Ideas of René Descartes, by Theme

[French, 1596 - 1650, Born at La Haye. Pupil at Jesuit College. Lived mostly in Holland. Died working for Queen Christina in Stockholm.]

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1. Philosophy / B. History of Ideas / 5. Later European Thought
Modern science comes from Descartes' view that knowledge doesn't need moral purity
     Full Idea: Before Descartes, one could not be impure, immoral, and know the truth. After Descartes, direct evidence is enough, and we have a nonascetic subject of knowledge; this change makes possible the institutionalisation of modern science.
     From: report of René Descartes (Meditations [1641]) by Michel Foucault - On the Genealogy of Ethics
     A reaction: I would have thought Gassendi and the British Empiricists would be a more plausible source for this shift of attitude. Plato would relegate modern science to a lower level of knowledge.
1. Philosophy / D. Nature of Philosophy / 1. Philosophy
Slow and accurate thought makes the greatest progress
     Full Idea: Those who go forward only very slowly can progress much further if they always keep to the right path, than those who run and wander off it.
     From: René Descartes (A Discourse on Method [1637], §1.2)
     A reaction: Like Descartes' 'Method'. This seems to place a low value on 'nous' or intuition.
1. Philosophy / D. Nature of Philosophy / 2. Invocation to Philosophy
The greatest good for a state is true philosophers
     Full Idea: The greatest good which can exist in a state is to have true philosophers.
     From: René Descartes (Principles of Philosophy [1646], Pref)
     A reaction: …because they understand true reality, especially the Good.
1. Philosophy / D. Nature of Philosophy / 7. Despair over Philosophy
Clever scholars can obscure things which are obvious even to peasants
     Full Idea: Scholars are usually ingenious enough to find ways of spreading darkness even in things which are obvious by themselves, and which the peasants are not ignorant of.
     From: René Descartes (Rules for the Direction of the Mind [1628], 12)
     A reaction: Wonderful! I see it everywhere in philosophy. It is usually the result of finding ingenious and surprising grounds for scepticism. The amazing thing is not their lovely arguments, but that fools then take their conclusions seriously. Modus tollens.
Most things in human life seem vain and useless
     Full Idea: Looking at the various activities and enterprises of mankind with the eye of a philosopher, there is hardly one which does not seem to me vain and useless.
     From: René Descartes (A Discourse on Method [1637], §1.3)
     A reaction: Well, yes. The obvious retort is that everything is vain and useless; or if not, then certainly metaphysics is. Useful for what? Is ornamental gardening useless, or sport? Art? What is the use of cosmology? He's right, of course.
Almost every daft idea has been expressed by some philosopher
     Full Idea: There is nothing one can imagine so strange or so unbelievable that has not been said by one or other of the philosophers.
     From: René Descartes (A Discourse on Method [1637], §2.16)
     A reaction: Actually I think that extensive areas of logical possibilities for existence remain totally unexplored. On the other hand, most of the metaphysical beliefs of most of the human race, including the majority of philosophers, strike me as being false.
1. Philosophy / E. Nature of Metaphysics / 4. Metaphysics as Science
Metaphysics is the roots of the tree of science
     Full Idea: The whole of philosophy is like a tree. The roots are metaphysics, the trunk is physics, and the branches emerging from the trunk are all the other sciences.
     From: René Descartes (Preface to 'Principles of Philosophy' [1647]), quoted by A.W. Moore - The Evolution of Modern Metaphysics 01.2
     A reaction: If Descartes had not believed this he would not have bothered with metaphysics, and philosophy might have been dead by 1650.
1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
Most scholastic disputes concern words, where agreeing on meanings would settle them
     Full Idea: The questions on which scholars argue are almost always questions of word. …If philosophers were agreed on the meaning of words, almost all their controversies would cease.
     From: René Descartes (Rules for the Direction of the Mind [1628], 13)
     A reaction: He has a low opinion of 'scholars'! It isn't that difficult to agree on the meanings of key words, in a given context. The aim isn't to get rid of the problems, but to focus on the real problems. Some words contain problems.
1. Philosophy / G. Scientific Philosophy / 3. Scientism
My Meditations are the complete foundation of my physics
     Full Idea: My six Meditations contain all the foundations of my physics, …and their principles destroy those of Aristotle.
     From: René Descartes (Letters to Mersenne [1640], 1641.01.28)
2. Reason / A. Nature of Reason / 2. Logos
Descartes impoverished the classical idea of logos, and it no longer covered human experience
     Full Idea: Descartes attacked and fundamentally altered classical logos. The result is an impoverished conception of reason, one that is unable to do justice to the significance and value of human experience.
     From: comment on René Descartes (Meditations [1641]) by David Roochnik - The Tragedy of Reason Prol. Xii
2. Reason / A. Nature of Reason / 4. Aims of Reason
The secret of the method is to recognise which thing in a series is the simplest
     Full Idea: It is necessary, in a series of objects, to recognise which is the simplest thing, and how all the others depart from it. This rule contains the whole secret of the method.
     From: René Descartes (Rules for the Direction of the Mind [1628], 06)
     A reaction: This is an appealing thought, though deciding the criteria for 'simplest' looks tough. Are electrons, for example, simple? Is a person a simple basic thing?
Methodical thinking is cautious, analytical, systematic, and panoramic
     Full Idea: Descartes' four principles for his method of thinking are: be cautious, analyse the problem, be systematic from simple to complex, and keep an overview of the problem
     From: report of René Descartes (A Discourse on Method [1637], §2.18) by PG - Db (ideas)
Reason says don't assent to uncertain principles, just as much as totally false ones
     Full Idea: Reason now persuades me that I should withhold my assent no less carefully from opinions that are not completely certain and indubitable than I would from those that are patently false.
     From: René Descartes (Meditations [1641], §1.18)
2. Reason / A. Nature of Reason / 5. Objectivity
One truth leads us to another
     Full Idea: One truth discovered helps us to discover another.
     From: René Descartes (Rules for the Direction of the Mind [1628], 01)
     A reaction: I take this to be one of the key ingredients of objectivity. People who know very little have almost no chance of objectivity. A mind full of falsehoods also blocks it.
2. Reason / A. Nature of Reason / 7. Status of Reason
Since Plato all philosophers have followed the herd, except Descartes, stuck in superficial reason
     Full Idea: Since Plato all philosophers have followed moral 'instinct', or 'faith', or (as I call it) 'the herd'. One might exclude Descartes, the father of rationalism, who recognised only reason - but reason is only an instrument, and Descartes was superficial.
     From: comment on René Descartes (Meditations [1641]) by Friedrich Nietzsche - Beyond Good and Evil §191
2. Reason / F. Fallacies / 4. Circularity
Clear and distinct conceptions are true because a perfect God exists
     Full Idea: That the things we grasp very clearly and very distinctly are all true, is assured only because God is or exists, and because he is a perfect Being.
     From: René Descartes (A Discourse on Method [1637], §4.38)
It is circular to make truth depend on believing God's existence is true
     Full Idea: How does the author avoid reasoning in a circle when he says that we are sure that what we clearly and distinctly perceive is true only because God exists? But we can be sure that God exists only because we clearly and distinctly perceive this.
     From: comment on René Descartes (Meditations [1641], §5.71) by Antoine Arnauld - Objections to 'Meditations' (Fourth) 214
Descartes is right that in the Christian view only God can guarantee the reliability of senses
     Full Idea: Even Descartes had a notion that in a Christian mode of thought (where God is a good creator), only God's veracity guarantees to us the judgements of our senses.
     From: comment on René Descartes (Meditations [1641], §5.71) by Friedrich Nietzsche - The Will to Power (notebooks) §436
     A reaction: An unusual defence of the notorious Cartesian Circle. Of course, Descartes claims that God guarantees reason (as 'clear and distinct conception'), not senses, and only reason led Descartes to God.
Once it is clear that there is a God who is no deceiver, I conclude that clear and distinct perceptions must be true
     Full Idea: Once I perceived that there is a God,…and that he is no deceiver, I then concluded that everything that I clearly and distinctly perceived is necessarily true.
     From: René Descartes (Meditations [1641], §5.70)
     A reaction: spotted by Arnauld
I know the truth that God exists and is the author of truth
     Full Idea: I have very clearly deduced the following truths, that there is a God who is the author of all that is in the world, and who is the source of all truth.
     From: René Descartes (Preface to 'Principles of Philosophy' [1647], p.180)
3. Truth / A. Truth Problems / 2. Defining Truth
Truth is such a transcendentally clear notion that it cannot be further defined
     Full Idea: Truth is such a transcendentally clear notion that it cannot be further defined.
     From: René Descartes (Letters to Mersenne [1640], 1642), quoted by Pascal Engel - Truth Intro
     A reaction: This is the view endorsed by Davidson. It is tempting to take basic concepts as axiomatic, but philosophers can't make that move every time they are in trouble. I have to say, though, that truth is a good candidate.
3. Truth / A. Truth Problems / 8. Subjective Truth
Truth is clear and distinct conception - of which it is hard to be sure
     Full Idea: I take it as a general rule that the things we conceive very clearly and very distinctly are all true, but that there is merely some difficulty in properly discerning which are those which we distinctly conceive.
     From: René Descartes (A Discourse on Method [1637], §4.33)
My general rule is that everything that I perceive clearly and distinctly is true
     Full Idea: I now seem able to posit as a general rule that everything I very clearly and distinctly perceive is true.
     From: René Descartes (Meditations [1641], §3.35)
Someone may think a thing is 'clear and distinct', but be wrong
     Full Idea: Leibniz objected to Descartes' theory of truth, saying that people may think something is clear and distinct, and yet be wrong.
     From: comment on René Descartes (Meditations [1641], §3.36) by Gottfried Leibniz - works
     A reaction: Quite so. Descartes has misunderstood what sort of concept 'truth' is meant to be. It's the usual confusion of epistemology and metaphysics. Truth is not a feature of the human mind.
3. Truth / D. Coherence Truth / 1. Coherence Truth
All items of possible human knowledge are interconnected, and can be reached by inference
     Full Idea: All the items of knowledge that lie within the reach of the human mind are linked together with a marvellous bond, and can be derived from each other by necessary inferences.
     From: René Descartes (unfinished dialogue [1649])
     A reaction: It does seem that God ought to be able to infer all empirical facts from first principles. But how do you get started?
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
Arithmetic and geometry achieve some certainty without worrying about existence
     Full Idea: Arithmetic, geometry and sciences of that kind only treat of things without taking any great trouble to ascertain whether they are actually existent or not, and contain some measure of certainty.
     From: René Descartes (Meditations [1641], §1), quoted by Alan Musgrave - Logicism Revisited §4
     A reaction: This is Musgrave's earliest quotation which seems to take the if-thenist view.
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
Surely maths is true even if I am dreaming?
     Full Idea: Surely whether I am asleep or awake, two plus three makes five, and a square does not have more than four sides.
     From: René Descartes (Meditations [1641], §1.20)
I can learn the concepts of duration and number just from observing my own thoughts
     Full Idea: When I think that I exist now, and recollect that I existed in the past, and when I conceive various thoughts, the number of which I know, then I acquire the ideas of duration and number which I can thereafter transfer to all the other objects I wish.
     From: René Descartes (Meditations [1641], §3.44)
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Descartes showed a one-one order-preserving match between points on a line and the real numbers
     Full Idea: Descartes founded analytic geometry on the assumption that there is a one-one order-preserving correspondence between the points on a line and the real numbers.
     From: report of René Descartes (works [1643]) by William D. Hart - The Evolution of Logic 1
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / a. Units
Unity is something shared by many things, so in that respect they are equals
     Full Idea: Unity is that common nature in which all things that are compared with each other must participate equally.
     From: René Descartes (Rules for the Direction of the Mind [1628], 14)
     A reaction: A lovely explanation of the concept of 'units' for counting. Fregeans hate units, but we Grecian thinkers love them.
I can only see the proportion of two to three if there is a common measure - their unity
     Full Idea: I do not recognise what the proportion of magnitude is between two and three, unless I consider a third term, namely unity, which is the common measure of the one and the other.
     From: René Descartes (Rules for the Direction of the Mind [1628], 14)
     A reaction: A striking defence of the concept of the need for the unit in arithmetic. To say 'three is half as big again', you must be discussing the same size of 'half' in each instance.
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / c. Against mathematical empiricism
It is possible that an omnipotent God might make one and two fail to equal three
     Full Idea: Since every basic truth depends on God's omnipotence, I would not dare to say that God cannot make it....that one and two should not be three.
     From: René Descartes (Letters to Antoine Arnauld [1645]), quoted by A.W. Moore - The Evolution of Modern Metaphysics 01.3
     A reaction: An unusual view. Most people would say that if Descartes can doubt something that simple, he should also doubt his reasons for believing in God's existence.
7. Existence / A. Nature of Existence / 3. Being / d. Non-being
Among the simples are the graspable negations, such as rest and instants
     Full Idea: Among the simple things, we must also place their negation and deprivation, insofar as they fall under out intelligence, because the idea of nothingness, of the instant, of rest, is no less true an idea than that of existence, of duration, of motion.
     From: René Descartes (Rules for the Direction of the Mind [1628], 12)
     A reaction: He sees the 'simple' things as the foundation of all knowledge, because they are self-evident. Not sure about 'no less true', since the specific nothings are parasitic on the somethings.
7. Existence / C. Structure of Existence / 5. Supervenience / c. Significance of supervenience
Two things being joined together doesn't prove they are the same
     Full Idea: The fact that we often see two things joined together does not license the inference that they are one and the same.
     From: René Descartes (Reply to Sixth Objections [1641], 444)
     A reaction: Correct. The problem comes when they are never ever apart, and you begin to suspect that they are conjoined in all possible worlds. Why might this be so? It can only be identity or a causal link.
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
Incorporeal substances are powers or forces
     Full Idea: In one of his last letters Descartes describes incorporeal substances as 'powers or forces'.
     From: report of René Descartes (Two letters on mind [1649], Feb 1649) by Robert Pasnau - Metaphysical Themes 1274-1671 08.4
     A reaction: Only a glimmer, but I really like this idea. (Ellis flirts with it somewhere). Minds are deeply and intrinsically active things. Try ceasing to think for five minutes. Apparently 12th century Cistercian authors were keen on the idea.
8. Modes of Existence / C. Powers and Dispositions / 3. Powers as Derived
All powers can be explained by obvious features like size, shape and motion of matter
     Full Idea: There are no powers in stones and plants that are not so mysterious that they cannot be explained …from principles that are known to all and admitted by all, namely the shape, size, position, and motion of particles of matter.
     From: René Descartes (Principles of Philosophy [1646], IV.187), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 23.6
     A reaction: This is an invocation of 'categorical' properties, against dispositions. I take this to be quite wrong. The explanation goes the other way. What supports the structures; what drives the motion; what initiates anything?
8. Modes of Existence / D. Universals / 1. Universals
Five universals: genus, species, difference, property, accident
     Full Idea: The five commonly enumerated universals are: genus, species, difference, property and accident.
     From: René Descartes (Principles of Philosophy [1646], I.59)
     A reaction: Interestingly, this seems to be Descartes passing on his medieval Aristotelian inheritance, in which things are defined by placing them in a class, and then noting what distinguishes them within that class.
8. Modes of Existence / E. Nominalism / 2. Resemblance Nominalism
A universal is a single idea applied to individual things that are similar to one another
     Full Idea: Universals arise solely from the fact that we avail ourselves of one idea in order to think of all individual things that have a certain similitude. When we understand under the same name all the objects represented by this idea, that name is universal.
     From: René Descartes (Principles of Philosophy [1646], I.59)
     A reaction: Judging by the boldness of the pronouncement, it looks as if Descartes hasn't recognised the complexity of the problem. How do we spot a 'similarity', especially an abstraction like 'tool' or 'useful'? This sounds like Descartes trying to avoid Platonism.
9. Objects / B. Unity of Objects / 1. Unifying an Object / c. Unity as conceptual
If I can separate two things in my understanding, then God can separate them in reality
     Full Idea: My ability clearly and distinctly to understand one thing without another suffices to make me certain that the one thing is different from the other, since they can be separated from each other (at least by God).
     From: René Descartes (Meditations [1641], §6.78)
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
Knowing the attributes is enough to reveal a substance
     Full Idea: I have never thought that anything more is required to reveal a substance than its various attributes.
     From: René Descartes (Reply to Fifth Objections [1641], 360)
If we perceive an attribute, we infer the existence of some substance
     Full Idea: Based on perceiving the presence of some attribute, we conclude there must also be present an existing thing or substance to which it can be attributed.
     From: René Descartes (Principles of Philosophy [1646], I.52), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 08.1
     A reaction: A rainbow might be a tricky case. This illustrates the persistent belief in substances, even among philosophers who embraced the new corpuscular and mechanistic view of matter.
9. Objects / B. Unity of Objects / 2. Substance / d. Substance defined
A substance needs nothing else in order to exist
     Full Idea: By substance we can understand nothing else than a thing which so exists that it needs no other thing in order to exist.
     From: René Descartes (Principles of Philosophy [1646], I.51)
     A reaction: Properties, of course, are the things which have dependent existence. Can properties be reduced to substances (e.g. by adopting a materialist theory of mind)? Note that Descartes does not think that substances depend on God for existence.
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
Substance cannot be conceived or explained to others
     Full Idea: The alleged naked, or rather hidden, substance of wax is something that we can neither ourselves conceive nor explain to others.
     From: comment on René Descartes (Meditations [1641], §2.31) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 273
Descartes thinks distinguishing substances from aggregates is pointless
     Full Idea: Descartes thinks it is a pointless relic of scholastic metaphysics to dispute over the boundaries between substances and mere aggregates.
     From: report of René Descartes (works [1643]) by Robert Pasnau - Metaphysical Themes 1274-1671 25.6
     A reaction: This is Pasnau's carefully considered conclusion, with which others may not agree. It presumably captures the attitude of modern science generally to such issues.
9. Objects / C. Structure of Objects / 7. Substratum
If we remove surface qualities from wax, we have an extended, flexible, changeable thing
     Full Idea: After taking away what does not belong to the wax, let us see what is left: surely, it is nothing other than a thing that is extended, flexible and changeable.
     From: René Descartes (Meditations [1641], (VII:30-1)), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 08.2
     A reaction: Aristotle worried about nothing being left when you 'stripped' an object, so this could be seen as a positive contribution to scholastic philosophy. Why is the substrate 'flexible'? He talks elsewhere of taking the clothes off the wax and seeing it naked.
9. Objects / D. Essence of Objects / 4. Essence as Definition
Descartes gives an essence by an encapsulating formula
     Full Idea: For Descartes in providing an essence for an item [such as God, wax, or a mathematical kind] we provide an encapsulating formula defining the phenomenon.
     From: report of René Descartes (Meditations [1641]) by Joseph Almog - Nature Without Essence I
     A reaction: I argue that this is not what Aristotle intended be an essentialist definition, which can be quite long, like a scientific monograph. Descartes firmly rejected Aristotle's 'substantial form' as essence.
9. Objects / D. Essence of Objects / 9. Essence and Properties
A substance has one principal property which is its nature and essence
     Full Idea: Each substance has one principal property that constitutes its nature and essence, to which all its other properties are referred. Extension in length, breadth, and depth constitutes the nature of corporeal substance; and thought of thinking substances.
     From: René Descartes (Principles of Philosophy [1646], I.53), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 08.3
     A reaction: Property is likely to be 'propria', which is a property distinctive of some thing, not just any old modern property. This is quite a strikingly original view of the nature of essence. Descartes despised 'substantial forms'.
9. Objects / D. Essence of Objects / 15. Against Essentialism
Substantial forms are not understood, and explain nothing
     Full Idea: Clearly no explanation can be given by these substantial forms for any natural action, since their defenders admit that they are occult and that they do not understand them themselves, ...so they explain nothing.
     From: René Descartes (Letters to Regius [1642], 1642.01), quoted by David S. Oderberg - Real Essentialism 267 n5
     A reaction: [Oderberg gives refs for attack by Locke and Hume, p.66] Descartes' target is Aristotle's hylomorphism. The problem seems to be understanding what Aristotle meant, which is much more than mere 'shape'. More like 'controlling principle'.
10. Modality / C. Sources of Modality / 4. Necessity from Concepts
3+4=7 is necessary because we cannot conceive of seven without including three and four
     Full Idea: When I say that four and three make seven, this connection is necessary, because one cannot conceive the number seven distinctly without including in it in a confused way the number four and the number three.
     From: René Descartes (Rules for the Direction of the Mind [1628], 12)
     A reaction: This seems to make the truths of arithmetic conceptual, and hence analytic.
10. Modality / D. Knowledge of Modality / 1. A Priori Necessary
We know by thought that what is done cannot be undone
     Full Idea: Some ideas belong exclusively to the mind, such as perceiving that what has been done cannot be undone, and everything else that is known by the light of nature.
     From: René Descartes (Meditations [1641], §6.82)
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / b. Conceivable but impossible
Pythagoras' Theorem doesn't cease to be part of the essence of triangles just because we doubt it
     Full Idea: You can't reason 'I know the triangle is right-angled, but I doubt Pythagoras' Theorem, therefore it does not belong to the essence of right-angled triangles that the square on the hypotenuse is equal to the sum of the squares on the other two sides'.
     From: comment on René Descartes (Meditations [1641], §6.78) by Antoine Arnauld - Objections to 'Meditations' (Fourth) 202
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
We can believe a thing without knowing we believe it
     Full Idea: The action of thought by which one believes a thing, being different from that by which one knows that one believes it, they often exist the one without the other.
     From: René Descartes (A Discourse on Method [1637], §3.23)
11. Knowledge Aims / A. Knowledge / 4. Belief / d. Cause of beliefs
Belief is not an intellectual state or act, because propositions are affirmed or denied by the will
     Full Idea: Descartes claimed that belief is not purely an intellectual state or act, since it is not the intellect that affirms or denies a proposition proposed for its consideration, but the will.
     From: report of René Descartes (Meditations [1641], IV) by Linda Trinkaus Zagzebski - Virtues of the Mind 4.2
     A reaction: This is the canonical idea of 'doxastic voluntarism' - that we choose what to believe or not believe. In modern times this view has become deeply unfashionable. I don't we should wholly reject the possibility of choosing to believe something.
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
If we accept mere probabilities as true we undermine our existing knowledge
     Full Idea: It is better never to study than to be unable to distinguish the true from the false, and be obliged to accept as certain what is doubtful. One risks losing the knowledge one already has. Hence we reject all those knowledges which are only probable.
     From: René Descartes (Rules for the Direction of the Mind [1628], 02)
     A reaction: This is usually seen nowadays (and I agree) that this is a false dichotomy. Knowledge can't be all-or-nothing. We should accept probabilities as probable, not as knowledge. Probability became a science after Descartes.
In pursuing truth, anything less certain than mathematics is a waste of time
     Full Idea: In our search for the direct road towards truth we should busy ourselves with no object about which we cannot attain a certitude equal to that of the demonstrations of Arithmetic and Geometry.
     From: René Descartes (Rules for the Direction of the Mind [1628], Rule II), quoted by Alain Badiou - Mathematics and Philosophy: grand and little p.8
     A reaction: A beautiful statement of the way in which rationalist philosophy was founded on the model of mathematics (esp. Euclid), with all its concomitant problems. The most important concept of the last hundred years may well be fallibilist rationalism.
In morals Descartes accepts the conventional, but rejects it in epistemology
     Full Idea: Descartes' procedure for treating values (accepting normal conventions when faced with uncertainty) is the exact antithesis of that used to attain knowledge.
     From: comment on René Descartes (A Discourse on Method [1637], §3.23) by David Roochnik - The Tragedy of Reason p.73
Descartes tried to model reason on maths instead of 'logos'
     Full Idea: Descartes rejects logos because it does not achieve the certainty he craves. He replaces it with his own model of rationality, one modelled essentially on mathematics.
     From: comment on René Descartes (Meditations [1641], §1) by David Roochnik - The Tragedy of Reason p.76
Maybe there is only one certain fact, which is that nothing is certain
     Full Idea: If I suppose that everything I see is false. Nothing I remember actually existed. I have no senses, and body, shape, extension, movement and place are all chimeras. What then is true? Perhaps just the single fact that nothing is certain.
     From: René Descartes (Meditations [1641], §2.24)
Labelling slightly doubtful things as false is irrational
     Full Idea: To declare that which is the least bit dubious as absolutely false is to declare war on logos.
     From: comment on René Descartes (Meditations [1641], §1.17) by David Roochnik - The Tragedy of Reason p.72
Understanding, not the senses, gives certainty
     Full Idea: Certainty is not in the sense but in the understanding alone, when it has evident perceptions.
     From: René Descartes (Preface to 'Principles of Philosophy' [1647], p.177)
11. Knowledge Aims / B. Certain Knowledge / 4. The Cogito
We all see intuitively that we exist, where intuition is attentive, clear and distinct rational understanding
     Full Idea: By intuition I mean the conception of an attentive mind, so distinct and clear that it has no doubt about what it understands, …a conception that is borne of the sole light of reason. Thus everyone can see intuitively that he exists.
     From: René Descartes (Rules for the Direction of the Mind [1628], 03)
     A reaction: By 'intuition' he means self-evident certainty, whereas my concept is of a judgement of which I am reasonably confident, but without sufficient grounds for certainty. This is an early assertion of the Cogito, with a clear statement of its grounding.
When Socrates doubts, he know he doubts, and that truth is possible
     Full Idea: If Socrates says he doubts everything, it necessarily follows that he at least understands that he doubts, and that he knows that something can be true or false: for these are notions that necessarily accompany doubt.
     From: René Descartes (Rules for the Direction of the Mind [1628], 12)
     A reaction: An early commitment to the Cogito. But note that the inescapable commitment is not just to his existence, but also to his own reasoning, and his own commitment, and to the possibility of truth. Many, many things are undeniable.
In thinking everything else false, my own existence remains totally certain
     Full Idea: While I decided to think that everything was false, it followed necessarily that I who thought thus must be something; the truth 'I think therefore I am' was so certain that the most extravagant scepticism could never shake it.
     From: René Descartes (A Discourse on Method [1637], §4.32)
Modern philosophy set the self-conscious ego in place of God
     Full Idea: Modern philosophy set the thinking being, the ego, and the self-conscious mind in the place of the merely ideated being, in place of God.
     From: report of René Descartes (Meditations [1641]) by Ludwig Feuerbach - Principles of Philosophy of the Future §37
     A reaction: Descartes would be shocked by this interpretation, but God comes third in his logical priorities, after the existence of his ego, and its reliance on what is clear and distinct.
"I think therefore I am" is the absolute truth of consciousness
     Full Idea: "I think therefore I am" is the absolute truth of consciousness as it attains to itself.
     From: comment on René Descartes (Meditations [1641], §2) by Jean-Paul Sartre - Existentialism and Humanism p.44
I must even exist if I am being deceived by something
     Full Idea: Doubtless I exist if I persuade myself of something. But there is some powerful and cunning deceiver who is deliberately deceiving me. Then too there is no doubt that I exist, if he is deceiving me.
     From: René Descartes (Meditations [1641], §2.25)
"I am, I exist" is necessarily true every time I utter it or conceive it in my mind
     Full Idea: "I am, I exist" is necessarily true every time I utter it or conceive it in my mind.
     From: René Descartes (Meditations [1641], §2.25)
The Cogito is a transcendental argument, not a piece of a priori knowledge
     Full Idea: The Cogito is a transcendental argument; Descartes doesn't claim that it is a priori that he exists, but that any doubt or denial that he exists would presuppose his existence.
     From: comment on René Descartes (Meditations [1641], §2.26) by Georges Rey - Contemporary Philosophy of Mind 3.2.1
Descartes transformed 'God is thinkable, so he exists' into 'I think, so I exist'
     Full Idea: Descartes transformed the proposition 'because God is thinkable, therefore he exists' into the proposition 'I think, therefore I am'.
     From: report of René Descartes (Meditations [1641], 2) by Ludwig Feuerbach - Principles of Philosophy of the Future §18
     A reaction: This implies that Descartes' foundation is the Ontological Argument rather than the Cogito. It certainly shows how a priori synthetic thinking is basic in Descartes - that views of existence derive from pure thought. Was Descartes an idealist?
In the Meditations version of the Cogito he says "I am; I exist", which avoids presenting it as an argument
     Full Idea: Descartes may have been aware of the danger of begging the question (in claiming "I think therefore I am") because in 'Meditations' he says "I am; I exist", which is not presented in the form of an argument.
     From: report of René Descartes (Meditations [1641], 2) by J Baggini / PS Fosl - The Philosopher's Toolkit §3.22
     A reaction: Certainly the word 'therefore' cries out for a strict analysis of what is being inferred from what, but presenting the Cogito as a self-evident intuition for the 'natural light' has its own problems.
The Cogito is not a syllogism but a self-evident intuition
     Full Idea: When someone says 'I am thinking, therefore I am, or I exist', he does not deduce existence from thought by means of a syllogism, but recognises it as something self-evident by a simple intuition of the mind.
     From: René Descartes (Reply to Second Objections [1641], 140)
If I don't think, there is no reason to think that I exist
     Full Idea: It could be that if I were to cease all thinking I would then utterly cease to exist. …I am therefore precisely nothing but a thinking thing; that is, a mind, or intellect, or understanding, or reason.
     From: René Descartes (Meditations [1641], §2.27)
Total doubt can't include your existence while doubting
     Full Idea: He who decides to doubt everything cannot nevertheless doubt that he exists while he doubts.
     From: René Descartes (Principles of Philosophy [1646], Pref)
I think, therefore I am, because for a thinking thing to not exist is a contradiction
     Full Idea: There is a contradiction in conceiving that what thinks does not (at the same time as it thinks) exist. Hence this conclusion I think, therefore I am, is the first and most certain that occurs to one who philosophises in an orderly way.
     From: René Descartes (Principles of Philosophy [1646], I.07)
     A reaction: The classic statement of his argument. The significance here is that it seems to have the structure of an argument, as it involves 'philosophising', which leads to a 'contradiction', and hence to the famous conclusion. It is not just intuitive.
'Thought' is all our conscious awareness, including feeling as well as understanding
     Full Idea: By the word 'thought' I understand everything we are conscious of as operating in us. And that is why not only understanding, willing, imagining, but also feeling, are here the same thing as thinking.
     From: René Descartes (Principles of Philosophy [1646], I.09)
     A reaction: There is a bit of tension here between Descartes' correct need to include feeling in thought for his Cogito argument, and his tendency to dismiss animal consciousness, on the grounds that they only sense things, and don't make judgements.
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
The Cogito proves subjective experience is basic, but makes false claims about the Self
     Full Idea: The Cogito argument proves that subjective experience is the most reliable, but it makes unjustified claims about the certainty of the Self.
     From: comment on René Descartes (Meditations [1641], §2.26) by Bertrand Russell - Problems of Philosophy Ch 2
It is a precondition of the use of the word 'I' that I exist
     Full Idea: In the Cogito the work is all done by the demonstrative word 'I', because it is a precondition of the use of such a word that the thing to which it points has to exist.
     From: comment on René Descartes (Meditations [1641], §2.26) by A.J. Ayer - The Problem of Knowledge Ch 2 (iii)
Maybe 'I' am not the thinker, but something produced by thought
     Full Idea: In the past one said 'I' is the condition, 'think' is the predicate and conditioned - thinking is an activity which the subject causes; but maybe the reverse is true - and 'I' is only a synthesis produced by thinking.
     From: comment on René Descartes (Meditations [1641], §2.26) by Friedrich Nietzsche - Beyond Good and Evil §54
The thing which experiences may be momentary, and change with the next experience
     Full Idea: It might be that the something which sees a brown colour is quite momentary, and not the same thing which has some different experience the next moment.
     From: comment on René Descartes (Meditations [1641], §2.26) by Bertrand Russell - Problems of Philosophy Ch.2
     A reaction: This has become one of the standard objections to the Cogito. Note that Descartes himself was aware of the problem (Idea 1400). Sometimes experiences make no sense if there isn't something connecting them to previous experiences.
'I think' assumes I exist, that thinking is known and caused, and that I am doing it
     Full Idea: The sentence "I think" contains a series of unprovable assertions; for example, it is I who think, that it must be something at all which thinks, that thinking is by an entity thought of as a cause, that an 'I' exists, and that I know what thinking is.
     From: comment on René Descartes (Meditations [1641], §2.26) by Friedrich Nietzsche - Beyond Good and Evil §16
A thought doesn't imply other thoughts, or enough thoughts to make up a self
     Full Idea: The fact that a thought occurs at a given moment does not entail that any other thought has occurred at any other moment, still less that there has occurred a series of thoughts sufficient to constitute a single self.
     From: comment on René Descartes (Meditations [1641], §2.26) by A.J. Ayer - Language,Truth and Logic Ch.2
     A reaction: This seems to be the main objection to the Cogito. It doesn't refute it, but simply recommends cautious restraint in what is being claimed as its conclusion. I can't make much sense of a thought which has no thinker at all.
That I perform an activity (thinking) doesn't prove what type of thing I am
     Full Idea: From the fact that I am thinking it follows that I exist, since that which thinks is not nothing. But when he adds 'that is, I am a mind, or intelligence, or intellect', a doubt arises. ..You might as well say 'I am walking, therefore I am a walk'.
     From: comment on René Descartes (Meditations [1641], §2.26) by Thomas Hobbes - Objections to 'Meditations' (Third) 172
The Cogito assumes a priori the existence of substance, when actually it is a grammatical custom
     Full Idea: Descartes' Cogito posits as 'true a priori' our belief in the concept of substance, but the idea that when there is a thought there has to be something 'that thinks' is simply a formulation of our grammatical custom that adds a doer to every deed.
     From: comment on René Descartes (Meditations [1641], §2.26) by Friedrich Nietzsche - The Will to Power (notebooks) §484
     A reaction: This anticipates the sort of thing Ayer and the logical positivists said. It is not clear that Descartes does think the mind is a substance, but this pinpoints a possible presupposition in Descartes.
How can we infer that all thinking involves self-consciousness, just from my own case?
     Full Idea: It seems strange that the condition under which I think is to be valid for everything that thinks, and that on an empirical-seeming proposition we can presume to ground a universal judgement, that everything that thinks has self-consciousness.
     From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason A346
     A reaction: Kant is not bothered by this, and says we know it a priori. If it is indeed an empirical proposition, it becomes an induction with one instance, which is the notorious weakness of the 'argument from analogy' to other minds. The Cogito is not empirical.
My self is not an inference from 'I think', but a presupposition of it
     Full Idea: The simplicity of my self is not inferred from the proposition "I think", but rather the former lies in every thought. 'I am simple' is an immediate apperception, just as the Cogito is tautological, since 'cogito' immediately asserts the reality.
     From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason A355
     A reaction: This is why Kant thinks the self is the result of a transcendental deduction, rather than of a direct observation of the self-evident. Personally I side with Descartes. I do not 'observe' my self, but I am acutely aware of its presence and actions.
We cannot give any information a priori about the nature of the 'thing that thinks'
     Full Idea: If anyone asks me: What is the constitution of a thing that thinks? I do not know how to answer a priori, because the answer ought to be synthetic (for an analytic answer explains thinking, but gives no cognition of that on which thinking rests).
     From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason A398
     A reaction: This has always seemed a problem with Descartes' very thin account of his 'res cogitans', but then what exactly does Kant want to know? Is it a metaphysical disaster if we think of the self as having no more identity than a geometrical point?
The fact that I am a subject is not enough evidence to show that I am a substantial object
     Full Idea: The fact that I am a subject ..does not signify that as object I am a self-subsisting being or substance; the latter goes too far, and hence demands data that are not encountered at all in thinking.
     From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason B407
     A reaction: This is a key problem with the Cogito - that so little can be said about the 'I' of which the existence has been proved that it is not clear that anything has been proved at all - certainly not that there is a continuous and stable Ego.
Descartes' claim to know his existence before his essence is misleading or absurd
     Full Idea: Descartes claimed to know that he existed before he knew what he was - before he grasped his own essence. This is either disingenuous or intended non-literally, if it is not to be dismissed as incomprehensible.
     From: report of René Descartes (Meditations [1641], 2) by E.J. Lowe - Two Notions of Being: Entity and Essence 2 n32
     A reaction: If something comes at you from the mist, you can know that it exists before you know what it is. How could you understand the essence of something if you hadn't first encountered its existence? Lowe has it the wrong way round.
Modern self-consciousness is a doubtful abstraction; only senses and feelings are certain
     Full Idea: The self-consciousness of modern philosophy is only a being ideated and mediated through abstraction and thus a doubtful being; certain and immediately assured is only that which is an object of the senses, perception and feeling.
     From: comment on René Descartes (Meditations [1641], 2) by Ludwig Feuerbach - Principles of Philosophy of the Future §37
     A reaction: This seems to agree with Hume's empirical doubts about the self (Idea 1316). The comment that 'abstraction' is involved in the Cogito argument is interesting. Descartes said the Cogito was a 'simply intuition of the mind' (Idea 3622).
The Cogito only works if you already understand what thought and existence are
     Full Idea: In order to be certain that you are thinking you must know what thought or thinking is, and what your existence is; but since you do not yet know what these things are, how can you know that you are thinking or that you exist?
     From: comment on René Descartes (Meditations [1641], §2.26) by Marin Mersenne - Objections to 'Meditations' (Sixth) 413
Autistic children seem to use the 'I' concept without seeing themselves as thinkers
     Full Idea: It really does not seem (as a result of research into autism) that when one thinks of oneself with one's 'I' concept, one must thereby represent oneself as a thinker.
     From: comment on René Descartes (Meditations [1641], §2.26) by Gabriel M.A. Segal - A Slim Book about Narrow Content 4.2
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
My perceiving of things may be false, but my seeming to perceive them cannot be false
     Full Idea: I now see a light, I hear a noise, I feel heat. Perhaps these things are false, since I am asleep. Yet I certainly do seem to see, hear, and feel warmth. This cannot be false.
     From: René Descartes (Meditations [1641], §2.29)
11. Knowledge Aims / C. Knowing Reality / 4. Solipsism
I myself could be the author of all these self-delusions
     Full Idea: I myself could be the author of all these self-delusions.
     From: René Descartes (Meditations [1641], §2.24)
12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
Clear and distinct truths must be known all at once (unlike deductions)
     Full Idea: We require two conditions for intuition, namely that the proposition appear clear and distinct, and then that it be understood all at once and not successively. Deduction, on the other hand, implies a certain movement of the mind.
     From: René Descartes (Rules for the Direction of the Mind [1628], 11)
     A reaction: A nice distinction. Presumably with deduction you grasp each step clearly, and then the inference and conclusion, and you can then forget the previous steps because you have something secure.
12. Knowledge Sources / A. A Priori Knowledge / 3. Innate Knowledge / a. Innate knowledge
Our souls possess divine seeds of knowledge, which can bear spontaneous fruit
     Full Idea: The human soul possesses something divine in which are deposited the first seeds of useful knowledge, which, in spite of the negligence and embarrassment of poorly done studies, bear spontaneous fruit.
     From: René Descartes (Rules for the Direction of the Mind [1628], 04)
     A reaction: This makes clear the religious underpinning which is required for his commitment to such useful innate ideas (such as basic geometry)
Our thinking about external things doesn't disprove the existence of innate ideas
     Full Idea: You can't prove that Praxiteles never made any statues on the grounds that he did not get from within himself the marble from which he sculpted them.
     From: René Descartes (Reply to Fifth Objections [1641], 362)
12. Knowledge Sources / A. A Priori Knowledge / 4. A Priori as Necessities
A triangle has a separate non-invented nature, shown by my ability to prove facts about it
     Full Idea: A triangle has a determinate nature, which I did not fabricate, and which does not depend on my mind. This is evident from the fact that various properties can be demonstrated regarding it, such as that its three angles are equal to two right angles.
     From: René Descartes (Meditations [1641], §5.64)
What experience could prove 'If a=c and b=c then a=b'?
     Full Idea: Please tell me what the corporeal motion is that is capable of forming some common notion to the effect that 'things which are equal to a third thing are equal to each other'.
     From: René Descartes (Comments on a Certain Broadsheet [1644], p.366)
'Nothing comes from nothing' is an eternal truth found within the mind
     Full Idea: The proposition 'nothing comes from nothing' is not to be considered as an existing thing, or the mode of a thing, but as a certain eternal truth which has its seat in our mind and is a common notion or axiom.
     From: René Descartes (Principles of Philosophy [1646], I.49)
     A reaction: There is a tension here, in his assertion that it is 'eternal', but 'not existing'. How does one distinguish an innate idea from an innate truth? 'Eternal' sounds like an external guarantee of truth, but being 'in our mind' sounds less reliable.
12. Knowledge Sources / A. A Priori Knowledge / 6. A Priori from Reason
I aim to find the principles and causes of everything, using the seeds within my mind
     Full Idea: I have tried to find in general the principles or first causes of everything which is or which may be in the world, ..without taking them from any other source than from certain seeds of truth which are naturally in our minds.
     From: René Descartes (A Discourse on Method [1637], §6.64)
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / c. Primary qualities
For Descartes, objects have one primary quality, which is geometrical
     Full Idea: Descartes denies any similarity between the physical world and ideas, as matter possesses only geometrical properties; Locke allows more primary qualities, but follows Boyle and the atomists in treating secondary qualities as creations of sense.
     From: report of René Descartes (Meditations [1641]) by Howard Robinson - Perception 1.5
     A reaction: The interesting point to note here is that Descartes' geometrical view of objects (they are defined purely by 'extension') is the view that they have one minimal primary quality. I prefer Locke's view, of which the history (given here) is interesting.
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / d. Secondary qualities
Our sensation of light may not be the same as what produces the sensation
     Full Idea: There can be a difference between our sensation of light and what is in the objects that produce that sensation in us.
     From: René Descartes (The World [1631]), quoted by Ian Dunt - How to be a Liberal 1
     A reaction: Note only that they 'may' differ, and that he does not assert that they are entirely different. Secondary qualities give information, and are not just mental events.
12. Knowledge Sources / B. Perception / 3. Representation
Descartes said images can refer to objects without resembling them (as words do)
     Full Idea: Descartes argued (in 'The World') that just as words refer to objects, but they do not resemble them, in the same way, visual images or other sensory inputs relate to objects without depicting them.
     From: report of René Descartes (works [1643]) by Richard Tuck - Hobbes
     A reaction: This strikes me as a rather significant and plausible claim, which might contain the germ of the idea of a language of thought. It is also the basis for the recent view that language is the best route to understanding the mind.
12. Knowledge Sources / B. Perception / 5. Interpretation
Why does pain make us sad?
     Full Idea: Why should a certain sadness of spirit arise from a sensation of pain?
     From: René Descartes (Meditations [1641], §6.76)
12. Knowledge Sources / C. Rationalism / 1. Rationalism
Understanding, rather than imagination or senses, gives knowledge
     Full Idea: Neither our imagination nor our senses could ever assure us of anything, if our understanding did not intervene.
     From: René Descartes (A Discourse on Method [1637], §4.37)
The wax is not perceived by the senses, but by the mind alone
     Full Idea: The perception of the wax is neither a seeing, nor a touching, nor an imagining. Rather, it is an inspection on the part of the mind alone.
     From: René Descartes (Meditations [1641], §2.31)
We perceive objects by intellect, not by senses or imagination
     Full Idea: Bodies are not, properly speaking, perceived by the senses or by the faculty of imagination, but by the intellect alone.
     From: René Descartes (Meditations [1641], §2.34)
We don't 'see' men in heavy clothes, we judge them to be men
     Full Idea: Were I to look out of my window and observe men crossing the square, I would ordinarily say that I see the men themselves. But what do I see but hats and clothes, which could conceal automata? Yet I judge them to be men.
     From: René Descartes (Meditations [1641], §2.32)
Dogs can make the same judgements as us about variable things
     Full Idea: A dog certainly makes similar kinds of judgement to your perceiving men by their hats and cloaks when they see their master's hat or clothes, …and they can recognise their master even if he is standing, sitting, lying down, or crouching.
     From: comment on René Descartes (Meditations [1641], §2.32) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 272
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
If someone had only seen the basic colours, they could deduce the others from resemblance
     Full Idea: Let there be a man who has sometimes seen the fundamental colours, and never the intermediate and mixed colours; it may be that by a sort of deduction he will represent those he has not seen, by their resemblance to the others.
     From: René Descartes (Rules for the Direction of the Mind [1628], 14)
     A reaction: Thus Descartes solved Hume's shade of blue problem, by means of 'a sort of deduction' from resemblance, where Hume was paralysed by his need to actually experience it. Dogmatic empiricism is a false doctrine!
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
The method starts with clear intuitions, followed by a process of deduction
     Full Idea: If the method shows clearly how we must use intuition to avoid mistaking the false for the true, and how deduction must operate to lead us to the knowledge of all things, it will be complete in my opinion.
     From: René Descartes (Rules for the Direction of the Mind [1628], 04)
     A reaction: A perfect statement of his foundationalist view. It needs a clear and distinct basis, and the steps of building must be strictly logical. Of course, most of our knowledge relies on induction, rather than deduction.
I was searching for reliable rock under the shifting sand
     Full Idea: My whole plan had for its aim simply to give me assurance, and the rejection of shifting ground and sand in order to find rock or clay.
     From: René Descartes (A Discourse on Method [1637], §3.29)
     A reaction: I take this to be characteristic of an age when religion is being quietly rocked by the revival of ancient scepticism. If he'd settled for fallibilism, our civilization would have gone differently.
To achieve good science we must rebuild from the foundations
     Full Idea: Once in my life I had to raze everything to the ground and begin again from the original foundations, if I wanted to establish anything firm and lasting in the sciences.
     From: René Descartes (Meditations [1641], §1.17)
     A reaction: This sentence is the beginning of the Enlightenment. The project of proving absolutely everything, and in a foundational way, is now met with much scepticism. I will never abandon the project!
Only one certainty is needed for progress (like a lever's fulcrum)
     Full Idea: Archimedes sought but one firm and immovable point in order to move the entire earth. Just so, great things are to be hoped for if I succeed in finding just one thing, however slight, that is certain and unshaken.
     From: René Descartes (Meditations [1641], §2.24)
     A reaction: The classic foundationalist difficulty is that you may find something totally certain, but is it a fulcrum? Or is it just minimal, boring and useless?
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / b. Basic beliefs
We can know basic Principles without further knowledge, but not the other way round
     Full Idea: It is on the Principles, or first causes, that the knowledge of other things depends, so the Principles can be known without these last, but the other things cannot reciprocally be known without the Principles.
     From: René Descartes (Principles of Philosophy [1646], Pref)
     A reaction: A particularly strong assertion of foundationalism, as it says that not only must the foundations exist, but also we must actually know them. This sounds false, as elementary knowledge then seems to require far too much sophistication.
13. Knowledge Criteria / D. Scepticism / 1. Scepticism
Even if my body and objects are imaginary, there may be simpler things which are true
     Full Idea: Perhaps even though general things like eyes could be imaginary, still one must admit that certain other things that are even more simple and universal are true.
     From: René Descartes (Meditations [1641], §1.20)
Descartes can't begin again, because sceptics doubt cognitive processes as well as beliefs
     Full Idea: Descartes' strategy of starting over will not work, because the skeptic is not just questioning our beliefs, he is also questioning the cognitive processes by which we arrive at our beliefs, and if we start all over again we use the same processes.
     From: comment on René Descartes (Meditations [1641], §1) by J Pollock / J Cruz - Contemporary theories of Knowledge (2nd)
     A reaction: Scepticism comes in degrees, so there is not one strategy employed by sceptics. It is certainly true, though, that nothing can resist extreme scepticism. The most extreme view is to refuse to accept the meaningfulness of all belief language.
13. Knowledge Criteria / D. Scepticism / 3. Illusion Scepticism
If pain is felt in a lost limb, I cannot be certain that a felt pain exists in my real limbs
     Full Idea: I have heard it said by people whose arm or leg has been amputated that they still sensed pain in the lost limb. Thus it does not seem certain that one of my bodily members causes me pain, even though I sense pain in it.
     From: René Descartes (Meditations [1641], §6.77)
We correct sense errors with other senses, not intellect
     Full Idea: Owing to refraction a stick which is in fact straight appears bent in water. What corrects the error? The intellect? Not at all; it is the sense of touch.
     From: comment on René Descartes (Meditations [1641], §1.18) by Marin Mersenne - Objections to 'Meditations' (Sixth) 418
Only judgement decides which of our senses are reliable
     Full Idea: Sense alone does not suffice to correct visual error: we also need a degree of reason to tell us that we should believe the judgement based on touch rather than vision. Since we don't have this power in infancy, it must be attributed to the intellect.
     From: René Descartes (Reply to Sixth Objections [1641], 439)
The senses can only report, so perception errors are in the judgment
     Full Idea: Although there is deception or falsity, it is not to be found in the senses; for the sense are quite passive and report only appearances, which must appear the way they do owing to their causes. The error or falsity is in the judgement or the mind.
     From: comment on René Descartes (Meditations [1641], §1.18) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 332
It is prudent never to trust your senses if they have deceived you even once
     Full Idea: The senses are sometimes deceptive, and it is a mark of prudence never to place our complete trust in those who have deceived us even once.
     From: René Descartes (Meditations [1641], §1.18)
13. Knowledge Criteria / D. Scepticism / 4. Demon Scepticism
God may have created nothing, but made his creation appear to me as it does now
     Full Idea: How do I know that God did not bring it about that there is no earth or heavens, no extension, shape, size or place, and yet that all these things appear to me precisely as they do now?
     From: René Descartes (Meditations [1641], §1.21)
To achieve full scepticism, I imagine a devil who deceives me about the external world and my own body and senses
     Full Idea: I will suppose an evil genius, supremely powerful and clever, who has directed his entire effort at deceiving me. I will regard all external things as devilish hoaxes, and myself as not possessed of a body or senses, but falsely believing these things.
     From: René Descartes (Meditations [1641], §1.22)
13. Knowledge Criteria / D. Scepticism / 5. Dream Scepticism
Waking actions are joined by memory to all our other actions, unlike actions of which we dream
     Full Idea: Dreams are never joined by the memory with all the actions of life, as is the case with those actions that occur when one is awake.
     From: René Descartes (Meditations [1641], §6.89)
13. Knowledge Criteria / D. Scepticism / 6. Scepticism Critique
When rebuilding a house, one needs alternative lodgings
     Full Idea: Before beginning to rebuild the house in which one lives…. one must also provide oneself with some other accommodation in which to be lodge conveniently while the work is going on.
     From: René Descartes (A Discourse on Method [1637], §3.22)
I can only sense an object if it is present, and can't fail to sense it when it is
     Full Idea: Perceptions come upon me without my consent, to the extent that, wish as I may, I could not sense any object unless it was present to a sense organ, nor could I fail to sense it when it was present.
     From: René Descartes (Meditations [1641], §6.75)
14. Science / A. Basis of Science / 3. Experiment
Only experiments can settle disagreements between rival explanations
     Full Idea: I observe almost no individual effect without immediately knowing that it can be deduced in many different ways, ..and I know of no way to resolve this but by experiments such that the results are different according to different explanations.
     From: René Descartes (A Discourse on Method [1637], §6.65)
15. Nature of Minds / A. Nature of Mind / 3. Mental Causation
Can the pineal gland be moved more slowly or quickly by the mind than by animal spirits?
     Full Idea: I am in ignorance whether the pineal gland can be agitated more slowly or more quickly by the mind than by the animal spirits.
     From: comment on René Descartes (Meditations [1641], §6.82) by Baruch de Spinoza - The Ethics V Pref
     A reaction: Is this the earliest statement of the problem of double causation? It is a classic difficulty for dualists, highlighted by Ryle, among others. Avoidance of double causation is a classic reason for moving to monism about mind.
15. Nature of Minds / A. Nature of Mind / 4. Other Minds / c. Knowing other minds
We discovers others as well as ourselves in the Cogito
     Full Idea: It is not only oneself that one discovers in the Cogito, but those of others too.
     From: comment on René Descartes (Meditations [1641], §2) by Jean-Paul Sartre - Existentialism and Humanism p.45
     A reaction: The analytical tradition requires a bit more than an instant perception of others in oneself. The problem of 'other minds' must at least be mentioned. However, the way to get to know a universal is to fully study a single instance.
15. Nature of Minds / A. Nature of Mind / 5. Unity of Mind
Faculties of the mind aren't parts, as one mind uses them
     Full Idea: The faculties of willing, sensing, understanding and so on cannot be called "parts" of the mind, since it is one and the same mind that wills, senses and understands.
     From: René Descartes (Meditations [1641], §6.86)
     A reaction: It is best here to say that Descartes has confused the 'mind' with the 'person'. These faculties make (I think) no sense without a person to perform them, but the 'mind' surely includes these conscious activities, and many fringe events as well.
15. Nature of Minds / A. Nature of Mind / 7. Animal Minds
Little reason is needed to speak, so animals have no reason at all
     Full Idea: Animals not only have less reason than men, but they have none at all; for we see that very little of it is required in order to be able to speak.
     From: René Descartes (A Discourse on Method [1637], §5.58)
15. Nature of Minds / A. Nature of Mind / 8. Brain
Nerves and movement originate in the brain, where imagination moves them
     Full Idea: The motive power or the nerves themselves originate in the brain, which contains the imagination, which moves them in a thousand ways, as the common sense is moved by the external sense.
     From: René Descartes (Rules for the Direction of the Mind [1628], 12)
     A reaction: This sounds a lot more physicalist than his later explicit dualism in Meditations. Even in that work the famous passage on the ship's pilot acknowledged tight integration of mind and brain.
15. Nature of Minds / B. Features of Minds / 1. Consciousness / b. Essence of consciousness
We can understand thinking occuring without imagination or sensation
     Full Idea: We can understand thinking without imagination or sensation, as is quite clear to anyone who attends to the matter.
     From: René Descartes (Principles of Philosophy [1646], I.53)
     A reaction: We may certainly take it that Descartes means if it is understandable then it is logically possible. To believe that thinking could occur without imagination strikes me as an astonishing error. I take imagination to be more central than understanding.
15. Nature of Minds / B. Features of Minds / 2. Unconscious Mind
I can't be unaware of anything which is in me
     Full Idea: Nothing can be in me of which I am entirely unaware.
     From: René Descartes (Reply to First Objections [1641]), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 08.4
     A reaction: This I take to be a place where Descartes is utterly and catastrophically wrong. Until you grasp the utter falseness of this thought, the possibility of you (dear reader) understanding human beings is zero. Here 'I' obviously means his mind.
15. Nature of Minds / B. Features of Minds / 5. Qualia / a. Nature of qualia
Descartes put thought at the centre of the mind problem, but we put sensation
     Full Idea: Descartes confined his dualism to problems of reason and language. Sensation and even imagination seemed to him physically unproblematic. Nowadays it is the reverse: thinking seems easy - but feeling?
     From: comment on René Descartes (Meditations [1641], 2) by Georges Rey - Contemporary Philosophy of Mind 2 n16
     A reaction: Thinking only 'seems easy' if it can be done without consciousness, and that is beginning to look like a dubious assumption. The most interesting and promising area is the borderline between a chess-playing machine and a human chess player.
15. Nature of Minds / C. Capacities of Minds / 1. Faculties
Our four knowledge faculties are intelligence, imagination, the senses, and memory
     Full Idea: There are four faculties in us which we can use to know: intelligence, imagination, the senses, and memory.
     From: René Descartes (Rules for the Direction of the Mind [1628], 12)
     A reaction: Philosophers have to attribute faculties to the mind, even if the psychologists and neuroscientists won't accept them. We must infer the sources of our modes of understanding. He is cautious about imagination.
Descartes mentions many cognitive faculties, but reduces them to will and intellect
     Full Idea: Although Descartes accepted a variety of cognitive faculties like the intellect, will, power of judgement, imagination, memory, and perception, he took them all to be ultimately reducible to different operations of the will and intellect.
     From: report of René Descartes (Meditations [1641], 4) by Stephan Schmid - Faculties in Early Modern Philosophy 2
     A reaction: In Med 4, it is most clear, when he reduces 'judgement' to will and intellect, which enable his to assent to an idea. Nietzsche saw Descartes' view as simplistic.
15. Nature of Minds / C. Capacities of Minds / 2. Imagination
Imagination and sensation are non-essential to mind
     Full Idea: This power of imagination which is in me, in so far as it differs from the power of conceiving, is in no way necessary to my nature or essence.
     From: René Descartes (Meditations [1641], §6.73)
     A reaction: This is my candidate for the biggest blunder ever made by a great philosopher. But it was thanks to his mistake that I began to realise how totally central imagination is to the very act of thinking. Thank you, René.
16. Persons / A. Concept of a Person / 1. Existence of Persons
Some cause must unite the separate temporal sections of a person
     Full Idea: Because the entire span of one's life can be divided into countless parts, each one wholly independent of the rest, it does not follow from the fact that I existed a short time ago that I exist now, unless some cause creates and preserves me each moment.
     From: René Descartes (Meditations [1641], §3.49)
     A reaction: How could I 'prove' that this computer is the same computer as it was five minutes ago, even after I have accepted the straightforward existence of the computer? This is the Enlightenment Project, the mad desire to prove absolutely everything.
16. Persons / B. Nature of the Self / 3. Self as Non-physical
I am a thinking substance, which doesn't need a place or material support
     Full Idea: I concluded that I was a substance, of which the whole essence or nature consists in thinking, and which, in order to exist, needs no place and depends on no material thing.
     From: René Descartes (A Discourse on Method [1637], §4.33)
     A reaction: To me that sounds like "I concluded that I wasn't a human being", which highlights the bizarre wishful thinking that seems to have gripped the human race for the first few thousand years of its serious thinking.
16. Persons / D. Continuity of the Self / 7. Self and Thinking
Since I only observe myself to be thinking, I conclude that that is my essence
     Full Idea: Since I do not observe that any other thing belongs necessarily to my nature or essence except that I am a thinking thing, I rightly conclude that my essence consists in this alone, that I am a thinking thing, or substance whose essence is thinking.
     From: René Descartes (Meditations [1641], §6.78)
     A reaction: This actually appears to be my favourite confusion - of episemology with ontology. Compare 'whenever I see him he is smiling, so he must be happy'. Personally I am happy to say that my essence is thinking, as long as it needn't be conscious.
I can exist without imagination and sensing, but they can't exist without me
     Full Idea: I can understand myself without the faculties of imagining and sensing, but not vice versa; I cannot understand them without me - a substance endowed with understanding.
     From: René Descartes (Meditations [1641], §6.78)
     A reaction: I think this is a fundamental and important error on Descartes' part. The idea that understanding is possible without imagination (and even sensation) is wrong, and it leads to the misleading concept of 'pure' reason.
For Descartes a person's essence is the mind because objects are perceived by mind, not senses
     Full Idea: For Descartes the essence of corporeal things is not an object of the senses, but only of the mind; and hence it is not the senses but the mind that is the essence of the perceiving subject, that is, of man.
     From: report of René Descartes (Meditations [1641], 2) by Ludwig Feuerbach - Principles of Philosophy of the Future §17
     A reaction: This, of course, is why Descartes' approach can lead to idealism and solipsism, whereas the other approach leads to empiricism and animalism (Idea 6669).
In thinking we shut ourselves off from other substances, showing our identity and separateness
     Full Idea: Because each one of us understands what he thinks, and that in thinking he can shut himself off from every other substance, we may conclude that each of us is really distinct from every other thinking substance and from corporeal substance.
     From: René Descartes (Principles of Philosophy [1646], I.60)
     A reaction: This seems to be a novel argument which requires elucidation. I can 'shut myself off from every other substance'? If I shut myself off from thinking about food, does that mean hunger is not part of me? Or convince yourself that you don't have a brother?
16. Persons / F. Free Will / 1. Nature of Free Will
Our 'will' just consists of the feeling that when we are motivated to do something, there are no external pressures
     Full Idea: The will consists solely in the fact that when something is proposed to us by our intellect either to affirm or deny, we are moved in such a way that we sense we are determined to it by no external force.
     From: René Descartes (Meditations [1641], §4.57)
Our free will is so self-evident to us that it must be a basic innate idea
     Full Idea: It is so evident that we are possessed of a free will that can give or withhold its assent, that this may be counted as one of the first and most common notions found innately in us.
     From: René Descartes (Principles of Philosophy [1646], I.39)
     A reaction: It seems to me plausible to say that we have an innate conception of our own will (our ability to make decisions), though Hume says we only learn about the will from experience, but the idea that it is absolutely 'free' might never cross our minds.
16. Persons / F. Free Will / 3. Constraints on the will
The more reasons that compel me, the freer I am
     Full Idea: I move the more freely towards an object in proportion to the number of reasons which compel me.
     From: René Descartes (Letter to Mersenne [1642])
16. Persons / F. Free Will / 4. For Free Will
My capacity to make choices with my free will extends as far as any faculty ever could
     Full Idea: I experience that the will or free choice I have received from God is limited by no boundaries whatever, …indeed it is so great in me that I cannot grasp the idea of any greater faculty.
     From: René Descartes (Meditations [1641], §4.56)
We have inner awareness of our freedom
     Full Idea: We have inner awareness of our freedom.
     From: René Descartes (works [1643])
     A reaction: This begs a few questions. I may be directly aware that I have not been hypnotised, but no one would accept it as proof.
17. Mind and Body / A. Mind-Body Dualism / 1. Dualism
The force by which we know things is spiritual, and quite distinct from the body
     Full Idea: This force by which we properly know objects is purely spiritual, and is no less distinct from the body than is the blood from the bones.
     From: René Descartes (Rules for the Direction of the Mind [1628], 12)
     A reaction: This firmly contradicts any physicalism I thought I detected in Idea 24027! He uses the word 'spiritual' of the mind here, which I don't think he uses in later writings.
I can deny my body and the world, but not my own existence
     Full Idea: I could pretend that I had no body, and that there was no world or place that I was in, but I could not, for all that, pretend that I did not exist.
     From: René Descartes (A Discourse on Method [1637], §4.32)
     A reaction: He makes the (in my opinion) appalling blunder of thinking that because he can pretend that he has no body, that therefore he might not have one. I can pretend that gold is an unusual form of cheese. However, "I don't exist" certainly sounds wrong.
Reason is universal in its responses, but a physical machine is constrained by its organs
     Full Idea: Whereas reason is a universal instrument which can serve on any kind of occasion, the organs of a machine need a disposition for each action; so it is impossible to have enough different organs in a machine to respond to all the occurrences of life.
     From: René Descartes (A Discourse on Method [1637], §5.57)
     A reaction: How can Descartes know that reason is 'universal' rather than just 'very extensive'? Is there any information which cannot be encoded in a computer? It doesn't feel as if there any intrinsic restrictions to reason, but note Idea 4688.
The mind is a non-extended thing which thinks
     Full Idea: My concept of the human mind is a thinking thing, not extended in length, breadth or depth, and having nothing else from the body.
     From: René Descartes (Meditations [1641], §4.53)
     A reaction: But he admits (in Med 6) that the mind is so closely integrated with the body that they seem inseparable. Perhaps he shouldn't trust his own concept of the thing, because he is too close to the subject matter. You can't count a crowd if you are in it.
Mind is not extended, unlike the body
     Full Idea: Since I am clearly a thinking thing and not an extended thing, and on the other hand I have a distinct idea of a body, as merely an extended thing and not a thinking thing, it is certain that I am really distinct from my body, and can exist without it.
     From: René Descartes (Meditations [1641], §6.78)
     A reaction: How can he be 'certain' for this reason? This is a classic confusion of ontology and epistemology. Given that the mind is a special case, he should be asking WHY his thinking is clear to him, but his body isn't. Maybe it is because of his viewpoint.
Descartes is a substance AND property dualist
     Full Idea: Descartes' dualism combines substance dualism and property dualism; two disparate domains of substances, and two mutually exclusive families of properties.
     From: report of René Descartes (Meditations [1641], §6.78) by Jaegwon Kim - Philosophy of Mind p.211
     A reaction: I would have thought that substance dualism entailed property dualism. How would you distinguish two substances from one another except by their properties? There seems a merely logical possibility that God gives two substances the same properties.
The mind is utterly indivisible
     Full Idea: There is a great difference between a mind and a body, in that a body, by its very nature, is always divisible, but the mind is utterly indivisible.
     From: René Descartes (Meditations [1641], §6.85)
     A reaction: This strikes me as being simply false. I don't just mean that surgeons can split the mind in half. We should think of the mind as a team of conscious and non-conscious processes, which are held together by a self in normal healthy people. Selves change.
There are two ultimate classes of existence: thinking substance and extended substance
     Full Idea: I observe two ultimate classes of things: intellectual or thinking things, pertaining to the mind or to thinking substance, and material things, pertaining to extended substance or to body.
     From: René Descartes (Principles of Philosophy [1646], I.48)
     A reaction: This is clear confirmation that Descartes believed the mind is a substance, rather than an insubstantial world of thinking. It leaves open the possibility of a different theory: that mind is not a substance, but is a Platonic adjunct to reality.
17. Mind and Body / A. Mind-Body Dualism / 2. Interactionism
The soul must unite with the body to have appetites and sensations
     Full Idea: It is not sufficient that the reasonable soul should be lodged in the body like a pilot in a ship, unless perhaps to move its limbs, but it needs to be united more closely with the body in order to have sensations and appetites, and so be a true man.
     From: René Descartes (A Discourse on Method [1637], §5.59)
     A reaction: The idea that the pineal gland is the link suggests that Descartes has the 'pilot' view, but this idea shows that he believes in very close and complex interaction between mind and body. But how can a mind 'have' appetites if it has no physical needs?
Interaction between mental and physical seems to violate the principle of conservation of energy
     Full Idea: It is often argued that any interaction between the physical and the mental - as defined by Descartes - would require a violation of the first law of thermodynamics, the principle of conservation of energy.
     From: comment on René Descartes (Meditations [1641]) by Mark Rowlands - Externalism Ch.2
     A reaction: This would be because consciousness is adding energy to the system (in order to generate movement) without it having come from anywhere else in the physical system. A good objection, which only a miracle could overcome.
Descartes discussed the interaction problem, and compared it with gravity
     Full Idea: Descartes himself was well aware of the interaction problem, and corresponded uncomfortably with Princess Elizabeth on the matter; …he pointed out that gravity is causal despite not being a physical object.
     From: report of René Descartes (works [1643]) by William Lycan - Consciousness n1.3
     A reaction: Lycan observes that at least gravity is in space-time, unlike the Cartesian mind. Pierre Gassendi had pointed out the problem to Descartes in the Fifth Objection to the 'Meditations' (see Idea 3400).
The pineal gland links soul to body, and unites the two symmetrical sides of the body
     Full Idea: The soul is united with the body in just one place, a gland (the pineal) in the centre of the brain. It is placed so that its slightest movement will affect the passions, and it plays the essential role of uniting the two symmetrical sides of the body.
     From: report of René Descartes (The Passions of the Soul [1649], §31) by PG - Db (ideas)
     A reaction: See Idea 4862 for Spinoza's nice response to Descartes' proposal. If Descartes had followed brain research for the last four hundred years, at what point would he have wavered? If every single part of the brain seems to 'interact', dualism looks unlikely.
17. Mind and Body / A. Mind-Body Dualism / 8. Dualism of Mind Critique
The 'thinking thing' may be the physical basis of the mind
     Full Idea: It may be that the thing that thinks is the subject to which mind, reason or intellect belong; and this subject may thus be something corporeal.
     From: comment on René Descartes (Meditations [1641], §2.27) by Thomas Hobbes - Objections to 'Meditations' (Third) 173
     A reaction: Of course, Descartes goes on to reject this view. Presumably he is suggesting that mind etc. might be properties of something corporeal, rather than being identical with it. Descartes was well aware of materialism in Hobbes and Gassendi.
Knowing different aspects of brain/mind doesn't make them different
     Full Idea: Why should an epistemic distinction reflect an ontological distinction? Why should our epistemic privilege of being incorrigible about how things seem to us reflect a distinction between two realms of being?
     From: comment on René Descartes (Meditations [1641], §6.78) by Richard Rorty - Philosophy and the Mirror of Nature 1.2
     A reaction: This strikes me as being one of the most important ideas in philosophy, mainly as a corrective to a lot of bad philosophy, rather than as wisdom offered to non-philosophers (for whom Rorty's thought is probably common sense. How is it? How do we know?
Descartes gives no clear criterion for individuating mental substances
     Full Idea: Descartes gives no clear criterion for individuating mental substances.
     From: comment on René Descartes (Meditations [1641], §6.78) by John Cottingham - The Rationalists p.86
     A reaction: Presumably I can individuate my own mind by the 'natural light' of reason, and the implications of the Cogito. The minds of others do seem to be a problem. Why should they coincide with bodies, and not overlap or blend or swap?
Does Descartes have a clear conception of how mind unites with body?
     Full Idea: What does Descartes understand by the union of the mind and the body? What clear and distinct conception has he got of thought in most intimate union with a certain particle of extended matter?
     From: comment on René Descartes (Meditations [1641], §6.82) by Baruch de Spinoza - The Ethics V Pref
     A reaction: This is the classic, original and strongest objection to Cartesian dualism - that mind and body are held to be too different to interact. Spinoza may have overreacted a bit when he saw the only solution as the total identity of the two things.
Even Descartes may concede that mental supervenes on neuroanatomical
     Full Idea: Even Descartes may have conceded that the mental supervenes on the neuroanatomical.
     From: comment on René Descartes (Meditations [1641], 6) by William Lycan - Consciousness 5.2
     A reaction: This is true (early in Meditation Six) despite his later suggestion of the pineal gland as the linking point. It proves nothing, but I have heard John Cottingham suggest that Descartes might well be a materialist if he came back today.
Superman's strength is indubitable, Clark Kent's is doubtful, so they are not the same?
     Full Idea: Descartes's claim that mind and body are separate because the first is necessary when thinking and the second isn't, is like arguing 'Superman's strength is indubitable; Clark Kent's strength is widely doubted; so Clark Kent is not Superman'.
     From: comment on René Descartes (Meditations [1641], p.156) by Keith T. Maslin - Introduction to the Philosophy of Mind 2.7.1
     A reaction: I've heard people defend Descartes on this, and Kripke is interesting on the subject, but Descartes had better not be following this pattern of argument, or else a great philosopher would really be presenting an absurdity.
17. Mind and Body / D. Property Dualism / 5. Supervenience of mind
Even if tightly united, mind and body are different, as God could separate them
     Full Idea: Even if we suppose God had united a body and a soul so closely that they couldn't be closer, and made a single thing out of the two, they would still remain distinct, because God has the power of separating them, or conserving out without the other.
     From: René Descartes (Principles of Philosophy [1646], I.60)
     A reaction: If Descartes lost his belief in God (after discussing existence with Kant) would he cease to be a dualist? This quotation seems to be close to conceding a mind-body relationship more like supervenience than interaction.
17. Mind and Body / E. Mind as Physical / 6. Conceptual Dualism
The concept of mind excludes body, and vice versa
     Full Idea: The concept of body includes nothing at all which belongs to the mind, and the concept of mind includes nothing at all which belongs to the body.
     From: René Descartes (Reply to Fourth Objections [1641], 225)
     A reaction: A headache? Hunger? The mistake, I think, is to regard the mind as entirely conscious, thus creating a sharp boundary between two aspects of our lives. As shown by blindsight, I take many of my central mental operations to be pre- or non-conscious.
18. Thought / A. Modes of Thought / 2. Propositional Attitudes
In some thoughts I grasp a subject, but also I will or fear or affirm or deny it
     Full Idea: Other thoughts are different from ideas, as when I will, or fear, or affirm, or deny, there is always some thing that I grasp as the subject of my thought, yet I embrace in my thought something more than the likeness of that thing.
     From: René Descartes (Meditations [1641], §3.37)
     A reaction: Note that the class of mental events we call 'propositional attitudes' had already been identified by Descartes. His categories of thinking in Med. Three might be one of his most important contributions, because that is what matters in the mind.
18. Thought / A. Modes of Thought / 3. Emotions / c. Role of emotions
For Descartes passions are God-given preservers of the mind-body union
     Full Idea: Descartes sees passions not as opinions, but as functional devices that the Creator has designed for us to help preserve the body-soul substantial union.
     From: report of René Descartes (The Passions of the Soul [1649]) by Charles Taylor - Sources of the Self §8
     A reaction: I wonder what Descartes would have made of the theory of evolution?
18. Thought / A. Modes of Thought / 3. Emotions / e. Basic emotions
There are six primitive passions: wonder, love, hatred, desire, joy and sadness
     Full Idea: Descartes said there are six primitive passions, namely wonder, love, hatred, desire, joy and sadness. The others are either species of these, or composed of them.
     From: report of René Descartes (The Passions of the Soul [1649], 353) by Peter Goldie - The Emotions 4 'Evidence'
     A reaction: [not sure about ref] It's a nice touch to add 'wonder', which doesn't make it onto anyone else's list.
Are there a few primary passions (say, joy, sadness and desire)?
     Full Idea: Descartes says there are six primary passions (wonder, love, hatred, desire, joy and sadness); Spinoza says there are just three (joy, sadness and desire).
     From: report of René Descartes (The Passions of the Soul [1649]) by John Cottingham - The Rationalists p.172
     A reaction: A dubious project. However, it is now agreed that there are a few (six?) basic universal facial expressions, to which these passions may correspond.
18. Thought / A. Modes of Thought / 5. Rationality / b. Human rationality
Descartes created the modern view of rationality, as an internal feature instead of an external vision
     Full Idea: Rationality is now an internal property of subjective thinking, rather than its consisting in (according to Plato) its vision of reality. This view of Descartes' has become the standard modern view.
     From: report of René Descartes (Meditations [1641]) by Charles Taylor - Sources of the Self §8
     A reaction: Greek 'logos' actually seemed to be both internal and external. We have certainly lost the idea that the universe is rational, even though it is ordered.
18. Thought / A. Modes of Thought / 6. Judgement / b. Error
I make errors because my will extends beyond my understanding
     Full Idea: My errors are owing simply to the fact that, since the will extends further than the intellect, I do not contain the will within the same boundaries, but extend it to things I do not understand.
     From: René Descartes (Meditations [1641], §4.58)
Most errors of judgement result from an inaccurate perception of the facts
     Full Idea: What usually misleads us is that we very frequently form a judgement although we do not have an accurate perception of what we judge.
     From: René Descartes (Principles of Philosophy [1646], I.33)
     A reaction: This seems to me a generally accurate observation, particularly in the making of moral judgements (which was probably not what Descartes was considering). The implication is that judgements are to a large extent forced by our perceptions.
18. Thought / B. Mechanics of Thought / 6. Artificial Thought / c. Turing Test
A machine could speak in response to physical stimulus, but not hold a conversation
     Full Idea: One may conceive of a machine made so as to emit words, and even emit them in response to a change in its bodily organs, such as being touched, but not to reply to the sense of everything said in its presence, as the most unintelligent men can.
     From: René Descartes (A Discourse on Method [1637], §5.56)
     A reaction: A critique of the Turing Test, written in 1637! You have to admire. Because of the advent of the microprocessor, we can 'conceive' more sophisticated, multi-level machines than Descartes could come up with.
18. Thought / C. Content / 2. Ideas
True ideas are images, such as of a man, a chimera, or God
     Full Idea: Some of my thoughts are like images of things; to these alone does the word 'idea' properly apply, as when I think of a man, or a chimera, or the sky, or an angel, or God.
     From: René Descartes (Meditations [1641], §3.37)
     A reaction: Descartes is obviously aware of a problem with the application of the word 'idea'. This definition seems rather narrow (and visual), but it is certainly confined to concepts, and does not expand to include propositions.
18. Thought / C. Content / 10. Causal Semantics
All ideas are adventitious, and come from the senses
     Full Idea: I would go further than you and note that all our ideas seem to be adventitious - to proceed from things which exist outside the mind and come under one of our senses. ..The idea of a giant is a man of ordinary size which the mind enlarges at will.
     From: comment on René Descartes (Meditations [1641], §3.38) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 280
     A reaction: A classic early statement of modern empiricism. Gassendi needed to think about logic, maths, and necessities to make his case more secure. Where did his idea to 'enlarge' the giant come from?
18. Thought / D. Concepts / 2. Origin of Concepts / c. Nativist concepts
A blind man may still contain the idea of colour
     Full Idea: How do you know that there is no idea of colour in a man born blind?
     From: René Descartes (Reply to Fifth Objections [1641], 363)
The idea of a supremely perfect being is within me, like the basic concepts of mathematics
     Full Idea: The idea of God, that is, the idea of a supremely perfect being, is one discovered to be no less within me than the idea of any figure or number.
     From: René Descartes (Meditations [1641], §5.65)
The ideas of God and of my self are innate in me
     Full Idea: The idea of God is innate in me, just as the idea of myself is innate in me.
     From: René Descartes (Meditations [1641], §3.51)
I can think of innumerable shapes I have never experienced
     Full Idea: I can think of countless geometrical figures, concerning which there can be no suspicion of their ever having entered me through the senses.
     From: René Descartes (Meditations [1641], §5.64)
Qualia must be innate, because physical motions do not contain them
     Full Idea: The ideas of pains, colours, sounds etc. must be all the more innate if, on the occasion of certain corporeal motions, our mind is to be capable of representing them to itself, for there is no similarity between these ideas and the corporeal motions.
     From: René Descartes (Comments on a Certain Broadsheet [1644], p.365)
     A reaction: Simple and brilliant! We know perfectly well that there is no redness zooming through the air from a tomato (or the air would be pink!). Redness occurs when the light arrives, so we add the redness, so it is innate.
The mind's innate ideas are part of its capacity for thought
     Full Idea: I have never written or taken the view that the mind requires innate ideas which are something distinct from its own faculty of thinking.
     From: René Descartes (Comments on a Certain Broadsheet [1644], p.365)
20. Action / B. Preliminaries of Action / 2. Willed Action / b. Volitionism
Merely willing to walk leads to our walking
     Full Idea: Our merely willing to walk has the consequence that our legs move and we walk.
     From: René Descartes (The Passions of the Soul [1649], 18), quoted by Rowland Stout - Action 1 'Volitionism'
     A reaction: Stout attributes this to Descartes' dualism, as if legs are separate from persons. Stout says the idea of a prior mental act is not usually now considered as part of an action, or even to exist at all. If the volition is intentional, there is a regress.
20. Action / C. Motives for Action / 4. Responsibility for Actions
We do not praise the acts of an efficient automaton, as their acts are necessary
     Full Idea: We do not praise automata, although they respond exactly to the movements they were designed to produce, since their actions are performed necessarily
     From: René Descartes (Principles of Philosophy [1646], I.37)
     A reaction: I say we attribute responsibility when we perceive something like a 'person' as causing them. We don't blame small animals, because there is 'no one at home', but we blame children as they develop a full character and identity. We can ignore free will.
The greatest perfection of man is to act by free will, and thus merit praise or blame
     Full Idea: That the will should extend widely accords with its nature, and it is the greatest perfection in man to be able to act by its means, that is, freely, and by so doing we are in peculiar way masters of our actions, and thereby merit praise or blame.
     From: René Descartes (Principles of Philosophy [1646], I.37)
     A reaction: This seems to me to be a deep-rooted and false understanding which philosophy has inherited from theology. It doesn't strike me that there must an absolute 'buck-stop' to make us responsible. Why is it better for a decision to appear out of nowhere?
22. Metaethics / B. Value / 2. Values / e. Death
We don't die because the soul departs; the soul departs because the organs cease functioning
     Full Idea: We ought to hold, on the contrary, that the soul takes its leave when we die only because this heat ceases and the organs that bring about bodily movement decay.
     From: René Descartes (The Passions of the Soul [1649], I.5), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 24.5
     A reaction: This sounds like a pretty major change in our concept of death, given that we all now agree with Descartes.
23. Ethics / C. Virtue Theory / 1. Virtue Theory / d. Virtue theory critique
Greeks elevate virtues enormously, but never explain them
     Full Idea: The ancient pagans place virtues on a high plateau and make them appear the most valuable thing in the world, but they do not sufficiently instruct us about how to know them.
     From: René Descartes (A Discourse on Method [1637], §1.8)
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
Descartes makes strength of will the central virtue
     Full Idea: Descartes makes strength of will the central virtue.
     From: report of René Descartes (The Passions of the Soul [1649]) by Charles Taylor - Sources of the Self §8
     A reaction: Presumably strength of will can serve evil ends, so this is a bit confusing.
23. Ethics / F. Existentialism / 5. Existence-Essence
Essence must be known before we discuss existence
     Full Idea: According to the laws of true logic, we must never ask about the existence of anything until we first understand its essence.
     From: René Descartes (Reply to First Objections [1641], 108)
26. Natural Theory / A. Speculations on Nature / 1. Nature
Nature is devoid of thought
     Full Idea: It is Descartes who ratifies the idea that nature is devoid of thought.
     From: report of René Descartes (works [1643]) by Quentin Meillassoux - After Finitude; the necessity of contingency 5
     A reaction: His dualism is crucial, along with his ontological argument, because they make all mentality supernatural. Remember, for Descartes animals are mindless machines.
Physics only needs geometry or abstract mathematics, which can explain and demonstrate everything
     Full Idea: I do not accept or desire any other principle in physics than in geometry or abstract mathematics, because all the phenomena of nature may be explained by their means, and sure demonstrations can be given of them.
     From: René Descartes (Principles of Philosophy [1646], 2.64), quoted by Peter Alexander - Ideas, Qualities and Corpuscles 7
     A reaction: This is his famous and rather extreme view, which might be described as hyper-pythagoreanism (by adding geometry to numbers). It seems to leave out matter, forces and activity.
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / a. Final purpose
Many causes are quite baffling, so it is absurd to deduce causes from final purposes
     Full Idea: God can make unnumerable things whose cause escapes me, and for this reason alone the entire class of causes which people customarily derive from a thing's "end", I judge to be utterly useless in physics.
     From: René Descartes (Meditations [1641], §4.55)
     A reaction: anti-Aristotle
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / c. Purpose denied
We will not try to understand natural or divine ends, or final causes
     Full Idea: We will not seek for the reason of natural things from the end which God or nature has set before him in their creation .
     From: René Descartes (Principles of Philosophy [1646], §28)
     A reaction: Teleology is more relevant to biology than to the other sciences, and it is hard to understand an eye without a notion of 'what it is for'. Planetary motion reveals nothing about purposes. If you demand a purpose, it becomes more baffling.
26. Natural Theory / A. Speculations on Nature / 4. Mathematical Nature
All the sciences searching for order and measure are related to mathematics
     Full Idea: I have discovered that all the sciences which have as their aim the search for order and measure are related to mathematics.
     From: René Descartes (Rules for the Direction of the Mind [1628], 04)
     A reaction: Note that he sound a more cautious note than Galileo's famous remark. It leaves room for biology to still be a science, even when it fails to be mathematical.
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / f. Ancient elements
The Hot, Cold, Wet and Dry of the philosophers need themselves to be explained
     Full Idea: If you find it strange that in explaining these elements I do not use the qualities called Hot, Cold, Wet and Dry - as the philosophers do - I shall say to you that these qualities themselves seem to me to need explanation.
     From: René Descartes (The World [1631], 9:25-6), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 1.3
     A reaction: Nice. I take pushing the boundaries of explanation back (or down) to be the basic driving force of all human thought, in metaphysics as well as in physics.
26. Natural Theory / A. Speculations on Nature / 7. Later Matter Theories / c. Matter as extension
Matter can't just be Descartes's geometry, because a filler of the spaces is needed
     Full Idea: Notoriously, the Cartesian idea that matter is purely geometrical will not do, for it leaves no distinction between matter and empty volumes: a filler for these volumes is required.
     From: comment on René Descartes (works [1643]) by Howard Robinson - Perception IX.3
     A reaction: Descartes thinks of matter as 'extension'. Descartes's error seems so obvious that it is a puzzle why he made it. He may have confused epistemology and ontology - all we can know of matter is its extension in space.
Matter is not hard, heavy or coloured, but merely extended in space
     Full Idea: The nature of matter, or body viewed as a whole, consists not in its being something which is hard, heavy, or colored, or which in any other way affects the senses, but only in its being a thing extended in length, breadth and depth.
     From: René Descartes (Principles of Philosophy [1646], 2.4), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 04.5
Impenetrability only belongs to the essence of extension
     Full Idea: It is demonstrated that impenetrability belongs to the essence of extension and not to the essence of any other thing.
     From: René Descartes (Two letters on mind [1649], More, Apr 1649), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 15.5
     A reaction: I'm not sure that I understand how pure extension can be impenetrable.
26. Natural Theory / C. Causation / 8. Particular Causation / c. Conditions of causation
There must be at least as much in the cause as there is in the effect
     Full Idea: There must be at least as much in the cause as there is in the effect.
     From: René Descartes (Meditations [1641], §3.49)
26. Natural Theory / D. Laws of Nature / 7. Strictness of Laws
God has established laws throughout nature, and implanted ideas of them within us
     Full Idea: I have noticed certain laws that God has so established in nature, and of which he has implanted such notions in our souls, that …we cannot doubt that they are exactly observed in everything that exists or occurs in the world.
     From: René Descartes (A Discourse on Method [1637], pt 5), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 15.5
     A reaction: This is the view of laws which still seems to be with us (and needs extirpating) - that some outside agency imposes them on nature. I suspect that even Richard Feynman thought of laws like that, because he despised philosophy, and was thus naďve.
27. Natural Reality / A. Classical Physics / 1. Mechanics / b. Laws of motion
Descartes said there was conservation of 'quantity of motion'
     Full Idea: Descartes incorporated the conservation of what he called 'quantity of motion', by which he meant mass times speed.
     From: report of René Descartes (The World [1631]) by David Papineau - Thinking about Consciousness App 2
     A reaction: Mass times velocity is now called 'momentum'. Is this the first ever conservation law? There are now lots of them.
28. God / A. Divine Nature / 2. Divine Nature
God the creator is an intelligent, infinite, powerful substance
     Full Idea: I understand by the name "God" a certain substance that is infinite, independent, supremely intelligent and supremely powerful, and created me along with everything that exists.
     From: René Descartes (Meditations [1641], §3.45)
Nothing apart from God could have essential existence, and such a being must be unique and eternal
     Full Idea: I cannot think of anything aside from God alone to whose essence existence belongs, and I cannot conceive of two or more such Gods. I also perceive that God must be eternal, and have other perfect qualities.
     From: René Descartes (Meditations [1641], §5.68)
28. God / A. Divine Nature / 3. Divine Perfections
It is self-evident that deception is a natural defect, so God could not be a deceiver
     Full Idea: It is quite obvious that a perfect God cannot be a deceiver, for it is manifest by the light of nature that all fraud and deception depend on some defect.
     From: René Descartes (Meditations [1641], §3.52)
28. God / A. Divine Nature / 6. Divine Morality / d. God decrees morality
Ideas in God's mind only have value if he makes it so
     Full Idea: It is impossible to imagine that anything is thought of in the divine intellect as good or true, or worthy of belief or action or omission, prior to the decision of the divine will to make it so.
     From: René Descartes (Reply to Sixth Objections [1641], 432)
28. God / B. Proving God / 2. Proofs of Reason / a. Ontological Proof
Existence and God's essence are inseparable, like a valley and a mountain, or a triangle and its properties
     Full Idea: Existence can no more be separated from God's essence than its having three angles equal to two right angles can be separated from the essence of a triangle, or than the idea of a valley can be separated from the idea of a mountain.
     From: René Descartes (Meditations [1641], §5.66)
One idea leads to another, but there must be an initial idea that contains the reality of all the others
     Full Idea: Although one idea can perhaps issue from another, nevertheless no infinite regress is permitted here; eventually some first idea must be reached whose cause is a sort of archetype that contains formally all the reality that is in the idea.
     From: René Descartes (Meditations [1641], §3.42)
The idea of God in my mind is like the mark a craftsman puts on his work
     Full Idea: In creating me, God has endowed me with the idea of God, so that it would be like the mark of the craftsman impressed upon his work, although this mark need not be something distinct from the work itself.
     From: René Descartes (Meditations [1641], §3.51)
Necessary existence is a property which is uniquely part of God's essence
     Full Idea: In the case of God necessary existence is in fact a property in the strictest sense of the term, since it applies to him alone and forms a part of his essence as it does of no other thing
     From: René Descartes (Reply to Fifth Objections [1641], 383)
Possible existence is a perfection in the idea of a triangle
     Full Idea: Possible existence is a perfection in the idea of a triangle, just as necessary existence is a perfection in the idea of God.
     From: René Descartes (Reply to Fifth Objections [1641], 383)
I cannot think of a supremely perfect being without the supreme perfection of existence
     Full Idea: I am not free to think of God without existence, that is, a supremely perfect being without a supreme perfection.
     From: René Descartes (Meditations [1641], §5.67)
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
We mustn't worship God as an image because we have no idea of him
     Full Idea: We are forbidden to worship God in the form of an image, for otherwise we might think that we were conceiving of him who is incapable of being conceived. It seems, then, that there is no idea of God in us.
     From: comment on René Descartes (Meditations [1641], §5.65) by Thomas Hobbes - Objections to 'Meditations' (Third) 180
Existence is not a perfection; it is what makes perfection possible
     Full Idea: Existence is not a perfection in God or in anything else; it is that without which no perfections can be present.
     From: comment on René Descartes (Meditations [1641], §5.67) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 323
We can never conceive of an infinite being
     Full Idea: The human intellect is not capable of conceiving of infinity, and hence it neither has nor can contemplate any idea representing an infinite thing.
     From: comment on René Descartes (Meditations [1641], §5.65) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 286
Descartes cannot assume that a most perfect being exists without contradictions
     Full Idea: Descartes' error is in assuming without proof that a most perfect being does not involve a contradiction.
     From: comment on René Descartes (Meditations [1641], §5.67) by Gottfried Leibniz - A Specimen of Discoveries p.76
     A reaction: Certainly Descartes seems obliged to grasp the concept of God 'clearly and distinctly', so there must be an absence of contradictions. But does Descartes have to prove that there are no contradictions in his concept of a triangle? Is self-evidence enough?
28. God / B. Proving God / 3. Proofs of Evidence / a. Cosmological Proof
We can't prove a first cause from our inability to grasp infinity
     Full Idea: My inability to grasp an infinite chain of successive causes without a first cause does not entail that there must be a first cause, just as my inability to grasp infinite divisibility of finite things does not make that impossible.
     From: René Descartes (Reply to First Objections [1641], 106)
28. God / C. Attitudes to God / 5. Atheism
Atheism is an atrocious and intolerable crime in any country
     Full Idea: Atheism is the most atrocious crime, and should be tolerated in no republic, however free.
     From: René Descartes (Letters to Voetius [1640], VIIIB:174), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 20.2
Atheism arises from empiricism, because God is intangible
     Full Idea: The existence of God has been doubted by some, because they attributed too much to the perceptions of the senses, and God can be neither seen nor touched.
     From: René Descartes (Preface to 'Principles of Philosophy' [1647], p.180)
29. Religion / B. Monotheistic Religion / 4. Christianity / c. Angels
An angelic mind would not experience pain, even when connected to a human body
     Full Idea: Descartes points out that an angelic mind, even if causally connected to a human body, would not experience the same sort of bodily sensations; it would, instead, simply observe flesh being torn, like a piece of paper.
     From: report of René Descartes (Letters to Regius [1642], III:493) by Robert Pasnau - Metaphysical Themes 1274-1671 25.6
     A reaction: Does that mean that the angel could not have the experience even if it wanted to have it. So they can't pick up a cup either? So they can't make themselves known to us, even if they are desperate to? So the Annunciation never happened?
29. Religion / D. Religious Issues / 2. Immortality / b. Soul
I can't prove the soul is indestructible, only that it is separate from the mortal body
     Full Idea: I don't know how to demonstrate that God cannot annihilate the soul, but only that it is entirely distinct from the body, and consequently that it is not naturally subject to die with it, which is all that is required to establish religion.
     From: René Descartes (Letters to Mersenne [1640], 1640.02.24)
29. Religion / D. Religious Issues / 3. Problem of Evil / c. Human Error
God didn't give us good judgement even about our own lives
     Full Idea: God is not to be blamed for giving puny man a faculty of judging that is too small to cope with everything, but we may still wonder why our judgement is uncertain, confused and inadequate even for the few matters he did want us to decide upon.
     From: comment on René Descartes (Meditations [1641], §4.58) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 314
Error arises because my faculty for judging truth is not infinite
     Full Idea: I make mistakes because the faculty of judging the truth, which I got from God, is not, in my case, infinite.
     From: René Descartes (Meditations [1641], §4.54)
Since God does not wish to deceive me, my judgement won't make errors if I use it properly
     Full Idea: Since God does not wish to deceive me, he assuredly has not given me a faculty of judgement with which I could never make a mistake, when I use it properly.
     From: René Descartes (Meditations [1641], §4.54)
29. Religion / D. Religious Issues / 3. Problem of Evil / d. Natural Evil
If we ask whether God's works are perfect, we must not take a narrow viewpoint, but look at the universe as a whole
     Full Idea: Whenever we ask whether the works of God are perfect, we should keep in view not simply some one creature in isolation from the rest, but the universe as a whole.
     From: René Descartes (Meditations [1641], §4.55)