97 ideas
| 1708 | In "Callias is just/not just/unjust", which of these are contraries? [Aristotle] |
| Full Idea: Take, for example, "Callias is just", "Callias is not just", and "Callias is unjust"; which of these are contraries? | |
| From: Aristotle (On Interpretation [c.330 BCE], 23a31) |
| 1703 | It is necessary that either a sea-fight occurs tomorrow or it doesn't, though neither option is in itself necessary [Aristotle] |
| Full Idea: It is not necessary for a sea-battle to take place tomorrow, nor for one not to take place tomorrow - though it is necessary for one to take place OR not take place tomorrow. | |
| From: Aristotle (On Interpretation [c.330 BCE], 19a30) |
| 1704 | Statements are true according to how things actually are [Aristotle] |
| Full Idea: Statements are true according to how things actually are. | |
| From: Aristotle (On Interpretation [c.330 BCE], 19a33) |
| 22272 | Aristotle's later logic had to treat 'Socrates' as 'everything that is Socrates' [Potter on Aristotle] |
| Full Idea: When Aristotle moved from basic name+verb (in 'De Interpretatione') to noun+noun logic...names had to be treated as special cases, so that 'Socrates' is treated as short for 'everything that is Socrates'. | |
| From: comment on Aristotle (On Interpretation [c.330 BCE]) by Michael Potter - The Rise of Analytic Philosophy 1879-1930 02 'Supp' | |
| A reaction: Just the sort of rewriting that Russell introduced for definite descriptions. 'Twas ever the logicians' fate to shoehorn ordinary speech into awkward containers. |
| 9405 | Square of Opposition: not both true, or not both false; one-way implication; opposite truth-values [Aristotle] |
| Full Idea: Square of Opposition: horizontals - 'contraries' can't both be true, and 'subcontraries' can't both be false; verticals - 'subalternatives' have downwards-only implication; diagonals - 'contradictories' have opposite truth values. | |
| From: Aristotle (On Interpretation [c.330 BCE], Ch.12-13) | |
| A reaction: This is still used in modern discussion (e.g. by Stalnaker against Kripke), and there is a modal version of it (Fitting and Mendelsohn p.7). Corners read: 'All F are G', 'No F are G', 'Some F are G' and 'Some F are not G'. |
| 9728 | Modal Square 1: □P and ¬◊¬P are 'contraries' of □¬P and ¬◊P [Aristotle, by Fitting/Mendelsohn] |
| Full Idea: Modal Square of Opposition 1: 'It is necessary that P' and 'It is not possible that not P' are the contraries (not both true) of 'It is necessary that not P' and 'It is not possible that P'. | |
| From: report of Aristotle (On Interpretation [c.330 BCE], Ch.12a) by M Fitting/R Mendelsohn - First-Order Modal Logic 1.4 |
| 9729 | Modal Square 2: ¬□¬P and ◊P are 'subcontraries' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn] |
| Full Idea: Modal Square of Opposition 2: 'It is not necessary that not P' and 'It is possible that P' are the subcontraries (not both false) of 'It is not necessary that P' and 'It is possible that not P'. | |
| From: report of Aristotle (On Interpretation [c.330 BCE], Ch.12b) by M Fitting/R Mendelsohn - First-Order Modal Logic 1.4 |
| 9730 | Modal Square 3: □P and ¬◊¬P are 'contradictories' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn] |
| Full Idea: Modal Square of Opposition 3: 'It is necessary that P' and 'It is not possible that not P' are the contradictories (different truth values) of 'It is not necessary that P' and 'It is possible that not P'. | |
| From: report of Aristotle (On Interpretation [c.330 BCE], Ch.12c) by M Fitting/R Mendelsohn - First-Order Modal Logic 1.4 |
| 9731 | Modal Square 4: □¬P and ¬◊P are 'contradictories' of ¬□¬P and ◊P [Aristotle, by Fitting/Mendelsohn] |
| Full Idea: Modal Square of Opposition 4: 'It is necessary that not P' and 'It is not possible that P' are the contradictories (different truth values) of 'It is not necessary that not P' and 'It is possible that P'. | |
| From: report of Aristotle (On Interpretation [c.330 BCE], Ch.12d) by M Fitting/R Mendelsohn - First-Order Modal Logic 1.4 |
| 9732 | Modal Square 5: □P and ¬◊¬P are 'subalternatives' of ¬□¬P and ◊P [Aristotle, by Fitting/Mendelsohn] |
| Full Idea: Modal Square of Opposition 5: 'It is necessary that P' and 'It is not possible that not P' are the subalternatives (first implies second) of 'It is not necessary that not P' and 'It is possible that P'. | |
| From: report of Aristotle (On Interpretation [c.330 BCE], Ch.12e) by M Fitting/R Mendelsohn - First-Order Modal Logic 1.4 |
| 9733 | Modal Square 6: □¬P and ¬◊P are 'subalternatives' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn] |
| Full Idea: Modal Square of Opposition 6: 'It is necessary that not P' and 'It is not possible that P' are the subalternatives (first implies second) of 'It is not necessary that P' and 'It is possible that not P'. | |
| From: report of Aristotle (On Interpretation [c.330 BCE], Ch.12f) by M Fitting/R Mendelsohn - First-Order Modal Logic 1.4 |
| 14684 | A world is 'accessible' to another iff the first is possible according to the second [Salmon,N] |
| Full Idea: A world w' is accessible to a consistent world w if and only if w' is possible in w. Being 'inaccessible to' or 'possible relative to' a consistent world is simply being possible according to that world, nothing more and nothing less. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) | |
| A reaction: More illuminating than just saying that w can 'see' w'. Accessibility is internal to worIds. It gives some connection to why we spend time examining modal logic. There is no more important metaphysical notion than what is possible according to actuality. |
| 14669 | For metaphysics, T may be the only correct system of modal logic [Salmon,N] |
| Full Idea: Insofar as modal logic is concerned exclusively with the logic of metaphysical modality, ..T may well be the one and only (strongest) correct system of (first-order) propositional logic. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], Intro) | |
| A reaction: This contrasts sharply with the orthodox view, that S5 (or at the very least S4) is the correct system for metaphysics. |
| 14667 | System B has not been justified as fallacy-free for reasoning on what might have been [Salmon,N] |
| Full Idea: Even the conventionally accepted system B, which is weaker than S5 and independent of S4, has not been adequately justified as a fallacy-free system of reasoning about what might have been. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], Intro) |
| 14668 | In B it seems logically possible to have both p true and p is necessarily possibly false [Salmon,N] |
| Full Idea: The characteristic of B has the form φ⊃□◊φ. ...Even if these axioms are necessarily true, it seems logically possible for p to be true while the proposition that p is necessarily possible is at the same time false. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], Intro) |
| 14692 | System B implies that possibly-being-realized is an essential property of the world [Salmon,N] |
| Full Idea: Friends of B modal logic commit themselves to the loaded claim that it is logically true that the property of possibly being realized (or being a way things might have been) is an essential property of the world. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], V) | |
| A reaction: I think this 'loaded' formulation captures quite nicely the dispositional view I favour, that the possibilities of the actual world are built into the actual world, and define its nature just as much as the 'categorial' facts do. |
| 14671 | What is necessary is not always necessarily necessary, so S4 is fallacious [Salmon,N] |
| Full Idea: We can say of a wooden table that it would have been possible for it to have originated from some different matter, even though it is not actually possible. So what is necessary fails to be necessarily necessary, and S4 modal logic is fallacious. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], I) | |
| A reaction: [compressed] |
| 14686 | S5 modal logic ignores accessibility altogether [Salmon,N] |
| Full Idea: When we ignore accessibility altogether, we have finally zeroed in on S5 modal logic. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) |
| 14691 | S5 believers say that-things-might-have-been-that-way is essential to ways things might have been [Salmon,N] |
| Full Idea: Believers in S5 as a correct system of propositional reasoning about what might have been must claim that it is an essential property of any way things might have been that things might have been that way. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], V) | |
| A reaction: Salmon is working in a view where you are probably safe to substitute 'necessary' for 'essential' without loss of meaning. |
| 14693 | The unsatisfactory counterpart-theory allows the retention of S5 [Salmon,N] |
| Full Idea: Counterpart-theoretic modal semantics allows for the retention of S5 modal propositional logic, at a considerable cost. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], V n18) | |
| A reaction: See the other ideas in this paper by Salmon for his general attack on S5 as the appropriate system for metaphysical necessity. He favours the very modest System T. |
| 14670 | Metaphysical (alethic) modal logic concerns simple necessity and possibility (not physical, epistemic..) [Salmon,N] |
| Full Idea: Metaphysical modal logic concerns metaphysical (or alethic) necessity and metaphysical (alethic) possibility, or necessity and possibility tout court - as opposed to such other types of modality as physical necessity, epistemic necessity etc. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], Intro n2) |
| 8625 | What physical facts could underlie 0 or 1, or very large numbers? [Frege on Mill] |
| Full Idea: What in the world can be the observed fact, or the physical fact, which is asserted in the definition of the number 777864? ...What a pity that Mill did not also illustrate the physical facts underlying the numbers 0 and 1! | |
| From: comment on John Stuart Mill (System of Logic [1843]) by Gottlob Frege - Grundlagen der Arithmetik (Foundations) §7 | |
| A reaction: I still think patterns could be an empirical foundation for arithmetic, though you still have to grasp the abstract concept of the pattern. An innate capacity to spot resemblance gets you a long way. |
| 21593 | In talking of future sea-fights, Aristotle rejects bivalence [Aristotle, by Williamson] |
| Full Idea: Unlike Aristotle, Stoics did not reject Bivalence for future contingencies; it is true or false that there will be a sea-fight tomorrow. | |
| From: report of Aristotle (On Interpretation [c.330 BCE], 19a31) by Timothy Williamson - Vagueness 1.2 | |
| A reaction: I'd never quite registered this simple account of the sea-fight. As Williamson emphasises, one should not lightly reject the principle of bivalence. Has Aristotle entered a slippery slope? Stoics disagreed with Aristotle. |
| 1701 | A prayer is a sentence which is neither true nor false [Aristotle] |
| Full Idea: A prayer is a sentence which is neither true nor false. | |
| From: Aristotle (On Interpretation [c.330 BCE], 17a01) |
| 17895 | Combining two distinct assertions does not necessarily lead to a single 'complex proposition' [Mill] |
| Full Idea: In 'Caesar is dead, and Brutus is alive' ...there are here two distinct assertions; and we might as well call a street a complex house, as these two propositions a complex proposition. | |
| From: John Stuart Mill (System of Logic [1843], 1.04.3) | |
| A reaction: Arthur Prior, in his article on 'tonk', cites this to claim that the mere account of the and-introduction rule does not guarantee the existence of any conjunctive proposition that can result from it. Mill says you are adding a third proposition. |
| 10427 | All names are names of something, real or imaginary [Mill] |
| Full Idea: All names are names of something, real or imaginary. | |
| From: John Stuart Mill (System of Logic [1843], p.32), quoted by Mark Sainsbury - The Essence of Reference 18.2 | |
| A reaction: Mill's example of of being like a chalk mark on a door, but Sainsbury points out that names can be detached from bearers in a way that chalk marks can't. |
| 4944 | Mill says names have denotation but not connotation [Mill, by Kripke] |
| Full Idea: It is a well known doctrine of Mill that names have denotation but not connotation. | |
| From: report of John Stuart Mill (System of Logic [1843]) by Saul A. Kripke - Naming and Necessity lectures Lecture 1 | |
| A reaction: A nice starting point for any discussion of the topic. The obvious response is that a name like 'Attila the Hun' seems to have a very vague denotation for most of us, but a rather powerful connotation. |
| 7762 | Proper names are just labels for persons or objects, and the meaning is the object [Mill, by Lycan] |
| Full Idea: Mill seemed to defend the view that proper names are merely labels for individual persons or objects, and contribute no more than those individuals themselves to the meanings of sentences in which they occur. | |
| From: report of John Stuart Mill (System of Logic [1843]) by William Lycan - Philosophy of Language | |
| A reaction: Identity statements can become trivial on this view ('Twain is Clemens'). Modern views have become more sympathetic to Mill, since externalism places meanings outside the head of the speaker. |
| 9801 | Numbers must be assumed to have identical units, as horses are equalised in 'horse-power' [Mill] |
| Full Idea: There is one hypothetical element in the basis of arithmetic, without which none of it would be true: all the numbers are numbers of the same or of equal units. When we talk of forty horse-power, we assume all horses are of equal strength. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.3) | |
| A reaction: Of course, horses are not all of equal strength, so there is a problem here for your hard-line empiricist. Mill needs processes of idealisation and abstraction before his empirical arithmetic can get off the ground. |
| 8742 | The only axioms needed are for equality, addition, and successive numbers [Mill, by Shapiro] |
| Full Idea: Mill says arithmetic has two axioms, that 'things which are equal to the same thing are equal to each other', and 'equals added to equals make equal sums', plus a definition for each numeral as 'formed by the addition of a unit to the previous number'. | |
| From: report of John Stuart Mill (System of Logic [1843], p.610?) by Stewart Shapiro - Thinking About Mathematics 4.3 | |
| A reaction: The difficulty here seems to be the definition of 1, and (even worse for an empiricist), of 0. Then he may have a little trouble when he reaches infinity. |
| 9800 | Arithmetic is based on definitions, and Sums of equals are equal, and Differences of equals are equal [Mill] |
| Full Idea: The inductions of arithmetic are based on so-called definitions (such as '2 and 1 are three'), and on two axioms: The sums of equals are equal, The differences of equals are equal. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.3) | |
| A reaction: These are axioms for arithmetical operations, rather than for numbers themselves (which, for Mill, do not require axioms as they are empirically derived). |
| 5201 | Mill says logic and maths is induction based on a very large number of instances [Mill, by Ayer] |
| Full Idea: Mill maintained that the truths of logic and mathematics are not necessary or certain, by saying these propositions are inductive generalisations based on an extremely large number of instances. | |
| From: report of John Stuart Mill (System of Logic [1843]) by A.J. Ayer - Language,Truth and Logic Ch.4 | |
| A reaction: Ayer asserts that they are necessary (but only because they are tautological). I like the idea that maths is the 'science of patterns', but that might lead from an empirical start to a rationalist belief in a priori synthetic truths. |
| 9360 | If two black and two white objects in practice produced five, what colour is the fifth one? [Lewis,CI on Mill] |
| Full Idea: If Mill has a demon who, every time two things are brought together with two other things, always introduces a fifth, then if two black marbles and two white ones are put in an urn, the demon could choose his color, but there would be more of one colour. | |
| From: comment on John Stuart Mill (System of Logic [1843]) by C.I. Lewis - A Pragmatic Conception of the A Priori p.367 | |
| A reaction: Nice to see philosophers fighting back against demons. This is a lovely argument against the absurdity of thinking that experience could ever controvert a priori knowledge (though Lewis is no great fan of the latter). |
| 9888 | Mill mistakes particular applications as integral to arithmetic, instead of general patterns [Dummett on Mill] |
| Full Idea: Mill's mistake is taking particular applications as integral to the sense of arithmetical propositions. But what is integral to arithmetic is the general principle that explains its applicability, and determines the pattern of particular applications. | |
| From: comment on John Stuart Mill (System of Logic [1843], 2.6) by Michael Dummett - Frege philosophy of mathematics Ch.20 | |
| A reaction: [Dummett is summarising Frege's view] Sounds like a tidy objection, but you still have to connect the general principles and patterns to the physical world. 'Structure' could be the magic word to achieve this. |
| 9794 | There are no such things as numbers in the abstract [Mill] |
| Full Idea: There are no such things as numbers in the abstract. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.2) | |
| A reaction: Depends. Would we want to say that 'horses don't exist' (although each individual horse does exist)? It sounds odd to say of an idea that it doesn't exist, when you are currently thinking about it. I am, however, sympathetic to Mill. |
| 9796 | Things possess the properties of numbers, as quantity, and as countable parts [Mill] |
| Full Idea: All things possess quantity; consist of parts which can be numbered; and in that character possess all the properties which are called properties of numbers. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.2) | |
| A reaction: Here Mill is skating on the very thinnest of ice, and I find myself reluctantly siding with Frege. It is a very optimistic empiricist who hopes to find the numbers actually occurring as properties of experienced objects. A pack of cards, for example. |
| 9795 | Numbers have generalised application to entities (such as bodies or sounds) [Mill] |
| Full Idea: 'Ten' must mean ten bodies, or ten sounds, or ten beatings of the pulse. But though numbers must be numbers of something, they may be numbers of anything. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.2) | |
| A reaction: Mill always prefers things in close proximity, in space or time. 'I've had ten headaches in the last year'. 'There are ten reasons for doubting p'. His second point puts him very close to Aristotle in his view. |
| 9798 | Different parcels made from three pebbles produce different actual sensations [Mill] |
| Full Idea: Three pebbles make different sense impressions in one parcel or in two. That the same pebbles by an alteration of place and arrangement may be made to produce either sensation is not the identical proposition. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.2) | |
| A reaction: [compressed] Not quite clear, but Mill seems to be adamant that we really must experience the separation, and not just think what 'may' happen, so Frege is right that Mill is lucky that everything is not 'nailed down'. |
| 9797 | '2 pebbles and 1 pebble' and '3 pebbles' name the same aggregation, but different facts [Mill] |
| Full Idea: The expressions '2 pebbles and 1 pebble' and '3 pebbles' stand for the same aggregation of objects, but do not stand for the same physical fact. They name the same objects in different states, 'denoting' the same things, with different 'connotations'. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.2) | |
| A reaction: Nothing in this would convert me from the analytic view to the empirical view of simple arithmetic, if I were that way inclined. Personally I think of three pebbles as 4 minus 1, because I am haunted by the thought of a missing stone. |
| 9799 | 3=2+1 presupposes collections of objects ('Threes'), which may be divided thus [Mill] |
| Full Idea: 'Three is two and one' presupposes that collections of objects exist, which while they impress the senses thus, ¶¶¶, may be separated into two parts, thus, ¶¶ ¶. This being granted, we term all such parcels Threes. | |
| From: John Stuart Mill (System of Logic [1843], 2.6.2) | |
| A reaction: Mill is clearly in trouble here because he sticks to simple arithmetic. He must deal with parcels too big for humans to count, and parcels so big that they could not naturally exist, and that is before you even reach infinite parcels. |
| 9802 | Numbers denote physical properties of physical phenomena [Mill] |
| Full Idea: The fact asserted in the definition of a number is a physical fact. Each of the numbers two, three, four denotes physical phenomena, and connotes a physical property of those phenomena. Two denotes all pairs of things, and twelve all dozens. | |
| From: John Stuart Mill (System of Logic [1843], 3.24.5) | |
| A reaction: The least plausible part of Mill's thesis. Is the fact that a pair of things is fewer than five things also a property? You see two boots, or you see a pair of boots, depending partly on you. Is pure two a visible property? Courage and an onion? |
| 9803 | We can't easily distinguish 102 horses from 103, but we could arrange them to make it obvious [Mill] |
| Full Idea: 102 horses are not as easily distinguished from 103 as two are from three, yet the horses may be so placed that a difference will be perceptible. | |
| From: John Stuart Mill (System of Logic [1843], 3.24.5) | |
| A reaction: More trouble for Mill. We are now moving from the claim that we actually perceive numbers to the claim that we could if we arranged things right. But we would still only see which group of horses was bigger by one, not how many horses there were. |
| 9804 | Arithmetical results give a mode of formation of a given number [Mill] |
| Full Idea: Every statement of the result of an arithmetical operation is a statement of one of the modes of formation of a given number. | |
| From: John Stuart Mill (System of Logic [1843], 3.24.5) | |
| A reaction: Although Mill sticks cautiously to very simple arithmetic, inviting empirical accounts of much higher mathematics, I think the phrase 'modes of formation' of numbers is very helpful. It could take us either into structuralism, or into constructivism. |
| 9805 | 12 is the cube of 1728 means pebbles can be aggregated a certain way [Mill] |
| Full Idea: When we say 12 is the cube of 1728, we affirm that if we had sufficient pebbles, we put them into parcels or aggregates called twelves, and put those twelves into similar collections, and make twelve of these largests parcels, we have the aggregate 1728. | |
| From: John Stuart Mill (System of Logic [1843], 3.24.5) | |
| A reaction: There is always hidden modal thinking in Mill's proposals, despite his longing to stick to actual experience. Imagination actually plays a much bigger role in his theory than sense experience does. |
| 8741 | Numbers must be of something; they don't exist as abstractions [Mill] |
| Full Idea: All numbers must be numbers of something: there are no such things as numbers in the abstract. | |
| From: John Stuart Mill (System of Logic [1843], p.245?), quoted by Stewart Shapiro - Thinking About Mathematics 4.3 | |
| A reaction: This shows why the concept of 'abstraction' is such a deep problem. Numbers can't be properties of objects, because two boots can become one boot without changing the surviving boot. But why should abstractions have to 'exist'? |
| 12411 | Mill is too imprecise, and is restricted to simple arithmetic [Kitcher on Mill] |
| Full Idea: The problem with Mill is that many of his formulations are imprecise, and he only considers the most rudimentary parts of arithmetic. | |
| From: comment on John Stuart Mill (System of Logic [1843]) by Philip Kitcher - The Nature of Mathematical Knowledge Intro | |
| A reaction: This is from a fan of Mill, trying to restore his approach in the face of the authoritative and crushing criticisms offered by Frege. I too am a fan of Mill's approach. Patterns can be discerned in arrangements of pebbles. Infinities are a problem. |
| 5656 | Empirical theories of arithmetic ignore zero, limit our maths, and need probability to get started [Frege on Mill] |
| Full Idea: Mill does not give us a clue as to how to understand the number zero, he limits our mathematical knowledge to the limits of our experience, ..and induction can only give you probability, but that presupposes arithmetical laws. | |
| From: comment on John Stuart Mill (System of Logic [1843]) by Gottlob Frege - Grundlagen der Arithmetik (Foundations) | |
| A reaction: This summarises Frege's criticisms of Mill's empirical account of maths. I like 'maths is the science of patterns', in which case zero is just a late-introduced trick (it is hardly a Platonic Form!), and induction is the wrong account to give. |
| 9624 | Numbers are a very general property of objects [Mill, by Brown,JR] |
| Full Idea: Mill held that numbers are a kind of very general property that objects possess. | |
| From: report of John Stuart Mill (System of Logic [1843], Ch.4) by James Robert Brown - Philosophy of Mathematics | |
| A reaction: Intuitively this sounds hopeless, because if you place one apple next to another you introduce 'two', but which apple has changed its property? Both? It seems to be a Cambridge change. It isn't a change that would bother the apples. Kitcher pursues this. |
| 1706 | Non-existent things aren't made to exist by thought, because their non-existence is part of the thought [Aristotle] |
| Full Idea: It is not true to say that what is not, since it is thought about, is something that is; for what is thought about it is not that it is, but that it is not. | |
| From: Aristotle (On Interpretation [c.330 BCE], 21a31) | |
| A reaction: At least there has been one philosopher who was quite clear about the distinction between a thought and what the thought is about (its content). Often forgotten! |
| 1707 | Maybe necessity and non-necessity are the first principles of ontology [Aristotle] |
| Full Idea: Perhaps the necessary and non-necessary are first principles of everything's either being or not being. | |
| From: Aristotle (On Interpretation [c.330 BCE], 23a18) |
| 9806 | Whatever is made up of parts is made up of parts of those parts [Mill] |
| Full Idea: Whatever is made up of parts is made up of parts of those parts. | |
| From: John Stuart Mill (System of Logic [1843], 3.24.5) | |
| A reaction: Mill considers this principle to be fundamental to the possibilities of arithmetic. Presumably he thought of it as an inductive inference from our dealings with physical objects. |
| 11156 | The essence is that without which a thing can neither be, nor be conceived to be [Mill] |
| Full Idea: The essence of a thing was said to be that without which the thing could neither be, nor be conceived to be. | |
| From: John Stuart Mill (System of Logic [1843], 1.6.2) | |
| A reaction: Fine cites this as the 'modal' account of essence, as opposed to the 'definitional' account. |
| 14678 | Any property is attached to anything in some possible world, so I am a radical anti-essentialist [Salmon,N] |
| Full Idea: By admitting possible worlds of unlimited variation and recombination, I simply abandon true metaphysical essentialism. By my lights, any property is attached to anything in some possible world or other. I am a closet radical anti-essentialist. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], II) | |
| A reaction: Salmon includes impossible worlds within his scheme of understanding. It strikes me that this is metaphysical system which tells us nothing about how things are: it is sort of 'logical idealist'. Later he talks of 'we essentialists'. |
| 12190 | Necessity is what will be, despite any alternative suppositions whatever [Mill] |
| Full Idea: That which is necessary, that which must be, means that which will be, whatever suppositions we may make in regard to all other things. | |
| From: John Stuart Mill (System of Logic [1843], 3.06.6) | |
| A reaction: [Mill discusses causal necessity] This is quoted by McFetridge. This slightly firms up the definition as 'what has to be true', though it makes it dependent on our 'suppositions'. Presumably nothing beyond our powers of supposition could matter either. |
| 22623 | Necessity can only mean what must be, without conditions of any kind [Mill] |
| Full Idea: If there be any meaning which confessedly belongs to the term necessity, it is unconditionalness. That which is necessary, that which must be, means that which will be whatever supposition we make with regard to other things. | |
| From: John Stuart Mill (System of Logic [1843], p.339 [1974 ed]), quoted by R.D. Ingthorsson - A Powerful Particulars View of Causation 5.3 | |
| A reaction: 'It is necessary to leave now, if you want to catch the train' is a genuine type of necessity. Mill's type is probably Absolute necessity, to which nothing could make any difference. Or Metaphysical necessity, determined by all things. |
| 14680 | Logical possibility contains metaphysical possibility, which contains nomological possibility [Salmon,N] |
| Full Idea: Just as nomological possibility is a special kind of metaphysical possibility, so metaphysical possibility is a special kind of logical possibility. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], III) | |
| A reaction: This is the standard view of how the three types of necessity are nested. He gives a possible counterexample in footnote 7. |
| 14690 | In the S5 account, nested modalities may be unseen, but they are still there [Salmon,N] |
| Full Idea: The S5 theorist's miscontrual of English (in the meaning of 'possibly possible') makes nested modality unseen, but it does not make nested modality vanish. Inaccessible worlds are still worlds. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) |
| 14677 | Metaphysical necessity is said to be unrestricted necessity, true in every world whatsoever [Salmon,N] |
| Full Idea: It is held that it is the hallmark of metaphysical necessity is that it is completely unrestricted, the limiting case of restricted necessity, with no restrictions whatever. A proposition is necessary only if it is true in absolutely every world whatever. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], II) | |
| A reaction: This is the standard picture which leads to the claim that S5 modal logic is appropriate for metaphysical necessity, because there are no restrictions on accessibility. Salmon raises objections to this conventional view. |
| 14679 | Bizarre identities are logically but not metaphysically possible, so metaphysical modality is restricted [Salmon,N] |
| Full Idea: Though there is a way things logically could be according to which I am a credit card account, there is no way things metaphysically might be according to which I am a credit card account. This illustrates the restricted nature of metaphysical modality. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], III) | |
| A reaction: His drift is that metaphyical modality is restricted, but expressing it in S5 modal logic (where all worlds see one another) makes it unrestricted, so S5 logic is wrong for metaphysics. I'm impressed by his arguments. |
| 14688 | Without impossible worlds, the unrestricted modality that is metaphysical has S5 logic [Salmon,N] |
| Full Idea: If one confines one's sights to genuinely possible worlds, disavowing the impossible worlds, then metaphysical modality emerges as the limiting case - the 'unrestricted' modality that takes account of 'every' world - and S5 emerges as its proper logic. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) | |
| A reaction: He observes that this makes metaphysical modality 'restricted' simply because you have restricted what 'all worlds' means. Could there be non-maximal worlds? Are logical and metaphysical modality coextensive? I think I like the S5 view. |
| 14685 | Metaphysical necessity is NOT truth in all (unrestricted) worlds; necessity comes first, and is restricted [Salmon,N] |
| Full Idea: A mythology gave us the idea that metaphysical necessity is truth in every world whatsoever, without restriction. But the notion of metaphysical modality comes first, and, like every notion of modality, it is restricted. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) |
| 14681 | Logical necessity is free of constraints, and may accommodate all of S5 logic [Salmon,N] |
| Full Idea: With its freedom from the constraint of metaphysical possibility, logical necessity may be construed as accommodating all the axioms and rules of S5. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], III) | |
| A reaction: He goes on to raise problems for this simple thought. The big question: what are the limits of what is actually possible? Compare: what are the limits of what is imaginable? what are the limits of what is meaningfully sayable? |
| 14676 | Nomological necessity is expressed with intransitive relations in modal semantics [Salmon,N] |
| Full Idea: Intransitive relations are introduced into modal semantics for the purposes of interpreting various 'real' or restricted types of modalities, such as nomological necessity. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], II) | |
| A reaction: The point here is that the (so-called) 'laws of nature' are held to change from world to world, so necessity in one could peter out in some more remote world, rather than being carried over everywhere. A very Humean view of such things. |
| 14689 | Necessity and possibility are not just necessity and possibility according to the actual world [Salmon,N] |
| Full Idea: The real meanings of the simple modal terms 'necessary' and 'possible' are not the same as the concepts of actual necessity and actual possibility, necessity and possibility according to the actual world. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) | |
| A reaction: If you were an 'actualist' (who denies everything except the actual world) then you are unlikely to agree with this. In unrestricted possible worlds, being true in one world makes it possible in all worlds. So actual necessity is possible everywhere. |
| 14674 | Impossible worlds are also ways for things to be [Salmon,N] |
| Full Idea: Total ways things cannot be are also 'worlds', or maximal ways for things to be. They are impossible worlds. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], I) | |
| A reaction: This unorthodox view doesn't sound too plausible to me. To think of a circular square as a 'way things could be' sounds pretty empty, and mere playing with words. The number 7 could be the Emperor of China? |
| 14682 | Denial of impossible worlds involves two different confusions [Salmon,N] |
| Full Idea: Every argument I am aware of against impossible worlds confuses ways for things to be with ways things might have been, or worse, confuses ways things cannot be with ways for things to be that cannot exist - or worse yet, commits both errors. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], III) | |
| A reaction: He is claiming that 'ways for things to be' allows impossible worlds, whereas 'ways things might have been' appears not to. (I think! Read the paragraph yourself!) |
| 14687 | Without impossible worlds, how things might have been is the only way for things to be [Salmon,N] |
| Full Idea: If one ignores impossible worlds, then ways things might have been are the only ways for things to be that are left. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) | |
| A reaction: Impossible worlds are included in 'ways for things to be', but excluded from 'ways things might have been'. I struggle with a circle being square as a 'way for circles to be'. I suppose being the greatest philosopher is a way for me to be. |
| 14683 | Possible worlds rely on what might have been, so they can' be used to define or analyse modality [Salmon,N] |
| Full Idea: On my conception, the notions of metaphysical necessity and possibility are not defined or analyzed in terms of the apparatus of possible worlds. The order of analysis is just the reverse: possible worlds rely on the notion of what might have been. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], IV) | |
| A reaction: This view seems to be becoming the new orthodoxy, and I certainly agree with it. I have no idea how you can begin to talk about possible worlds if you don't already have some idea of what 'possible' means. |
| 14672 | Possible worlds are maximal abstract ways that things might have been [Salmon,N] |
| Full Idea: I conceive of possible worlds as certain sorts of maximal abstract entities according to which certain things (facts, states of affairs) obtain and certain other things do not obtain. They are total ways things might have been. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], I) |
| 14675 | Possible worlds just have to be 'maximal', but they don't have to be consistent [Salmon,N] |
| Full Idea: As far as I can tell, worlds need not be logically consistent. The only restriction on worlds is that they must be (in some sense) 'maximal' ways for things to be. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], I) | |
| A reaction: The normal idea of a maximal model is that it must contain either p or ¬p, and not both, so I don't think I understand this thought, but I pass it on. |
| 14673 | You can't define worlds as sets of propositions, and then define propositions using worlds [Salmon,N] |
| Full Idea: It is not a good idea to think of possible worlds as sets of propositions, and at the same time to think of propositions as sets of possible worlds. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], I n3) | |
| A reaction: Salmon favours thinking of worlds as sets of propositions, and hence rejects the account of propositions as sets of worlds. He favours the 'Russellian' view of propositions, which seem to me to be the same as 'facts'. |
| 16859 | Most perception is one-tenth observation and nine-tenths inference [Mill] |
| Full Idea: In almost every act of our perceiving faculties, observation and inference are intimately blended. What we are said to observe is usually a compound result, of which one-tenth may be observation, and the remaining nine-tenths inference. | |
| From: John Stuart Mill (System of Logic [1843], 4.1.2), quoted by Peter Lipton - Inference to the Best Explanation (2nd) 11 'The scientific' | |
| A reaction: We seem to think that his kind of observation is a great realisation of twentieth century thought, but thoughtful empiricists spotted it much earlier. |
| 9082 | Clear concepts result from good observation, extensive experience, and accurate memory [Mill] |
| Full Idea: The principle requisites of clear conceptions, are habits of attentive observation, an extensive experience, and a memory which receives and retains an exact image of what is observed. | |
| From: John Stuart Mill (System of Logic [1843], 4.2.5) | |
| A reaction: Empiricists are always crying out for people to 'attend to the evidence', and this is the deeper reason why. Not only will one know the world better in a direct way, but one will actually think more clearly. Darwin is the perfect model for this. |
| 16860 | Inductive generalisation is more reliable than one of its instances; they can't all be wrong [Mill] |
| Full Idea: A general proposition collected from particulars is often more certainly true than any one of the particular propositions from which, by an act of induction, it was inferred. It might be erroneous in any instance, but cannot be erroneous in all of them. | |
| From: John Stuart Mill (System of Logic [1843], 4.1.2), quoted by Peter Lipton - Inference to the Best Explanation (2nd) 11 'The scientific' | |
| A reaction: One anomaly can be ignored, but several can't, especially if the anomalies agree. |
| 16845 | The whole theory of induction rests on causes [Mill] |
| Full Idea: The notion of cause is the root of the whole theory of induction. | |
| From: John Stuart Mill (System of Logic [1843], 3.05.2), quoted by Peter Lipton - Inference to the Best Explanation (2nd) 08 'From cause' | |
| A reaction: This sounds much better to me than the Humean view that it rests on the psychology of regularity and habit. However, maybe Hume describes induction, and Mill is adding abduction (inference to the best explanation). |
| 16843 | Mill's methods (Difference,Agreement,Residues,Concomitance,Hypothesis) don't nail induction [Mill, by Lipton] |
| Full Idea: The Method of Difference, and even the full four 'experimental methods' (Difference, Agreement, Residues and Concomitant Variations) are agreed on all sides to be incomplete accounts of inductive inference. Mill himself added the Method of Hypothesis. | |
| From: report of John Stuart Mill (System of Logic [1843], 3.14.4-5) by Peter Lipton - Inference to the Best Explanation (2nd) 08 'Improved' | |
| A reaction: If induction is just 'learning from experience' (my preferred definition) then there is unlikely to be a precise account of its methods. Mill seems to have done a lovely job. |
| 17086 | Surprisingly, empiricists before Mill ignore explanation, which seems to transcend experience [Mill, by Ruben] |
| Full Idea: It is surprising that no empiricist philosopher before Mill turned in an explicit way to the scrutiny of the concept of explanation, which had …every appearance of being experience-transcendent. | |
| From: report of John Stuart Mill (System of Logic [1843]) by David-Hillel Ruben - Explaining Explanation Ch 4 | |
| A reaction: Yes indeed! This is why explanation is absolutely basic, to philosophy and to human understanding. The whole of philosophy is a quest for explanations, so to be strictly empirical about it strikes me as crazy. |
| 17091 | Explanation is fitting of facts into ever more general patterns of regularity [Mill, by Ruben] |
| Full Idea: For Mill, explanation was always the fitting of facts into ever more general patterns of regularity. | |
| From: report of John Stuart Mill (System of Logic [1843]) by David-Hillel Ruben - Explaining Explanation Ch 6 | |
| A reaction: This seems to nicely capture the standard empirical approach to explanation. If you say that this fitting in doesn't explain much, the answer (I think) is that this is the best we can do. |
| 16805 | Causal inference is by spotting either Agreements or Differences [Mill, by Lipton] |
| Full Idea: The best known account of causal inference is Mill's Method of Agreement (only one antecedent is shared by the effects), and the Method of Difference (there is only one difference prior to the effect occurring or not occurring). | |
| From: report of John Stuart Mill (System of Logic [1843], 3.07) by Peter Lipton - Inference to the Best Explanation (2nd) 01 'Descr' | |
| A reaction: [my summary of Lipton's summary of Mill] |
| 16835 | The Methods of Difference and of Agreement are forms of inference to the best explanation [Mill, by Lipton] |
| Full Idea: Like Mill's Method of Difference, applications of the Method of Agreement are naturally construed as inferences to the best explanation. | |
| From: report of John Stuart Mill (System of Logic [1843], 3.07/8) by Peter Lipton - Inference to the Best Explanation (2nd) 06 'The Method' | |
| A reaction: This sort of thoroughly sensible approach to understanding modes of investigation has been absurdly sidelined by the desire to 'deduce' observations from 'laws'. Scientific investigation is no different from enquiry in daily life. Where are my glasses? |
| 9079 | We can focus our minds on what is common to a whole class, neglecting other aspects [Mill] |
| Full Idea: The voluntary power which the mind has, of attending to one part of what is present at any moment, and neglecting another part, enables us to be unaffected by anything in the idea which is not really common to the whole class. | |
| From: John Stuart Mill (System of Logic [1843], 4.2.1) | |
| A reaction: There is a question for empiricists of whether abstraction is a 'voluntary' power or a mechanical one. Associationism presents it as more mechanical. I would say, with Mill, that it is a least partly voluntary, and even rational. |
| 9081 | We don't recognise comparisons by something in our minds; the concepts result from the comparisons [Mill] |
| Full Idea: It is not a law of our intellect that in comparing things and noting their agreements we recognise as realized in the outward world something we already had in our minds. The conception found its way to us as the result of such a comparison. | |
| From: John Stuart Mill (System of Logic [1843], 4.2.2) | |
| A reaction: He recognises, of course, that this gradually becomes a two-way process. In the physicalist view of things, it is not really of great importance which concepts are hard-wired, and which constructed culturally or through perception. |
| 9080 | General conceptions are a necessary preliminary to Induction [Mill] |
| Full Idea: Forming general conceptions is a necessary preliminary to Induction. | |
| From: John Stuart Mill (System of Logic [1843], 4.2.1) | |
| A reaction: A key link in the framework of empirical philosophies, which gets us from experience to science. Induction is the very process of generalisation. We can't bring a concept like 'evolution' to preliminary observations, so it must be formulated inductively. |
| 9078 | The study of the nature of Abstract Ideas does not belong to logic, but to a different science [Mill] |
| Full Idea: The metaphysical inquiry into the nature and composition of what have been called Abstract Ideas, or in other words, of the notions which answer in the mind to classes and to general names, belongs not to Logic, but to a different science. | |
| From: John Stuart Mill (System of Logic [1843], 4.2.1) | |
| A reaction: He doesn't name the science, but the point here seems to be precisely what Frege so vigorously disagreed with. I would say that the state of being 'abstract' has logical aspects, and can be partly described by logic, but that Mill is basically right. |
| 2337 | For Aristotle meaning and reference are linked to concepts [Aristotle, by Putnam] |
| Full Idea: In 'De Interpretatione' Aristotle laid out an enduring theory of reference and meaning, in which we understand a word or any other sign by associating that word with a concept. This concept determines what the word refers to. | |
| From: report of Aristotle (On Interpretation [c.330 BCE]) by Hilary Putnam - Representation and Reality 2 p.19 | |
| A reaction: Sounds right to me, despite all this Wittgensteinian stuff about beetles in boxes. When you meet a new technical term in philosophy, you must struggle to fully grasp the concept it proposes. |
| 13763 | Spoken sounds vary between people, but are signs of affections of soul, which are the same for all [Aristotle] |
| Full Idea: Spoken sounds are symbols of affections in the soul, ...and just as written marks are not the same for all men, neither are spoken sounds. But what these are in the first place signs of - affections of the soul - are the same for all. | |
| From: Aristotle (On Interpretation [c.330 BCE], 16a03-08) | |
| A reaction: Loux identifies this passage as the source of the 'conceptualist' view of propositions, which I immediately identify with. The view that these propositions are 'the same for all' is plausible for normal objects, but dubious for complex abstractions. |
| 1705 | It doesn't have to be the case that in opposed views one is true and the other false [Aristotle] |
| Full Idea: It is not necessary that of every affirmation and opposite negation one should be true and the other false. For what holds for things that are does not hold for things that are not but may possibly be or not be. | |
| From: Aristotle (On Interpretation [c.330 BCE], 19a39) | |
| A reaction: Thus even if Bivalence holds, and the only truth-values are T and F, it doesn't follow that Excluded Middle holds, which says that every proposition must have one of those two values. |
| 8345 | A cause is the total of all the conditions which inevitably produce the result [Mill] |
| Full Idea: A cause is the sum total of the conditions positive and negative taken together ...which being realized, the consequent invariably follows. | |
| From: John Stuart Mill (System of Logic [1843]), quoted by Donald Davidson - Causal Relations §1 | |
| A reaction: This has obvious problems. The absence of Napoleon was a cause of the English Civil War. The Big Bang was a cause of, well, every event. As Davidson notes, some narrowing down is needed. |
| 10391 | Causes and conditions are not distinct, because we select capriciously from among them [Mill] |
| Full Idea: Nothing can better show the absence of any scientific ground for the distinction between the cause of a phenomena and its conditions, than the capricious manner in which we select from among the conditions that which we choose to denominate the cause. | |
| From: John Stuart Mill (System of Logic [1843]), quoted by Jonathan Schaffer - The Metaphysics of Causation 2.2 | |
| A reaction: [ref Mill p.196, 1846 edn] Schaffer gives this as the main argument for the 'no-basis' view of the selection of what causes an event. The usual thought is that it is entirely our immediate interests which make us select THE cause. Not convinced. |
| 14547 | The strict cause is the total positive and negative conditions which ensure the consequent [Mill] |
| Full Idea: The cause, philosophically speaking, is the sum total of the conditions, positive and negative taken together; the whole of the contigencies of every description, which being realized, the consequent invariably follows. | |
| From: John Stuart Mill (System of Logic [1843], 3.05.3) | |
| A reaction: This somewhat notorious remark is not going to be much help in a law court or a laboratory. It is that view which says that the Big Bang must be included in every causal list ever compiled. Well, yes... |
| 8377 | Causation is just invariability of succession between every natural fact and a preceding fact [Mill] |
| Full Idea: The Law of Causation, the recognition of which is the main pillar of inductive science, is but the familiar truth, that invariability of succession is found by observation between every fact in nature and some other fact which has preceded it. | |
| From: John Stuart Mill (System of Logic [1843], 3.5.2), quoted by Bertrand Russell - On the Notion of Cause p.178 | |
| A reaction: Note that Mill rests causation on 'facts'. In the empiricist Mill endorsing the views of Hume. Russell attacks the bogus claim that science rests on causation. Personally I think Mill's view is incorrect. |
| 14545 | A cause is an antecedent which invariably and unconditionally leads to a phenomenon [Mill] |
| Full Idea: We may define the cause of a phenomenon to be the antecedent, or the concurrence of the antecedents, on which it is invariably and unconditionally consequent. | |
| From: John Stuart Mill (System of Logic [1843], 3.05.6) | |
| A reaction: This ignores the possibility of the world ending just before the effect occurs, the 'ceteris paribus' clause. If it only counts as a cause if the effect has actually occurred, we begin to suspect tautology. |
| 4773 | Mill's regularity theory of causation is based on an effect preceded by a conjunction of causes [Mill, by Psillos] |
| Full Idea: Millian causation is a version of the Regularity Theory, but with the addition that when claiming that an effect invariably follows from the cause, the cause is not a single factor, but a whole conjunction of necessary and sufficient conditions. | |
| From: report of John Stuart Mill (System of Logic [1843], p.217) by Stathis Psillos - Causation and Explanation §2.2 | |
| A reaction: Psillos endorses this as an improvement on Hume. But while we may replicate one event preceding another to get regularity, groups of events are hardly ever identical, so no precise pattern will ever be seen. |
| 4775 | In Mill's 'Method of Agreement' cause is the common factor in a range of different cases [Mill, by Psillos] |
| Full Idea: In Mill's 'Method of Agreement' the cause is the common factor in a number of otherwise different cases in which the effect occurs. | |
| From: report of John Stuart Mill (System of Logic [1843], p.255) by Stathis Psillos - Causation and Explanation §2.3 | |
| A reaction: This looks more likely to be good evidence for the cause of an event, rather than a definition of what a cause actually is. Suppose a footballer only scores if and only if I go to watch him? |
| 4776 | In Mill's 'Method of Difference' the cause is what stops the effect when it is removed [Mill, by Psillos] |
| Full Idea: In Mill's 'Method of Difference' the cause is the factor which is different in two cases which are similar, except that in one the effect occurs, and in the other it doesn't. | |
| From: report of John Stuart Mill (System of Logic [1843], p.256) by Stathis Psillos - Causation and Explanation §2.3 | |
| A reaction: Like the Method of Agreement, this is a good test, but is unlikely to be a conclusive hallmark of causation. A footballer may never score unless I go to watch him. I become his lucky mascot… |
| 9417 | What are the fewest propositions from which all natural uniformities could be inferred? [Mill] |
| Full Idea: What are the fewest general propositions from which all the uniformities which exist in the universe might be deductively inferred? | |
| From: John Stuart Mill (System of Logic [1843], 3.4.1) | |
| A reaction: This is the germ of the Mill-Ramsey-Lewis view. |
| 1702 | Things may be necessary once they occur, but not be unconditionally necessary [Aristotle] |
| Full Idea: To say that everything that is, is of necessity, when it is, is not the same as saying unconditionally that it is of necessity. | |
| From: Aristotle (On Interpretation [c.330 BCE], 19a25) |