146 ideas
| 9593 | Progress in philosophy is incremental, not an immature seeking after drama [Williamson] |
| 9184 | We can't presume that all interesting concepts can be analysed [Williamson] |
| 6859 | Analytic philosophy has much higher standards of thinking than continental philosophy [Williamson] |
| 21616 | Truth and falsity apply to suppositions as well as to assertions [Williamson] |
| 21623 | True and false are not symmetrical; false is more complex, involving negation [Williamson] |
| 15134 | The truthmaker principle requires some specific named thing to make the difference [Williamson] |
| 15141 | Truthmaker is incompatible with modal semantics of varying domains [Williamson] |
| 15140 | The converse Barcan formula will not allow contingent truths to have truthmakers [Williamson] |
| 9594 | Correspondence to the facts is a bad account of analytic truth [Williamson] |
| 15131 | If metaphysical possibility is not a contingent matter, then S5 seems to suit it best [Williamson] |
| 14626 | In S5 matters of possibility and necessity are non-contingent [Williamson] |
| 15135 | If the domain of propositional quantification is constant, the Barcan formulas hold [Williamson] |
| 15130 | If a property is possible, there is something which can have it [Williamson] |
| 15139 | Converse Barcan: could something fail to meet a condition, if everything meets that condition? [Williamson] |
| 21602 | Many-valued logics don't solve vagueness; its presence at the meta-level is ignored [Williamson] |
| 6862 | Fuzzy logic uses a continuum of truth, but it implies contradictions [Williamson] |
| 15901 | Trying to represent curves, we study arbitrary functions, leading to the ordinals, which produces set theory [Cantor, by Lavine] |
| 15946 | Cantor developed sets from a progression into infinity by addition, multiplication and exponentiation [Cantor, by Lavine] |
| 9616 | A set is a collection into a whole of distinct objects of our intuition or thought [Cantor] |
| 13444 | Cantor's Theorem: for any set x, its power set P(x) has more members than x [Cantor, by Hart,WD] |
| 18098 | Cantor proved that all sets have more subsets than they have members [Cantor, by Bostock] |
| 15505 | If a set is 'a many thought of as one', beginners should protest against singleton sets [Cantor, by Lewis] |
| 10701 | Cantor showed that supposed contradictions in infinity were just a lack of clarity [Cantor, by Potter] |
| 10865 | The continuum is the powerset of the integers, which moves up a level [Cantor, by Clegg] |
| 17831 | Cantor gives informal versions of ZF axioms as ways of getting from one set to another [Cantor, by Lake] |
| 13016 | The Axiom of Union dates from 1899, and seems fairly obvious [Cantor, by Maddy] |
| 14199 | Cantor's sets were just collections, but Dedekind's were containers [Cantor, by Oliver/Smiley] |
| 6858 | Formal logic struck me as exactly the language I wanted to think in [Williamson] |
| 21611 | Formal semantics defines validity as truth preserved in every model [Williamson] |
| 21606 | 'Bivalence' is the meta-linguistic principle that 'A' in the object language is true or false [Williamson] |
| 21605 | Excluded Middle is 'A or not A' in the object language [Williamson] |
| 18492 | Not all quantification is either objectual or substitutional [Williamson] |
| 15136 | Substitutional quantification is metaphysical neutral, and equivalent to a disjunction of instances [Williamson] |
| 15138 | Not all quantification is objectual or substitutional [Williamson] |
| 21612 | Or-elimination is 'Argument by Cases'; it shows how to derive C from 'A or B' [Williamson] |
| 10082 | There are infinite sets that are not enumerable [Cantor, by Smith,P] |
| 13483 | Cantor's Paradox: the power set of the universe must be bigger than the universe, yet a subset of it [Cantor, by Hart,WD] |
| 8710 | The powerset of all the cardinal numbers is required to be greater than itself [Cantor, by Friend] |
| 21599 | A sorites stops when it collides with an opposite sorites [Williamson] |
| 15910 | Cantor named the third realm between the finite and the Absolute the 'transfinite' [Cantor, by Lavine] |
| 15905 | Cantor proved the points on a plane are in one-to-one correspondence to the points on a line [Cantor, by Lavine] |
| 9983 | Cantor took the ordinal numbers to be primary [Cantor, by Tait] |
| 17798 | Cantor presented the totality of natural numbers as finite, not infinite [Cantor, by Mayberry] |
| 9971 | Cantor introduced the distinction between cardinals and ordinals [Cantor, by Tait] |
| 9892 | Cantor showed that ordinals are more basic than cardinals [Cantor, by Dummett] |
| 15911 | Ordinals are generated by endless succession, followed by a limit ordinal [Cantor, by Lavine] |
| 14136 | A cardinal is an abstraction, from the nature of a set's elements, and from their order [Cantor] |
| 15906 | Cantor tried to prove points on a line matched naturals or reals - but nothing in between [Cantor, by Lavine] |
| 11015 | Cantor's diagonal argument proved you can't list all decimal numbers between 0 and 1 [Cantor, by Read] |
| 15903 | A real is associated with an infinite set of infinite Cauchy sequences of rationals [Cantor, by Lavine] |
| 18251 | Irrational numbers are the limits of Cauchy sequences of rational numbers [Cantor, by Lavine] |
| 15902 | Irrationals and the Dedekind Cut implied infinite classes, but they seemed to have logical difficulties [Cantor, by Lavine] |
| 15908 | It was Cantor's diagonal argument which revealed infinities greater than that of the real numbers [Cantor, by Lavine] |
| 13464 | Cantor proposes that there won't be a potential infinity if there is no actual infinity [Cantor, by Hart,WD] |
| 10112 | The naturals won't map onto the reals, so there are different sizes of infinity [Cantor, by George/Velleman] |
| 15896 | Cantor needed Power Set for the reals, but then couldn't count the new collections [Cantor, by Lavine] |
| 17889 | CH: An infinite set of reals corresponds 1-1 either to the naturals or to the reals [Cantor, by Koellner] |
| 13447 | Cantor: there is no size between naturals and reals, or between a set and its power set [Cantor, by Hart,WD] |
| 10883 | Cantor's Continuum Hypothesis says there is a gap between the natural and the real numbers [Cantor, by Horsten] |
| 8733 | The Continuum Hypothesis says there are no sets between the natural numbers and reals [Cantor, by Shapiro] |
| 13528 | Continuum Hypothesis: there are no sets between N and P(N) [Cantor, by Wolf,RS] |
| 9555 | Continuum Hypothesis: no cardinal greater than aleph-null but less than cardinality of the continuum [Cantor, by Chihara] |
| 18174 | Cantor extended ordinals into the transfinite, and they can thus measure infinite cardinalities [Cantor, by Maddy] |
| 15893 | Cantor's theory concerns collections which can be counted, using the ordinals [Cantor, by Lavine] |
| 18173 | Cardinality strictly concerns one-one correspondence, to test infinite sameness of size [Cantor, by Maddy] |
| 9992 | The 'extension of a concept' in general may be quantitatively completely indeterminate [Cantor] |
| 10232 | Property extensions outstrip objects, so shortage of objects caused the Caesar problem [Cantor, by Shapiro] |
| 18176 | Pure mathematics is pure set theory [Cantor] |
| 9183 | Platonism claims that some true assertions have singular terms denoting abstractions, so abstractions exist [Williamson] |
| 8631 | Cantor says that maths originates only by abstraction from objects [Cantor, by Frege] |
| 9601 | The realist/anti-realist debate is notoriously obscure and fruitless [Williamson] |
| 15137 | If 'fact' is a noun, can we name the fact that dogs bark 'Mary'? [Williamson] |
| 21589 | When bivalence is rejected because of vagueness, we lose classical logic [Williamson] |
| 21596 | Vagueness undermines the stable references needed by logic [Williamson] |
| 21601 | A vague term can refer to very precise elements [Williamson] |
| 21629 | Equally fuzzy objects can be identical, so fuzziness doesn't entail vagueness [Williamson] |
| 9599 | There cannot be vague objects, so there may be no such thing as a mountain [Williamson] |
| 21591 | Vagueness is epistemic. Statements are true or false, but we often don't know which [Williamson] |
| 21619 | If a heap has a real boundary, omniscient speakers would agree where it is [Williamson] |
| 21620 | The epistemic view says that the essence of vagueness is ignorance [Williamson] |
| 21622 | If there is a true borderline of which we are ignorant, this drives a wedge between meaning and use [Williamson] |
| 9120 | Vagueness in a concept is its indiscriminability from other possible concepts [Williamson] |
| 6863 | Close to conceptual boundaries judgement is too unreliable to give knowledge [Williamson] |
| 21625 | The vagueness of 'heap' can remain even when the context is fixed [Williamson] |
| 21614 | The 'nihilist' view of vagueness says that 'heap' is not a legitimate concept [Williamson] |
| 21617 | We can say propositions are bivalent, but vague utterances don't express a proposition [Williamson] |
| 21618 | If the vague 'TW is thin' says nothing, what does 'TW is thin if his perfect twin is thin' say? [Williamson] |
| 21590 | Asking when someone is 'clearly' old is higher-order vagueness [Williamson] |
| 21592 | Supervaluation keeps classical logic, but changes the truth in classical semantics [Williamson] |
| 21603 | You can't give a precise description of a language which is intrinsically vague [Williamson] |
| 21604 | Supervaluation assigns truth when all the facts are respected [Williamson] |
| 21607 | Supervaluation has excluded middle but not bivalence; 'A or not-A' is true, even when A is undecided [Williamson] |
| 21608 | Truth-functionality for compound statements fails in supervaluation [Williamson] |
| 21609 | Supervaluationism defines 'supertruth', but neglects it when defining 'valid' [Williamson] |
| 21610 | Supervaluation adds a 'definitely' operator to classical logic [Williamson] |
| 21613 | Supervaluationism cannot eliminate higher-order vagueness [Williamson] |
| 21633 | Nominalists suspect that properties etc are our projections, and could have been different [Williamson] |
| 6861 | What sort of logic is needed for vague concepts, and what sort of concept of truth? [Williamson] |
| 9602 | Common sense and classical logic are often simultaneously abandoned in debates on vagueness [Williamson] |
| 21630 | If fuzzy edges are fine, then why not fuzzy temporal, modal or mereological boundaries? [Williamson] |
| 21632 | A river is not just event; it needs actual and counterfactual boundaries [Williamson] |
| 14625 | Necessity is counterfactually implied by its negation; possibility does not counterfactually imply its negation [Williamson] |
| 14623 | Strict conditionals imply counterfactual conditionals: □(A⊃B)⊃(A□→B) [Williamson] |
| 14624 | Counterfactual conditionals transmit possibility: (A□→B)⊃(◊A⊃◊B) [Williamson] |
| 14531 | Rather than define counterfactuals using necessity, maybe necessity is a special case of counterfactuals [Williamson, by Hale/Hoffmann,A] |
| 21621 | We can't infer metaphysical necessities to be a priori knowable - or indeed knowable in any way [Williamson] |
| 9598 | Modal thinking isn't a special intuition; it is part of ordinary counterfactual thinking [Williamson] |
| 16536 | Williamson can't base metaphysical necessity on the psychology of causal counterfactuals [Lowe on Williamson] |
| 9596 | We scorn imagination as a test of possibility, forgetting its role in counterfactuals [Williamson] |
| 15142 | Our ability to count objects across possibilities favours the Barcan formulas [Williamson] |
| 18925 | If talking donkeys are possible, something exists which could be a talking donkey [Williamson, by Cameron] |
| 21627 | We have inexact knowledge when we include margins of error [Williamson] |
| 4760 | Belief aims at knowledge (rather than truth), and mere believing is a kind of botched knowing [Williamson] |
| 19527 | We don't acquire evidence and then derive some knowledge, because evidence IS knowledge [Williamson] |
| 19512 | Don't analyse knowledge; use knowledge to analyse other concepts in epistemology [Williamson, by DeRose] |
| 19528 | Knowledge is prior to believing, just as doing is prior to trying to do [Williamson] |
| 19529 | Belief explains justification, and knowledge explains belief, so knowledge explains justification [Williamson] |
| 19530 | A neutral state of experience, between error and knowledge, is not basic; the successful state is basic [Williamson] |
| 19531 | Internalism about mind is an obsolete view, and knowledge-first epistemology develops externalism [Williamson] |
| 19536 | Knowledge-first says your total evidence IS your knowledge [Williamson] |
| 19526 | Surely I am acquainted with physical objects, not with appearances? [Williamson] |
| 9597 | There are 'armchair' truths which are not a priori, because experience was involved [Williamson] |
| 6860 | How can one discriminate yellow from red, but not the colours in between? [Williamson] |
| 9592 | Intuition is neither powerful nor vacuous, but reveals linguistic or conceptual competence [Williamson] |
| 20181 | When analytic philosophers run out of arguments, they present intuitions as their evidence [Williamson] |
| 21626 | Knowing you know (KK) is usually denied if the knowledge concept is missing, or not considered [Williamson] |
| 20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
| 14628 | Imagination is important, in evaluating possibility and necessity, via counterfactuals [Williamson] |
| 21631 | To know, believe, hope or fear, one must grasp the thought, but not when you fail to do them [Williamson] |
| 8715 | Infinities expand the bounds of the conceivable; we explore concepts to explore conceivability [Cantor, by Friend] |
| 21600 | 'Blue' is not a family resemblance, because all the blues resemble in some respect [Williamson] |
| 13454 | Cantor says (vaguely) that we abstract numbers from equal sized sets [Hart,WD on Cantor] |
| 9145 | We form the image of a cardinal number by a double abstraction, from the elements and from their order [Cantor] |
| 9595 | You might know that the word 'gob' meant 'mouth', but not be competent to use it [Williamson] |
| 21615 | References to the 'greatest prime number' have no reference, but are meaningful [Williamson] |
| 18038 | The 't' and 'f' of formal semantics has no philosophical interest, and may not refer to true and false [Williamson] |
| 19534 | How does inferentialism distinguish the patterns of inference that are essential to meaning? [Williamson] |
| 19535 | Internalist inferentialism has trouble explaining how meaning and reference relate [Williamson] |
| 19533 | Inferentialist semantics relies on internal inference relations, not on external references [Williamson] |
| 19532 | Truth-conditional referential semantics is externalist, referring to worldly items [Williamson] |
| 21624 | It is known that there is a cognitive loss in identifying propositions with possible worlds [Williamson] |
| 19216 | Propositions (such as 'that dog is barking') only exist if their items exist [Williamson] |
| 9600 | If languages are intertranslatable, and cognition is innate, then cultures are all similar [Williamson] |
| 10863 | Cantor proved that three dimensions have the same number of points as one dimension [Cantor, by Clegg] |
| 13465 | Only God is absolutely infinite [Cantor, by Hart,WD] |
| 15133 | A thing can't be the only necessary existent, because its singleton set would be as well [Williamson] |