
Entelechies are analogous to souls, as other minds are analogous to our own minds
     Full Idea: Just as we somehow conceive other souls and intelligences on analogy with our own souls, I wanted whatever other primitive entelechies there may be remote from our senses to be conceived on analogy with souls. They are not conceived perfectly.
     From: Gottfried Leibniz (Letters to Johann Bernoulli [1699], 1698.12.17)
     A reaction: This is the clearest evidence I can find that Leibniz does not think of monads as actually being souls. He is struggling to explain their active character. Garber thinks that Leibniz hasn't arrived at proper monads at this date.
Monads are not extended, but have a kind of situation in extension
     Full Idea: Even if monads are not extended, they nonetheless have a certain kind of situation in extension.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 8
     A reaction: This is the kind of metaphysical mess you get into if you start from the wrong premisses (in this case, a dualism of the spiritual and the material). Later (Garber p.359) he says they are situated because they 'preside' over a mass.
Only monads are substances, and bodies are collections of them
     Full Idea: A monad alone is a substance; a body is substances not a substance.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704.01.21), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 8
     A reaction: So how many monads in a drop of urine, as Voltaire bluntly wondered. I take the Cartesian dualism (without interaction) that ran through Leibniz's career to be the source of most of his metaphysical problems. In late career it went badly wrong.
All substances analyse down to simple substances, which are souls, or 'monads'
     Full Idea: What (in the analysis of substances) exist ultimately are simple substances - namely, souls, or, if you prefer a more general terms, 'monads', which are without parts.
     From: Gottfried Leibniz (Metaphysical conseqs of principle of reason [1712], §7)
     A reaction: This seems to me to be atomistic panpsychism. He is opposed to physical atomism, because infinite divisibility seems obvious, but unity is claimed to be equally obvious in the world of the mental. Does this mean bricks are made of souls? Odd.
A monad and its body are living, so life is everywhere, and comes in infinite degrees
     Full Idea: Each monad, together with a particular body, makes up a living substance. Thus, there is not only life everywhere, joined to limbs or organs, but there are also infinite degrees of life in the monads, some dominating more or less over others.
     From: Gottfried Leibniz (Principles of Nature and Grace based on Reason [1714], 4)
     A reaction: Two key ideas: that each monad is linked to a body (which is presumably passive), and the infinite degrees of life in monads. Thus rocks consist of monads, but at an exceedingly low degree of life. They are stubborn and responsive.
Without a substantial chain to link monads, they would just be coordinated dreams
     Full Idea: If that substantial chain [vinculum substantiale] for monads did not exist, all bodies, together with all of their qualities, would be nothing but well-founded phenomena, like a rainbow or an image in a mirror, continual dreams perfectly in agreement.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.02.05)
     A reaction: [The first appearance, apparently, of the 'susbtantial chain' in his writings] I take this to be a hugely significant move, either a defeat for monads, or the arrival of common sense. Spiritual monads must unify things, so they can't just be 'parallel'.
Monads control nothing outside of themselves
     Full Idea: Monads aren't a principle of operation for things outside of themselves.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: This is why Leibniz has got into a tangle, and is proposing his 'substantial chain' to join the monads together. I suspect that he would have dumped monads if he had lived a bit longer.
Monads do not make a unity unless a substantial chain is added to them
     Full Idea: Monads do not constitute a complete composite substance, since they make up, not something one per se, but only a mere aggregate, unless some substantial chain is added.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.05.26)
     A reaction: This is the clearest statement in the Des Bosses letters of the need for something extra to unite monads. Since the main role of monads was to replace substances, which are only postulated to provide unity, this is rather a climb-down.
The monad idea incomprehensibly spiritualises matter, instead of materialising soul
     Full Idea: The Leibnizians with their monads have constructed an incomprehensible hypothesis. They have spiritualized matter rather than materialising the soul.
     From: comment on Gottfried Leibniz (Monadology [1716]) by Julien Offray de La Mettrie - Machine Man p.3
     A reaction: I agree with La Mettrie. This disagreement shows, I think, how important the problem of interaction between mind and body was in the century after Descartes. Drastic action seemed needed to bridge the gap, one way or the other.
He replaced Aristotelian continuants with monads
     Full Idea: In the end Leibniz dethroned Aristotelian continuants, seen as imperfect from his point of view, in favour of monads.
     From: report of Gottfried Leibniz (Monadology [1716]) by David Wiggins - Sameness and Substance Renewed 3.1
     A reaction: I take the 'continuants' to be either the 'ultimate subject of predication' (in 'Categories'), or 'essences' (in 'Metaphysics'). Since monads seem to be mental (presumably to explain the powers of things), this strikes me as a bit mad.
Is a drop of urine really an infinity of thinking monads?
     Full Idea: Can you really maintain that a drop of urine is an infinity of monads, and that each one of these has ideas, however obscure, of the entire universe?
     From: comment on Gottfried Leibniz (Monadology [1716]) by Francois-Marie Voltaire - works Vol 22:434
     A reaction: Monads are a bit like Christian theology - if you meet them cold they seem totally ridiculous, but if you meet them after ten years of careful preliminary study they make (apparently) complete sense. Defenders of panpsychism presumably like them.
It is unclear in 'Monadology' how extended bodies relate to mind-like monads.
     Full Idea: It is never clear in the 'Monadologie' how exactly the world of extended bodies is related to the world of simple substances, the world of non-extended and mind-like monads.
     From: comment on Gottfried Leibniz (Monadology [1716]) by Daniel Garber - Leibniz:Body,Substance,Monad 9
     A reaction: Leibniz was always going to hit the interaction problem, as soon as he started giving an increasingly spiritual account of what a substance, and hence marginalising the 'force' which had held centre-stage earlier on. Presumably they are 'parallel'.
Changes in a monad come from an internal principle, and the diversity within its substance
     Full Idea: A monad's natural changes come from an internal principle, ...but there must be diversity in that which changes, which produces the specification and variety of substances.
     From: Gottfried Leibniz (Monadology [1716], §11-12)
     A reaction: You don't have to like monads to like this generalisation (and Perkins says Leibniz had a genius for generalisations). Metaphysics must give an account of change. Succeeding time-slices etc explain nothing. Principle and substance must meet.
A 'monad' has basic perception and appetite; a 'soul' has distinct perception and memory
     Full Idea: The general name 'monad' or 'entelechy' may suffice for those substances which have nothing but perception and appetition; the name 'souls' may be reserved for those having perception that is more distinct and accompanied by memory.
     From: Gottfried Leibniz (Monadology [1716], §19)
     A reaction: It is basic to the study of Leibniz that you don't think monads are full-blown consciousnesses. He isn't really a panpsychist, because the level of mental activity is so minimal. There seem to be degrees of monadhood.
All simply substances are in harmony, because they all represent the one universe
     Full Idea: All simple substances will always have a harmony among themselves, because they always represent the same universe.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], V §91), quoted by Richard T.W. Arthur - Leibniz
     A reaction: We can accept that the universe itself does not contain contradictions (how could it), but it is a leap of faith to say that all monads represent the universe well enough to avoid contradictions. Maps can contradict one another.
7. Existence / C. Structure of Existence / 7. Abstract/Concrete / a. Abstract/concrete
Objects of ideas can be divided into abstract and concrete, and then further subdivided
     Full Idea: Divide terms, objects of ideas, into abstract and concrete, then the abstract into absolute and relational, the absolute into attributes and modifications, and those two into simple and composite; the concrete are substances and their substantial things.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.22)
     A reaction: Make your tree from this: ABSTRACT{absolute[attributes(simple)(composite)][modifications(simple)(composite)],relations}CONCRETE{[substance][substantial form]}
7. Existence / D. Theories of Reality / 2. Realism
If experience is just a dream, it is still real enough if critical reason is never deceived
     Full Idea: Even if this whole life were said to be only a dream, and the visible world only a phantasm, I should call this dream or phantasm real enough if we were never deceived by it when we make good use of reason.
     From: Gottfried Leibniz (De modo distinguendi phaenomena [1685], A6.4.1502), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: I find this response more satisfactory than his response in Idea 12740. As a supporter of the coherence account of justification, I take the closest we get to knowledge to be when our full critical faculties and experience are brought to bear, and shared.
The strongest criterion that phenomena show reality is success in prediction
     Full Idea: The most powerful criterion of the reality of phenomena, sufficient even by itself, is success in predicting future phenomena from past and present ones.
     From: Gottfried Leibniz (De modo distinguendi phaenomena [1685], A6.4.1502), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: I would say that this is clutching at straws, as there is no reason at all to deny that dreams could be thoroughly coherent and predictable in their events. We must just live with these doubts, not try to defeat them.
The division of nature into matter makes distinct appearances, and that presupposes substances
     Full Idea: If there were no divisions of matter in nature, there would be no things that are different; just the mere possibility of things. It is the actual division into masses that really produces things that appear distinct, which presupposes simple substances.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704 or 1705)
     A reaction: This shows Leibniz to be a straightforward realist about the physical world, and certainly not an 'idealist', despite the mind-like character of monads. I take this to be an argument for reality from best explanation, which is all that's available.
The only indications of reality are agreement among phenomena, and their agreement with necessities
     Full Idea: We don't have, nor should we hope for, any mark of reality in phenomena, but the fact that they agree with one another and with eternal truths.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1706.01.19)
     A reaction: Elsewhere he says that divisions in appearance imply divisions in matter. Now he adds two further arguments in favour of realism, but admits that nothing conclusive is available. Quite right.
7. Existence / D. Theories of Reality / 3. Reality
Only unities have any reality
     Full Idea: There is no reality in anything except the reality of unities.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704.06.30), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 9
     A reaction: This seems to leave indeterminate stuff like air and water with no reality, as nicely discussed by Henry Laycock. Do we just force unities on the world because that is the only way our minds can cope with it?
7. Existence / D. Theories of Reality / 10. Vagueness / b. Vagueness of reality
In actual things nothing is indefinite
     Full Idea: In actual things nothing is indefinite.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1706.01.19)
     A reaction: This seems to be the germ of the controversial modern view of Williamson, that vagueness is entirely epistemic, and that the facts of nature are entirely definite. Thus there is a tallest short giraffe, which I find a bit hard to grasp.
7. Existence / E. Categories / 3. Proposed Categories
Have five categories - substance, quantity, quality, action/passion, relation - and their combinations
     Full Idea: The scheme of categories is very useful, and it might be that all that is needed are five general headings for beings - namely substance, quantity, quality, action or passion, and relation - with any formed by composition from those.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.10)
     A reaction: 'Action or passion' as a single category sounds intriguing. He is very keen on active force in the world of physical objects, which presumably falls into this category. His plan sounds, initially, as good as any I have heard.
7. Existence / E. Categories / 4. Category Realism
Our true divisions of nature match reality, but are probably incomplete
     Full Idea: It can be said that whatever we truthfully distinguish or compare is also distinguished or made alike by nature, although nature has distinctions and comparisons which are unknown to us and which may be better than ours.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.06)
     A reaction: This seems to me to be correct, though it is more like the credo of the sensible realist than it is like any sort of argument.
8. Modes of Existence / A. Relations / 1. Nature of Relations
If relations can be reduced to, or supervene on, monadic properties of relata, they are not real
     Full Idea: Leibniz argued that relations could be reduced to monadic properties and so were dispensable, and some still agree, saying relations supervene on monadic properties of the relata, and are not actually real.
     From: report of Gottfried Leibniz (works [1690]) by Chris Swoyer - Properties 7.4
     A reaction: At the very least a background of space and/or time seem required, in addition to any properties the relata may have. y only becomes 'to the left of x' when x appears to its right, so the relation doesn't seem to be intrinsic to y.
Relations aren't in any monad, so they are distributed, so they are not real
     Full Idea: The relations which connect two monads are not in either the one or the other, but equally in both at once; and therefore properly speaking, in neither. I do not think you would wish to posit an accident which would inhere simultaneously in two subjects.
     From: Gottfried Leibniz (works [1690], G II:517), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 2.4.3
     A reaction: Where Russell affirms relations as universals, and scholastics make them properties of individuals, Leibniz denies their reality entirely. It seems obvious that once the objects and properties are there, the relations come for free.
A man's distant wife dying is a real change in him
     Full Idea: No one can become a widower in India because of the death of his wife in Europe unless a real change occurs in him.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], GP ii 240), quoted by Richard T.W. Arthur - Leibniz 7 'Nominalist'
     A reaction: This is Leibniz heroically denying so-called 'Cambridge Change'. It is hard to see how a widower is changed if he has not yet heard the bad news. But his situation in life has changed. Compare eudaimonia, which you can lose without realising it.
The ratio between two lines can't be a feature of one, and cannot be in both
     Full Idea: If the ratio of two lines L and M is conceived as abstracted from them both, without considering which is the subject and which the object, which will then be the subject? We cannot say both, for then we should have an accident in two subjects.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 5th Paper, §47), quoted by John Heil - Relations 'External'
     A reaction: [compressed] Leibniz is rejecting external relations as having any status in ontology. It looks like a mistake (originating in Aristotle) to try to shoehorn the ontology of relations into the substance-properties framework.
8. Modes of Existence / C. Powers and Dispositions / 1. Powers
Because of the definitions of cause, effect and power, cause and effect have the same power
     Full Idea: The primary mechanical axiom is that the whole cause and the entire effect have the same power [potentia]. ..This depends on the definition of cause, effect and power.
     From: Gottfried Leibniz (De arcanus motus [1676], 203), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 6
     A reaction: This is a useful reminder that if one is going to build a metaphysics on powers (which I intend to do), then the conservation laws in physics are highly relevant.
Everything has a fixed power, as required by God, and by the possibility of reasoning
     Full Idea: It follows from the nature of God that there is a fixed power of a definite magnitude [non vagam] in anything whatsoever, otherwise there would be no reasonings about those things.
     From: Gottfried Leibniz (De aequopollentia causae et effectus [1679], A6.4.1964), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 6
     A reaction: This is double-edged. On the one hand there is the grand claim that the principle derives from divine nature, but on the other it derives from our capacity to reason and explain. No one doubts that powers are 'fixed'.
The immediate cause of movements is more real [than geometry]
     Full Idea: The force or proximate cause of these changes [of position] is something more real, and there is sufficient basis to attribute it to one body more than to another.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §18), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3
     A reaction: The force is said to be 'more real' than geometry. Leibniz seems to have embraced fairly physical powers in the period 1678-1698, and then seen them as more and more like spirits.
We discern active power from our minds, so mind must be involved in all active powers
     Full Idea: The clearest idea of active power comes to us from the mind. So active power occurs only in things which are analogous to minds, that is, in entelechies; for strictly matter exhibits only passive power.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: If this is meant to be a precise argument, then 'so' and 'only' are blatantly unjustified. I guess that if it isn't analogous to a mind then he won't allow it to be a TRUE active power! I say mind arises from the entelechies of the physical brain.
I use the word 'entelechy' for a power, to include endeavour, as well as mere aptitude
     Full Idea: If 'power' is the source of action, it means more than aptitude or ability. It also includes endeavour. It is in order to express this sense that I appropriate the term 'entelechy' to stand for power.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.22)
     A reaction: An 'entelechy' is, roughly, an instantiated thing, but I like what Leibniz is fishing for here - that we will never understand the world if we think of it as passive.
A complete monad is a substance with primitive active and passive power
     Full Idea: What I take to be the indivisible or complete monad is the substance endowed with primitive power, active and passive, like the 'I' or something similar.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20)
     A reaction: I love powers, so I really like this quotation. By this date even Garber thinks that he has more or less arrived at his mature view of monads. I used to think monads were mad, but I now think he is closing in on the right answer - sort of.
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
As well as extension, bodies contain powers
     Full Idea: Over and above what can be deduced from extension, we must add and recognise in bodies certain notions or forms that are immaterial, so to speak, or independent of extension, which you can call powers [potentia], by which speed is adjusted to magnitude.
     From: Gottfried Leibniz (De Natura Corporis [1678], A6.4.1980), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3
     A reaction: He boldly asserts that the powers are 'immaterial', but is then forced to qualify it (as he often does) with 'so to speak'. The notion that bodies just have extension (occupy space) comes from Descartes, and is firmly opposed by Leibniz.
A substance contains the laws of its operations, and its actions come from its own depth
     Full Idea: Each indivisible substance contains in its nature the law by which the series of its operations continues, and all that has happened and will happen to it. All its actions come from its own depths, except for dependence on God.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1688.01.4/14)
     A reaction: I take the combination of 'laws' and 'forces', which Leibniz attributes to Aristotelian essences, to be his distinctive contribution towards giving us an Aristotelian metaphysic which is suitable for modern science.
The soul is not a substance but a substantial form, the first active faculty
     Full Idea: The soul, properly and accurately speaking, is not a substance, but a substantial form, or the primitive form existing in substances, the first act, the first active faculty.
     From: Gottfried Leibniz (Letters to Fardella [1690], A6.4.1670), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 2
     A reaction: In all of Leibniz's many gropings towards what is at the heart of a unified object, I pounce on the phrase "the first active faculty" as the one that suits me. I take that to be a 'power'. It has two characteristics - it is active, and it is basic.
The most primitive thing in substances is force, which leads to their actions and dispositions
     Full Idea: Since everything that one conceives in substances reduces to their actions and passions and to the dispositions that they have for this effect, I don't see how one can find there anything more primitive than the principle of all of this, which is force.
     From: Gottfried Leibniz (Letters to Jacques Lenfant [1693], 1693.11.25), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: This is an attempt to connect Aristotelian essentialism with the notion of force in the new physics, and strikes me as an improvement on the original, and as good a basis for metaphysics as any I have heard of.
All occurrence in the depth of a substance is spontaneous 'action'
     Full Idea: Anything which occurs in what is strictly a substance must be a case of 'action' in the metaphysically rigorous sense of something which occurs in the substance spontaneously, arising out of its own depths.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: I love this idea, which fits in with scientific essentialism. The question is whether Leibniz has idenified the end point of all explanations. Cutting edge physics is trying to give further explanations for what seemed basic, such as mass and gravity.
Substances are primary powers; their ways of being are the derivative powers
     Full Idea: Primary powers are what make up the substances themselves; derivative powers, or 'faculties' if you like, are merely 'ways of being' - and they must be derived from substances.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.03)
     A reaction: We might talk of 'deep' and 'surface' properties, or maybe 'powers' and 'qualities' is better. 'Primary' and 'derivative' only gives the logical relationship, but not the causal relationship.
Derivate forces are in phenomena, but primitive forces are in the internal strivings of substances
     Full Idea: I relegate derivative forces to the phenomena, but I think that it is clear that primitive forces can be nothing other than the internal strivings of simple substances.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1705.01), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 8
     A reaction: I like 'internal strivings', which sounds to me like the Will to Power (Idea 7140). There seems to be an epistemological challenge in trying to disentangle the derivative forces from the primitive ones.
8. Modes of Existence / C. Powers and Dispositions / 4. Powers as Essence
Essence is primitive force, or a law of change
     Full Idea: The essence of substances consists in the primitive force of action, or the law of the sequence of changes.
     From: Gottfried Leibniz (Letters to Foucher [1675], 1676)
     A reaction: [a 1676 note on Foucher's reply] It take these to be the two key distinctive Leibnizian contributions to the sort of metaphysic that is needed by modern science. Nature works with intrinsic essences, which are forces determining action.
The substantial form is the principle of action or the primitive force of acting
     Full Idea: The substantial form is the principle of action or the primitive force of acting.
     From: Gottfried Leibniz (De Mundo Praesenti [1686], A6.4.1507-8), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3
     A reaction: The clearest statement of the modification of Aristotle's hylomorphism which Leibniz preferred in his middle period, and which strikes me as an improvement, and about right. Shame that monads got too much of a grip on him, but he was trying to dig deeper.
Forms have sensation and appetite, the latter being the ability to act on other bodies
     Full Idea: Leibniz's form contains both sensation and appetite, and he seems to associate appetite with the ability a body has to act on another.
     From: report of Gottfried Leibniz (works [1690]) by Daniel Garber - Leibniz:Body,Substance,Monad 3
     A reaction: It strikes me (you may be surprised to hear) that this concept is not unlike Nietzsche's all-mastering 'will to power'. I offer Idea 7140 in evidence.
The essence of a thing is its real possibilities
     Full Idea: In Leibniz's view, the essence of a thing is fundamentally the real possibilities of that thing.
     From: report of Gottfried Leibniz (works [1690]) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 4.3.3
     A reaction: Note that the essences are individual. On the whole I would prefer Leibniz in his own words, but this is too good to lose (..but see Idea 12981). It is the aspect of Leibniz that fits perfectly with modern scientific essentialism.
I call Aristotle's entelechies 'primitive forces', which originate activity
     Full Idea: Forms establish the true general principles of nature. Aristotle calls them 'first entelechies'; I call them, perhaps more intelligibly, 'primitive forces', which contain not only act or the completion of possibility, but also an original activity.
     From: Gottfried Leibniz (New system of communication of substances [1695], p.139)
     A reaction: As in Idea 13168, I take Leibniz to be unifying Aristotle with modern science, and offering an active view of nature in tune with modern scientific essentialism. Laws arise from primitive force, and are not imposed from without.
My formal unifying atoms are substantial forms, which are forces like appetites
     Full Idea: To find real entities I had recourse to a unified formal atom. Hence I rehabilitated the substantial forms in a way to render them intelligible. I found that their nature consists in force, from which follows something analogous to sensation and appetite.
     From: Gottfried Leibniz (New system of communication of substances [1695], p.139)
     A reaction: [several lines are here compressed] This passage sums up the key to Leibniz's essentialism, which I take to be a connection between Aristotelian form and the physicists' notion of force. This gives us a modern version of Aristotelianism for science.
Material or immaterial substances cannot be conceived without their essential activity
     Full Idea: I maintain that substances, whether material or immaterial, cannot be conceived in their bare essence without any activity, activity being of the essence of substance in general.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref)
     A reaction: Thus there could be no 'tabula rasa', because that would be an inactive mental substance. This strikes me as a nice question for modern physicists. Do they regard movement as essential, or an addition to bare particles? I'm with Leibniz. Essentialism.
Thought terminates in force, rather than extension
     Full Idea: I believe that our thought is completed and terminated more in the notion of the dynamic [i.e. force] than in that of extension.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], G II 170), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: Presenting this as the place where 'our thought' is 'terminated' seems to place it as mainly having a role in explanation, rather than in speculative metaphysics.
There is active and passive power in the substantial chain and in the essence of a composite
     Full Idea: I do not say there is a chain midway between matter and form, but that the substantial form and primary matter of the composite, in the Scholastic sense (the primitive power, active and passive) are in the chain, and in the essence of the composite.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: Note that this implies an essence of primitive power, and not just a collection of all properties. This is the clearest account in these letters of the nature of the 'substantial chain' he has added to his monads.
Primitive force is what gives a composite its reality
     Full Idea: The first entelechy of a composite is a constitutive part of the composite substance, namely its primitive force.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: For me, Leibniz's most interesting proposal is to characterise Aristotelian 'form' as an active thing, which offers an intrinsic account of movement, and a bottom level for explanations. There always remains the inexplicable. Why anything? Why this?
8. Modes of Existence / C. Powers and Dispositions / 5. Powers and Properties
The active powers which are not essential to the substance are the 'real qualities'
     Full Idea: Powers which are not essential to substance, and which include not merely an aptitude but also a certain endeavour, are exactly what are or should be meant by 'real qualities'.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.23)
     A reaction: An important part of Leibniz's account. There are thus essential powers, in the 'depth' of the substance, and more peripheral powers, which also initiate action, and give rise to the qualities. The second must derive from the first?
8. Modes of Existence / C. Powers and Dispositions / 6. Dispositions / b. Dispositions and powers
There cannot be power without action; the power is a disposition to act
     Full Idea: Where will one ever find in the world a faculty consisting in sheer power without performing an act? There is always a particular disposition to action, and towards one action rather than another.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: This is muddled. Leibniz defends powers in the possibilities of things, but he must then accept that some possibilities may never be realised, as with two complex chemicals which never ever come into contact with one another.
8. Modes of Existence / E. Nominalism / 4. Concept Nominalism
Abstracta are abbreviated ways of talking; there are just substances, and truths about them
     Full Idea: I consider abstracta not as real things but as abbreviated ways of talking ...and to that extent I am a nominalist, at least provisionally ...It suffices to posit only substances as real things, and, to assert truths about these.
     From: Gottfried Leibniz (On the Reality of Accidents [1688]), quoted by Richard T.W. Arthur - Leibniz
     A reaction: I am a modern nominalist, in my hostility to a serious ontological commitment to abstracta. You get into trouble, though, if you say there are only objects or substances. Physics says reality may all be 'fields', or something.... 'Truths' is good.
9. Objects / A. Existence of Objects / 2. Abstract Objects / a. Nature of abstracta
Real (non-logical) abstract terms are either essences or accidents
     Full Idea: Real (as opposed to logical) abstract terms, or at least those which are conceived as real, are either essences or parts of essences, or else accidents (i.e. beings added to a substance).
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.08)
     A reaction: Interesting to refer to accidents as 'beings'. This seems to fit abstraction by ignoring, since you can either ignore the accidents to get the essence, or ignore the essence to get the accidents.
9. Objects / A. Existence of Objects / 2. Abstract Objects / c. Modern abstracta
Wholly uniform things like space and numbers are mere abstractions
     Full Idea: Things which are uniform, containing no variety, are always mere abstractions: for instance, time, space, and the other entities of pure mathematics.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: I presume that being 'mere abstractions' denies them ontological status, and makes them creations of thought. If so, I like this idea a lot.
9. Objects / A. Existence of Objects / 5. Simples
The analysis of things leads to atoms of substance, which found both composition and action
     Full Idea: There are only atoms of substance, that is, real unities absolutely destitute of parts, which are the source of actions, the first absolute principles of the composition of things, and, as it were, the final elements in the analysis of substantial things.
     From: Gottfried Leibniz (New system of communication of substances [1695], p.142)
     A reaction: I like this because it addresses the pure issue of the identity of an individuated object, but also links it with an active view of nature, and not some mere inventory of objects.
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
Leibniz moved from individuation by whole entity to individuation by substantial form
     Full Idea: By 1680 Leibniz had clearly abandoned the 'whole entity' conception of individuation, for a conception grounded in substantial form alone.
     From: report of Gottfried Leibniz (works [1690]) by Daniel Garber - Leibniz:Body,Substance,Monad 2
     A reaction: In other words, Leibniz became more of an Aristotelian, and more of an essentialist.
The only way we can determine individuals is by keeping hold of them
     Full Idea: It is impossible for us to know individuals or to find any way of precisely determining the individuality of any thing except by keeping hold of the thing itself.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.03)
     A reaction: 'The tallest woman in London' seems to determine someone perfectly well, though only by cross-referencing universal concepts like 'tall'.
Things seem to be unified if we see duration, position, interaction and connection
     Full Idea: Important relations are duration (order of successive things) and position (order of coexisting things) and interaction. Position without a thing mediating is presence. Beyond these is connection when things move one another. Thus things seem to be one.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.02.05)
     A reaction: [compressed] This is the best account I can find of his epistemological angle on the unity of things. They are symptoms of the inner power of unification, and he says that God sees these relations most clearly.
9. Objects / A. Existence of Objects / 5. Individuation / b. Individuation by properties
If two individuals could be indistinguishable, there could be no principle of individuation
     Full Idea: If two individuals were perfectly similar and equal and, in short, indistinguishable in themselves, there would be no principle of individuation.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27)
     A reaction: This seems to be the main motive for Leibniz's unusual claim that there cannot be two indiscernible individuals, but it looks suspiciously like an a priori claim made about what should be an a posteriori discovery. Are electrons distinguishable?
The law of the series, which determines future states of a substance, is what individuates it
     Full Idea: That there should be a persistent law of the series, which involves the future states of that which we conceive to be the same, is exactly what I say constitutes it as the same substance.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704), quoted by Richard T.W. Arthur - Leibniz 4 'Applying'
     A reaction: The 'law of the series' is a bit dubious, but it is reasonable to say that a substance is individuated by its coherent progress of change over time. Disjointed change would imply an absence of substance. The law of the series is called 'primitive force'.
9. Objects / A. Existence of Objects / 5. Individuation / c. Individuation by location
A body is that which exists in space
     Full Idea: A body is defined as that which exists in space.
     From: Gottfried Leibniz (Confessio naturae contra atheistas [1669], A6.1.490), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1
     A reaction: A very early view. Leibniz notes that this tells you nothing about shape and motion.
We use things to distinguish places and times, not vice versa
     Full Idea: It is by means of things that we must distinguish one time and place from another, rather than vice versa.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27)
     A reaction: This rests on Leibniz's relative view of space (as opposed to Newton's absolute view). If you need to re-identify a thing to individuate it, re-identifying the exact place or time seems impossible, but it is usually manageable with thing.
9. Objects / A. Existence of Objects / 5. Individuation / d. Individuation by haecceity
The laws-of-the-series plays a haecceitist role
     Full Idea: Leibniz takes the laws-of-the-series to play a haecceitistic role.
     From: report of Gottfried Leibniz (works [1690]) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 7.5
     A reaction: Idea 13092 for law-in-the-series. He thinks that a law-in-a-series is unique to a substance, and so can individuate it. That is a pretty good proposal, if anything is going to do the job. Perhaps I do believe in haecceities, as unique bundles of powers?
No two things are quite the same, so there must be an internal principle of distinction
     Full Idea: In addition to the difference of time or of place there must always be an internal principle of distinction: although there can be many things of the same kind, it is still the case that none of them are ever exactly alike.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27)
     A reaction: This rests on Leibniz's unusual view that all things (even electrons) are qualitatively distinct. Personally I disagree with that, but agree with the idea. Things have time and place because they have identity, not the other way around.
9. Objects / A. Existence of Objects / 6. Nihilism about Objects
Fluidity is basic, and we divide into bodies according to our needs
     Full Idea: Fluidity is the fundamental condition, and the division into bodies is carried out - there being no obstacle to it - according to our need.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.13)
     A reaction: Leibniz is referring to what he usually calls 'aggregates', like piles of bricks, which are things lacking a unifying substance. There may be no true substances, in which fluidity is the order of the day.
9. Objects / B. Unity of Objects / 1. Unifying an Object / a. Intrinsic unification
Philosophy needs the precision of the unity given by substances
     Full Idea: Philosophy cannot be better reduced to something precise, than by recognising only substances or complete beings endowed with a true unity, with different states that succeed one another; all else is phenomena, abstractions or relations.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.04.30), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: This idea bothers me. Has the whole of modern philosophy been distorted by this yearning for 'precision'? It has put mathematicians and logicians in the driving seat. Do we only attribute unity because it suits our thinking?
Identity of a substance is the law of its persistence
     Full Idea: For there to be a certain persisting law which involves the future states of that which we conceive as one and the same continuant, this is what I say constitute's a substance's identity.
     From: Gottfried Leibniz (works [1690], G II:264), quoted by David Wiggins - Sameness and Substance 3.1
     A reaction: This is a key remark for those who thing 'persistence conditions' are basic to metaphysics. I'm not so sure.
9. Objects / B. Unity of Objects / 1. Unifying an Object / b. Unifying aggregates
A body would be endless disunited parts, if it did not have a unifying form or soul
     Full Idea: Without soul or form of some kind, a body would have no being, because no part of it can be designated which does not in turn consist of more parts. Thus nothing could be designated in a body which could be called 'this thing', or a unity.
     From: Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.1988), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1
     A reaction: The locution 'soul or form' is disconcerting, and you have to spend some time with Leibniz to get the hang of it. The 'soul' is not intelligent, and is more like a source of action and response.
Accidental unity has degrees, from a mob to a society to a machine or organism
     Full Idea: There are degrees of accidental unity, and an ordered society has more unity than a chaotic mob, and an organic body or a machine has more unity than a society.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.04.30)
     A reaction: This immediately invites questions about the extremes. Why does the very highest degree of 'accidental unity' not achieve 'true unity'? And why cannot a very ununified aggregate have a bit of unity (as in unrestricted mereological composition)?
9. Objects / B. Unity of Objects / 1. Unifying an Object / c. Unity as conceptual
We find unity in reason, and unity in perception, but these are not true unity
     Full Idea: A pair of diamonds is merely an entity of reason, and even if one of them is brought close to another, it is an entity of imagination or perception, that is to say a phenomenon; contiguity, common movement and the same end don't make substantial unity.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.04.30), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: This invites the question of what you have to do to two objects to give them substantial unity. The distinction between unity 'of reason' and unity 'of perception' is good.
Leibniz bases pure primitive entities on conjunctions of qualitative properties
     Full Idea: Leibniz is committed with apparent consistency to both a purely qualitative character of all thisnesses, and to primitiveness of individual identity. He regards thisnesses as conjunctions of simpler, logically independent suchnesses.
     From: report of Gottfried Leibniz (works [1690]) by Robert Merrihew Adams - Primitive Thisness and Primitive Identity 5
     A reaction: Hence Leibniz is held to say that all of the qualitative properties are 'essential' to the object, since all of them are needed to constitute its identity. Hence absolutely nothing about an object, even an electron, could be different, which is daft.
To exist and be understood, a multitude must first be reduced to a unity
     Full Idea: A plurality of things can neither be understood nor can exist unless one first understands the thing that is one, that to which the multitude necessarily reduces.
     From: Gottfried Leibniz (Notes on Comments by Fardella [1690], Prop 3)
     A reaction: Notice that it is our need to understand which imposes the unity on the multitude. It is not just some random fiction, or a meaningless mechanical act of thought.
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
The complete notion of a substance implies all of its predicates or attributes
     Full Idea: The nature of an individual substance or of a complete being is to have a notion so complete that it is sufficient to contain and to allow us to deduce from it all the predicates of the subject to which this notion is attributed.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §8)
     A reaction: This is the unusual Leibnizian view of such things, which he takes to extremes. I think it depends on whether you are talking of predicates, or of real intrinsic properties. I don't see how what happens to a substance can be contained in the subject.
A body is a unified aggregate, unless it has an indivisible substance
     Full Idea: One will never find a body of which it may be said that it is truly one substance, ...because entities made up by aggregation have only as much reality as exists in the constituent parts. Hence the substance of a body must be indivisible.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.11)
     A reaction: Leibniz rejected atomism, and he evidently believed that pure materialists must deny the real existence of physical objects. Common sense suggests that causal bonds bestow a high degree of unity on bodies (if degrees are allowed).
Unity needs an indestructible substance, to contain everything which will happen to it
     Full Idea: Substantial unity requires a complete, indivisible and naturally indestructible entity, since its concept embraces everything that is to happen to it, which cannot be found in shape or motion.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.11.28/12.8)
     A reaction: Hence if a tile is due to be broken in half (Arnauld's example), it cannot have had unity in the first place. To what do we refer when we say 'the tile was broken'?
Every bodily substance must have a soul, or something analogous to a soul
     Full Idea: Every bodily substance must have a soul, or at least an entelechy which is analogous to the soul.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.10.09)
     A reaction: He routinely commits to a 'soul', and then pulls back and says it may only be an 'analogy'. He had deep doubts about his whole scheme, which emerged in the late correspondence with Des Bosses. This not monads, says Garber.
The concept of forces or powers best reveals the true concept of substance
     Full Idea: The concept of forces or powers ..for whose explanation I have set up a distinct science of dynamics, brings the strongest light to bear upon our understanding of the true concept of substance.
     From: Gottfried Leibniz (De primae philosophiae emendatione [1694], G IV 469), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: My own experience was that as soon as I encountered the notion of a 'power' in the metaphysics of science (see Molnar on this) the whole thing began to form a coherent picture. Powers rule.
The notion of substance is one of the keys to true philosophy
     Full Idea: I consider the notion of substance to be one of the keys to the true philosophy. ....I imagine that philosophers will one day know the notion of substance a bit better than they do now.
     From: Gottfried Leibniz (Letters to Thomas Burnett [1703], 1699.01.20/30)
     A reaction: This is a controversial remark at this historical moment, when the apparent Aristotelian commitment to substances was becoming discredited. Personally I would eliminate substance, but not just because physicists don't refer to it.
Individuality is in the bond substance gives between past and future
     Full Idea: Within each substance there is a perfect bond between the future and the past, which is what creates the identity of the individual.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: I'm not quite sure if this means anything, but the idea that a bond across time is a necessity for intrinsic identity is interesting. The 'bond' would, I take it, have to be a causal one.
Every substance is alive
     Full Idea: Every substance is alive.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.02.05)
     A reaction: The most charitable interpretation of this is that substances are what have unity, and the best model of unity that we can grasp is the unity of an organism. The less charitable view is that he literally thinks a pebble is 'alive'. Hm.
9. Objects / B. Unity of Objects / 2. Substance / b. Need for substance
Aggregates don’t reduce to points, or atoms, or illusion, so must reduce to substance
     Full Idea: In aggregates one must necessarily arrive either at mathematical points from which some make up extension, or at atoms (which I dismiss), or else no reality can be found in bodies, or finally one must recognises substances that possess a true unity.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.04.30), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 2
     A reaction: Garber calls this Leibniz's Aggregate Argument. Leibniz is, of course, talking of physical aggregates which have unity. He consistently points out that a pile of logs has no unity at all. But is substance just that-which-provides-unity?
9. Objects / B. Unity of Objects / 2. Substance / c. Types of substance
Substances mirror God or the universe, each from its own viewpoint
     Full Idea: Each substance is like a whole world, and like a mirror of God, or indeed of the whole universe, which each one expresses in its own fashion.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686]), quoted by Nicholas Jolley - Leibniz Intro
     A reaction: Leibniz isn't a pantheist, so he does not identify God with the universe, so it is a bit revealing that substance could reflect either one or the other, and he doesn't seem to care which. In the end, for all the sophistication, he just made it up.
Substances are everywhere in matter, like points in a line
     Full Idea: There are substances everywhere in matter, just as points are everywhere in a line.
     From: Gottfried Leibniz (Notes on Comments by Fardella [1690], Clarif)
     A reaction: Since Leibniz is unlikely to believe in the reality of the points, we must wonder whether he was really committed to this infinity of substances. The more traditional notion of substance is always called 'substantial form' by Leibniz.
Substance must necessarily involve progress and change
     Full Idea: The nature of substance necessarily requires and essentially involves progress or change, without which it would not have the force to act.
     From: Gottfried Leibniz (New system of communication of substances [1695], p.144)
     A reaction: Bravo. Most metaphysical musings regarding 'substance' seem entirely wrapped up in the problem of pure identity, and forget about the role of objects in activity and change.
9. Objects / B. Unity of Objects / 2. Substance / d. Substance defined
Substance is that which can act
     Full Idea: I define substance as that which can act.
     From: Gottfried Leibniz (Definitiones cogitationesque metaphysicae [1678], A6.4.1398), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3
     A reaction: This is in tune with the notion that to exist is to have causal powers. I find the view congenial, and the middle period of Leibniz's thought, before monads became too spiritual, chimes in with my view.
Substances are essentially active
     Full Idea: For Leibniz, it is the very essence of substances to be sources of activity.
     From: report of Gottfried Leibniz (works [1690]) by Nicholas Jolley - Leibniz Ch.2
     A reaction: This makes the views of Leibniz sympathetic to modern essentialism (of which I am a fan), because it places active power at the centre of what it is to exist, rather than action being imposed on matter which is otherwise passive.
Leibnizian substances add concept, law, force, form and soul
     Full Idea: To the traditional idea of substance (independent, subjects of predication, active, persistent) Leibniz adds, distinctively, complete individual concept, law-of-the-series, active force, form and soul or entelechy.
     From: report of Gottfried Leibniz (works [1690]) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 6.1.1
     A reaction: 'Form' seems to be Aristotelian, and 'soul' seems ridiculous. I don't think the 'complete concept' is much help. However, the 'law-in-the-series' is very interesting (Idea 13079), if employed sensibly, and 'active force' is spot-on. Powers define reality.
Substance is a force for acting and being acted upon
     Full Idea: The very substance in things consists of a force for acting and being acted upon.
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], §08)
     A reaction: Garber places this text just before the spiritual notion of monads took a grip on Leibniz. He seems to have thought that only some non-physical entity, with appetite and perception, could generate force. Wrong.
Substances cannot be bare, but have activity as their essence
     Full Idea: I maintain that substances (material or immaterial) cannot be conceived in their bare essence devoid of activity; that activity is of the essence of substance in general
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref 65)
     A reaction: Leibniz liked the idea that God was the source of this activity, but this remark makes Leibniz a direct ancestor of modern scientific essentialism.
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
If a substance is just a thing that has properties, it seems to be a characterless non-entity
     Full Idea: For Leibniz, to distinguish between a substance and its properties in order to provide a thing or entity in which properties can inhere leads necessarily to the absurd conclusion that the substance itself must be a truly characterless non-entity.
     From: report of Gottfried Leibniz (Monadology [1716]) by Cynthia Macdonald - Varieties of Things Ch.3
     A reaction: This is obviously one of the basic thoughts in any discussion of substances. It is why physicists ignore them, and Leibniz opted for a 'bundle' theory. But the alternative seems daft too - free-floating properties, hooked onto one another.
9. Objects / B. Unity of Objects / 3. Unity Problems / d. Coincident objects
We can imagine two bodies interpenetrating, as two rays of light seem to
     Full Idea: We find that two shadows or two rays of light interpenetrate, and we could devise an imaginary world where bodies did the same.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27)
     A reaction: I suspect this is a case of being able to imagine something when you don't fully understand it (like a bonfire on the Moon), but when you fully understand the modern physics of it, you see the necessity of separation between objects.
9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects
The essence of baldness is vague and imperfect
     Full Idea: There are vague and imperfect essences, as in the question of how few hairs a man can have without being bald.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.05)
     A reaction: This example is much discussed in contemporary debate, but I now learn that it has a venerable history. The surprise here is the word 'essences', because I had taken Leibnizian essences to be 'perfect ideas', and hence precise.
9. Objects / C. Structure of Objects / 2. Hylomorphism / b. Form as principle
Forms are of no value in physics, but are indispensable in metaphysics
     Full Idea: The consideration of forms serves no purpose in the details of physics and must not be used to explain particular phenomena. …but their misuse must not lead us to reject something which is so useful to metaphysics.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], 10), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 24.5
     A reaction: This is a key test for the question of whether metaphysics is separate from science (as Leibniz and Pasnau think), or whether there is a continuum. Is 'substantial form' an illuminating way to undestand modern physics?
9. Objects / C. Structure of Objects / 2. Hylomorphism / c. Form as causal
Leibniz strengthened hylomorphism by connecting it to force in physics
     Full Idea: A standard criticism of the scholastic notions of matter and form is that they are obscure and unintelligible. But in Leibniz's system they are connected directly with notions of active and passive force that play an intelligible roles in his physics.
     From: report of Gottfried Leibniz (works [1690]) by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: This seems to me to be very appealing. Aristotle was clearly on the right lines, but just ran out of things to say, once he had pointed in the right direction. Maybe 'fields' and 'strings' can fill out the Aristotelian conception of form.
9. Objects / C. Structure of Objects / 2. Hylomorphism / d. Form as unifier
Form or soul gives unity and duration; matter gives multiplicity and change
     Full Idea: Substantial form, or soul, is the principle of unity and duration, matter is that of multiplicity and change
     From: Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.1398-9), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 2
     A reaction: Leibniz was a fan of the unfashionable Aristotle, and tried to put a spin on his views consonant with contemporary Hobbesian mechanistic views. Oddly, he likes the idea that 'form' is indestructable, which I don't understand.
9. Objects / C. Structure of Objects / 7. Substratum
A 'substratum' is just a metaphor for whatever supports several predicates
     Full Idea: From the beginning we conceive several predicates in a single subject, and that is all there is to these metaphorical words 'support' and 'substratum'. So I do not see why it is made out to involve a problem.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.23)
     A reaction: The question is whether the substratum is 'bare' if you remove all the predicates, and clearly Leibniz believes you are left with true essential substance (although the removal process is presumably only possible in thought, thanks to God).
9. Objects / C. Structure of Objects / 8. Parts of Objects / a. Parts of objects
Indivisibles are not parts, but the extrema of parts
     Full Idea: Indivisibles are not parts, but the extrema of parts.
     From: Gottfried Leibniz (Pacidius Philalethi dialogue [1676], A6.3.565-6), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1
     A reaction: This is incipient monadology, that the bottom level of division ceases to be parts of a thing, and arrives at a different order of entity, to explain the parts of things. Leibniz denies that this subdivision comes down to points.
9. Objects / D. Essence of Objects / 1. Essences of Objects
The essence of a circle is the equality of its radii
     Full Idea: The essence of a circle consists in the equality of all lines drawn from its centre to its circumference.
     From: Gottfried Leibniz (Letters to Thomasius [1669], 1669)
     A reaction: Compare Locke in Idea 13431 and Spinoza in Idea 13073 on the essence of geometrical figures. A key question is whether the essence is in the simplest definition, or in a complex and wide-ranging account, e.g. including conic sections for circles.
Subjects include predicates, so full understanding of subjects reveals all the predicates
     Full Idea: The subject-term must always include the predicate-term, in such a way that the man who understood the notion of the subject perfectly would also judge that the predicate belongs to it.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §8)
     A reaction: Sounds as if every sentence is analytic, but he doesn't mean that. He does, oddly, mean that if we fully understand the name 'Alexander', we understand his complete history, which is a bit silly, I'm afraid. Even God doesn't learn things just from names.
Basic predicates give the complete concept, which then predicts all of the actions
     Full Idea: Apart from those that depend on others, one must only consider together all the basic predicates in order to form the complete concept of Adam adequate to deduce from it everything that is ever to happen to him, as much as is necessary to account for it.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.06)
     A reaction: This (implausibly) goes beyond mere prediction of properties. Eve's essence seems to be relevant to Adam's life. Note that the complete concept is not every predicate, but only those 'necessary' to predict the events. Cf Idea 13082.
Essences exist in the divine understanding
     Full Idea: Essences exist in the divine understanding before one considers will.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 X)
     A reaction: This is a sort of religious neo-platonism. The great dream seems to be that of mind-reading God, and the result is either Pythagoras (it's numbers!), or Plato (it's pure ideas!), or this (it's essences!). See D.H.Lawrence's poem on geranium and mignottes.
A true being must (unlike a chain) have united parts, with a substantial form as its subject
     Full Idea: In a Being one per se a real union is required consisting not in the situation or motion of parts, as in a chain or a house, but in a unique individual principle and subject of attributes and operations, in us a soul and in a body a substantial form.
     From: Gottfried Leibniz (De Mundo Praesenti [1686], A6.4.1506), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: Leibniz is said not to be an essentialist, by making all properties essential, but he is certainly committed to substance, and it sounds like essence here (or one view of essence), when it makes identity possible. This idea is pure Aristotle.
9. Objects / D. Essence of Objects / 3. Individual Essences
Particular truths are just instances of general truths
     Full Idea: The reasons for particular truths rest wholly on the more general ones of which they are mere instances.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01)
     A reaction: Clearly particulars have their own distinctive truth, but the Leibniz case seems to be that a particular is a unique intersection for an array of general truths - and nothing else. Audrey Hepburn's smile has no generalities to it.
We can't know individuals, or determine their exact individuality
     Full Idea: It is impossible for us to have knowledge of individuals and to find the means of determining exactly the individuality of everything.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.3)
     A reaction: Aristotle was clearly also tempted by this doubt (since universals are involved), though individuals are what he wanted to understand. I think they are wrong. Leibniz gives the bizarre reason that we can't know individuals as they each contain infinity.
9. Objects / D. Essence of Objects / 4. Essence as Definition
Essence is just the possibility of a thing
     Full Idea: Essence is fundamentally nothing but the possibility of the thing under consideration. Something which is thought possible is expressed by a definition.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.03)
     A reaction: It is unclear whether he means 'possible modes of existence' or 'possible actions of the thing'. Leibniz sees more clearly than Aristotle that essences extend beyond the actual thing, because Leibniz is more aware of the active powers.
9. Objects / D. Essence of Objects / 6. Essence as Unifier
Bodies need a soul (or something like it) to avoid being mere phenomena
     Full Idea: Every substance is indivisible and consequently every corporeal substance must have a soul or at least an entelechy which is analogous to the soul, since otherwise bodies would be no more than phenomena.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], G II 121), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 2
     A reaction: There is a large gap between having 'a soul' and having something 'analogous to a soul'. I take the analogy to be merely as originators of action. Leibniz wants to add appetite and sensation to the Aristotelian forms (but knows this is dubious!).
A substantial bond of powers is needed to unite composites, in addition to monads
     Full Idea: Some realising thing must bring it about that composite substance contains something substantial besides monads, otherwise composites will be mere phenomena. The scholastics' active and passive powers are the substantial bond I am urging.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.01.13), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 9
     A reaction: [compressed] This appears to be a major retreat, in the last year of Leibniz's life, from the full monadology he had espoused. How do monads connect to matter, and thus unify it? He is returning to Aristotelian hylomorphism.
9. Objects / D. Essence of Objects / 7. Essence and Necessity / a. Essence as necessary properties
The essence is the necessary properties, and the concept includes what is contingent
     Full Idea: Of the essence of a particular thing is what pertains to it necessarily and perpetually; of the concept of an individual thing on the other hand is what pertains to it contingently or per accidens.
     From: Gottfried Leibniz (Human Freedom and Divine choice [1690], Grua 383), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 3.3.1
     A reaction: This arbitrates on the apparent conflict between his remarks in Idea 13077 and Idea 10382. There seems to be a distinction between the 'concept' of a thing, and the 'complete concept', the latter including the contingent properties.
9. Objects / D. Essence of Objects / 7. Essence and Necessity / b. Essence not necessities
The complete concept of an individual includes contingent properties, as well as necessary ones
     Full Idea: In this complete concept of possible Peter are contained not only essential or necessary things, ..but also existential things, or contingent items included there, because the nature of an individual substance is to have a perfect or complete concept.
     From: Gottfried Leibniz (Of liberty, Fate and God's grace [1690], Grua 311), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 3.3.1
     A reaction: Compare Idea 13077, where he seems to say that the complete concept is only necessarily linked to properties which will predict future events - though I suppose that would have to include all of the contingent properties mentioned here.
A necessary feature (such as air for humans) is not therefore part of the essence
     Full Idea: That which is necessary for something does not constitute its essence. Air is necessary for our life, but our life is something other than air.
     From: Gottfried Leibniz (Letters to Queen Charlotte [1702], 1702)
     A reaction: Bravo. Why can't modern philosophers hang on to this distinction? They seem to think that because they don't believe in traditional essences they can purloin the word for something else. Same with the word 'abstraction'.
9. Objects / D. Essence of Objects / 8. Essence as Explanatory
If you fully understand a subject and its qualities, you see how the second derive from the first
     Full Idea: Every time we find some quality in a subject, we ought to think that, if we understood the nature of this subject and of this quality, we should conceive how this quality could result from it.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref)
     A reaction: Thus (in Kripke's analogy) God cannot make 'subjects' on Thursday and then add 'qualities' on Friday. Add the point that all subjects are physical, and I say you have the whole story. The physical entails the mental. The laws result from the qualities.
9. Objects / D. Essence of Objects / 9. Essence and Properties
Leibniz's view (that all properties are essential) is extreme essentialism, not its denial
     Full Idea: The view standardly attributed to Leibniz, that makes all an individual's properties essential to it should be regarded as an extreme version of essentialism, not a denial of essentialism.
     From: report of Gottfried Leibniz (works [1690]) by Penelope Mackie - How Things Might Have Been 1.1
     A reaction: Wiggins disagrees, saying that Leibniz was not an essentialist, which is an interesting topic of research for those who are interested. I would take Leibniz to be not an essentialist, on that basis, as essentialism makes a distinction. See Quine on that.
The properties of a thing flow from its essence
     Full Idea: It is the same to look for perfection in an essence and in the properties that flow from an essence.
     From: Gottfried Leibniz (Letters to Wolff [1715], 1715.05.18)
     A reaction: It is helpful to have Leibniz spelling out his commitment to the traditional view of essence, as that from which the more evident properties flow.
9. Objects / D. Essence of Objects / 10. Essence as Species
Truths about species are eternal or necessary, but individual truths concern what exists
     Full Idea: The concept of a species contains only eternal or necessary truths, whereas the concept of an individual contains, regarded as possible, what in fact exists or what is related to the existence of things and to time.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.06)
     A reaction: This seems to be what is behind the preference some have for kind-essences rather than individual essences. But the individual must be explained, as well as the kind. Not all tigers are identical. The two are, of course, compatible.
For some sorts, a member of it is necessarily a member
     Full Idea: There are sorts or species such that if an individual has ever been of such a sort or species it cannot (naturally, at least) stop being of it.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.06)
     A reaction: Note the thoughtful 'naturally, at least', which blocks genetic engineering. But natural selection is genetic engineering. Crucially, Leibniz is not attributing this to all sorts or species, and allows exceptions.
9. Objects / D. Essence of Objects / 12. Essential Parts
The same whole ceases to exist if a part is lost
     Full Idea: We cannot say - with complete fidelity to the truth of things - that the same whole continues to exist if a part of it is lost.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27.11)
     A reaction: This is the reference Simons 1987:319 gives when he claims that Leibniz accepts mereological essentialism. I think this is mereological necessity of identity, but not what I call 'essentialism'. That has to distinguish essential from non-essential.
A composite substance is a mere aggregate if its essence is just its parts
     Full Idea: An aggregate, but not a composite substance, is resolved into parts. A composite substance only needs the coming together of parts, but is not essentially constituted by them, otherwise it would be an aggregate.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: The point is that there is more to some things than there mere parts. Only some unifying principle, in addition to the mere parts, bestows a unity. Mereology is a limited activity if it has nothing to say about this issue.
9. Objects / D. Essence of Objects / 13. Nominal Essence
We have a distinct idea of gold, to define it, but not a perfect idea, to understand it
     Full Idea: That gold is a metal which resists cupellation and is insoluble in aquafortis is a distinct idea, for it gives us the criteria or definition of 'gold'. But it is not a perfect idea, because we know too little about cupellation and actions of aquafortis.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.31)
     A reaction: This connects the 'perfect idea' of something with knowing its active substance, and hence its essence. See Idea 12976 for the connection between perfect ideas and definitions.
If two people apply a single term to different resemblances, they refer to two different things
     Full Idea: If one person applies the name 'avarice' to one resemblance, and some one else to another, there will be two different species designated by the same name.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 6.6.292), quoted by Nicholas Jolley - Leibniz and Locke on Essences p.199
     A reaction: Part of Leibniz's sustained attack on Locke's nominal essences. There is clearly an uninteresting nominal essence, where a 'big brown bear' is necessarily brown, but in the interesting respects I think Leibniz is right.
Locke needs many instances to show a natural kind, but why not a single instance?
     Full Idea: Leibniz points out that it is a concealed premise of Locke's argument that if a natural kind exists it must have many instances, but there seems no a priori objection to the idea of a species with just one member.
     From: report of Gottfried Leibniz (New Essays on Human Understanding [1704], 6.6.311) by Nicholas Jolley - Leibniz and Locke on Essences p.200
     A reaction: I can't see this bothering Locke. Generally we formulate nominal essences by induction from bundles of ideas, but we can formulate a cautious first stab at it from one instance. If you see a new creature, is it a normal one, or a 'monster'?
9. Objects / D. Essence of Objects / 14. Knowledge of Essences
Essence is the distinct thinkability of anything
     Full Idea: (Essence) is the distinct thinkability (cogitabilitas) of anything.
     From: Gottfried Leibniz (Notes on John Wilkins [1672], A6.2.487-8), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1
     A reaction: A very original remark from the young Leibniz. It is neutral as to whether this is a real feature of objects, or a feature of human mental capacities. Presumably accidental features are thinkable, so 'distinct' is the key word.
9. Objects / D. Essence of Objects / 15. Against Essentialism
Leibniz was not an essentialist
     Full Idea: Leibniz was not an essentialist.
     From: report of Gottfried Leibniz (works [1690]) by David Wiggins - Sameness and Substance Renewed 4.2 n4
     A reaction: Assuming this is right, it is rather helpful, because you can read mountains of Leibniz without ever being quite sure. Mackie says he IS an extreme essentialist, treating all properties as essential. Wiggins makes more sense there.
9. Objects / E. Objects over Time / 1. Objects over Time
Changeable accidents are modifications of unchanging essences
     Full Idea: Everything accidental or changeable ought to be a modification of something essential or perpetual.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704.06.30)
     A reaction: Clear evidence that Leibniz is very much a traditional Aristotelian essentialist, and not as modal logicians tend to characterise him, as a super-essentialist who thinks all properties are essential. They are necessary for identity, but that's different.
9. Objects / E. Objects over Time / 9. Ship of Theseus
Bodies, like Theseus's ship, are only the same in appearance, and never strictly the same
     Full Idea: We must acknowledge that organic bodies as well as others remain 'the same' only in appearance, and not strictly speaking. It is rather like the river whose water is continually changing, or like Theseus's ship which Athenians constantly repaired.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27)
     A reaction: This is Leibniz's standard view, that something only remains the same if it has a unifying substance, and so a collection of planks is just an aggregate, and doesn't have any identity to begin with.
9. Objects / F. Identity among Objects / 1. Concept of Identity
Inequality can be brought infinitely close to equality
     Full Idea: Equality may be considered as an infinitely small inequality, and we may make inequality approach equality as much as we wish.
     From: Gottfried Leibniz (A General Principle to Explain Laws of Nature [1687], p.67)
     A reaction: An interesting response to David Lewis's brusque dismissal of the problem of identity, as all-or-nothing...end of story.
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
Two eggs can't be identical, because the same truths can't apply to both of them
     Full Idea: It isn't possible to have two particulars that are similar in all respects - for example two eggs - for it is necessary that some things can be said about one of them that cannot be said about the other, else they could be substituted for one another.
     From: Gottfried Leibniz (works [1690]), quoted by David Wiggins - Sameness and Substance 2.2
     A reaction: [from a 'fragment' for which Wiggins gives a reference] This quotation doesn't rest the distinctness of the eggs on some intrinsic difference, but on the fact that we can say different things about the two eggs.
No two things are totally identical
     Full Idea: By virtue of insensible variations, two individual things can never be perfectly alike.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref)
     A reaction: This sounds a bit like the 'discernibility of non-identicals', except that he says that the differences may not be 'sensible'. He has to be talking of physical things, since I presume that, say, the symmetry of two circles is perfectly identical.
Things in different locations are different because they 'express' those locations
     Full Idea: Things that differ in place must express their place, that is, they must express the things surrounding, and thus they must be distinguished not only by place, that is, not by an extrinsic denomination alone, as is commonly thought.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20)
     A reaction: This is an unusual view, which has some attractions, as it enables the relations of a thing to individuate it, while maintaining that this is a real difference in character.
If two bodies only seem to differ in their position, those different environments will matter
     Full Idea: If two bodies differ only in their position, their individual relations to the environment must be taken into account, so that more is involved in their distinguishability than just position.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20)
     A reaction: This seems to allow that two bodies could be intrinsically type-identical (though differing in extrinsic features), which is contrary to his normal view. I suppose a different location in the gravitational field will make an intrinsic difference.
In nature there aren't even two identical straight lines, so no two bodies are alike
     Full Idea: In nature any straight line you may take is individually different from any other straight line you may find. Accordingly, it cannot come about that two bodies are perfectly equal and alike.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20)
     A reaction: Leibniz was very good at persuasive examples! It remains unclear, though, why he takes the Identity of Indiscernibles to be a necessary truth, when he seems to have only observed it from experience. This is counter to his other principles.
There must be some internal difference between any two beings in nature
     Full Idea: There are never two beings in nature that are perfectly alike, two beings in which it is not possible to discover an internal difference, that is, one founded on an intrinsic denomination.
     From: Gottfried Leibniz (Monadology [1716], §09)
     A reaction: From this it follows that if two things really are indiscernible, then we must say that they are one thing. He says monads all differ from one another. People certainly do. Leibniz must say this of electrons. How can he know this?
9. Objects / F. Identity among Objects / 9. Sameness
Things are the same if one can be substituted for the other without loss of truth
     Full Idea: Leibniz's definition is as follows: Things are the same as each other, of which one can be substituted for the other without loss of truth ('salva veritate').
     From: Gottfried Leibniz (works [1690]), quoted by Gottlob Frege - Grundlagen der Arithmetik (Foundations) §65
     A reaction: Frege doesn't give a reference. (Anyone know it?). This famous definition is impressive, but has problems when the items being substituted appear in contexts of belief. 'Oedipus believes Jocasta (his mother!) would make a good wife'.
10. Modality / A. Necessity / 2. Nature of Necessity
Every necessary proposition is demonstrable to someone who understands
     Full Idea: Every necessary proposition is demonstrable, at least by someone who understands it.
     From: Gottfried Leibniz (De arcanus motus [1676], 203), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 6
     A reaction: This kind of optimism leads to the crisis of the Hilbert Programme in the 1930s. Gödel seems to have conclusively proved that Leibniz was wrong. What would Leibniz have made of Gödel?
Necessary truths are those provable from identities by pure logic in finite steps
     Full Idea: Leibniz argued that the necessary truths are just those which can be proved from identities by pure logic in a finite number of steps. ...[232] this claim is vindicated by Gentzen's sequent calculus.
     From: report of Gottfried Leibniz (works [1690]) by Ian Hacking - What is Logic? §01
     A reaction: This seems an odd idea, as if there were no necessary truths other than those for which a proof could be constructed. Sounds like intuitionism.
10. Modality / A. Necessity / 7. Natural Necessity
The world is physically necessary, as its contrary would imply imperfection or moral absurdity
     Full Idea: Although the world is not metaphysically necessary, such that its contrary would imply a contradiction or logical absurdity, it is necessary physically, that is, determined in such a way that its contrary would imply imperfection or moral absurdity.
     From: Gottfried Leibniz (On the Ultimate Origination of Things [1697], p.139)
     A reaction: How does Leibniz know things like this? The distinction between 'metaphysical' necessity and 'natural' (what he calls 'physical') necessity is a key idea. But natural necessity is controversial. See 'Essentialism'.
10. Modality / B. Possibility / 1. Possibility
How can things be incompatible, if all positive terms seem to be compatible?
     Full Idea: It is yet unknown to me what is the reason of the incompossibility of things, or how it is that different essences can be opposed to each other, seeing that all purely positive terms seem to be compatible.
     From: Gottfried Leibniz (works [1690], G VII:194), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 3.4.4
     A reaction: Since 'heavy' seems straightforwardly opposed to 'light', we would have to ask what he means by 'positive'. The suspicion is that all things are compossible by definition, so it is not surprising that impossibilities are a bit puzzling.
There is a reason why not every possible thing exists
     Full Idea: There is a reason why not every possible thing exists.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: This is the kind of wonderful speculative metaphysical remark that we are not allowed to make any more. Needless to say, he doesn't tell us what the reason is. Overcrowding, perhaps.
10. Modality / B. Possibility / 5. Contingency
Necessary truths can be analysed into original truths; contingent truths are infinitely analysable
     Full Idea: Derivative truths are of two sorts: some are analysed into original truths, others admit of an infinite process of analysis. The former are necessary, the latter are contingent.
     From: Gottfried Leibniz (On Freedom [1689], p.108)
     A reaction: An intriguing proposal. Hume would presumably see contingent truths as being analysed until you reach 'impressions'. Analysis of necessary truths soon comes to the blinding light of what is obvious, but analysis of contingency never gets there.
A reason must be given why contingent beings should exist rather than not exist
     Full Idea: A reason must be given why contingent beings should exist rather than not exist.
     From: Gottfried Leibniz (works [1690])
     A reaction: Spinoza rejects all contingency, but this seems an interesting support for it, even though we may need a reason for something where God does not because it is self-evident.
10. Modality / C. Sources of Modality / 2. Necessity as Primitive
Some necessary truths are brute, and others derive from final causes
     Full Idea: There is a difference between truths whose necessity is brute and geometric and those truths which have their source in fitness and final causes.
     From: Gottfried Leibniz (Letters to Remond de Montmort [1715], 1715.06.22/G III 645), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 6
     A reaction: The second one is a necessity deriving from God's wisdom. Strictly it could have been otherwise, unlike 'geometrical' necessity, which is utterly fixed.
10. Modality / C. Sources of Modality / 5. Modality from Actuality
A perfect idea of an object shows that the object is possible
     Full Idea: One mark of a perfect idea is that it shows conclusively that the object is possible.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.31)
     A reaction: Subtle but nice. My favourite example would be that the perfect idea of a bonfire on the Moon shows that it is not possible. Essence reveals necessity, as Aristotle and Kit Fine claim. A perfect idea has a single definition.
10. Modality / D. Knowledge of Modality / 1. A Priori Necessary
Intelligible truth is independent of any external things or experiences
     Full Idea: Intelligible truth is independent of the truth or of the existence outside us of sensible and material things. ....It is generally true that we only know necessary truths by the natural light [of reason]
     From: Gottfried Leibniz (Letters to Queen Charlotte [1702], 1702)
     A reaction: A nice quotation summarising a view for which Leibniz is famous - that there is a tight correlation between necessary truths and our a priori knowledge of them. The obvious challenge comes from Kripke's claim that scientists can discover necessities.
Proofs of necessity come from the understanding, where they have their source
     Full Idea: The fundamental proof of necessary truths comes from the understanding alone, and other truths come from experience or from observations of the senses. Our mind is capable of knowing truths of both sorts, but it is the source of the former.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01)
     A reaction: Interesting because it not only spells out that necessary truths are known a priori, but also explicitly says that the understanding is the 'source' of the truths, or at least the source of their proofs. He also says possibilities derive from essences.
Truths of reason are known by analysis, and are necessary; facts are contingent, and their opposites possible
     Full Idea: There are two kinds of truths: of reasoning and of facts. Truths of reasoning are necessary and their opposites impossible. Facts are contingent and their opposites possible. A necessary truth is known by analysis.
     From: Gottfried Leibniz (Monadology [1716], §33)
10. Modality / D. Knowledge of Modality / 2. A Priori Contingent
If we understand God and his choices, we have a priori knowledge of contingent truths
     Full Idea: Insofar as we have some insight into how God chooses, we can know a priori the laws of nature that God chooses for this best of all possible worlds. In this way, it is possible to have genuine a priori knowledge of contingent truths.
     From: report of Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.1998-9) by Daniel Garber - Leibniz:Body,Substance,Monad 6
     A reaction: I think it would be doubtful whether our knowledge of God's choosings would count as a priori. How do we discover them? Ah! We derive God from the ontological argument, and his choosings from the divine perfection implied thereby.
Only God sees contingent truths a priori
     Full Idea: Only God sees contingent truths a priori.
     From: Gottfried Leibniz (On Freedom [1689], p.95)
     A reaction: This because everything is interconnected, and the whole picture must be seen to understand a contingent truth.
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / c. Possible but inconceivable
What we cannot imagine may still exist
     Full Idea: It does not follow that what we can't imagine does not exist.
     From: Gottfried Leibniz (Letters to Johann Bernoulli [1699], 1698.11.18)
     A reaction: This just establishes the common sense end of the debate - that you cannot just use your imagination as the final authority on what exists, or what is possible.
10. Modality / E. Possible worlds / 1. Possible Worlds / a. Possible worlds
Leibniz narrows down God's options to one, by non-contradiction, sufficient reason, indiscernibles, compossibility
     Full Idea: Leibniz sets up increasingly stringent conditions possible worlds must meet. The weakest is non-contradiction, for truths of reason; then sufficient reason, for rational worlds; then identity of indiscernibles, for duplicates; then compossibility.
     From: report of Gottfried Leibniz (works [1690]) by Rom Harré - Laws of Nature 4
     A reaction: [my summary of a very nice two pages by Harré] God is the source of the principles which do the narrowing down.
Each monad expresses all its compatible monads; a possible world is the resulting equivalence class
     Full Idea: Leibniz argued that each monad mirrors or expresses every monad with which it is compossible. Hence compossibility is an equivalence relation among monads; possible worlds may then be identified as the corresponding equivalence classes.
     From: report of Gottfried Leibniz (works [1690]) by Ian Rumfitt - The Boundary Stones of Thought 6.1
     A reaction: [Rumfitt cites Benson Mates 1986:IV.1 for this claim] There is an analogous world of all the human minds that are in communication with one another - something like a 'culture'.
Leibniz proposed possible worlds, because they might be evil, where God would not create evil things
     Full Idea: In his early writings the principle of sufficient reason made it difficult for Leibniz to conceive of possible things;...raising this to possible worlds means God does not choose things that are evil, but chooses a world which must have evil in it.
     From: report of Gottfried Leibniz (works [1690]) by Matthew Stewart - The Courtier and the Heretic Ch.14
     A reaction: Where we think of possible worlds as explanations for conditional and counterfactual truths (I take it), Leibniz developed the original idea as part of his huge effort to achieve a consistent theodicy.
The actual universe is the richest composite of what is possible
     Full Idea: The actual universe is the collection of the possibles which forms the richest composite.
     From: Gottfried Leibniz (Exigency to Exist in Essences [1690], p.92)
     A reaction: 'Richest' for Leibniz means a maximum combination of existence, order and variety. It's rather like picking the best starting team from a squad of footballers.
There may be a world where dogs smell their game at a thousand leagues
     Full Idea: There will perhaps be a world in which dogs will have sufficiently good noses to scent their game at a thousand leagues.
     From: Gottfried Leibniz (Letters to Coste [1707], 1707)
     A reaction: Wonderful. This should immediately replace Lewis's much repeated example of a world containing a talking donkey. We should always honour the first person to suggest an idea. That is one of the motivations for this collection of ideas.
10. Modality / E. Possible worlds / 3. Transworld Objects / a. Transworld identity
If varieties of myself can be conceived of as distinct from me, then they are not me
     Full Idea: I can as little conceive of different varieties of myself as of a circle whose diameters are not all of equal length. These variations would all be distinct one from another, and thus one of these varieties of myself would necessarily not be me.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.05.13)
     A reaction: This seems to be, at the very least, a rejection of any idea that I could have a 'counterpart'. It is unclear, though, where he would place a version of himself who learned a new language, or who might have had, but didn't have, a haircut.
If someone's life went differently, then that would be another individual
     Full Idea: If the life of some person, or something went differently than it does, nothing would stop us from saying that it would be another person, or another possible universe which God had chosen. So truly it would be another individual.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.14)
     A reaction: Plantinga quotes this as an example of 'worldbound individuals'. This sort of remark leads to people saying that Leibniz believes all properties are essential, since they assume that his notion of essence is bound up with identity. But is it?
10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
Leibniz has a counterpart view of de re counterfactuals
     Full Idea: When Leibniz has the grounds of de re counterfactuals in mind, a counterpart picture, we have argued, is at work.
     From: report of Gottfried Leibniz (works [1690]) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 3.2.2
     A reaction: If Leibniz were a 'superessentialist', then individuals would be totally worldbound (because their relations would be essential). Cover/Hawthorne argue that he is just a 'strong' essentialist, allowing possible counterparts. Quite persuasive.
10. Modality / E. Possible worlds / 3. Transworld Objects / d. Haecceitism
Leibniz is some form of haecceitist
     Full Idea: Some form of haecceitism is central to the Leibnizian metaphysic.
     From: report of Gottfried Leibniz (Discourse on Metaphysics [1686], §8) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 5.2.1
     A reaction: That is, there is some inner hallmark that individuates each thing (though they don't mean the Duns Scotus idea of a haecceity which has no qualities apart from the capacity to individuate). Leibniz thinks essences individuate.
10. Modality / E. Possible worlds / 3. Transworld Objects / e. Possible Objects
If non-existents are possible, their existence would replace what now exists, which cannot therefore be necessary
     Full Idea: If certain possibles never exist, then existing things are not always necessary; otherwise it would be impossible for other things to exist instead of them, and so all things that never exist would be impossible.
     From: Gottfried Leibniz (On Freedom [1689], p.106)
     A reaction: A neat argument, though it is not self-evident that when possibles came into existence they would have to replace what is already there. Can't something be possible, but only in another world, because this one is already booked?
11. Knowledge Aims / A. Knowledge / 1. Knowledge
Knowledge needs clarity, distinctness, and adequacy, and it should be intuitive
     Full Idea: Knowledge is either obscure or clear; clear ideas are either indistinct or distinct; distinct ideas are either adequate or inadequate, symbolic or intuitive; perfect knowledge is that which is both adequate and intuitive.
     From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.283)
     A reaction: This is Leibniz's expansion of Descartes's idea that knowledge rests on 'clear and distinct conceptions'. The ultimate target seems to be close to an Aristotelian 'real definition', which is comprehensive and precise. Does 'intuitive' mean coherent?
Perfect knowledge implies complete explanations and perfect prediction
     Full Idea: The mark of perfect knowledge is that nothing appears in the thing under consideration which cannot be accounted for, and that nothing is encountered whose occurrence cannot be predicted in advance.
     From: Gottfried Leibniz (On Wisdom [1693], 1)
     A reaction: I would track both of these back to the concept of perfect understanding, which is admittedly a bit vague. Does a finite mind need to predict every speck of dust to have perfect knowledge? Do we have perfect knowledge of triangles?
11. Knowledge Aims / A. Knowledge / 2. Understanding
For Leibniz, divine understanding grasps every conceivable possibility
     Full Idea: For Leibniz, what is this understanding which God has? What does it contain? All possibilities in all possible combinations, that is, everything which can be conceived.
     From: report of Gottfried Leibniz (works [1690]) by Franklin Perkins - Leibniz: Guide for the Perplexed 2.III
     A reaction: I like this, because it strikes me as essential that understanding should embrace possibilities as well as actualities. Perkins points out that the possibilities are restricted by an awareness of the limitations imposed by combination.
We understand things when they are distinct, and we can derive necessities from them
     Full Idea: We understand the things of which we are aware only when we have distinct ideas of them accompanied by the power to reflect and to derive necessary truths from those ideas.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: A rather startling way of putting it, but we also say that good understanding brings the power to predict. What must you understand in order to predict? What has to happen next!
Understanding grasps the agreements and disagreements of ideas
     Full Idea: Ordinarily, when ideas are thoroughly understood, their agreements and disagreements are apparent.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.02)
     A reaction: In other words, there is a holistic aspect of understanding, which makes us ask how understanding ever gets off the ground. Is it not possible to understand a single idea in isolation?
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
Certainty is where practical doubt is insane, or at least blameworthy
     Full Idea: Certainty might be knowledge of a truth such that to doubt it in a practical way would be insane; and sometimes it is taken more broadly, to cover cases where doubt would be very blameworthy.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.11)
     A reaction: The normative aspect of the second half of this touches on a trend in recent epistemology. You have rights to believe, and duties to believe, and virtues for the justifying process. I prefer more neutral, value-free epistemology.
11. Knowledge Aims / B. Certain Knowledge / 4. The Cogito
I cannot think my non-existence, nor exist without being myself
     Full Idea: I am assured that as long as I think, I am myself. For I cannot think that I do not exist, nor exist so that I be not myself.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.05.13)
     A reaction: Elsewhere he qualifies the Cogito, but here he seems to straighforwardly endorse it.
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
I can't just know myself to be a substance; I must distinguish myself from others, which is hard
     Full Idea: It is not enough for understanding the nature of myself, that I feel myself to be a thinking substance, one would have to form a distinct idea of what distinguishes me from all other possible minds; but of that I have only a confused experience.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14)
     A reaction: Not a criticism I have encountered before. Does he mean that I might be two minds, or might be a multitude of minds? It seems to be Hume's problem, that you are aware of experiences, but not of the substance that unites them.
I know more than I think, since I know I think A then B then C
     Full Idea: Not only is it immediately evident to me that I think, but it is just as evident that I think various thoughts: at one time I think about A and at another about B and so on. Thus the Cartesian principle is sound, but it is not the only one of its kind.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.02)
     A reaction: I don't suppose that Descartes would object to this, but he was aware that there didn't seem to be any actual introspective experience that united the various thoughts into a single thinker. Only logical connections between the thoughts does that.
The Cogito doesn't prove existence, because 'I am thinking' already includes 'I am'
     Full Idea: To say 'I think therefore I am' is not really to prove existence from thought, since 'to think' and 'to be thinking' are one and the same, and to say 'I am thinking' [je suis pensant] is already to say 'I am' [je suis].
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.07)
     A reaction: This is the objection which was offered by A.J. Ayer, and I take it to the one of the two principle objections to the Cogito (i.e. that it may be a tautology), along with the objection about the assumption of the continuity of the same thinker.
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
If we are dreaming, it is sufficient that the events are coherent, and obey laws
     Full Idea: Skeptics may doubt the truth of things, and if it pleases them to call the things that occur to us dreams, it suffices for these dreams to be in agreement with each other, and to obey certain laws.
     From: Gottfried Leibniz (On Perceptions [1680], A6.4.1398), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: Leibniz flirted a great deal with phenomenalism throughout the middle of his career, as charted by Garber. Descartes made similar points. It is really only Berkeley who took this idea seriously.
11. Knowledge Aims / C. Knowing Reality / 3. Idealism / a. Idealism
A whole is just its parts, but there are no smallest parts, so only minds and perceptions exist
     Full Idea: The whole, if it is assumed to be body or matter, is nothing other than all of its parts; but this is absurd, since there aren't any smallest parts. Therefore there really exist only minds and their perceptions.
     From: Gottfried Leibniz (Calculus Ratiocinator [1679], A6.4.279), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: Leibniz is sometimes labelled as an 'idealist', but this text is unusual in being so explicit, and he was mainly concerned to explain the reality of individual bodies. Monads were his final attempt to do this, not an attempt to escape into pure minds.
Leibniz said dualism of mind and body is illusion, and there is only mind
     Full Idea: Leibniz held that dualism of mind and body is an illusion and that both are really the same thing, and that this thing is mind.
     From: report of Gottfried Leibniz (works [1690]) by R Martin / J Barresi - Introduction to 'Personal Identity' p.22
     A reaction: I am puzzled by this, as Leibniz is famous for the view that mind and body are parallel. See idea 5038, and also 2109 and 2596. Monads are, of course, entirely mental, and are the building blocks of reality. Clearly I (and you) must read more Leibniz.
Leibniz is an idealist insofar as the basic components of his universe are all mental
     Full Idea: To say that Leibniz is an idealist is to say that simple substances, the basic building-blocks of the universe, are all mental or at least quasi-mental in nature
     From: report of Gottfried Leibniz (works [1690]) by Nicholas Jolley - Leibniz Ch.3
     A reaction: This is a bit different from the Berkelian type of idealism, which says that reality consists entirely of events within thinking minds. Is a monad the thinker or the thought?
12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
Descartes needs to demonstrate how other people can attain his clear and distinct conceptions
     Full Idea: It is not sufficient for Descartes to claim that he perceives something in himself clearly and distinctly, for this is to not complete the demonstration, unless he shows the method through which others can attain the same experience.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], App X)
     A reaction: For the simplest rational insight this seems a rather tough requirement. If you say A>B, and B>C, so A>C, then once you have grasped the concept of 'greater than' I'm not sure there is a further possible demonstration.
12. Knowledge Sources / A. A Priori Knowledge / 3. Innate Knowledge / a. Innate knowledge
All of our thoughts come from within the soul, and not from the senses
     Full Idea: I always accepted the innate idea of God, but my new system says all the thoughts and actions of the soul come from its own depths and could not be given to it by the senses.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01)
     A reaction: It is hard to adjudicate on this one. The counterexamples would be associations. I see a face in the crowd and think of my friend. But Leibniz could be right even about that. Who cares? Externalism is designed to bypass this problem.
Arithmetic and geometry are implicitly innate, awaiting revelation
     Full Idea: I would name the propositions of arithmetic and geometry as innate. ...The actual knowledge of them is not innate. What is innate is what might be called the implicit knowledge of them, as the veins of marble outline a shape for the sculptor.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01)
     A reaction: This seems to walk straight into the empiricist guns. The marble example shows the problem, because the 'veins' will hardly outline David in the block. Locke's challenge is to show that merely 'implicit' ideas have demonstrable reality.
Children learn language fast, with little instruction and few definitions
     Full Idea: I have sometimes been amazed that children can learn languages so early, ...considering how little trouble is taken to instruct children in their native tongue, and how little thought adults give to getting sharp definitions.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.10)
     A reaction: A striking anticipation of the key observation on which Chomsky built his theories, from a philosopher who was equally concerned to defend innate ideas and innate knowledge.
12. Knowledge Sources / A. A Priori Knowledge / 3. Innate Knowledge / c. Tabula rasa
What is left of the 'blank page' if you remove the ideas?
     Full Idea: Those who hold forth about the 'blank page' cannot say what is left of it once the ideas have been taken away.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: This is a decisive criticism of the total tabula rasa idea, but empiricists responded by developing associationism - that what remains is principles of association for incoming experience. Brain mechanisms, we might say.
12. Knowledge Sources / A. A Priori Knowledge / 4. A Priori as Necessities
An a priori proof is independent of experience
     Full Idea: An a priori proof is a proof independent of experience.
     From: Gottfried Leibniz (Primary Truths [1686])
     A reaction: Burge says Leibniz gave the first modern account of a priori knowledge. There may be no explicit reference to experience involved, but it would beg many questions to deny that implicit experience may be at the root of the proof.
Mathematical analysis ends in primitive principles, which cannot be and need not be demonstrated
     Full Idea: At the end of the analytical method in mathematics there are simple ideas of which no definition can be given. Moreover there are axioms and postulates, in short, primitive principles, which cannot be demonstrated and do not need demonstration.
     From: Gottfried Leibniz (Monadology [1716], §35)
     A reaction: My view is that we do not know such principles when we apprehend them in isolation. I would call them 'intuitions'. They only ascend to the status of knowledge when the mathematics is extended and derived from them, and found to work.
12. Knowledge Sources / B. Perception / 1. Perception
Not all of perception is accompanied by consciousness
     Full Idea: I do not think that the Cartesians have ever proved or can prove that every perception is accompanied by consciousness.
     From: Gottfried Leibniz (Principle of Life and Plastic Natures [1705], p.195)
     A reaction: This idea is very important in Leibniz, because non-conscious or barely conscious thoughts and perceptions explain a huge amount about behaviour, reality and morality.
'Perception' is basic internal representation, and 'apperception' is reflective knowledge of perception
     Full Idea: We distinguish between 'perception', the internal state of the monad representing external things, and 'apperception', which is consciousness, or the reflective knowledge of this internal state, not given to all souls, nor at all times to a given soul.
     From: Gottfried Leibniz (Principles of Nature and Grace based on Reason [1714], §4)
     A reaction: The word 'apperception' is standard in Kant. I find it surprising that modern analytic philosophers don't seem to use it when they write about perception. It strikes me as useful, but maybe specialists have a reason for avoiding it.
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / d. Secondary qualities
We know objects by perceptions, but their qualities don't reveal what it is we are perceiving
     Full Idea: We use the external senses ...to make us know their particular objects ...but they do not make us know what those sensible qualities are ...whether red is small revolving globules causing light, heat a whirling of dust, or sound is waves in air.
     From: Gottfried Leibniz (Letters to Queen Charlotte [1702], 1702)
     A reaction: These seems to be exactly the concept of secondary qualities which Locke was promoting. They are unreliable information about the objects we perceive. Primary qualities are reliable information. I like that distinction.
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / e. Primary/secondary critique
Light, heat and colour are apparent qualities, and so are motion, figure and extension
     Full Idea: Concerning bodies I can demonstrate that not merely light, heat, color, and similar qualities are apparent but also motion, figure, and extension.
     From: Gottfried Leibniz (De modo distinguendi phaenomena [1685], A6.4.1504), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: Leibniz is not consistent on this. Here he is flirting with idealism, but he often backs away from that. In Discourse §12 he makes secondary qualities certainly subjective, and primary qualities possibly so. He admits the primaries contain eternal truths.
Colour and pain must express the nature of their stimuli, without exact resemblance
     Full Idea: Ideas such as those of colour and pain are not arbitrary. ...That is not God's way ...I would say there is a resemblance of a kind, not a perfect one, but a resemblance in which one thing expresses another through some orderly relationship between them.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.08)
     A reaction: The main point of Locke's idea of 'secondary' qualities is that (unlike the 'primary' ones) they bear no resemblance to their stimuli. It's not much of an argument from Leibniz, to say that is not God's way, but he has a vast system to support his claim.
12. Knowledge Sources / B. Perception / 3. Representation
A pain doesn't resemble the movement of a pin, but it resembles the bodily movement pins cause
     Full Idea: It is true that pain does not resemble the movement of a pin; but it might thoroughly resemble the motions which the pin causes in our body, and it might resemble them in the soul; and I have not the least doubt that it does.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.08)
     A reaction: He may not have the least doubt, but the rest of us do, I should think. Try as I will, I cannot see any resemblance between pain and a motion. What feeling does a pendulum resemble?
12. Knowledge Sources / B. Perception / 6. Inference in Perception
Truth arises among sensations from grounding reasons and from regularities
     Full Idea: The truth of sensible things is established by the links amongst them; these depend upon intellectual truths, grounded in reason, and upon observations of regularities among sensible things themselves, even when the reasons are not apparent.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.11)
     A reaction: It's not clear why regularities would establish truths, given that most hallucinations have regularities in them. I'm thinking that Leibniz is not sufficiently rationalist here, and that it is the rational coherence of experience which validates it.
12. Knowledge Sources / C. Rationalism / 1. Rationalism
We only believe in sensible things when reason helps the senses
     Full Idea: The senses could not convince us of the existence of sensible things without help from reason.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.07)
     A reaction: This nicely pinpoints the big difficulty which keeps besetting orthodox empiricism. I've been educated as an empiricist, but I prefer Leibniz to Berkeley or Hume, and even to the more sensible Locke.
You may experience a universal truth, but only reason can tell you that it is always true
     Full Idea: However often one experiences instances of a universal truth, one could never know inductively that it would always hold unless one knew through reason that it was necessary.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01)
     A reaction: The problem, though, is that as soon as we go beyond experience we are not very reliable, and are liable to arrogance, error and lack of imagination.
The senses are confused, and necessities come from distinct intellectual ideas
     Full Idea: Intellectual ideas, from which necessary truths arise, do not come from the senses. ...The ideas that come from the senses are confused; and so too, at least in part, are the truths which depend on them, whereas intellectual ideas are distinct.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.01)
     A reaction: One might compare Descartes' example of the chiliagon, which is only grasped clearly by the intellect. However, the problem of vagueness seems to intrude as much into intellectual ideas as it does into the senses. He was a mathematician...
We all expect the sun to rise tomorrow by experience, but astronomers expect it by reason
     Full Idea: When we expect it to be day tomorrow, we all behave as empiricists, because until now it has always happened thus. The astronomer alone knows this by reason.
     From: Gottfried Leibniz (Monadology [1716], §28)
12. Knowledge Sources / D. Empiricism / 1. Empiricism
There is nothing in the understanding but experiences, plus the understanding itself, and the understander
     Full Idea: It can be said that there is nothing in the understanding which does not come from the senses, except the understanding itself, or that which understands.
     From: Gottfried Leibniz (Letters to Queen Charlotte [1702], 1702)
     A reaction: Given that Leibniz is labelled as a 'rationalist', this is awfully close to empiricism. Not Locke's 'tabula rasa' perhaps, but Hume's experiences plus associations. Leibniz has a much loftier notion of understanding and reason than Hume does.
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
Knowledge doesn't just come from the senses; we know the self, substance, identity, being etc.
     Full Idea: It is always false to say that all our notions come from the so-called external senses, for the notion I have of myself and of my thoughts, and consequently of being, substance, action, identity, and many others, come from an internal experience.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §27)
     A reaction: Of course, an empiricist like Hume would not deny this, as he bases his views on 'experience' (including anger, for example), not just 'sense experience'. But Hume, famously, said he has no experience of a Self, so can't get started on Leibniz's journey.
Our sensation of green is a confused idea, like objects blurred by movement
     Full Idea: The sensory idea of green (made of blue and yellow) is a confused idea, like the swift rotation of a cog-wheel which makes us perceive an artificial transparency, and we are not able to discern the cause, the idea of the teeth on the wheel.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 4.06)
     A reaction: This is one of Leibniz's less well-known objections to empiricism. He always says that intellectual ideas are capable of a clarity which is never found in sensory experience.
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
Nothing should be taken as certain without foundations
     Full Idea: Nothing should be taken as certain without foundations.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.04.30)
     A reaction: This might leave open the option, if you were a modern 'Fallibilist', that something might lack foundations, and so not be certain, and yet still qualify as 'knowledge'. That is my view. Knowledge resides somewhere between opinion and certainty.
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / d. Rational foundations
Our thoughts are either dependent, or self-evident. All thoughts seem to end in the self-evident
     Full Idea: Whatever is thought by us is either conceived through itself, or involves the concept of another. …Thus one must proceed to infinity, or all thoughts are resolved into those which are conceived through themselves.
     From: Gottfried Leibniz (Of Organum or Ars Magna of Thinking [1679], p.1)
     A reaction: This seems to embody the rationalist attitude to foundations. I am sympathetic. Experiences just come to us as basic, but they don't qualify as 'thoughts', let alone knowledge. Experiences are more 'given' than 'conceptual'.
13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / b. Pro-coherentism
Scientific truths are supported by mutual agreement, as well as agreement with the phenomena
     Full Idea: Among the most powerful indications of truth belongs the fact that scientific propositions agree with one another as well as with phenomena.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1699.03.24/04.03)
     A reaction: I take this to be the case not only with science, but with all other truths. Leibniz is particularly keen on the interconnectedness of things, so coherence justification suits him especially well. But surely all scientists embrace this idea?
13. Knowledge Criteria / D. Scepticism / 1. Scepticism
Light takes time to reach us, so objects we see may now not exist
     Full Idea: Since rays of light need time - however little - to reach us, it is possible that the object should be destroyed during the interval and no longer exist when the light reaches the eye.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.09)
     A reaction: This is the well know 'time lag' argument. Leibniz is no sceptic, but he can hardly fail to accept the truth of this problem. It seems self-evident that stars we observe may no longer exist, although special relativity confuses that issue.
13. Knowledge Criteria / D. Scepticism / 6. Scepticism Critique
I don't recommend universal doubt; we constantly seek reasons for things which are indubitable
     Full Idea: I do not think it necessary to recommend to people universal doubt ...in fact, we are constantly seeking reasons for thoughts about which there is no doubt at all.
     From: Gottfried Leibniz (Precepts for Advancing Science and Arts [1680], p.34)
     A reaction: Such confidence is, of course, asking for trouble. I prefer Peirce's fallibilism - that robust realism is the most coherent view, and the only one worth pursuing and relying on, but you never know....
13. Knowledge Criteria / E. Relativism / 2. Knowledge as Convention
Truth is mutually agreed perception
     Full Idea: In the mutual agreement of perceivers consists the truth of the phenomena.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: This remark is startling close to the 'perspectivism' that crops up in the late notebooks of Nietzsche. Leibniz was keen on relativism in many areas, starting with the nature of space. I personally think Leibniz meant 'knowledge' rather than 'truth'.
14. Science / A. Basis of Science / 4. Prediction
Successful prediction shows proficiency in nature
     Full Idea: He who can finally make predictions with success must be said to have become sufficiently proficient in nature.
     From: Gottfried Leibniz (On Perceptions [1680], A6.4.1398), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: Is prediction achieved by knowledge of laws, or knowledge of essences and powers? The trouble with most laws is that they permit exceptions. 'Things fall, unless prevented' etc.
14. Science / C. Induction / 2. Aims of Induction
Hypotheses come from induction, which is comparison of experiences
     Full Idea: We construct a hypothesis on the basis of an induction, that is on the basis of a comparison of experiences.
     From: Gottfried Leibniz (Elements of Law and Justice [1669], p.2)
     A reaction: This fits the traditional positivist picture of science (observe-hypothesise-predict-observe). I like the definition of induction as 'comparison of experiences', because it doesn't reduce it to sequences of objects, and points to coherence.
14. Science / C. Induction / 3. Limits of Induction
The instances confirming a general truth are never enough to establish its necessity
     Full Idea: All the instances which confirm a general truth, however numerous they may be, are not sufficient to establish the universal necessity of this same truth.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref)
     A reaction: This is Leibniz's standardly rationalist view of induction. We can either say that induction is therefore inadequate, or (a better option) that there isn't much evidence for claims of necessity, and they must be treated with caution.
14. Science / D. Explanation / 2. Types of Explanation / a. Types of explanation
Nature is explained by mathematics and mechanism, but the laws rest on metaphysics
     Full Idea: One must always explain nature along mathematical and mechanical lines, provided one knows that the very principles or laws of mechanics or of force do not depend upon mathematical extension alone but upon certain metaphysical reasons.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 X)
     A reaction: I like this, and may even use it as the epigraph of my masterwork. Recently Stephen Hawking (physicist) has been denigrating philosophy, but I am with Leibniz on this one.
14. Science / D. Explanation / 2. Types of Explanation / g. Causal explanations
Minds are best explained by their ends, and bodies by efficient causes
     Full Idea: Whatever concerns reasonable substances (the minds of men) is more naturally explained by the consideration of ends, whereas other substances (bodies) are better explained by efficient causes.
     From: Gottfried Leibniz (Geometrical Method and Metaphysics [1712], p.89)
     A reaction: That is, I take it, that the type of causal explanation considered most appropriate is the one that leads to the greatest understanding. So there is no absolute or correct answer as to which type of causation is the more important.
14. Science / D. Explanation / 2. Types of Explanation / h. Explanations by function
Final causes can help with explanations in physics
     Full Idea: Final causes not only advance virtue and piety in ethics and natural theology, but also help us to find and lay bare hidden truths in physics itself.
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], §04)
     A reaction: This rearguard action against the attack on teleology is certainly aimed at Spinoza. The notion of purpose still seems to have a role to play in evolutionary biology, but probably not in physics.
To explain a house we must describe its use, as well as its parts
     Full Idea: A house would be badly explained if we were to describe only the arrangement of its parts, but not its use.
     From: Gottfried Leibniz (On Body and Force, Against the Cartesians [1702], p.255)
     A reaction: This must partly fall under pragmatics (i.e. what the enquirer is interested in). But function plays a genuine role in artefacts, and also in evolved biological organs.
14. Science / D. Explanation / 2. Types of Explanation / k. Explanations by essence
To fully conceive the subject is to explain the resulting predicates and events
     Full Idea: Even in the most contingent truths, there is always something to be conceived in the subject which serves to explain why this predicate or event pertains to it, or why this has happened rather than not.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.06)
     A reaction: The last bit, about containing what has happened, seems absurd, but the rest of it makes sense. It is just the Aristotelian essentialist view, that a full understanding of the inner subject will both explain and predict the surface properties.
The cause of a change is not the real influence, but whatever gives a reason for the change
     Full Idea: That thing from whose state a reason for the changes is most readily provided is adjudged to be the cause. ...Causes are not derived from a real influence, but from the providing of a reason.
     From: Gottfried Leibniz (Specimen inventorum [1689], A6.4.1620), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 5
     A reaction: Leibniz is not denying that there are real influences. He seems to be offering the thesis which I am pursuing, that the need for explanation is the crucial factor in shaping the structure of our metaphysics.
The essence of substance is the law of its changes, as in the series of numbers
     Full Idea: The essence of substance consists in ...the law of the sequence of changes, as in the nature of the series in numbers.
     From: Gottfried Leibniz (works [1690], A 6.3.326), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 6.1.2
     A reaction: Thus we might say, in this spirit, that the essence of number is the successor operation, as defined by Dedekind and Peano (and perhaps their amenability to inductive proof). I like this. Metaphysicians rule - they penetrate the heart of nature.
We will only connect our various definitions of gold when we understand it more deeply
     Full Idea: We can define gold as the heaviest metal, or by assaying procedures, but only when men have penetrated more deeply into the nature of things will they be able to see why one belongs with the other.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.31)
     A reaction: He mentions that geometry is different, because we do have perfect ideas of things. This is part of Leibniz's optimism about the future of science, in comparison with the surprising pessimism of the empiricists. See Idea 12976 and Idea 12975.
14. Science / D. Explanation / 3. Best Explanation / a. Best explanation
The Copernican theory is right because it is the only one offering a good explanation
     Full Idea: The Copernican account is the truest theory, that is, the most intelligible theory and the only one capable of an explanation sufficient for a person of sound reason.
     From: Gottfried Leibniz (On Copernicanism and Relativity of Motion [1689], p.92)
     A reaction: The word 'intelligible' here seems to be linked to the notion of a best explanation.
14. Science / D. Explanation / 3. Best Explanation / b. Ultimate explanation
Nature can be fully explained by final causes alone, or by efficient causes alone
     Full Idea: All the phenomena of nature can be explained solely by final causes, exactly as if there were no efficient causes; and all the phenomena of nature can be explained solely by efficient causes, as if there were no final causes.
     From: Gottfried Leibniz (Definitiones cogitationesque metaphysicae [1678], A6.4.1403), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 6
     A reaction: Somewhat speculative (a virtue!), but it is interesting to see him suggesting that there might be two complete and satisfactory explanations, which never touched one another. I can't see Aristotle agreeing with that.
15. Nature of Minds / A. Nature of Mind / 1. Mind / b. Purpose of mind
Mind is a thinking substance which can know God and eternal truths
     Full Idea: Minds are substances which think, and are capable of knowing God and of discovering eternal truths.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1687.10.09)
     A reaction: 'God' is there because the ability to grasp the ontological argument is seen as basic. Note a firm commitment to substance-dualism, and a rationalist commitment to the spotting of necessary truths as basic. He is not totally wrong.
15. Nature of Minds / A. Nature of Mind / 5. Unity of Mind
No machine or mere organised matter could have a unified self
     Full Idea: By means of the soul or form, there is a true unity which is called the 'I' in us; a thing which could not occur in artificial machines, nor in the simple mass of matter, however organised it may be.
     From: Gottfried Leibniz (New System and Explanation of New System [1696], p.120)
     A reaction: I think the unity of consciousness and the unified Self are different phenomena. A wonderful remark about artificial intelligence for 1696! Note the idea of functionalism contained in 'organised'. Personally I see the brain as a 'mass of matter'.
15. Nature of Minds / A. Nature of Mind / 7. Animal Minds
It seems probable that animals have souls, but not consciousness
     Full Idea: It appears probable that the brutes have souls, though they are without consciousness.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.12.08)
     A reaction: This will be a response to Descartes, who allowed animals sensations, but not minds or souls. Personally I cannot make head or tail of Leibniz's claim. What makes it "apparent" to him?
Animal thought is a shadow of reasoning, connecting sequences of images by imagination
     Full Idea: The sequences of the brutes are but a shadow of reasoning, that is to say, they are but connexions of imagination, transitions from one image to another.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref)
     A reaction: This account of animal thought cannot capture the fact that they are motivated by their images, and obviously make decisions based on them. Externally, there is usually an obvious reason why even an insect does something.
Animals are semi-rational because they connect facts, but they don't see causes
     Full Idea: There is a connexion between the perceptions of animals, which bears some resemblance to reason: but it is based only on the memory of facts or effects, and not at all on the knowledge of causes.
     From: Gottfried Leibniz (Principles of Nature and Grace based on Reason [1714], §5)
     A reaction: This amounts to the view that animals can do Humean induction (where you see regularities), but not Leibnizian induction (where you see necessities). I say all minds perceive patterns, but only humans can think about the patterns they have perceived.
15. Nature of Minds / B. Features of Minds / 1. Consciousness / a. Consciousness
Leibniz introduced the idea of degrees of consciousness, essential for his monads
     Full Idea: The designation of degrees of conscious awareness is one of Leibniz's most significant innovations, and it is fundamental to almost every aspect of his account of monads.
     From: report of Gottfried Leibniz (works [1690]) by Franklin Perkins - Leibniz: Guide for the Perplexed 4.I
     A reaction: A very important development, which seems to have been ignored by philosophers for three hundred years, since they usually treat consciousness as all-or-nothing. Introspection makes degrees obvious, and I suspect sparrows are down the scale.
15. Nature of Minds / B. Features of Minds / 1. Consciousness / c. Parts of consciousness
Our large perceptions and appetites are made up tiny unconscious fragments
     Full Idea: Our great perceptions and our great appetites of which we are conscious, are composed of innumerable little perceptions and little inclinations of which we cannot be conscious.
     From: Gottfried Leibniz (Letters to Remond de Montmort [1715], 1715 §2)
     A reaction: I think this is a wonderfully accurate report of how the mind is, in comparison with the much more simplistic views presented by most philosophers of that era. And so much understanding flows from Leibniz's account.
15. Nature of Minds / B. Features of Minds / 2. Unconscious Mind
It is a serious mistake to think that we are aware of all of our perceptions
     Full Idea: Many errors can flow from the belief that the only perceptions in the soul are the ones of which it is aware.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: What a perceptive remark, for its time! I took it that it was only modern neuroscience and psychology which had woken us up to how much non-conscious activity is central to the mind.
The soul doesn't understand many of its own actions, if perceptions are confused and desires buried
     Full Idea: The soul does many things without knowing how it does them - when it does them by means of confused perceptions and unconscious inclinations or appetites.
     From: Gottfried Leibniz (On Note L to Bayle's 'Rorarius' [1705], [L])
     A reaction: This increasingly strikes me as a wonderful and important insight for its time. He's really paid attention to his own mind, and given up the simplistic view that derives from Descartes. Are birds conscious? Yes or no! Silly.
15. Nature of Minds / B. Features of Minds / 3. Privacy
Increase a conscious machine to the size of a mill - you still won't see perceptions in it
     Full Idea: If a conscious machine were increased in size, one might enter it like a mill, but we should only see the parts impinging on one another; we should not see anything which would explain a perception.
     From: Gottfried Leibniz (Monadology [1716], §17)
     A reaction: A wonderful image for capturing a widely held intuition. It seems to motivate Colin McGinn's 'Mysterianism'. The trouble is Leibniz didn't think big/small enough. Down at the level of molecules it might become obvious what a perception is. 'Might'.
15. Nature of Minds / C. Capacities of Minds / 5. Generalisation by mind
Abstraction attends to the general, not the particular, and involves universal truths
     Full Idea: Beasts recognise whiteness, but this does not amount to abstraction, which requires attention to the general apart from the particular, and consequently involves knowledge of universal truths.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.11)
     A reaction: I'm not sure where 'truth' creeps into this. I might hallucinate pink elephants, and abstract the general notion of pink from them. Nevertheless, the features picked out in abstraction tend to be the shared features.
15. Nature of Minds / C. Capacities of Minds / 10. Conatus/Striving
Active force is not just potential for action, since it involves a real effort or striving
     Full Idea: Active force should not be thought of as the simple and common potential [potentia] or receptivity to action of the schools. Rather, active force involves an effort [conatus] or striving [tendentia] toward action.
     From: Gottfried Leibniz (On Body and Force, Against the Cartesians [1702], p.252)
     A reaction: This is why Leibniz is lured into making his active forces more and more animistic, till they end up like proto-minds (though never, remember, conscious and willing minds).
Volition automatically endeavours to move towards what it sees as good (and away from bad)
     Full Idea: Volition is the effort or endeavour ('conatus') to move towards what one finds good and away from what one finds bad, the endeavour arising immediately out of one's awareness of those things.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: Modern neuroscience seems to confirm that there is a chicken-and-egg problem here. Is the moment of perception as good or bad itself an act of volition, or is it neutral?
Primitive forces are internal strivings of substances, acting according to their internal laws
     Full Idea: Primitive forces can be nothing but the internal strivings [tendentia] of simple substances, striving by means of which they pass from perception to perception in accordance with a certain law of their nature.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704 or 1705)
     A reaction: 'Perception' sounds a bit crazy, but he usually qualifies that sort of remark by saying that it is an 'analogy' with conscious willing souls. The 'internal strivings of substances' is a nice phrase for the basic powers in nature where explanations stop.
16. Persons / C. Self-Awareness / 2. Knowing the Self
We know the 'I' and its contents by abstraction from awareness of necessary truths
     Full Idea: It is through the knowledge of necessary truths and through their abstraction that we rise to reflective acts, which enable us to think of that which is called "I" and enable us to consider that this or that is in us.
     From: Gottfried Leibniz (Monadology [1716], §30)
     A reaction: For Leibniz, necessary truth can only be known a priori. Sense experience won't reveal the self, as Hume observed. We evidently 'abstract' the idea of 'I' from the nature of a priori thought. Animals have no self (or morals) for this reason.
16. Persons / D. Continuity of the Self / 2. Mental Continuity / a. Memory is Self
If a person's memories became totally those of the King of China, he would be the King of China
     Full Idea: If someone were suddenly to become the King of China, forgetting what he has been, as if born anew, is this not as if he were annihilated, and a King of China created in his place at the same moment?
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §34)
     A reaction: Strikingly, this clearly endorse the view of the empiricist Locke. It is a view about the continuity of the self, not its essence, but Descartes must have turned in his grave when he read this. When this 'King of China' introspects his self, what is it?
Memory doesn't make identity; a man who relearned everything would still be the same man
     Full Idea: If a man were made young again, and learned everything anew - would that make him a different man? So it is not memory that makes the very same man.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: Leibniz takes this as a foregone conclusion. If you flipped to a possible world where someone you know well, as a physical being, has been brought up entirely differently (new language, culture, ethics etc), is it really the same person?
16. Persons / D. Continuity of the Self / 2. Mental Continuity / b. Self as mental continuity
We know our own identity by psychological continuity, even if there are some gaps
     Full Idea: To discover one's own moral identity unaided, it is sufficient that between one state and a neighbouring (or just a nearby) one there be a mediating bond of consciousness, even if this has a jump or forgotten interval mixed into it.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27)
     A reaction: Leibniz appears to accept the psychological continuity view of personal identity (which was probably a new problem to him), even though he rightly rejects the account based purely on memory.
16. Persons / F. Free Will / 1. Nature of Free Will
Future contingent events are certain, because God foresees them, but that doesn't make them necessary
     Full Idea: We must distinguish between what is certain and what is necessary; everyone agrees that future contingents are certain, since God foresees them, but it is not thereby admitted that they are necessary.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §13)
     A reaction: An interesting point, since there is presumably a difference between God foreseeing that future squares will have four corners, and His foreseeing the next war. It seems to me, though, that 'certainty' is bad enough news for free will, without necessity.
16. Persons / F. Free Will / 5. Against Free Will
If we know what is good or rational, our knowledge is extended, and our free will restricted
     Full Idea: The more perfect one is, the more one is determined to the good, and so is more free at the same time. ...Our power and knowledge are more extended, and our will much the more limited within the bounds of perfect reason.
     From: Gottfried Leibniz (Letters to Pierre Bayle [1702], 1702)
     A reaction: I like this idea, which seems to me to derive from Aquinas. When I choose to eat and drink each day, or agree that 7+5 is 12, I don't complain about my lack of freedom in the choices. Goodness and reason are constraints I welcome.
Saying we must will whatever we decide to will leads to an infinite regress
     Full Idea: As for volition itself, to say that it is the object of free will is incorrect. We will to act, strictly speaking, and we do not will to will, else we should still say we will to have the will to will, and that would go on to infinity.
     From: Gottfried Leibniz (The Theodicy [1710], p.151), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 4.IV
     A reaction: This strikes me as an elementary difficulty which most fans of free will appear to evade. Thoughts just arise in us, and some of them are volitions. We can say there is then a 'gap' (Searle) where we choose, but what happens in the gap?
16. Persons / F. Free Will / 6. Determinism / a. Determinism
People argue for God's free will, but it isn't needed if God acts in perfection following supreme reason
     Full Idea: People try to safeguard God's freedom, as though it were not freedom of the highest sort to act in perfection following sovereign reason.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §03)
We think we are free because the causes of the will are unknown; determinism is a false problem
     Full Idea: The will has its causes, but since we are ignorant of them, we believe ourselves independent. It is this chimera of imaginary independence which revolts us against determinism, and which brings us to believe there are difficulties where there are none.
     From: Gottfried Leibniz (works [1690]), quoted by Matthew Stewart - The Courtier and the Heretic Ch.16
     A reaction: It seems that in his notebooks Leibniz was actually a (Spinozan) determinist. So he should have been, given his view that we live in the best of all possible worlds, and his claim that mind and brain run like two clocks. (Ideas 2114 and 2596)
16. Persons / F. Free Will / 6. Determinism / b. Fate
Sloth's Syllogism: either it can't happen, or it is inevitable without my effort
     Full Idea: The ancient Sloth's Syllogism says that if something is foreseen and infallible, it will happen without my effort, and if it is not foreseen, it will not happen, even though I am able to do it.
     From: Gottfried Leibniz (Dialogue on human freedom and origin of evil [1695], p.113)
     A reaction: Presumable the foreseeing is to be done by the oracle, and not by the slothful person.
16. Persons / F. Free Will / 7. Compatibilism
Everything which happens is not necessary, but is certain after God chooses this universe
     Full Idea: It is not the case that everything which happens is necessary; rather, everything which happens is certain after God made choice of this possible universe, whose notion contains this series of things.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.05)
     A reaction: I think this distinction is best captured as 'metaphysical necessity' (Leibniz's 'necessity'), and 'natural necessity' (his 'certainty'). 'Certainty' seems a bad word, as it is either certain de dicto or de re. Is God certain, or is the thing certain?
The will determines action, by what is seen as good, but it does not necessitate it
     Full Idea: Choice, however much the will is determined to make it, should not be called absolutely and strictly necessary: a predominance of goods of which one is aware inclines without necessitating, though this is determining and never fails to have its effect.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: Something like seeing that 7+5 equals 12 makes you say '12', but it doesn't actually necessitate your saying '12'? Certain facts seem determined by nature, but not necessitated. Or not necessarily necessitated?
17. Mind and Body / A. Mind-Body Dualism / 1. Dualism
Soul represents body, but soul remains unchanged, while body continuously changes
     Full Idea: The essence of the soul is to represent bodies. ...The soul and the idea of the body do not signify the same thing. For the soul remains one and the same, while the idea of the body perpetually changes as the body itself changes.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1699.03.24/04.03)
     A reaction: This seems to rest on the Cartesian Ego, as the essence of mind which does not change. And yet elsewhere he describes the Ego as a mere abstraction from introspected mental life.
17. Mind and Body / A. Mind-Body Dualism / 3. Panpsychism
Every body contains a kind of sense and appetite, or a soul
     Full Idea: I believe that there is in every body a kind of sense and appetite, or a soul.
     From: Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.2010), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1
     A reaction: Note that he never says that there is any intelligence present. This eventually becomes his monadology, but Leibniz is the most obvious post-Greek philosopher to flirt with panpsychism.
Leibniz has a panpsychist view that physical points are spiritual
     Full Idea: In Leibniz's panpsychism, the so-called 'physical' points are souls or spiritual 'monads'.
     From: report of Gottfried Leibniz (works [1690]) by R Martin / J Barresi - Introduction to 'Personal Identity' p.23
     A reaction: I'm not convinced that 'panpsychism' is the right description for Leibniz's theory of monads. I take panpsychism to be either a dualist or a dual aspect (or property dualism) view. Leibniz seems to believe there is strictly one substance.
Something rather like souls (though not intelligent) could be found everywhere
     Full Idea: Nor is there any reason why souls or things analogous to souls should not be everywhere, even if dominant and consequently intelligent souls, like human souls, cannot be everywhere.
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], §12)
     A reaction: He is always flirting with panpsychism, though he doesn't seem to offer any account of how these little baby souls can be built up to create one intelligent soul, the latter being indivisible. 'Souls' are very different from things 'analous to souls'!
17. Mind and Body / A. Mind-Body Dualism / 4. Occasionalism
Mind and body can't influence one another, but God wouldn't intervene in the daily routine
     Full Idea: It is inconceivable that mind and body should have any influence on one another, and it is unreasonable simply to have recourse to the extraordinary operation of the universal cause in a matter which is ordinary and particular.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §33)
     A reaction: Leibniz was the ultimate intellectual contortionist! Here he is rejecting Cartesian interactionism, and also Malebranche's Occasionalism (God bridges the gap), in order to prepare for his own (daft) theory of what is now called Parallelism.
Occasionalism give a false view of natural laws, miracles, and substances
     Full Idea: Leibniz's three objections to occasionalism are: it disturbs the concept of laws of nature used in physics; it introduces perpetual miracles; and it doesn't recognise activity of substances (leading to the Spinozan heresy that God is the only substance).
     From: report of Gottfried Leibniz (works [1690]) by Nicholas Jolley - Leibniz Ch.2
     A reaction: I wonder what would happen if, within the viewpoint of occasionalism, God suddenly packed up and abandoned his job? Presumably the world wouldn't disappear, so there would still be substances, but passive ones, in chaos.
17. Mind and Body / A. Mind-Body Dualism / 5. Parallelism
Assume that mind and body follow their own laws, but God has harmonised them
     Full Idea: Why not assume that God initially created the soul and body with so much ingenuity that, whilst each follows its own laws and properties and operations, all thing agree most beautifull among themselves? This is the 'hypothesis of concomitance'.
     From: Gottfried Leibniz (A Specimen of Discoveries [1686], p.80)
     A reaction: They may be in beautifully planned harmony, but how do we know that they are in harmony? Presumably their actions must be compared, and God would even have to harmonise the comparison. Parallelism seems to imply epiphenomenalism or idealism.
Maybe mind and body are parallel, like two good clocks
     Full Idea: Two clocks in perfect agreement must be by natural influence, or the control of a craftsman, or their perfect construction at the beginning. Only the third way (of "preestablished harmony" by God) is possible.
     From: Gottfried Leibniz (The Nature and Communication of Substance [1690], p.121)
     A reaction: Presumably 'natural influence' would cover the possibility that (unnoticed by you, apparently) one clock is attached to the other clock at the relevant points. If they are unconnected, presumably they are quite unaware of one another's existence.
The soul does know bodies, although they do not influence one another
     Full Idea: I do not admit that the soul does not know bodies, although this knowledge arises without their influencing one another.
     From: Gottfried Leibniz (New System and Explanation of New System [1696], Reply 11)
     A reaction: He couldn't very well admit this without moving into pure idealism. Presumably it is like "I know her - she'll be in Harrods this morning". I wonder if Satan could steal my body, but my mind continue to believe it was still there?
We should say that body is mechanism and soul is immaterial, asserting their independence
     Full Idea: I think we should keep both sides: we should be more Democritean and make all actions of bodies mechanical and independent of souls, and we should also be more than Platonic and hold that all actions of souls are immaterial and independent of mechanism.
     From: Gottfried Leibniz (On Note L to Bayle's 'Rorarius' [1705], [C])
     A reaction: This is about as dualist as it is possible to get. It certainly looks as if many of Leibniz's doctrines are rebellions against Spinoza (in this case his 'dual aspect monism'). I take Leibniz to be utterly but heroically wrong.
Souls act as if there were no bodies, and bodies act as if there were no souls
     Full Idea: Everything takes place in souls as if there were no body, and everything takes place in bodies as if there were no souls.
     From: Gottfried Leibniz (Principle of Life and Plastic Natures [1705], p.198)
     A reaction: I don't think I have ever encountered a modern thinker who accepts this view. Leibniz rejected Occasionalism, but his account depends entirely on the role of God, to set up the pre-established harmony. Why would God do that?
Perfections of soul subordinate the body, but imperfections of soul submit to the body
     Full Idea: Insofar as the soul has perfection ...God has accommodated the body to the soul, and has arranged beforehand that the body is impelled to execute its orders. Insofar as it is imperfect and confused, God accommodates soul to body, swayed by passions.
     From: Gottfried Leibniz (The Theodicy [1710], p.159), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 3.IV
     A reaction: Perkins says this is the nearest Leibniz gets to the idea of interaction between body and soul. Perfection and confusion are on a continuum for Leibniz. With such speculations I always wonder how these things can be known. How perfect is my mind?
17. Mind and Body / A. Mind-Body Dualism / 7. Zombies
It's impossible, but imagine a body carrying on normally, but with no mind
     Full Idea: If it could be supposed that a body exists without a mind, then a man would do everything in the same way as if he did not have a mind, and men would speak and write the same things, without knowing what they do. ...But this supposition is impossible.
     From: Gottfried Leibniz (Paper of December 1676 [1676], A6.3.400), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 5
     A reaction: This is clearly the zombie dream, three centuries before Robert Kirk's modern invention of the idea. Leibniz's reason for denying the possibility of zombies won't be the modern physicalist reason.
18. Thought / A. Modes of Thought / 3. Emotions / c. Role of emotions
Passions reside in confused perceptions
     Full Idea: The passions of monads reside in their confused perceptions.
     From: Gottfried Leibniz (Letters to Remond de Montmort [1715], 1715)
     A reaction: He thinks perceptions come in degrees of confusion, all the way up to God, who alone has fully clear perceptions. He blames in on these confused perceptions.
18. Thought / A. Modes of Thought / 3. Emotions / f. Emotion and reason
Every feeling is the perception of a truth
     Full Idea: Every feeling is the perception of a truth.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.02)
     A reaction: I wouldn't say feelings ARE perceptions of truths, but I might say that every experience we have has an intellectual dimension as well as an emotional one. Our beliefs drift and solidify in just the same way that feelings do.
18. Thought / C. Content / 2. Ideas
By an 'idea' I mean not an actual thought, but the resources we can draw on to think
     Full Idea: What I mean by an idea is not a certain act of thinking, but a power or faculty such that we have an idea of a thing even if we are not thinking about it but know that we can think it when the occasion arises.
     From: Gottfried Leibniz (What is an Idea? [1676], p.281)
     A reaction: 'Idea' tends to be used in the seventeenth century to mean an actual mental event. It is because Leibniz believes in the unconscious mind that he can offer this rather different, and probably superior, notion of an 'idea'.
True ideas represent what is possible; false ideas represent contradictions
     Full Idea: An idea is true if what it represents is possible; false if the representation contains a contradiction.
     From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.287)
     A reaction: Odd in the analytic tradition to talk of a single idea or concept (rather than a proposition or utterance) as being 'true'. But there is clearly a notion of valid or legitimate or useful concepts here. Hilbert said true just meant non-contradictory.
An idea is an independent inner object, which expresses the qualities of things
     Full Idea: An idea is an immediate inner object, which expresses the nature or qualities of things, ..but since it is the object of thought it can exist before and after the thoughts.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: This sounds something like Frege's 'third realm' between mind and world (Idea 7740). Notice that Leibniz is also using the word 'object' in this context. Leibniz doesn't make the mistake of confusing concepts and images, as many did.
Thoughts correspond to sensations, but ideas are independent of thoughts
     Full Idea: I distinguish ideas from thoughts. For we always have all our pure or distinct ideas independently of the senses, but thoughts always correspond to some sensation.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
     A reaction: Leibniz's concept of an 'idea' is quite different from the empiricist notion of them, and strikes me as being much closer to Frege's notion of a concept. On the whole I like the Leibniz account best.
We must distinguish images from exact defined ideas
     Full Idea: It is essential to distinguish images from exact ideas which are composed of definitions.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.09)
     A reaction: See Idea 12615, which is attacking Descartes and Locke, I think, but fails to register that Spinoza and Leibniz had got the notion of an 'idea' much more clearly.
The idea of green seems simple, but it must be compounded of the ideas of blue and yellow
     Full Idea: It is obvious that green comes from a mixture of blue and yellow; which makes it credible that the idea of green is composed of the ideas of those two colours, although the idea of green appears to us as simple as that of blue.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.07)
     A reaction: This shows the use of 'idea' at that time for non-verbal mental events and concepts. Ideas are not, then, just undestood as phenomena, but can be analysed and explained more deeply.
18. Thought / C. Content / 6. Broad Content
The name 'gold' means what we know of gold, and also further facts about it which only others know
     Full Idea: The name 'gold' signifies not merely what the speaker knows of gold , but also what he does not know, which may be known by someone else: an inner constitution from which flow colour and weight, and generates other properties.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.11)
     A reaction: [compressed] Thus in the course of defending true essences of gold (against Locke's claim that we are stuck with the nominal essence), Leibniz drifts into an externalist account of meaning. He mentions experts, as so often does Putnam.
The word 'gold' means a hidden constitution known to experts, and not just its appearances
     Full Idea: The name 'gold' signifies not only what he who pronounces it knows about it, for example, something very heavy and yellow, but also what he does not know, and that another can know about it, its internal constitution from which colour and weight flow.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 6.6.354), quoted by Nicholas Jolley - Leibniz and Locke on Essences
     A reaction: Leibniz goes on to use the word 'expert'. This isn't just a hint of Putnam's externalism about concepts like 'water' - it is a clear spelling out of the full idea. Locke would have been astounded by 'atomic number 79', and Leibniz would be, like, 'yeah'.
18. Thought / D. Concepts / 1. Concepts / a. Nature of concepts
Concepts are what unite a proposition
     Full Idea: There must always be some basis for the connexion between the terms of a proposition, and it is to be found in their concepts.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 X)
     A reaction: We face the problem that bothered Russell, of the unity of the proposition. We are also led to the question of HOW our concepts connect the parts of a proposition. Do concepts have valencies? Are they incomplete, as Frege suggests?
18. Thought / D. Concepts / 2. Origin of Concepts / a. Origin of concepts
Concepts are ordered, and show eternal possibilities, deriving from God
     Full Idea: Leibniz understood concepts as corresponding to eternal possibilities, with both concepts and their ordering having their foundation in the divine mind.
     From: report of Gottfried Leibniz (works [1690]) by Richard T.W. Arthur - Leibniz 2 'Nominalism'
     A reaction: It is is no longer the fashion to think of concepts as 'ordered', and yet there is a multitude of dependence relations between them.
18. Thought / D. Concepts / 3. Ontology of Concepts / a. Concepts as representations
Our notions may be formed from concepts, but concepts are formed from things
     Full Idea: You assert that the notion of substance is formed from concepts, and not from things. But are not concepts themselves formed from things?
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1699.06.23), quoted by David Wiggins - Sameness and Substance Renewed 5.7
     A reaction: A nice remark, which is true even of highly abstruse, abstract or fanciful concepts. You are still left with the question of how far away from reality you have moved when you construct things from your reality-based concepts.
18. Thought / E. Abstraction / 3. Abstracta by Ignoring
Universals are just abstractions by concealing some of the circumstances
     Full Idea: In forming universals the soul only abstracts certain circumstances by concealing innumerable others. ..A spherical body complete in all respects is nowhere in nature; the soul forms such a notion by concealing aberrations.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704 or 1705)
     A reaction: This is Leibniz's affirmation of traditional 'abstraction by ignoring', which everyone seems to have believed in before Frege, and which I personally think is simply correct, even though it is deeply unfashionable and I keep it to myself.
19. Language / A. Nature of Meaning / 7. Meaning Holism / a. Sentence meaning
Leibniz was the first modern to focus on sentence-sized units (where empiricists preferred word-size)
     Full Idea: Leibniz seems to be the first modern philosopher to focus on sentence-sized units that he called propositions. The Empiricists among the moderns focused on word-sized units like ideas.
     From: report of Gottfried Leibniz (works [1690]) by William D. Hart - The Evolution of Logic 2
     A reaction: Historically, the sentential logic of the Stoics has a claim to have started this one. I find my initial sympathies to be with the empiricists.
20. Action / B. Preliminaries of Action / 2. Willed Action / a. Will to Act
The idea of the will includes the understanding
     Full Idea: The idea of the will includes that of the understanding.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.06)
     A reaction: A nice remark, although I am not sure that I agree with it. The understanding (if we allow such talk of faculties, with which I have no problem) sometimes lags behind and sometimes forges ahead of the will. What else is weakness of the will?
Will is an inclination to pursue something good
     Full Idea: One may say that 'will' consists in the inclination to do something in proportion to the good it contains.
     From: Gottfried Leibniz (The Theodicy [1710], p.136), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.III
     A reaction: This emphasises that the will is faced with options, rather than generating the options. The context is a discussion of the nature of God's will. I think 'will' is a really useful concept, and dislike the Hobbesian rejection of will.
20. Action / B. Preliminaries of Action / 2. Willed Action / d. Weakness of will
Limited awareness leads to bad choices, and unconscious awareness makes us choose the bad
     Full Idea: For Leibniz, while the limits of our knowledge explain why we sometimes choose things we think are good but which turn out to be bad, the force of minute perceptions explains why we sometimes choose things that we know are bad.
     From: report of Gottfried Leibniz (works [1690]) by Franklin Perkins - Leibniz: Guide for the Perplexed 4.IV
     A reaction: To be overwhelmed by selfish greed doesn't sound like a 'minute perception'. Leibniz thinks all desires are reactions to perceptions. Observing our degrees of knowledge is an interesting response to the intellectualist view of weakness of will.
20. Action / C. Motives for Action / 3. Acting on Reason / a. Practical reason
We follow the practical rule which always seeks maximum effect for minimum cost
     Full Idea: In practical affairs one always follows the decision rule in accordance with which one ought to seek the maximum or the minimum: namely, one prefers the maximum effect at the minimum cost, so to speak.
     From: Gottfried Leibniz (On the Ultimate Origination of Things [1697], p.150)
     A reaction: Animals probably do that too, and even water sort of obeys the rule when it runs downhill.
21. Aesthetics / A. Aesthetic Experience / 3. Taste
If would be absurd not to disagree with someone's taste if it was a taste for poisons
     Full Idea: If someone acquired a taste for poisons which would kill him or make him wretched, it would be absurd to say that we ought not to argue with him about his tastes.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: This seems to be a first step in any discussion of taste on which you would hope that sensible persons would agree. 'It is just a matter of taste' is definitely not the end of discussion. Aesthetic taste is important, just as values are important.
21. Aesthetics / A. Aesthetic Experience / 4. Beauty
Beauty increases with familiarity
     Full Idea: The more one is familiar with things, the more beautiful one finds them.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1688.01.4/14)
     A reaction: This is always the reply given to those who say that science kills our sense of beauty. The first step in aesthetic life is certainly to really really pay attention to things.
Leibniz identified beauty with intellectual perfection
     Full Idea: Leibniz identified beauty with intellectual perfection.
     From: report of Gottfried Leibniz (works [1690]) by Sebastian Gardner - Aesthetics 1.2.1
     A reaction: Well he would, wouldn't he? Swots like Leibniz are inclined to value things which only they can fully appreciate. There may be intellectual subject matter in the study of a rose, but I do not believe that it is needed to appreciate the beauty.
21. Aesthetics / B. Nature of Art / 8. The Arts / a. Music
Music charms, although its beauty is the harmony of numbers
     Full Idea: Music charms us although its beauty only consists in the harmony of numbers.
     From: Gottfried Leibniz (Principles of Nature and Grace based on Reason [1714], §17)
     A reaction: 'Only'! This is a super-pythagorean view of music, as you might expect from a great mathematician. Did he understand the horrible compromises that had just been made to achieve even-tempered tuning? Patterns are the key, as always.
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / a. Preconditions for ethics
Animals lack morality because they lack self-reflection
     Full Idea: It is for lack of reflection on themselves that beasts have no moral qualities.
     From: Gottfried Leibniz (Discourse on Metaphysics [1686], §34)
     A reaction: Interesting, but I think this is false. I would say animals do have a sense of their self, because that is the most basic feature of any mind, but what they lack is second-order thought, that is, ability to reflect on and judge their own beliefs and acts.
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / g. Moral responsibility
Humans are moral, and capable of reward and punishment, because of memory and self-consciousness
     Full Idea: For Leibniz, it is by virtue of possessing memory and self-consciousness that human minds are moral beings, capable of reward and punishment.
     From: report of Gottfried Leibniz (works [1690]) by Nicholas Jolley - Leibniz Ch.4
     A reaction: I like this because it makes no mention of free will (though Leibniz struggled to defend free will). I would add meta-thought (the ability to ponder and evaluate our own thinking), which makes a change of mind possible.
22. Metaethics / B. Value / 2. Values / e. Death
Death is just the contraction of an animal
     Full Idea: Death is nothing but the contraction of an animal, just as generation is nothing but its unfolding.
     From: Gottfried Leibniz (Letters to Johann Bernoulli [1699], 1698.11.18)
     A reaction: This is possibly the most bizarre view that I have found in Leibniz. He seemed to thing that if you burnt an animal on a bonfire, some little atom of life would remain among the ashes. I can't see why he would believe such a thing.
Death and generation are just transformations of an animal, augmented or diminished
     Full Idea: Death, like generation, is only the transformation of the same animal, which is sometimes augmented and sometimes diminished.
     From: Gottfried Leibniz (Principle of Life and Plastic Natures [1705], p.195)
     A reaction: Leibniz has a very unusual view of death, since neither minds nor their bodies can ever be wholly destroyed. Death is a kind of shrinking. I suspect that he was wrong about that.
Most people facing death would happily re-live a similar life, with just a bit of variety
     Full Idea: I believe there would be few persons who, being at the point of death, were not content to take up life again, on condition of passing through the same amount of good and evil, provided that it were not the same kind.
     From: Gottfried Leibniz (The Theodicy [1710], p.130), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.IV
     A reaction: Nice challenge. People who refuse the offer are not necessarily suicidal. He's probably right, but Leibniz doesn't recognise the factor of boredom. Look up the suicide note of the actor George Sanders! One life may be enough.
22. Metaethics / B. Value / 2. Values / g. Love
Love is pleasure in the perfection, well-being or happiness of its object
     Full Idea: To love is to be disposed to take pleasure in the perfection, well-being or happiness of the object of one's love.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.20)
     A reaction: I suppose so, though one might love a pathetic little plant that hangs on in the corner of the garden, just for its fighting qualities. He goes on to deny that we can truly love something that is incapable of happiness. Hm.
22. Metaethics / B. Value / 2. Values / j. Evil
Metaphysical evil is imperfection; physical evil is suffering; moral evil is sin
     Full Idea: Evil may be taken metaphysically, physically, and morally. Metaphysical evil consists in mere imperfection, physical evil is suffering, and moral evil is sin.
     From: Gottfried Leibniz (The Theodicy [1710], p.136), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.IV
     A reaction: There seem to be plenty of imperfections in the world which don't look like evil. Or do you only declare it to be an imperfection because it seems to be evil (by some other standard)? Human evil comes from ignorance, so metaphysical explains moral.
22. Metaethics / C. The Good / 1. Goodness / b. Types of good
The good is the virtuous, the pleasing, or the useful
     Full Idea: The good is divided into the virtuous, the pleasing, and the useful. ..The good is either pleasing or useful; and virtue itself consists of a pleasure of the mind.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.20)
     A reaction: I presume that the useful could be reduced to the pleasing. It strikes me as quite bizarre to define virtue as merely a pleasure of the mind. Aristotle says true virtue must also please the mind, but that is a different idea.
22. Metaethics / C. The Good / 1. Goodness / g. Consequentialism
You can't assess moral actions without referring to the qualities of character that produce them
     Full Idea: One is more worthy of praise when one owes the action to one's good qualities, and more culpable in proportion as one has been impelled by one's evil qualities; assessing actions without weighing the qualities whence they spring is to talk at random.
     From: Gottfried Leibniz (The Theodicy [1710], p.426), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 4.IV
     A reaction: Mill tries to separate judgement of the agent from judgement of the consequences of the action, but I think Leibniz has spotted that just judging outcomes ceases to be a 'moral' judgement.
22. Metaethics / C. The Good / 2. Happiness / a. Nature of happiness
Happiness is advancement towards perfection
     Full Idea: Happiness, or lasting contentment, consists of continual advancement towards a greater perfection.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1690.03.23)
     A reaction: To the modern mind this smacks of the sort of hubris to which only the religious mind can aspire, but it's still rather nice. The idea of grubby little mammals approaching perfection sounds wrong, but which other animal has even thought of perfection?
22. Metaethics / C. The Good / 2. Happiness / d. Routes to happiness
Supreme human happiness is the greatest possible increase of his perfection
     Full Idea: The supreme happiness of man consists in the greatest possible increase of his perfection.
     From: Gottfried Leibniz (Of Organum or Ars Magna of Thinking [1679], p.1)
     A reaction: I fear that (being a great intellectual) he had a rather intellectual interpretation of 'perfection'. This is in danger of being a tautology, but if the proposal is given an Aritotelian slant I am sympathetic.
22. Metaethics / C. The Good / 3. Pleasure / a. Nature of pleasure
Intelligent pleasure is the perception of beauty, order and perfection
     Full Idea: An intelligent being's pleasure is simply the perception of beauty, order and perfection.
     From: Gottfried Leibniz (A Résumé of Metaphysics [1697], §18)
     A reaction: Leibniz seems to have inherited this from the Greeks, especially Pythagoras and Plato. Buried in Leibniz's remark I see the Christian fear of physical pleasure. He should have got out more. Must an intelligent being always be intelligent?
Pleasure is a sense of perfection
     Full Idea: Fundamentally, pleasure is a sense of perfection, and pain a sense of imperfection.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
     A reaction: A bit odd, but I like the idea that there is an intellectual aspect to even the most visceral feelings.
23. Ethics / B. Contract Ethics / 2. Golden Rule
We can't want everyone to have more than their share, so a further standard is needed
     Full Idea: We would wish for more than our share if we had our own way; so do we also owe to others more than their share? If the rule applies only to a just will, the rule will need a standard. The rule means that to judge fairly we must adopt others' viewpoints.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.02)
     A reaction: The first part of this is moving towards Kant's rational overview of ethics. Leibniz is wholly right here. All ethics faces the problem that initial values are needed to get it off the ground. What's wrong with pain, or unfairness, or hatred?
23. Ethics / D. Deontological Ethics / 1. Deontology
We want good education and sociability, rather than lots of moral precepts
     Full Idea: The true practical philosophy consists in good rules for education, intercourse and sociability among men, rather than in general precepts on virtues and duties.
     From: Gottfried Leibniz (Letters to Bouvet [1697], p.165)
     A reaction: I would interpret that as saying that the main aim of morality is to enable people to hold a good conversation. I've heard worse theories of morality. The remark shows why Leibniz has little to say explicitly about morality.
25. Social Practice / D. Justice / 2. The Law / c. Natural law
Natural law theory is found in Aquinas, in Leibniz, and at the Nuremberg trials
     Full Idea: Leibniz rejects Hobbes's legal positivism in favour of the older natural law theory associated with Aquinas (which says nothing can be a law unless it derives from natural justice). The older view was revived at Nuremberg, to prosecute Nazis.
     From: report of Gottfried Leibniz (works [1690]) by Nicholas Jolley - Leibniz Ch.7
     A reaction: This seems to suggest that Hobbes and co were using Ockham's Razor to eliminate morality from the law, but that the Nuremberg situation (and modern trials in The Hague) show that there is a necessity for natural law in international situations.
25. Social Practice / D. Justice / 3. Punishment / a. Right to punish
There are natural rewards and punishments, like illness after over-indulgence
     Full Idea: There can be natural rewards and punishments without a law-maker; intemperance, for instance, is punished by illness.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 1.02)
     A reaction: Hm. Maybe if it didn't result in illness it wouldn't be labelled as 'intemperance'. Why isn't studying philosophy all day long classed as intemperance?
26. Natural Theory / A. Speculations on Nature / 1. Nature
The principle of determination in things obtains the greatest effect with the least effort
     Full Idea: There is always in things a principle of determination which is based on consideration of maximum and minimum, such that the greatest effect is obtained with the least, so to speak, expenditure.
     From: Gottfried Leibniz (On the Ultimate Origination of Things [1697], p.347)
     A reaction: This is obvious in human endeavours. Leibniz applied it to physics, producing a principle that shortest paths are always employed. It has a different formal name in modern physics, I think. He says if you make an unrestricted triangle, it is equilateral.
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / b. Limited purposes
A machine is best defined by its final cause, which explains the roles of the parts
     Full Idea: Any machine ...is best defined in terms of its final cause, so that in the description of the parts it is therefore apparent in what way each of them is coordinated with the others for the intended us.
     From: Gottfried Leibniz (The Human Body is a sort of Machine [1683], p.290), quoted by Richard T.W. Arthur - Leibniz 3 'Machines'
     A reaction: We would use the 'function', an inherently teleological concept, and a concept which is almost indispensable for giving an illuminating description of the world. If nature is dispositional, it points towards things. Leibniz views persons as machines.
26. Natural Theory / A. Speculations on Nature / 4. Mathematical Nature
Minds unconsciously count vibration beats in music, and enjoy it when they coincide
     Full Idea: In music, the soul counts the beats of the vibrating object which makes the sound, and when these beats regularly coincide at short intervals, it finds them pleasing. Thus it counts without knowing it.
     From: Gottfried Leibniz (On Note L to Bayle's 'Rorarius' [1705], [L])
     A reaction: Only a mathematician would see music this way! He is defending his account of the unconscious mind. The proposal that we unconsciously count sounds highly implausible. He needs to recognise the patterns that ground mathematics.
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / b. Prime matter
Prime matter is nothing when it is at rest
     Full Idea: Primary matter is nothing if considered at rest.
     From: Gottfried Leibniz (Aristotle and Descartes on Matter [1671], p.90)
     A reaction: This goes with Leibniz's Idea 13393, that activity is the hallmark of existence. No one seems to have been able to make good sense of prime matter, and it plays little role in Aristotle's writings.
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / f. Ancient elements
The true elements are atomic monads
     Full Idea: Monads are the true atoms of nature and, in brief, the elements of things.
     From: Gottfried Leibniz (Monadology [1716], (opening)), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 2
     A reaction: Thus in one sentence Leibniz gives us a theory of natural elements, and an account of atoms. This kind of speculation got metaphysics a bad name when science unravelled a more accurate picture. The bones must be picked out of Leibniz.
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / g. Atomism
I think the corpuscular theory, rather than forms or qualities, best explains particular phenomena
     Full Idea: I still subscribe fully to the corpuscular theory in the explanation of particular phenomena; in this sphere it is of no value to speak of forms or qualities.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 14.07.1686)
     A reaction: I am puzzled by Garber's summary in Idea 12728, and a bit unclear on Leibniz's views on atoms. More needed.
Leibniz rejected atoms, because they must be elastic, and hence have parts
     Full Idea: Leibniz held that there can be no atoms in nature, nothing perfectly solid and hard, since elasticity entails the existence of smaller parts that can move with respect to one another.
     From: report of Gottfried Leibniz (works [1690]) by Daniel Garber - Leibniz:Body,Substance,Monad 5
     A reaction: Thus, I suppose, we discover that atoms have mercurial electron shells. Are quarks or electrons elastic? The debate about true atoms is not over, and probably never will be. Leibniz's point is a good one.
Microscopes and the continuum suggest that matter is endlessly divisible
     Full Idea: Micrographers observe qualities of larger things found in smaller things. And if this proceeds to infinity - which is possible since the continuum is divisible to infinity - any atom will be an infinite species, and there will be worlds within worlds.
     From: Gottfried Leibniz (works [1690], A VI ii 241)
     A reaction: [a work of the 1670s] The microscope had a huge impact on Leibniz, much more than the telescope.
There are atoms of substance, but no atoms of bulk or extension
     Full Idea: Although there are atoms of substance, namely monads, which lack parts, there are no atoms of bulk [moles], that is, atoms of the least possible extension, nor are there any ultimate elements, since a continuum cannot be composed out of points.
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], §11)
     A reaction: Leibniz has a constant battle for the rest of his career to explain what these 'atoms of substance' are, since they have location but no extension, they are self-sufficient yet generate force, and are non-physical but interact with matter.
The only simple things are monads, with no parts or extension
     Full Idea: According to me there is nothing simple except true monads, which have no parts and no extensions.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 5.24)
Atomism is irrational because it suggests that two atoms can be indistinguishable
     Full Idea: There are no two individuals indiscernible from one another - leaves, or drops of water, for example. This is an argument against atoms, which, like the void, are opposed to the principles of a true metaphysic.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 4.04)
Things are infinitely subdivisible and contain new worlds, which atoms would make impossible
     Full Idea: The least corpuscle is actually subdivided ad infinitum and contains a world of new created things, which this universe would lack if this corpuscle were an atom.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 4.PS)
26. Natural Theory / A. Speculations on Nature / 7. Later Matter Theories / a. Early Modern matter
Leibniz struggled to reconcile bodies with a reality of purely soul-like entities
     Full Idea: Leibniz seems never to have made up his mind completely on how to accommodate bodies within a metaphysic which recognises only soul-like entities as fully real.
     From: comment on Gottfried Leibniz (works [1690]) by Nicholas Jolley - Leibniz Intro
     A reaction: [The soul-like entities are his 'monads']. His choice must be to either say they are unreal, or that they are real and separate from the monads, or that they are a manifestation of the monads. His problem, not mine.
Secondary matter is active and complete; primary matter is passive and incomplete
     Full Idea: I understand matter as either secondary or primary. Secondary matter is, indeed, a complete substance, but it is not merely passive; primary matter is merely passive, but it is not a complete substance. So we must add a soul or form...
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], §12), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: It sounds as if primary matter is redundant, but Garber suggests that secondary matter is just the combination of primary matter with form.
Not all of matter is animated, any more than a pond full of living fish is animated
     Full Idea: It must not be said that each portion of matter is animated, just as we do not say that a pond full of fishes is an animated body, although a fish is.
     From: Gottfried Leibniz (Principle of Life and Plastic Natures [1705], p.190)
     A reaction: This is a particularly clear picture of the role of monads in matter. Monads are attached to bodies, which are entirely inanimate, but monads suffuse matter and give it its properties, like particularly bubbly champagne. Cf Idea 19422.
Every particle of matter contains organic bodies
     Full Idea: There is no particle of matter which does not contain organic bodies.
     From: Gottfried Leibniz (Principle of Life and Plastic Natures [1705], p.198)
     A reaction: Cf Idea 19416. There seems to be an interaction problem here (solved, presumably, by pre-established harmony). The organic bodies are there to explain the active behaviour of matter, but the related matter seems intrinsically inert.
Bare or primary matter is passive; it is clothed or secondary matter which contains action
     Full Idea: The active principle is not attributed by me to bare or primary matter, which is merely passive ...but to clothed or secondary matter which in addition contains a primitive entelechy, or active principle.
     From: Gottfried Leibniz (Letters to Wagner [1710], 1710 §2)
     A reaction: Secondary matter contains monads. The puzzling question is what primary matter consists of. It is not atoms, because it is infinitely divisible, and it seems to be composed of corpuscles. But what is it made of? Just gunge? He says it is 'flux'.
26. Natural Theory / A. Speculations on Nature / 7. Later Matter Theories / c. Matter as extension
Leibniz eventually said resistance, rather than extension, was the essence of body
     Full Idea: Leibniz eventually rejected extension altogether as part of the essence of body, and replaced it with resistance.
     From: report of Gottfried Leibniz (works [1690]) by Robert Pasnau - Metaphysical Themes 1274-1671 15.5
     A reaction: This makes body consist of active force, rather than mere geometry. Much better.
Even if extension is impenetrable, this still offers no explanation for motion and its laws
     Full Idea: Even if we grant impenetrability is added to extension, nothing complete is brought about, nothing from which a reason for motion, and especially the laws of motion, can be given.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704 or 1705)
     A reaction: When it comes to the reasons for the so-called 'laws of nature', scientists give up, because they've only got mathematical descriptions, whereas the philosopher won't give up (even though, embarassingly, the evidence is running a bit thin).
26. Natural Theory / C. Causation / 2. Types of cause
In the schools the Four Causes are just lumped together in a very obscure way
     Full Idea: In the schools the four causes are lumped together as material, formal, efficient, and final causes, but they have no clear definitions, and I would call such a judgment 'obscure'.
     From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.283)
     A reaction: He picks this to illustrate what he means by 'obscure', so he must feel strongly about it. Elsewhere Leibniz embraces efficient and final causes, but says little of the other two. This immediately become clearer as the Four Modes of Explanation.
26. Natural Theory / C. Causation / 3. Final causes
Power rules in efficient causes, but wisdom rules in connecting them to final causes
     Full Idea: In all of nature efficient causes correspond to final causes, because everything proceeds from a cause which is not only powerful, but wise; and with the rule of power through efficient causes, there is involved the rule of wisdom through final causes.
     From: Gottfried Leibniz (Metaphysical conseqs of principle of reason [1712], §5)
     A reaction: Nowadays this carrot-and-stick view of causation is unfashionable, but I won't rule it out. The deepest 'why?' we can ask won't just go away. This unity by a divine mind strikes me as too simple, but Leibniz is right to try to unify Aristotelian causes.
26. Natural Theory / C. Causation / 9. General Causation / d. Causal necessity
The connection in events enables us to successfully predict the future, so there must be a constant cause
     Full Idea: There is a connection among our appearances that provides us the means to predict future appearances with success, and this connection must have a constant cause.
     From: Gottfried Leibniz (Letters to Foucher [1675])
Causes can be inferred from perfect knowledge of their effects
     Full Idea: Whoever understands some effect perfectly will also arrive at the knowledge of its cause.
     From: Gottfried Leibniz (Meditatio de principio individui [1676], A6.3.490), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 2
     A reaction: This sounds highly improbable, given that you would have thought that there could be lots of ways to bring about the same effect. Predicting effects is rather more plausible. I suppose if you can record all the ripples in the pond before they fade...
26. Natural Theory / D. Laws of Nature / 1. Laws of Nature
Each possible world contains its own laws, reflected in the possible individuals of that world
     Full Idea: As there exist an infinite number of possible worlds, there exists also an infinite number of laws, some peculiar to one world, some to another, and each individual of any one world contains in the concept of him the laws of his world.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.06)
     A reaction: Since Leibniz's metaphysics is thoroughly God-driven, he will obviously allow God to create any laws He wishes, and hence scientific essentialism seems to be rejected, even though Leibniz is keen on essences. Unless the stuff is different...
God's laws would be meaningless without internal powers for following them
     Full Idea: To say that, in creation, God gave bodies a law for acting means nothing, unless, at the same time, he gave them something by means of which it could happen that the law is followed.
     From: Gottfried Leibniz (On Body and Force, Against the Cartesians [1702], p.253)
     A reaction: This is the beginning of the modern rebellion against the medieval view of laws as imposed from outside on passive matter. Unfortunately for Leibniz, once you have postulated active internal powers, the external laws become redundant.
An entelechy is a law of the series of its event within some entity
     Full Idea: I recognize a primitive entelechy in the active force found in motion, something analogous to the soul, whose nature consists in a certain law of the same series of changes.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1699.03.24)
     A reaction: This is his 'law-of-the-series', which is a speculative attempt to pin down the character of the active essence of things which gives rise to activity. The law of such activity is within the things themselves, as scientific essentialists claim.
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
If there is some trace of God in things, that would explain their natural force
     Full Idea: If the law of God does indeed leave some vestige of him expressed in things...then it must be granted that there is a certain efficacy residing in things, a form or force such as we usually designate by the name of nature, from which the phenomena follow.
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], §06)
     A reaction: I wouldn't rate this as a very promising theory of powers, but it seems to me important that Leibniz recognises the innate power in things as needing explanation. If you remove divine power, you are left with unexplained intrinsic powers.
Qualities should be predictable from the nature of the subject
     Full Idea: Whenever we find some quality in a subject, we ought to believe that if we understood the nature of both the subject and the quality we would conceive how the quality could arise from it.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref 66)
     A reaction: This is the idea that powers are prior to properties, which seems right to me. I take essence to be something like the best explanation of qualities.
Gold has a real essence, unknown to us, which produces its properties
     Full Idea: The complex idea of gold includes its being something which has a real essence whose detailed constitution is unknown to us, except for the fact that such qualities as malleability depend upon it.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.10)
     A reaction: This is precisely the view of modern scientific essentialism. The underlying idea I take to be the conception of essence as the thing which explains the properties.
Part of our idea of gold is its real essence, which is not known to us in detail
     Full Idea: It is very true that it is part of the complex idea of gold that it is a thing which has a real essence, the constitution of which is not otherwise known to us in detail.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 6.6.345), quoted by Nicholas Jolley - Leibniz and Locke on Essences p.201
     A reaction: See also Idea 12807. This is the clearest possible statement of Leibniz's clear-cut scientific essentialism, here presented in opposition to Locke (thought I take the latter to be only bothered by our inability to know the hidden constitution).
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / c. Essence and laws
Each of the infinite possible worlds has its own laws, and the individuals contain those laws
     Full Idea: As there are an infinity of possible worlds, there are also an infinity of laws, some proper to one, another to another, and each possible individual of any world contains in its own notion the laws of its world.
     From: Gottfried Leibniz (On Sufficient Reason [1686], p.95)
     A reaction: Hence Leibniz is not really a scientific essentialist, in that he doesn't think the laws arise out of the nature of the matter consituting the world. I wonder if the primitive matter of bodies which attaches to the monads is the same in each world?
Leibniz wanted to explain motion and its laws by the nature of body
     Full Idea: Leibniz seeks the big picture: the nature of body as a grounding for an account of motion and its laws.
     From: report of Gottfried Leibniz (works [1690]) by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: Garber is contrasting this with Newton's approaches, who just pleads ignorance of the bigger picture. Essentialists must beware of inventing a bigger picture simply because they desperately want a bigger picture.
The law within something fixes its persistence, and accords with general laws of nature
     Full Idea: Nothing is permanent in a substance except the law itself which determines the continuous succession of its states and accords within the individual substance with the laws of nature that govern the whole world.
     From: Gottfried Leibniz (works [1690], G II:263), quoted by David Wiggins - Sameness and Substance 3 epig
     A reaction: An interesting link between the law-of-series within a substance, and the broader concept of laws outside it.
In addition to laws, God must also create appropriate natures for things
     Full Idea: It isn't sufficient to say that God has made a general law, for in addition to the decree there has also to be a natural way of carrying it out. It is necessary, that is, that what happens should be explicable in terms of the God-given nature of things.
     From: Gottfried Leibniz (Letter to the Editor about Bayle [1698], p.205)
     A reaction: Thus Leibniz is an ancestor of scientific essentialism, but he was too frightened to take the next step, which is to see that once God has endowed the natures, he doesn't need to wield his laws as well. The natures will do the whole job.
Gravity is within matter because of its structure, and it can be explained.
     Full Idea: I believe that both gravity and elasticity are in matter only because of the structure of the system and can be explained mechanically or through impulsion.
     From: Gottfried Leibniz (Letters to Thomas Burnett [1703], 1699 draft)
     A reaction: The significance of this remark is that gravity is held (in full knowledge of Newton's work) to be within matter, and not imposed from the outside. I believe we now postulate a particle as part of the explanation.
The only permanence in things, constituting their substance, is a law of continuity
     Full Idea: Nothing is permanent in things except the law itself, which involves a continuous succession ...The fact that a certain law persists ...is the very fact that constitutes the same substance.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704)
     A reaction: Aristotle and Leibniz are the very clear ancestors of modern scientific essentialism. I've left out a few inconvenient bits, about containing 'the whole universe', and containing all 'future states'. For Leibniz, laws are entirely rooted in things.
26. Natural Theory / D. Laws of Nature / 10. Closure of Physics
Leibniz had an unusual commitment to the causal completeness of physics
     Full Idea: Unlike most philosophers prior to the twentieth century, Leibniz was committed to the causal completeness of physics.
     From: report of Gottfried Leibniz (works [1690]) by David Papineau - Thinking about Consciousness 1.4
     A reaction: It has been suggested that Leibniz was actually, in private, a determinist (see Idea 7841), which would fit. Leibniz is enigmatic, but he may have proposed the closure of physics to glorify God, only to find that God was beginning to look irrelevant.
27. Natural Reality / A. Classical Physics / 1. Mechanics / a. Explaining movement
Bodies are recreated in motion, and don't exist in intervening instants
     Full Idea: I have demonstrated that whatever moves is continuously created and that bodies are nothing at any time between the instants in motion.
     From: Gottfried Leibniz (Letters to Thomasius [1669], 1669.04), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1
     A reaction: Leibniz is a little over-confident about what he has 'demonstrated', but I think (from this remark) that he would not have been displeased with quantum theory, and the notion of a 'quantum leap' and a 'Planck time'. A 'conatus' is a 'smallest motion'.
All that is real in motion is the force or power which produces change
     Full Idea: As for motion, what is real in it is force or power; that is to say, what there is in the present state which carries with it a change in the future. The rest is only phenomena and relations.
     From: Gottfried Leibniz (Letter to the Editor about Bayle [1698], §13)
     A reaction: This presumably contradicts Newton's concept of inertia, which allows constant motion without force. I always like a reference to powers. What is 'kinetic energy' in this context?
Maybe motion is definable as 'change of place'
     Full Idea: I believe 'motion' to be definable, and the definition which says that it is 'change of place' deserves respect.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.04)
     A reaction: This seems to be the 'at-at' view of motion, championed by Bertrand Russell. (At p1 at t1, at p2 at t2...). Leibniz's version only mentions space and not time, and it includes 'change', which would need definition without mentioning motion.
27. Natural Reality / A. Classical Physics / 1. Mechanics / c. Forces
Motion alone is relative, but force is real, and establishes its subject
     Full Idea: Motion in itself separated from force is merely relative, and one cannot establish its subject. But force is something real and absolute.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1688.01.4/14)
     A reaction: The striking phrase here is that force enables us to 'establish its subject'. That is, force is at the heart of reality, and hence, through causal relations, individuates objects. That's how I read it.
Leibniz uses 'force' to mean both activity and potential
     Full Idea: At this early period exegetical problems abound, since Leibniz uses 'force' both for actually acting forces and for potentials or powers.
     From: Gottfried Leibniz (works [1690], 9.II), quoted by Harré,R./Madden,E.H. - Causal Powers 9.II.B
     A reaction: I take Leibniz to be a key figure in the development of the Aristotelian approach, because he connected Aristotelian potential and essence with 'force' in the new physics. This is helpful in reading him correctly.
Clearly, force is that from which action follows, when unimpeded
     Full Idea: The notion of force is as clear as that of action and passion, because it is that from which action follows when nothing prevents it.
     From: Gottfried Leibniz (Letters to Paul Pellison-Fontinier [1691], A1.6.226), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: For Leibniz, force seems to be a metaphysical notion, rather than a feature of the physical world. I take it to be the bottom level of explanation, and it equates with Aristotelian form and essence.
We need the metaphysical notion of force to explain mechanics, and not just extended mass
     Full Idea: Considering 'extended mass' alone was not sufficient to explain the principles of mechanics and the laws of nature, but it is necessary to make use of the notion of 'force', which is very intelligible, despite belonging in the domain of metaphysics.
     From: Gottfried Leibniz (New system of communication of substances [1695], p.139)
     A reaction: We may find it surprising that force is a metaphysical concept, but that is worth pondering. It is a mysterious notion within physics. Notice the emphasis on what explains, and what is intelligible. He sees Descartes's system as too passive.
It is plausible to think substances contain the same immanent force seen in our free will
     Full Idea: If we attribute an inherent force to our mind, a force acting immanently, then nothing forbids us to suppose that the same force would be found in other souls or forms, or, if you prefer, in the nature of substances.
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], §10)
     A reaction: This is the kind of bizarre idea that you are driven to, once you start thinking that God must have a will outside nature, and then that we have the same thing. Why shouldn't such a thing pop up all over the place? Only Leibniz spots the slippery slope.
Power is passive force, which is mass, and active force, which is entelechy or form
     Full Idea: The dynamicon or power [potentia] in bodies is twofold, passive and active. Passive force [vis] constitutes matter or mass [massa], and active force constitutes entelechy or form.
     From: Gottfried Leibniz (On Body and Force, Against the Cartesians [1702], p.252)
     A reaction: This is explicitly equating the innate force understood in physics with Aristotelian form. The passive force is to explain the resistance of bodies. I like the equation of force with power. He says the entelechy is 'analogous' to a soul.
All qualities of bodies reduce to forces
     Full Idea: All qualities of bodies .....are in the end reduced [revoco] to forces.
     From: Gottfried Leibniz (On Body and Force, Against the Cartesians [1702], p.256)
     A reaction: The dots conceal a long qualification, but he is essentially standing by this simple remark. If you substitute the word 'powers' for 'forces', I think that is just about right.
The force behind motion is like a soul, with its own laws of continual change
     Full Idea: I recognise, in the active force which exerts itself through motion, the primitive entelechy or in a word, something analogous to the soul, whose nature consists in a certain perpetual law of the same series of changes through which it runs unhindered.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1699), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 6.1.3
     A reaction: This is a hugely metaphysical account of force, contrasting with Newton's largely mathematical account. He very often says that force is 'analogous' to the soul, rather than that it actually is a soul. He never quite believes that monads are real minds.
Force in substance makes state follow state, and ensures the very existence of substance
     Full Idea: By the force I give to substances, I understand a state from which another state follows, if nothing prevents it. ...I dare say that without force, there would be no substance.
     From: Gottfried Leibniz (Letters to Lelong [1712], 1712), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 7.1
     A reaction: [the whole quote is interesting] This remark, more than any other I have found, places force at the centre of Leibniz's metaphysics. He is using it to resist Spinoza's one-substance view.
Some people return to scholastic mysterious qualities, disguising them as 'forces'
     Full Idea: It pleases others to return to occult qualities or scholastic faculties, but since these crude philosophers and physicians see that those terms are in bad repute they change their name, calling them 'forces'.
     From: Gottfried Leibniz (Against Barbaric physics [1716], A&G:313), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 19.7
     A reaction: Deceptive, because Leibniz embraced forces in his revised Aristotelian essentialism. Leibniz placed forces within essences, and he is worried about forces as separate entities, unsupported by any substance.
27. Natural Reality / A. Classical Physics / 2. Thermodynamics / c. Conservation of energy
Leibniz upheld conservations of momentum and energy
     Full Idea: In place of Descartes's conservation of 'quantity of motion', Leibniz upheld both the conservation of linear momentum and the conservation of kinetic energy.
     From: report of Gottfried Leibniz (Letters to Samuel Clarke [1716], 5th paper) by David Papineau - Thinking about Consciousness App 2
     A reaction: The point is that momentum involves velocity (which includes direction) rather than speed. Leibniz more or less invented the concept of 'energy' ('vis viva'). Papineau says these two leave no room for causation by mental substance.
27. Natural Reality / B. Modern Physics / 1. Relativity / a. Special relativity
Motion is not absolute, but consists in relation
     Full Idea: In reality motion is not something absolute, but consists in relation.
     From: Gottfried Leibniz (On Motion [1677], A6.4.1968), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3
     A reaction: It is often thought that motion being relative was invented by Einstein, but Leibniz wholeheartedly embraced 'Galilean relativity', and refused to even consider any absolute concept of motion. Acceleration is a bit trickier than velocity.
27. Natural Reality / C. Space / 2. Space
Space is the order of coexisting possibles
     Full Idea: Extension is the order of coexisting possibles.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20)
     A reaction: [In his next letter he uses the word 'space' instead of 'extension'] This is a rather startling different and modal definition of space. Cf Idea 13181.
27. Natural Reality / C. Space / 4. Substantival Space
The idea that the universe could be moved forward with no other change is just a fantasy
     Full Idea: To say that God could cause the universe to move forward in a straight line or otherwise without changing it in any other way is another fanciful supposition.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 4.14)
27. Natural Reality / C. Space / 5. Relational Space
Space is an order among actual and possible things
     Full Idea: Space is a relationship: an order, not only among existents, but also among possibles as though they existed.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.13)
     A reaction: The modal end to this idea is a bit puzzling. Would there be any space if there were only possibles, and nothing yet existed, as in God's mind the instant before he got to work?
27. Natural Reality / D. Time / 1. Nature of Time / b. Relative time
Space and time are the order of all possibilities, and don't just relate to what is actual
     Full Idea: Space and time taken together constitute the order of possibilities of the one entire universe, so that these orders relate not only to what actually is, but also to anything that could be put in its place.
     From: Gottfried Leibniz (Reply to 'Rorarius' 2nd ed [1702], GP iv 568), quoted by Richard T.W. Arthur - Leibniz 7 'Space and Time'
     A reaction: A very nice idea. Rather like the 'space of reasons', where all rational thought must exist, space and time are the 'space of existence and action'. Their concepts involve more than relations between what actually exists.
Time is the order of inconsistent possibilities
     Full Idea: Time is the order of inconsistent possibilities.
     From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20)
     A reaction: Cf. Idea 13180. This sounds wonderfully bold and interesting, but I can't make much sense of it. One might say it is 'an' order for such things, but 'the' order is weird.
Space and time are purely relative
     Full Idea: I have more than once stated that I held space to be something purely relative, like time.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 3.4)
27. Natural Reality / D. Time / 1. Nature of Time / e. Eventless time
If there were duration without change, we could never establish its length
     Full Idea: If there were a vacuum in space, one could establish its size. But if there were a vacuum in time, i.e. a duration without change, it would be impossible to establish its length.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.15)
     A reaction: See Idea 4226 for Shoemaker's wonderful counterproposal to this apparently unanswerable claim. I suppose Leibniz is right, but it just might be possible to bring induction to bear on the problem.
27. Natural Reality / D. Time / 1. Nature of Time / i. Denying time
Time doesn't exist, since its parts don't coexist
     Full Idea: Time never exists, since all of its parts never exist together.
     From: Gottfried Leibniz (Letters to Paul Pellison-Fontinier [1691], A1.6.226), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 4
     A reaction: The problem here is that he seems to be admitting that time has 'parts'. Can something have parts and not exist? Events will also fail to exist by this criterion, though we could hardly deny that events (or some such) 'happen'.
No time exists except instants, and instants are not even a part of time, so time does not exist
     Full Idea: How could a thing exist, no part of which ever exists? In the case of time, nothing exists but instants, and an instant is not even a part of time.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 5.49)
27. Natural Reality / D. Time / 2. Passage of Time / a. Experience of time
If everything in the universe happened a year earlier, there would be no discernible difference
     Full Idea: To ask why God did not make everything a year sooner would be reasonable if time were something apart from temporal things, but time is just the succession of things, which remains the same if the universe is created a year sooner.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], 3.6)
27. Natural Reality / D. Time / 2. Passage of Time / g. Time's arrow
When one element contains the grounds of the other, the first one is prior in time
     Full Idea: When one of two non-contemporaneous elements contains the grounds for the other, the former is regarded as the antecedent, and the latter as the consequence
     From: Gottfried Leibniz (Metaphysical Foundations of Mathematics [1715], p.201)
     A reaction: Bardon cites this passage of Leibniz as the origin of the idea that time's arrow is explained by the direction of causation. Bardon prefers it to the psychological and entropy accounts.
27. Natural Reality / G. Biology / 2. Life
To regard animals as mere machines may be possible, but seems improbable
     Full Idea: It seems to me that the opinion of those who transform or degrade the lower animals into mere machines, although it seems possible, is improbable, and even against the order of things.
     From: Gottfried Leibniz (New System and Explanation of New System [1696], p.116)
     A reaction: His target is Descartes. 'Against the order of things' seems to beg the question. What IS the order of things? Only a thorough-going dualist would worry about this question, and that isn't me.
27. Natural Reality / G. Biology / 3. Evolution
Men are related to animals, which are related to plants, then to fossils, and then to the apparently inert
     Full Idea: Men are related to animals, these to plants, and the latter directly to fossils which will be linked in their turn to bodies which the senses and the imagination represent to us as perfectly dead and formless.
     From: Gottfried Leibniz (Letters to Varignon [1702], 1702)
     A reaction: Leibniz would be a bit surprised to find the way in which this has turned out to be largely true, since he is basing it on his picture of a hierarchy of monads. Nevertheless, the idea that we are all related wasn't invented in 1859.
28. God / A. Divine Nature / 2. Divine Nature
God's essence is the source of possibilities, and his will the source of existents
     Full Idea: God is the source of possibilities and of existents alike, the one by his essence and the other by his will.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.15)
     A reaction: Every now and then I rebel against metaphysics, and think 'how do these people know all this great things about which they make these dogmatic claims?' And this is one of those occasions. I get the idea, though...
God must be intelligible, to select the actual world from the possibilities
     Full Idea: The cause of the world must be intelligent: for this existing world being contingent and an infinity of worlds being equally possible, with equal claim to existence, the cause of the world must have regarded all of these worlds to fix on one of them.
     From: Gottfried Leibniz (The Theodicy [1710], p.127), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.II
     A reaction: A wonderfully Leibnizian way of putting what looks like the design argument.
God produces possibilities, and thus ideas
     Full Idea: God is the source of possibilities and consequently of ideas.
     From: Gottfried Leibniz (Letters to Remond de Montmort [1715], 1715 §8)
     A reaction: A wonderfully individual conception of the nature of God. He produces the possibilities from which creation is chosen, and ideas and concepts are of everything which is non-contradictory, and thus possible. It all makes lovely sense!
28. God / A. Divine Nature / 3. Divine Perfections
God does everything in a perfect way, and never acts contrary to reason
     Full Idea: We can regard it as certain that everything is done by God in the most perfect way, that he does nothing which is contrary to reason.
     From: Gottfried Leibniz (On Freedom [1689], p.109)
     A reaction: The famous optimism which Voltaire laughed at in 'Candide'. I can't help thinking that there is an ideal of God being ABOVE reason. We reason, and give reasons, because we are unsure, and life is a struggle. The highest ideal is mystically self-evident.
Perfection is simply quantity of reality
     Full Idea: Perfection is simply quantity of reality.
     From: Gottfried Leibniz (A Résumé of Metaphysics [1697], §11)
     A reaction: An interesting claim, but totally beyond my personal comprehension. I presume he inherited 'quantity of reality' from Plato, e.g. as you move up the Line from shadows to Forms you increase the degree of reality. I see 'real' as all-or-nothing.
A perfection is a simple quality, which is positive and absolute, and has no limit
     Full Idea: I call every simple quality which is positive and absolute, or expresses whatever it expresses without any limits, a perfection. But a quality of this sort, because it is simple, is therefore irresolvable or indefinable.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], App X)
     A reaction: I don't think this definition of perfections would have occurred to anyone who wasn't planning to prove that perfections cannot be incompatible (as Leibniz is about to do).
The universe contains everything possible for its perfect harmony
     Full Idea: The universe contains everything that its perfect harmony could admit.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.06)
     A reaction: This sort of Leibnizian remark leaves most modern readers, including me, totally bewildered. The claim depends entirely on the perfect nature of God.
The intelligent cause must be unique and all-perfect, to handle all the interconnected possibilities
     Full Idea: The intelligent cause ought to be infinite in all ways, and absolutely perfect in power, in wisdom, and in goodness, since it relates to all that which is possible. Also, since all is connected together, there is no ground for admitting more than one.
     From: Gottfried Leibniz (The Theodicy [1710], p.128), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.II
     A reaction: Notice that Leibniz's possible worlds seem to be all connected together, unlike David Lewis's worlds, which are discrete. Personally I suspect that all perfections will lead to contradiction, though Leibniz strongly argues against it.
This is the most perfect possible universe, in its combination of variety with order
     Full Idea: From all the possible universes God chooses this one to obtain as much variety as possible, but with the greatest order possible; that is, it is the means of obtaining the greatest perfection possible.
     From: Gottfried Leibniz (Monadology [1716], §58)
28. God / A. Divine Nature / 4. Divine Contradictions
Perfections must have overlapping parts if their incompatibility is to be proved
     Full Idea: If two propositions (about perfections) are incompatible, that cannot be demonstrated without a resolution of the terms, for otherwise their nature would not enter into the ratiocination.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], App X)
     A reaction: If God is omnipotent and wholly free, these appear to be fully separate perfections. But it is their implications (can God decide to do otherwise, given His foreknowledge?) which lead to a problem. So this analyis of contradiction is wrong.
28. God / A. Divine Nature / 5. God and Time
If time were absolute that would make God's existence dependent on it
     Full Idea: Leibniz argues that if time is a thing in itself, and God is 'in' time, then God would be dependent for His existence on the existence of time.
     From: report of Gottfried Leibniz (Letters to Samuel Clarke [1716]) by Adrian Bardon - Brief History of the Philosophy of Time 3 'Newton'
     A reaction: Hence Leibniz says time is merely relations between events. Not sure what he thinks an event is. What is God made of? Is there some divine matter upon which God's existence must depend?
28. God / A. Divine Nature / 6. Divine Morality / a. Divine morality
God prefers men to lions, but might not exterminate lions to save one man
     Full Idea: It is certain that God sets greater store by a man than a lion; nevertheless it can hardly be said with certainty that God prefers a single man in all respects to the whole of lion-kind.
     From: Gottfried Leibniz (The Theodicy [1710], p.189), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.IV
     A reaction: Lovely problems arise when you guess at God's values! We have the same problem. Would you kill a poacher who was wiping out the last remaining lions? How many lions would you kill to save a human?
28. God / A. Divine Nature / 6. Divine Morality / b. Euthyphro question
If justice is arbitrary, or fixed but not observed, or not human justice, this undermines God
     Full Idea: The three dogmas (1) that the nature of justice is arbitrary, (2) it is fixed, but not certain God will observe it, or (3) the justice we know is not that which God observes, destroy our confidence in the love of God.
     From: Gottfried Leibniz (The Theodicy [1710], p.237), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.III
     A reaction: Leibniz proceeds to carefully refute these three responses to the dilemma about how justice relates to God.
28. God / B. Proving God / 1. Proof of God
Without the principle of sufficient reason, God's existence could not be demonstrated
     Full Idea: There is a fundamental axiom that 'nothing happens without reason', without which the existence of God and other great truths cannot be properly demonstrated.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21.13)
     A reaction: I'm rather drawn to the Principle of Sufficient Reason, but also to John Keats's 'negative capability'. Belief that there must be a reason in each case is not a justification for inventing a reason every time. There may be a reason for the universe....
28. God / B. Proving God / 2. Proofs of Reason / a. Ontological Proof
God's existence is either necessary or impossible
     Full Idea: Leibniz said that the ontological argument does not prove God's existence, but only the God's existence is either necessary or impossible.
     From: report of Gottfried Leibniz (works [1690]) by Roger Scruton - Modern Philosophy:introduction and survey 13.5
The concept of an existing thing must contain more than the concept of a non-existing thing
     Full Idea: There must be more in the concept of a thing which exists than in that of one which does not exist.
     From: Gottfried Leibniz (On the Principles of Indiscernibles [1696], p.134)
God is the first reason of things; our experiences are contingent, and contain no necessity
     Full Idea: God is the first reason of things: all that we see and experience is contingent and nothing in them renders their existence necessary.
     From: Gottfried Leibniz (The Theodicy [1710], p.127), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.II
     A reaction: Perkins presents this as the first step in one of Leibniz's arguments for God. They all seem to be variants of the ontological argument. [His 'Theodicy' is the Huggard translation, 1985] This resembles Aquinas's Third Way.
God alone (the Necessary Being) has the privilege that He must exist if He is possible
     Full Idea: God alone (or the Necessary Being) has the privilege that He must exist if He is possible.
     From: Gottfried Leibniz (Monadology [1716], §45)
28. God / B. Proving God / 3. Proofs of Evidence / a. Cosmological Proof
Mechanics shows that all motion originates in other motion, so there is a Prime Mover
     Full Idea: The maxim that there is no motion which has not its origin in another motion, according to the laws of mechanics, leads us again to the Prime Mover.
     From: Gottfried Leibniz (Principle of Life and Plastic Natures [1705], p.194)
     A reaction: This is Leibniz's endorsement (uncredited) to Aquinas's First Way. It is hard to see how the laws of mechanics could have anything to say about the origin of movement. And doesn't the law say that the motions of God need a mover?
The existence of God, and all metaphysics, follows from the Principle of Sufficient Reason
     Full Idea: By this principle alone, that there must be a sufficient reason why things are thus rather than otherwise, I prove the existence of the Divinity, and all the rest of metaphysics or natural theology.
     From: Gottfried Leibniz (Letters to Samuel Clarke [1716], §2)
28. God / B. Proving God / 3. Proofs of Evidence / b. Teleological Proof
If the universe is a perfect agreement of uncommunicating substances, there must be a common source
     Full Idea: The perfect agreement of so many substances which have no communication whatever with each other can only come from a common source.
     From: Gottfried Leibniz (The Nature and Communication of Substance [1690], p.120)
All substances are in harmony, even though separate, so they must have one divine cause
     Full Idea: My system of Pre-established Harmony furnishes a new proof of God's existence, since it is manifest that the agreement of so many substances, of which the one has no influence upon the other, could only come from a general cause on which they all depend.
     From: Gottfried Leibniz (Principle of Life and Plastic Natures [1705], p.192)
     A reaction: Adjacent harmony seems self-explanatory, but remote harmony is interesting evidence for God. Hence modern quantum non-locality should make us all wonder whether there is a deeper explanation.
The laws of physics are wonderful evidence of an intelligent and free being
     Full Idea: These admirable laws [of physics] are wonderful evidence of an intelligent and free being, as opposed to the system of absolute and brute necessity, advocated by Strato and Spinoza.
     From: Gottfried Leibniz (The Theodicy [1710], p.332), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.II
     A reaction: Note the swipe at Spinoza. Leibniz defends the absolute necessities residing in God, but is too polite to call those 'brute', though personally I can't see the difference. But he says the laws arise from 'perfection and order', not from God's necessity.
28. God / B. Proving God / 3. Proofs of Evidence / e. Miracles
Everything, even miracles, belongs to order
     Full Idea: Everything, even miracles, belongs to order.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 X)
     A reaction: This is very reminiscent of Plato, for whom there was no more deeply held belief than that the cosmos is essentially orderly. Coincidences are a nice problem, if they are events with no cause.
Miracles are extraordinary operations by God, but are nevertheless part of his design
     Full Idea: Miracles, or the extraordinary operations of God, none the less belong within the general order; they are in conformity with the principal designs of God, and consequently are included in the notion of this universe, which is the result of those designs.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.05)
     A reaction: Some philosophers just make up things to suit themselves. What possible grounds can he have for claiming this? At best this is tautological, saying that, by definition, if anything at all happens, it must be part of God's design. Move on to Hume…
Allow no more miracles than are necessary
     Full Idea: Miracles should not be increased beyond necessity.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: Leibniz defends miracles (where Spinoza dismisses them). This remark is, of course, an echo of Ockham's Razor, that 'entities' should not be multiplied beyond necessity. It is hard to disagree with his proposal. Zero might be result, though.
28. God / C. Attitudes to God / 2. Pantheism
To say that nature or the one universal substance is God is a pernicious doctrine
     Full Idea: To say that nature itself or the substance of all things is God is a pernicious doctrine, recently introduced into the world or renewed by a subtle or profane author.
     From: Gottfried Leibniz (On Nature Itself (De Ipsa Natura) [1698], 8)
     A reaction: The dastardly profane author is, of course, Spinoza, whom Leibniz had met in 1676. The doctrine may be pernicious to religious orthodoxy, but to me it is rather baffling, since in my understanding nature and God have almost nothing in common.
28. God / C. Attitudes to God / 5. Atheism
Leibniz was closer than Spinoza to atheism
     Full Idea: Leibniz sailed closer to the winds of unbelief than Spinoza did.
     From: report of Gottfried Leibniz (works [1690]) by Matthew Stewart - The Courtier and the Heretic Ch.16
     A reaction: This is an unusual view, but Stewart's view is that whereas Spinoza is always sincere in his writings, Leibniz is inclined to put a very conservative spin on his opinions. A key question for Leibniz is "Is God merely a monad?"
29. Religion / D. Religious Issues / 1. Religious Commitment / a. Religious Belief
Prayers are useful, because God foresaw them in his great plan
     Full Idea: Not only cares and labours but also prayers are useful; God having had these prayers in view before he regulated things.
     From: Gottfried Leibniz (The Theodicy [1710], Abridge III)
     A reaction: Hm. I'm struggling with this one. So I can't skip prayers today, because God has foreseen them and included them in his great plan? Hard to motivate yourself, like starting a game of chess after you've already been declared the winner.
29. Religion / D. Religious Issues / 2. Immortality / a. Immortality
Immortality without memory is useless
     Full Idea: Immortality without memory would be useless.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.07.4/14 X)
     A reaction: I would say that having a mind of any sort needs memory. The question for immortality is whether it extends back to human life. See 'Wuthering Heights' (c. p90) for someone who remembers Earth as so superior to paradise that they long to return there.
29. Religion / D. Religious Issues / 2. Immortality / b. Soul
The soul is indestructible and always self-aware
     Full Idea: Not only is the soul indestructible, but it always knows itself and remains self-conscious.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.11)
     A reaction: Personally I am not even self-aware during much of my sleeping hours, and I would say that I cease to be self-aware if I am totally absorbed in something on which I concentrate.
29. Religion / D. Religious Issues / 2. Immortality / c. Animal Souls
Animals have souls, but lack consciousness
     Full Idea: It appears probable that animals have souls although they lack consciousness.
     From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.11)
     A reaction: Personally I would say that they lack souls but have consciousness, but then I am in no better position to know the answer than Leibniz was. Arnauld asks what would happen to the souls of 100,000 silkworms if they caught fire!
Animals have thought and sensation, and indestructible immaterial souls
     Full Idea: I hold (against the Cartesians) that brutes also have thought, and hold that they have sensation, and souls which are, properly speaking, immaterial, and as incapable of perishing as the atoms of Democritus or Gassendi.
     From: Gottfried Leibniz (New Essays on Human Understanding [1704], Pref)
     A reaction: Insect heaven will be a bit crowded. I can never grasp why theologians would claim that souls are 'indestructible', when they are held to come into existence at a particular moment in space-time. Transmigration of souls is a much more rational belief.
29. Religion / D. Religious Issues / 3. Problem of Evil / a. Problem of Evil
Evil is a negation of good, which arises from non-being
     Full Idea: The cause of good is positive, but evil is a defect, that is, a privation or negation, and consequently, it arises from nothingness or nonbeing.
     From: Gottfried Leibniz (Dialogue on human freedom and origin of evil [1695], p.114)
     A reaction: He goes on to illustrate his idea from mathematics. He is modifying Augustine's view that evil is an absence of good, by adding nonbeing as the driving force behind it. Doesn't sound very persuasive to me.
God only made sin possible because a much greater good can be derived from it
     Full Idea: We must believe that God would not have allowed sin nor would he have created things he knows will sin, if he could not derive from them a good incomparably greater than the resulting evil.
     From: Gottfried Leibniz (Dialogue on human freedom and origin of evil [1695], p.115)
     A reaction: Why 'must' we believe this? Do we have to imagine all the genocides shrinking to insignificance once we grasp the wonderful goods that can be derived from them? The end justifies the means. Genocide is actually a good thing. Hm.
How can an all-good, wise and powerful being allow evil, sin and apparent injustice?
     Full Idea: There is this question of natural theology, how a sole Principle, all-good, all-wise and all-powerful, has been able to admit evil, and especially to permit sin, and how it could resolve to make the wicked often happy and the good unhappy?
     From: Gottfried Leibniz (The Theodicy [1710], p.098), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.IV
     A reaction: His answer is, roughly, that there is an unavoidable trade-off, which humans cannot fully understand. Personally I would say that if there is a God, the evidence for his benevolence towards humanity is not encouraging.
Being confident of God's goodness, we disregard the apparent local evils in the visible world
     Full Idea: Being made confident by demonstrations of the goodness and the justice of God, we disregard the appearances of harshness and justice which we see in this small portion of his Kingdom that is exposed to our gaze.
     From: Gottfried Leibniz (The Theodicy [1710], p.120), quoted by Franklin Perkins - Leibniz: Guide for the Perplexed 2.IV
     A reaction: Hm. If this locality is full of evils, and the rest of it is much better, how come we are stuck in this miserable corner of things? God is obliged to compromise, but did he select us to get the worst of it?
29. Religion / D. Religious Issues / 3. Problem of Evil / b. Human Evil
God doesn't decide that Adam will sin, but that sinful Adam's existence is to be preferred
     Full Idea: God does not decide whether Adam should sin, but whether that series of things in which there is an Adam whose perfect individual notion involves sin should nevertheless be preferred to others.
     From: Gottfried Leibniz (A Specimen of Discoveries [1686], p.78)
     A reaction: Compare whether the person responsible for setting a road speed limit is responsible for subsequent accidents. Leibniz's belief that the world could have been made no better than it is (by an omnipotent being) strikes me as blind faith, not an argument.
Evil serves a greater good, and pain is necessary for higher pleasure
     Full Idea: Evils themselves serve a greater good, and the fact that pains are found in minds is necessary if they are to reach greater pleasures.
     From: Gottfried Leibniz (A Résumé of Metaphysics [1697], §23)
     A reaction: How much pain is needed to qualify for the 'greater pleasures'? Some people receive an awful lot. I am not sure exactly how an evil can 'serve' a greater good. Is he recommending evil?