141 ideas
| 11832 | We learn a concept's relations by using it, without reducing it to anything [Wiggins] |
| 16512 | Semantic facts are preferable to transcendental philosophical fiction [Wiggins] |
| 16325 | Analysis rests on natural language, but its ideal is a framework which revises language [Halbach] |
| 16292 | An explicit definition enables the elimination of what is defined [Halbach] |
| 16307 | Don't trust analogies; they are no more than a guideline [Halbach] |
| 16339 | Truth axioms prove objects exist, so truth doesn't seem to be a logical notion [Halbach] |
| 16330 | Truth-value 'gluts' allow two truth values together; 'gaps' give a partial conception of truth [Halbach] |
| 16324 | Any definition of truth requires a metalanguage [Halbach] |
| 15647 | Truth definitions don't produce a good theory, because they go beyond your current language [Halbach] |
| 16293 | Traditional definitions of truth often make it more obscure, rather than less [Halbach] |
| 16301 | If people have big doubts about truth, a definition might give it more credibility [Halbach] |
| 15649 | In semantic theories of truth, the predicate is in an object-language, and the definition in a metalanguage [Halbach] |
| 16297 | Semantic theories avoid Tarski's Theorem by sticking to a sublanguage [Halbach] |
| 16337 | Disquotational truth theories are short of deductive power [Halbach] |
| 15648 | Instead of a truth definition, add a primitive truth predicate, and axioms for how it works [Halbach] |
| 15655 | Should axiomatic truth be 'conservative' - not proving anything apart from implications of the axioms? [Halbach] |
| 15654 | If truth is defined it can be eliminated, whereas axiomatic truth has various commitments [Halbach] |
| 16294 | Axiomatic truth doesn't presuppose a truth-definition, though it could admit it at a later stage [Halbach] |
| 16311 | To axiomatise Tarski's truth definition, we need a binary predicate for his 'satisfaction' [Halbach] |
| 16318 | Compositional Truth CT has the truth of a sentence depending of the semantic values of its constituents [Halbach] |
| 16326 | The main semantic theories of truth are Kripke's theory, and revisions semantics [Halbach] |
| 16299 | Gödel numbering means a theory of truth can use Peano Arithmetic as its base theory [Halbach] |
| 16340 | Truth axioms need a base theory, because that is where truth issues arise [Halbach] |
| 16322 | CT proves PA consistent, which PA can't do on its own, so CT is not conservative over PA [Halbach] |
| 16305 | We know a complete axiomatisation of truth is not feasible [Halbach] |
| 16313 | A theory is 'conservative' if it adds no new theorems to its base theory [Halbach, by PG] |
| 16315 | The Tarski Biconditional theory TB is Peano Arithmetic, plus truth, plus all Tarski bi-conditionals [Halbach] |
| 15650 | Axiomatic theories of truth need a weak logical framework, and not a strong metatheory [Halbach] |
| 16314 | Theories of truth are 'typed' (truth can't apply to sentences containing 'true'), or 'type-free' [Halbach] |
| 16327 | Friedman-Sheard is type-free Compositional Truth, with two inference rules for truth [Halbach] |
| 16329 | Kripke-Feferman theory KF axiomatises Kripke fixed-points, with Strong Kleene logic with gluts [Halbach] |
| 16331 | The KF is much stronger deductively than FS, which relies on classical truth [Halbach] |
| 16332 | The KF theory is useful, but it is not a theory containing its own truth predicate [Halbach] |
| 15656 | Deflationists say truth merely serves to express infinite conjunctions [Halbach] |
| 16338 | Deflationism says truth is a disquotation device to express generalisations, adding no new knowledge [Halbach] |
| 16317 | The main problem for deflationists is they can express generalisations, but not prove them [Halbach] |
| 16316 | Deflationists say truth is just for expressing infinite conjunctions or generalisations [Halbach] |
| 16319 | Compositional Truth CT proves generalisations, so is preferred in discussions of deflationism [Halbach] |
| 16320 | Some say deflationism is axioms which are conservative over the base theory [Halbach] |
| 16335 | In Strong Kleene logic a disjunction just needs one disjunct to be true [Halbach] |
| 16334 | In Weak Kleene logic there are 'gaps', neither true nor false if one component lacks a truth value [Halbach] |
| 15657 | To prove the consistency of set theory, we must go beyond set theory [Halbach] |
| 16309 | Every attempt at formal rigour uses some set theory [Halbach] |
| 16333 | The underestimated costs of giving up classical logic are found in mathematical reasoning [Halbach] |
| 15652 | We can use truth instead of ontologically loaded second-order comprehension assumptions about properties [Halbach] |
| 15651 | Instead of saying x has a property, we can say a formula is true of x - as long as we have 'true' [Halbach] |
| 16310 | A theory is some formulae and all of their consequences [Halbach] |
| 11863 | (λx)[Man x] means 'the property x has iff x is a man'. [Wiggins] |
| 16342 | You cannot just say all of Peano arithmetic is true, as 'true' isn't part of the system [Halbach] |
| 16344 | Soundness must involve truth; the soundness of PA certainly needs it [Halbach] |
| 16341 | Normally we only endorse a theory if we believe it to be sound [Halbach] |
| 16347 | Many new paradoxes may await us when we study interactions between frameworks [Halbach] |
| 16336 | The liar paradox applies truth to a negated truth (but the conditional will serve equally) [Halbach] |
| 17529 | Maybe the concept needed under which things coincide must also yield a principle of counting [Wiggins] |
| 17530 | The sortal needed for identities may not always be sufficient to support counting [Wiggins] |
| 16321 | The compactness theorem can prove nonstandard models of PA [Halbach] |
| 16343 | The global reflection principle seems to express the soundness of Peano Arithmetic [Halbach] |
| 16312 | To reduce PA to ZF, we represent the non-negative integers with von Neumann ordinals [Halbach] |
| 16308 | Set theory was liberated early from types, and recent truth-theories are exploring type-free [Halbach] |
| 14746 | What exists can't depend on our conceptual scheme, and using all conceptual schemes is too liberal [Sider on Wiggins] |
| 16345 | That Peano arithmetic is interpretable in ZF set theory is taken by philosophers as a reduction [Halbach] |
| 16523 | Realist Conceptualists accept that our interests affect our concepts [Wiggins] |
| 16524 | Conceptualism says we must use our individuating concepts to grasp reality [Wiggins] |
| 16526 | Animal classifications: the Emperor's, fabulous, innumerable, like flies, stray dogs, embalmed…. [Wiggins] |
| 12056 | An ancestral relation is either direct or transitively indirect [Wiggins] |
| 12050 | Substances contain a source of change or principle of activity [Wiggins] |
| 16492 | Individuation needs accounts of identity, of change, and of singling out [Wiggins] |
| 16493 | Individuation can only be understood by the relation between things and thinkers [Wiggins] |
| 11900 | We can accept criteria of distinctness and persistence, without making the counterfactual claims [Mackie,P on Wiggins] |
| 11870 | Activity individuates natural things, functions do artefacts, and intentions do artworks [Wiggins] |
| 16496 | Singling out extends back and forward in time [Wiggins] |
| 11866 | The idea of 'thisness' is better expressed with designation/predication and particular/universal [Wiggins] |
| 13128 | 'Ultimate sortals' cannot explain ontological categories [Westerhoff on Wiggins] |
| 16495 | The only singling out is singling out 'as' something [Wiggins] |
| 16501 | In Aristotle's sense, saying x falls under f is to say what x is [Wiggins] |
| 16506 | Every determinate thing falls under a sortal, which fixes its persistence [Wiggins] |
| 12055 | Sortal predications are answers to the question 'what is x?' [Wiggins] |
| 12059 | A river may change constantly, but not in respect of being a river [Wiggins] |
| 12052 | We never single out just 'this', but always 'this something-or-other' [Wiggins] |
| 12063 | Sortal classification becomes science, with cross reference clarifying individuals [Wiggins] |
| 12051 | If the kinds are divided realistically, they fall into substances [Wiggins] |
| 12053 | 'Human being' is a better answer to 'what is it?' than 'poet', as the latter comes in degrees [Wiggins] |
| 12054 | Secondary substances correctly divide primary substances by activity-principles and relations [Wiggins] |
| 11896 | A sortal essence is a thing's principle of individuation [Wiggins, by Mackie,P] |
| 15835 | Wiggins's sortal essentialism rests on a thing's principle of individuation [Wiggins, by Mackie,P] |
| 11841 | The evening star is the same planet but not the same star as the morning star, since it is not a star [Wiggins] |
| 10679 | 'Sortalism' says parts only compose a whole if it falls under a sort or kind [Wiggins, by Hossack] |
| 14363 | Identity a=b is only possible with some concept to give persistence and existence conditions [Wiggins, by Strawson,P] |
| 14364 | A thing is necessarily its highest sortal kind, which entails an essential constitution [Wiggins, by Strawson,P] |
| 11851 | Many predicates are purely generic, or pure determiners, rather than sortals [Wiggins] |
| 11865 | The possibility of a property needs an essential sortal concept to conceive it [Wiggins] |
| 12047 | We refer to persisting substances, in perception and in thought, and they aid understanding [Wiggins] |
| 14744 | Objects can only coincide if they are of different kinds; trees can't coincide with other trees [Wiggins, by Sider] |
| 11852 | Is the Pope's crown one crown, if it is made of many crowns? [Wiggins] |
| 11875 | Boundaries are not crucial to mountains, so they are determinate without a determinate extent [Wiggins] |
| 12057 | Matter underlies things, composes things, and brings them to be [Wiggins] |
| 14749 | Identity is an atemporal relation, but composition is relative to times [Wiggins, by Sider] |
| 11844 | If I destroy an item, I do not destroy each part of it [Wiggins] |
| 12887 | A whole must have one characteristic, an internal relation, and a structure [Rescher/Oppenheim] |
| 11861 | We can forget about individual or particularized essences [Wiggins] |
| 16509 | Natural kinds are well suited to be the sortals which fix substances [Wiggins] |
| 11871 | Essences are not explanations, but individuations [Wiggins] |
| 11879 | Essentialism is best represented as a predicate-modifier: □(a exists → a is F) [Wiggins, by Mackie,P] |
| 16514 | Artefacts are individuated by some matter having a certain function [Wiggins] |
| 16510 | Nominal essences don't fix membership, ignore evolution, and aren't contextual [Wiggins] |
| 11835 | The nominal essence is the idea behind a name used for sorting [Wiggins] |
| 16503 | 'What is it?' gives the kind, nature, persistence conditions and identity over time of a thing [Wiggins] |
| 11876 | It is easier to go from horses to horse-stages than from horse-stages to horses [Wiggins] |
| 16499 | A restored church is the same 'church', but not the same 'building' or 'brickwork' [Wiggins] |
| 16515 | A thing begins only once; for a clock, it is when its making is first completed [Wiggins] |
| 16517 | Priests prefer the working ship; antiquarians prefer the reconstruction [Wiggins] |
| 11858 | The question is not what gets the title 'Theseus' Ship', but what is identical with the original [Wiggins] |
| 11843 | Identity over a time and at a time aren't different concepts [Wiggins] |
| 11864 | Hesperus=Hesperus, and Phosphorus=Hesperus, so necessarily Phosphorus=Hesperus [Wiggins] |
| 16502 | Identity is primitive [Wiggins] |
| 16498 | Identity cannot be defined, because definitions are identities [Wiggins] |
| 16497 | Leibniz's Law (not transitivity, symmetry, reflexivity) marks what is peculiar to identity [Wiggins] |
| 11831 | The formal properties of identity are reflexivity and Leibniz's Law [Wiggins] |
| 14362 | Relative Identity is incompatible with the Indiscernibility of Identicals [Wiggins, by Strawson,P] |
| 11838 | Relativity of Identity makes identity entirely depend on a category [Wiggins] |
| 11847 | To identify two items, we must have a common sort for them [Wiggins] |
| 16521 | A is necessarily A, so if B is A, then B is also necessarily A [Wiggins] |
| 16505 | By the principle of Indiscernibility, a symmetrical object could only be half of itself! [Wiggins] |
| 11839 | Do both 'same f as' and '=' support Leibniz's Law? [Wiggins] |
| 11845 | Substitutivity, and hence most reasoning, needs Leibniz's Law [Wiggins] |
| 16494 | We want to explain sameness as coincidence of substance, not as anything qualitative [Wiggins] |
| 16346 | Maybe necessity is a predicate, not the usual operator, to make it more like truth [Halbach] |
| 16522 | It is hard or impossible to think of Caesar as not human [Wiggins] |
| 11869 | Possible worlds rest on the objects about which we have suppositions [Wiggins] |
| 11850 | Not every story corresponds to a possible world [Wiggins] |
| 16525 | Our sortal concepts fix what we find in experience [Wiggins] |
| 12064 | The category of substance is more important for epistemology than for ontology [Wiggins] |
| 12049 | Naming the secondary substance provides a mass of general information [Wiggins] |
| 11848 | Asking 'what is it?' nicely points us to the persistence of a continuing entity [Wiggins] |
| 12065 | Seeing a group of soldiers as an army is irresistible, in ontology and explanation [Wiggins] |
| 11859 | The mind conceptualizes objects; yet objects impinge upon the mind [Wiggins] |
| 16518 | We conceptualise objects, but they impinge on us [Wiggins] |
| 11836 | We can use 'concept' for the reference, and 'conception' for sense [Wiggins] |
| 16511 | A 'conception' of a horse is a full theory of what it is (and not just the 'concept') [Wiggins] |
| 16298 | We need propositions to ascribe the same beliefs to people with different languages [Halbach] |
| 11860 | Lawlike propensities are enough to individuate natural kinds [Wiggins] |