58 ideas
7920 | Descriptive metaphysics aims at actual structure, revisionary metaphysics at a better structure [Strawson,P] |
7922 | Descriptive metaphysics concerns unchanging core concepts and categories [Strawson,P] |
7921 | Close examination of actual word usage is the only sure way in philosophy [Strawson,P] |
10842 | The fact which is stated by a true sentence is not something in the world [Strawson,P] |
10843 | Facts aren't exactly true statements, but they are what those statements say [Strawson,P] |
10844 | The statement that it is raining perfectly fits the fact that it is raining [Strawson,P] |
10841 | The word 'true' always refers to a possible statement [Strawson,P] |
15945 | Second-order set theory just adds a version of Replacement that quantifies over functions [Lavine] |
15914 | An 'upper bound' is the greatest member of a subset; there may be several of these, so there is a 'least' one [Lavine] |
15921 | Collections of things can't be too big, but collections by a rule seem unlimited in size [Lavine] |
15937 | Those who reject infinite collections also want to reject the Axiom of Choice [Lavine] |
15936 | The Power Set is just the collection of functions from one collection to another [Lavine] |
15899 | Replacement was immediately accepted, despite having very few implications [Lavine] |
15930 | Foundation says descending chains are of finite length, blocking circularity, or ungrounded sets [Lavine] |
15920 | Pure collections of things obey Choice, but collections defined by a rule may not [Lavine] |
15898 | The controversy was not about the Axiom of Choice, but about functions as arbitrary, or given by rules [Lavine] |
15919 | The 'logical' notion of class has some kind of definition or rule to characterise the class [Lavine] |
15900 | The iterative conception of set wasn't suggested until 1947 [Lavine] |
15931 | The iterative conception needs the Axiom of Infinity, to show how far we can iterate [Lavine] |
15932 | The iterative conception doesn't unify the axioms, and has had little impact on mathematical proofs [Lavine] |
15933 | Limitation of Size: if it's the same size as a set, it's a set; it uses Replacement [Lavine] |
15913 | A collection is 'well-ordered' if there is a least element, and all of its successors can be identified [Lavine] |
15926 | Second-order logic presupposes a set of relations already fixed by the first-order domain [Lavine] |
15934 | Mathematical proof by contradiction needs the law of excluded middle [Lavine] |
8358 | There are no rules for the exact logic of ordinary language, because that doesn't exist [Strawson,P] |
6413 | 'The present King of France is bald' presupposes existence, rather than stating it [Strawson,P, by Grayling] |
8354 | Russell asks when 'The King of France is wise' would be a true assertion [Strawson,P] |
15907 | Mathematics is nowadays (thanks to set theory) regarded as the study of structure, not of quantity [Lavine] |
15942 | Every rational number, unlike every natural number, is divisible by some other number [Lavine] |
15922 | For the real numbers to form a set, we need the Continuum Hypothesis to be true [Lavine] |
18250 | Cauchy gave a necessary condition for the convergence of a sequence [Lavine] |
15904 | The two sides of the Cut are, roughly, the bounding commensurable ratios [Lavine] |
15912 | Counting results in well-ordering, and well-ordering makes counting possible [Lavine] |
15949 | The theory of infinity must rest on our inability to distinguish between very large sizes [Lavine] |
15947 | The infinite is extrapolation from the experience of indefinitely large size [Lavine] |
15940 | The intuitionist endorses only the potential infinite [Lavine] |
15909 | 'Aleph-0' is cardinality of the naturals, 'aleph-1' the next cardinal, 'aleph-ω' the ω-th cardinal [Lavine] |
15915 | Ordinals are basic to Cantor's transfinite, to count the sets [Lavine] |
15917 | Paradox: the class of all ordinals is well-ordered, so must have an ordinal as type - giving a bigger ordinal [Lavine] |
15918 | Paradox: there is no largest cardinal, but the class of everything seems to be the largest [Lavine] |
15929 | Set theory will found all of mathematics - except for the notion of proof [Lavine] |
8921 | Structuralism is now common, studying relations, with no regard for what the objects might be [Hellman] |
8698 | Modal structuralism says mathematics studies possible structures, which may or may not be actualised [Hellman, by Friend] |
9557 | Statements of pure mathematics are elliptical for a sort of modal conditional [Hellman, by Chihara] |
10263 | Modal structuralism can only judge possibility by 'possible' models [Shapiro on Hellman] |
8922 | Maybe mathematical objects only have structural roles, and no intrinsic nature [Hellman] |
15935 | Modern mathematics works up to isomorphism, and doesn't care what things 'really are' [Lavine] |
15928 | Intuitionism rejects set-theory to found mathematics [Lavine] |
16980 | We need a logical use of 'object' as predicate-worthy, and an 'ontological' use [Strawson,P] |
16979 | It makes no sense to ask of some individual thing what it is that makes it that individual [Strawson,P] |
9282 | I can only apply consciousness predicates to myself if I can apply them to others [Strawson,P] |
9263 | A person is an entity to which we can ascribe predicates of consciousness and corporeality [Strawson,P] |
8356 | The meaning of an expression or sentence is general directions for its use, to refer or to assert [Strawson,P] |
10430 | Reference is mainly a social phenomenon [Strawson,P, by Sainsbury] |
10448 | If an expression can refer to anything, it may still instrinsically refer, but relative to a context [Bach on Strawson,P] |
8355 | Expressions don't refer; people use expressions to refer [Strawson,P] |
8357 | If an utterance fails to refer then it is a pseudo-use, though a speaker may think they assert something [Strawson,P] |
9281 | The idea of a predicate matches a range of things to which it can be applied [Strawson,P] |