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All the ideas for 'Structures and Structuralism in Phil of Maths', 'The Powers Metaphysics' and 'Letters to Des Bosses'

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54 ideas

1. Philosophy / E. Nature of Metaphysics / 5. Metaphysics beyond Science
We can grasp the wisdom of God a priori [Leibniz]
     Full Idea: We can grasp the wisdom of God a priori, and not from the order of the phenomena alone. ... For the senses put nothing forward concerning metaphysical matters.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: Nice instance of the aspirations of big metaphysics, before Kant cut it down to size. The claim is not far off Plato's, that by dialectic we can work out the necessities of the Forms, to which even the gods must bow. Are necessities really kept from us?
1. Philosophy / F. Analytic Philosophy / 4. Conceptual Analysis
Reductive analysis makes a concept clearer, by giving an alternative simpler set [Williams,NE]
     Full Idea: A reductive analysis is one that provides an alternative set of concepts by which some target concept can be understood. It must be non-circular, and given in terms of concepts that are themselves better understood.
     From: Neil E. Williams (The Powers Metaphysics [2019], 01.2)
     A reaction: There seem to be two aims of analysis: this one emphasises understanding, but the other one concerns ontology - by demonstrating that some concept or thing can be understood fully by what happens at a lower level.
2. Reason / E. Argument / 1. Argument
Promoting an ontology by its implied good metaphysic is an 'argument-by-display' [Williams,NE]
     Full Idea: The form of argument which sells an ontology on the basis a metaphysic is known as an 'argument-by-display'.
     From: Neil E. Williams (The Powers Metaphysics [2019], 01.2)
     A reaction: [Attributed to John Bigelow 1999] New to me, but I'm quite a fan of this. For example, my rejection of platonism is not based on specific arguments, but on looking at the whole platonic picture of reality.
3. Truth / F. Semantic Truth / 2. Semantic Truth
While true-in-a-model seems relative, true-in-all-models seems not to be [Reck/Price]
     Full Idea: While truth can be defined in a relative way, as truth in one particular model, a non-relative notion of truth is implied, as truth in all models.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: [The article is actually discussing arithmetic] This idea strikes me as extremely important. True-in-all-models is usually taken to be tautological, but it does seem to give a more universal notion of truth. See semantic truth, Tarski, Davidson etc etc.
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
ZFC set theory has only 'pure' sets, without 'urelements' [Reck/Price]
     Full Idea: In standard ZFC ('Zermelo-Fraenkel with Choice') set theory we deal merely with pure sets, not with additional urelements.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: The 'urelements' would the actual objects that are members of the sets, be they physical or abstract. This idea is crucial to understanding philosophy of mathematics, and especially logicism. Must the sets exist, just as the urelements do?
5. Theory of Logic / G. Quantification / 5. Second-Order Quantification
Three types of variable in second-order logic, for objects, functions, and predicates/sets [Reck/Price]
     Full Idea: In second-order logic there are three kinds of variables, for objects, for functions, and for predicates or sets.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: It is interesting that a predicate seems to be the same as a set, which begs rather a lot of questions. For those who dislike second-order logic, there seems nothing instrinsically wicked in having variables ranging over innumerable multi-order types.
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
'Analysis' is the theory of the real numbers [Reck/Price]
     Full Idea: 'Analysis' is the theory of the real numbers.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: 'Analysis' began with the infinitesimal calculus, which later built on the concept of 'limit'. A continuum of numbers seems to be required to make that work.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / a. Axioms for numbers
Mereological arithmetic needs infinite objects, and function definitions [Reck/Price]
     Full Idea: The difficulties for a nominalistic mereological approach to arithmetic is that an infinity of physical objects are needed (space-time points? strokes?), and it must define functions, such as 'successor'.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: Many ontologically austere accounts of arithmetic are faced with the problem of infinity. The obvious non-platonist response seems to be a modal or if-then approach. To postulate infinite abstract or physical entities so that we can add 3 and 2 is mad.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
Peano Arithmetic can have three second-order axioms, plus '1' and 'successor' [Reck/Price]
     Full Idea: A common formulation of Peano Arithmetic uses 2nd-order logic, the constant '1', and a one-place function 's' ('successor'). Three axioms then give '1 is not a successor', 'different numbers have different successors', and induction.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: This is 'second-order' Peano Arithmetic, though it is at least as common to formulate in first-order terms (only quantifying over objects, not over properties - as is done here in the induction axiom). I like the use of '1' as basic instead of '0'!
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Set-theory gives a unified and an explicit basis for mathematics [Reck/Price]
     Full Idea: The merits of basing an account of mathematics on set theory are that it allows for a comprehensive unified treatment of many otherwise separate branches of mathematics, and that all assumption, including existence, are explicit in the axioms.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: I am forming the impression that set-theory provides one rather good model (maybe the best available) for mathematics, but that doesn't mean that mathematics is set-theory. The best map of a landscape isn't a landscape.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism
Structuralism emerged from abstract algebra, axioms, and set theory and its structures [Reck/Price]
     Full Idea: Structuralism has emerged from the development of abstract algebra (such as group theory), the creation of axiom systems, the introduction of set theory, and Bourbaki's encyclopaedic survey of set theoretic structures.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: In other words, mathematics has gradually risen from one level of abstraction to the next, so that mathematical entities like points and numbers receive less and less attention, with relationships becoming more prominent.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / b. Varieties of structuralism
Relativist Structuralism just stipulates one successful model as its arithmetic [Reck/Price]
     Full Idea: Relativist Structuralism simply picks one particular model of axiomatised arithmetic (i.e. one particular interpretation that satisfies the axioms), and then stipulates what the elements, functions and quantifiers refer to.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: The point is that a successful model can be offered, and it doesn't matter which one, like having any sort of aeroplane, as long as it flies. I don't find this approach congenial, though having a model is good. What is the essence of flight?
There are 'particular' structures, and 'universal' structures (what the former have in common) [Reck/Price]
     Full Idea: The term 'structure' has two uses in the literature, what can be called 'particular structures' (which are particular relational systems), but also what can be called 'universal structures' - what particular systems share, or what they instantiate.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §6)
     A reaction: This is a very helpful distinction, because it clarifies why (rather to my surprise) some structuralists turn out to be platonists in a new guise. Personal my interest in structuralism has been anti-platonist from the start.
Pattern Structuralism studies what isomorphic arithmetic models have in common [Reck/Price]
     Full Idea: According to 'pattern' structuralism, what we study are not the various particular isomorphic models of arithmetic, but something in addition to them: a corresponding pattern.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §7)
     A reaction: Put like that, we have to feel a temptation to wield Ockham's Razor. It's bad enough trying to give the structure of all the isomorphic models, without seeking an even more abstract account of underlying patterns. But patterns connect to minds..
There are Formalist, Relativist, Universalist and Pattern structuralism [Reck/Price]
     Full Idea: There are four main variants of structuralism in the philosophy of mathematics - formalist structuralism, relativist structuralism, universalist structuralism (with modal variants), and pattern structuralism.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §9)
     A reaction: I'm not sure where Chihara's later book fits into this, though it is at the nominalist end of the spectrum. Shapiro and Resnik do patterns (the latter more loosely); Hellman does modal universalism; Quine does the relativist version. Dedekind?
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / c. Nominalist structuralism
Formalist Structuralism says the ontology is vacuous, or formal, or inference relations [Reck/Price]
     Full Idea: Formalist Structuralism endorses structural methodology in mathematics, but rejects semantic and metaphysical problems as either meaningless, or purely formal, or as inference relations.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §3)
     A reaction: [very compressed] I find the third option fairly congenial, certainly in preference to rather platonist accounts of structuralism. One still needs to distinguish the mathematical from the non-mathematical in the inference relations.
Maybe we should talk of an infinity of 'possible' objects, to avoid arithmetic being vacuous [Reck/Price]
     Full Idea: It is tempting to take a modal turn, and quantify over all possible objects, because if there are only a finite number of actual objects, then there are no models (of the right sort) for Peano Arithmetic, and arithmetic is vacuously true.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: [compressed; Geoffrey Hellman is the chief champion of this view] The article asks whether we are not still left with the puzzle of whether infinitely many objects are possible, instead of existent.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / d. Platonist structuralism
Universalist Structuralism is based on generalised if-then claims, not one particular model [Reck/Price]
     Full Idea: Universalist Structuralism is a semantic thesis, that an arithmetical statement asserts a universal if-then statement. We build an if-then statement (using quantifiers) into the structure, and we generalise away from any one particular model.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: There remains the question of what is distinctively mathematical about the highly generalised network of inferences that is being described. Presumable the axioms capture that, but why those particular axioms? Russell is cited as an originator.
Universalist Structuralism eliminates the base element, as a variable, which is then quantified out [Reck/Price]
     Full Idea: Universalist Structuralism is eliminativist about abstract objects, in a distinctive form. Instead of treating the base element (say '1') as an ambiguous referring expression (the Relativist approach), it is a variable which is quantified out.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: I am a temperamental eliminativist on this front (and most others) so this is tempting. I am also in love with the concept of a 'variable', which I take to be utterly fundamental to all conceptual thought, even in animals, and not just a trick of algebra.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / e. Structuralism critique
The existence of an infinite set is assumed by Relativist Structuralism [Reck/Price]
     Full Idea: Relativist Structuralism must first assume the existence of an infinite set, otherwise there would be no model to pick, and arithmetical terms would have no reference.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: See Idea 10169 for Relativist Structuralism. They point out that ZFC has an Axiom of Infinity.
7. Existence / B. Change in Existence / 1. Nature of Change
Change exists, it is causal, and it needs an explanation [Williams,NE]
     Full Idea: There is a phenomenon of change. I am starting with the assumptions that it is a causal phenomenon, and that it requires explanation.
     From: Neil E. Williams (The Powers Metaphysics [2019], 06.1)
     A reaction: That is, I take it, that we need a theory which explains change, rather than just describing it. Well said. Williams says, roughly, that each stage causes the next stage.
7. Existence / B. Change in Existence / 2. Processes
Processes don't begin or end; they just change direction unexpectedly [Williams,NE]
     Full Idea: No process every really starts or ends. …A process we see as derailed is really just an expected sequence that continues in an unexpected direction.
     From: Neil E. Williams (The Powers Metaphysics [2019], 06.3)
     A reaction: Obviously if you cannot individuate processes, then the concept of a process is not much use in ontology. Williams rejects processes, and I think he is probably right. He breaks processes down into smaller units.
Processes are either strings of short unchanging states, or continuous and unreducible events [Williams,NE]
     Full Idea: Processes can be modelled in two ways. They are drawn out events encompassing many changes, but dissectible into short-lived states, none including change. Or they are continuous and impenetrable, and to split them is impossible.
     From: Neil E. Williams (The Powers Metaphysics [2019], 09.3)
     A reaction: Obviously a process has temporal moments in it, so the unsplittability is conceptual. I find the concept of changeless parts baffling. But if processes are drawn out, they can't be basic to ontology.
7. Existence / C. Structure of Existence / 6. Fundamentals / c. Monads
Without a substantial chain to link monads, they would just be coordinated dreams [Leibniz]
     Full Idea: If that substantial chain [vinculum substantiale] for monads did not exist, all bodies, together with all of their qualities, would be nothing but well-founded phenomena, like a rainbow or an image in a mirror, continual dreams perfectly in agreement.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.02.05)
     A reaction: [The first appearance, apparently, of the 'susbtantial chain' in his writings] I take this to be a hugely significant move, either a defeat for monads, or the arrival of common sense. Spiritual monads must unify things, so they can't just be 'parallel'.
Monads do not make a unity unless a substantial chain is added to them [Leibniz]
     Full Idea: Monads do not constitute a complete composite substance, since they make up, not something one per se, but only a mere aggregate, unless some substantial chain is added.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.05.26)
     A reaction: This is the clearest statement in the Des Bosses letters of the need for something extra to unite monads. Since the main role of monads was to replace substances, which are only postulated to provide unity, this is rather a climb-down.
Monads control nothing outside of themselves [Leibniz]
     Full Idea: Monads aren't a principle of operation for things outside of themselves.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: This is why Leibniz has got into a tangle, and is proposing his 'substantial chain' to join the monads together. I suspect that he would have dumped monads if he had lived a bit longer.
7. Existence / D. Theories of Reality / 1. Ontologies
The status quo is part of what exists, and so needs metaphysical explanation [Williams,NE]
     Full Idea: The status quo is part of what exists, and thus it is a proper topic of concern for the metaphysician, and so it warrants explanation.
     From: Neil E. Williams (The Powers Metaphysics [2019], 07.2)
     A reaction: His point is that ontology as a mere inventory of things gives no account of why they remain unchanged, as well as their processes and connections.
A metaphysic is a set of wider explanations derived from a basic ontology [Williams,NE]
     Full Idea: A metaphysic is what you get when you embed a fundamental ontology within a larger metaphysical framework by repeatedly appealing to elements of that ontology in explaining metaphysical phenomena. …Only then do you see what the ontology is worth.
     From: Neil E. Williams (The Powers Metaphysics [2019], 01.1)
     A reaction: Confirming my mantra that metaphysics is an explanatory activity. I think it is important that the ontology includes relations (such as 'determinations'), and is not just an inventory of types of entity.
Humeans say properties are passive, possibility is vast, laws are descriptions, causation is weak [Williams,NE]
     Full Idea: The main components of neo-Humean metaphysics are that properties are inherently non-modal and passive, that what is possible is restricted only by imagination and coherence, that laws are non-governing descriptions, and causation is weak and extrinsic.
     From: Neil E. Williams (The Powers Metaphysics [2019], 02.1)
     A reaction: This is Williams identifying the enemy, prior to offering the much more active and restictive powers ontology. I'm with Williams.
We shouldn't posit the existence of anything we have a word for [Williams,NE]
     Full Idea: There seems to be a mysterious desire to posit entities simply because certain terms pop up in our vocabulary. But we should not be so indiscriminate about our posits, even if our talk is properly vetted.
     From: Neil E. Williams (The Powers Metaphysics [2019], 04.1)
     A reaction: This should hardly need saying, and the familiar example is 'for the sake of' entailing sakes, but it seems to be a vice that is still found in metaphysical philosophy. The word 'nothingness' comes to mind.
8. Modes of Existence / C. Powers and Dispositions / 1. Powers
Every possible state of affairs is written into its originating powers [Williams,NE]
     Full Idea: On the model of powers I prefer, every possible state of affairs that can arise is written into the powers that would constitute them.
     From: Neil E. Williams (The Powers Metaphysics [2019], 04.3)
     A reaction: I can't make any sense of 'written into', any more than I could when Leibniz proposed roughly the same thing about monads. I presume he means that any state of affairs which ever arises is the expression of the intrinsic nature of powers.
Naming powers is unwise, because that it usually done by a single manifestation [Williams,NE]
     Full Idea: Naming powers is unwise; the main reason is that there is a long tradition of naming powers according to the manifestations they can produce, and that does not square well with multi-track powers.
     From: Neil E. Williams (The Powers Metaphysics [2019], 08.4)
     A reaction: On the other hand there must be some attempt to individuate powers (by scientists, if not by philosophers), and that can only rely on the manifestations. Describe them, rather than name them? Just assign them a number!
Powers are 'multi-track' if they can produce a variety of manifestations [Williams,NE]
     Full Idea: Powers are 'multi-track', meaning that they are capable of producing a variety of different manifestations when me with diverse stimuli.
     From: Neil E. Williams (The Powers Metaphysics [2019], 03.1)
     A reaction: He later mentions magnetism. Not convinced of this. Powers probably never exist in isolation, so a different manifestation could be because a different power becomes involved. (Bird is a single-tracker).
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
Fundamental physics describes everything in terms of powers [Williams,NE]
     Full Idea: Physics describes fundamental entities exclusively in terms of what sound like powers. 'Charge' names the power to produce electromagnetic fields; 'spin' the power to contribute to the angular momentum of of system; 'mass' to produce gravitational force.
     From: Neil E. Williams (The Powers Metaphysics [2019], 01.4)
     A reaction: These are the three basic properties of an electron, which is fundamental in the standard model. You can say that their field is more fundamental than the particles, but the field is also only known as a set of powers. Powers rule!
8. Modes of Existence / C. Powers and Dispositions / 4. Powers as Essence
There is active and passive power in the substantial chain and in the essence of a composite [Leibniz]
     Full Idea: I do not say there is a chain midway between matter and form, but that the substantial form and primary matter of the composite, in the Scholastic sense (the primitive power, active and passive) are in the chain, and in the essence of the composite.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: Note that this implies an essence of primitive power, and not just a collection of all properties. This is the clearest account in these letters of the nature of the 'substantial chain' he has added to his monads.
Primitive force is what gives a composite its reality [Leibniz]
     Full Idea: The first entelechy of a composite is a constitutive part of the composite substance, namely its primitive force.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: For me, Leibniz's most interesting proposal is to characterise Aristotelian 'form' as an active thing, which offers an intrinsic account of movement, and a bottom level for explanations. There always remains the inexplicable. Why anything? Why this?
8. Modes of Existence / C. Powers and Dispositions / 5. Powers and Properties
Rather than pure powers or pure categoricals, I favour basics which are both at once [Williams,NE]
     Full Idea: Power Monism: all properties are powers. Categoricalism: all fundamentals are categorical. Dualism allows both types. I defend Mixed Monism - that there is a single class of fundamental properties that are at once powerful and categorical.
     From: Neil E. Williams (The Powers Metaphysics [2019], 03.3)
     A reaction: This is the main dilemma for the powers ontology - of how powers can be basic, if there needs to be some entity which possesses the power. But what possesses the powers of an electron? I like Williams's idea, without being clear about it.
Powers are more complicated than properties which are always on display [Williams,NE]
     Full Idea: The mode in which a power presents itself is more complicated than those properties that have (strictly) nothing more to them than that which is always on display.
     From: Neil E. Williams (The Powers Metaphysics [2019], 03.3)
     A reaction: This is the key idea that nature is dynamic, and so must consist of potentials as well as actuals. Interesting distinction. A basic division between those properties 'always on display', and those that are not?
8. Modes of Existence / C. Powers and Dispositions / 6. Dispositions / b. Dispositions and powers
There are basic powers, which underlie dispositions, potentialities, capacities etc [Williams,NE]
     Full Idea: It is no surprise that talk of dispositions, capacities, abilities, tendencies, powers, and potentialities are part of our everyday interactions. …I have in mind a basic set of powers, the sort which underlie all of these.
     From: Neil E. Williams (The Powers Metaphysics [2019], 03.1)
     A reaction: This strikes me as the correct picture. It is misleading say that a ball has a 'power' to roll smoothly. The powers are inside the ball.
Dispositions are just useful descriptions, which are explained by underlying powers [Williams,NE]
     Full Idea: Powers are the properties at the core of the powers ontology, and dispositions are more like useful talk. …Dispositions are the phenomena to be explained by the power metaphysic.
     From: Neil E. Williams (The Powers Metaphysics [2019], 10.2)
     A reaction: The picture I subscribe to. The first step is to see nature as dynamic (as Aristotle does with his 'potentialities'), and the next step to understand what must ground these dynamic dispositional properties. He calls dispositions 'process initiators'.
8. Modes of Existence / E. Nominalism / 6. Mereological Nominalism
A nominalist might avoid abstract objects by just appealing to mereological sums [Reck/Price]
     Full Idea: One way for a nominalist to reject appeal to all abstract objects, including sets, is to only appeal to nominalistically acceptable objects, including mereological sums.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: I'm suddenly thinking that this looks very interesting and might be the way to go. The issue seems to be whether mereological sums should be seen as constrained by nature, or whether they are unrestricted. See Mereology in Ontology...|Intrinsic Identity.
9. Objects / A. Existence of Objects / 1. Physical Objects
If objects are property bundles, the properties need combining powers [Williams,NE]
     Full Idea: If objects are bundles of properties …they must be robust enough to enter into building relations with one another such that they can form objects.
     From: Neil E. Williams (The Powers Metaphysics [2019], 01.5)
     A reaction: A very nice point. The Humean bundle view of objects just seems to take properties to be 'impressions' or verbal predicates, but they must have causal powers to be a grounding for ontology.
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
Things seem to be unified if we see duration, position, interaction and connection [Leibniz]
     Full Idea: Important relations are duration (order of successive things) and position (order of coexisting things) and interaction. Position without a thing mediating is presence. Beyond these is connection when things move one another. Thus things seem to be one.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.02.05)
     A reaction: [compressed] This is the best account I can find of his epistemological angle on the unity of things. They are symptoms of the inner power of unification, and he says that God sees these relations most clearly.
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
Every substance is alive [Leibniz]
     Full Idea: Every substance is alive.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1712.02.05)
     A reaction: The most charitable interpretation of this is that substances are what have unity, and the best model of unity that we can grasp is the unity of an organism. The less charitable view is that he literally thinks a pebble is 'alive'. Hm.
9. Objects / D. Essence of Objects / 6. Essence as Unifier
A substantial bond of powers is needed to unite composites, in addition to monads [Leibniz]
     Full Idea: Some realising thing must bring it about that composite substance contains something substantial besides monads, otherwise composites will be mere phenomena. The scholastics' active and passive powers are the substantial bond I am urging.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.01.13), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 9
     A reaction: [compressed] This appears to be a major retreat, in the last year of Leibniz's life, from the full monadology he had espoused. How do monads connect to matter, and thus unify it? He is returning to Aristotelian hylomorphism.
9. Objects / D. Essence of Objects / 12. Essential Parts
A composite substance is a mere aggregate if its essence is just its parts [Leibniz]
     Full Idea: An aggregate, but not a composite substance, is resolved into parts. A composite substance only needs the coming together of parts, but is not essentially constituted by them, otherwise it would be an aggregate.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: The point is that there is more to some things than there mere parts. Only some unifying principle, in addition to the mere parts, bestows a unity. Mereology is a limited activity if it has nothing to say about this issue.
9. Objects / E. Objects over Time / 4. Four-Dimensionalism
Four-Dimensional is Perdurantism (temporal parts), plus Eternalism [Williams,NE]
     Full Idea: 'Perdurantism' is the view that objects persist by being composed of temporal parts. When it is commonly combined with the eternalist account of the ontology of time, the result is known as 'four-dimensionalism'.
     From: Neil E. Williams (The Powers Metaphysics [2019], 08.1)
     A reaction: At last, a clear account of the distinction between these two! They're both wrong. He says the result is the spatiotemporal 'worm' view (i.e. one temporal extended thing, rather than a collection of parts).
10. Modality / B. Possibility / 1. Possibility
There is a reason why not every possible thing exists [Leibniz]
     Full Idea: There is a reason why not every possible thing exists.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: This is the kind of wonderful speculative metaphysical remark that we are not allowed to make any more. Needless to say, he doesn't tell us what the reason is. Overcrowding, perhaps.
13. Knowledge Criteria / E. Relativism / 2. Knowledge as Convention
Truth is mutually agreed perception [Leibniz]
     Full Idea: In the mutual agreement of perceivers consists the truth of the phenomena.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: This remark is startling close to the 'perspectivism' that crops up in the late notebooks of Nietzsche. Leibniz was keen on relativism in many areas, starting with the nature of space. I personally think Leibniz meant 'knowledge' rather than 'truth'.
26. Natural Theory / C. Causation / 1. Causation
Causation needs to explain stasis, as well as change [Williams,NE]
     Full Idea: I believe that it is also the job of a theory of causation to explain non-change
     From: Neil E. Williams (The Powers Metaphysics [2019], 07.2)
     A reaction: Good point. Most attempts to pin down causation refer only to changes and differences. Two playing cards propping one another up is his example.
Causation is the exercise of powers [Williams,NE]
     Full Idea: Causation is the exercising of powers.
     From: Neil E. Williams (The Powers Metaphysics [2019], 06.1)
     A reaction: Job done. Get over it. This is the view I prefer.
26. Natural Theory / C. Causation / 8. Particular Causation / b. Causal relata
If causes and effects overlap, that makes changes impossible [Williams,NE]
     Full Idea: It would be shocking if an account of causation ruled out the possibility of change. But if a cause perfectly overlaps its effect in time, then the rejection of change is precisely what follows.
     From: Neil E. Williams (The Powers Metaphysics [2019], 07.6)
     A reaction: He cites Kant, Martin, Heil and Mumford/Anjum for this view. The latter seem to see causation as a 'process' (allowing change), which Williams as ruled out. The Williams point must be correct.
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / c. Essence and laws
Powers contain lawlike features, pointing to possible future states [Williams,NE]
     Full Idea: Powers carry their lawlike features within them: it is part of their essence, qua power. Their pointing at future states just is their internal law-like nature; it is what gets expressed in such and such conditions.
     From: Neil E. Williams (The Powers Metaphysics [2019], 03.3)
     A reaction: Modern writers on powers seem unaware that Leibniz got there first. This seems to me the correct account of the ontology of laws. The formulation of laws is probably the best descriptive system for nature's patterns (over time as well as space).
28. God / B. Proving God / 3. Proofs of Evidence / e. Miracles
Allow no more miracles than are necessary [Leibniz]
     Full Idea: Miracles should not be increased beyond necessity.
     From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29)
     A reaction: Leibniz defends miracles (where Spinoza dismisses them). This remark is, of course, an echo of Ockham's Razor, that 'entities' should not be multiplied beyond necessity. It is hard to disagree with his proposal. Zero might be result, though.