81 ideas
| 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] |
| 16330 | Truth-value 'gluts' allow two truth values together; 'gaps' give a partial conception of truth [Halbach] |
| 16339 | Truth axioms prove objects exist, so truth doesn't seem to be a logical notion [Halbach] |
| 16324 | Any definition of truth requires a metalanguage [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] |
| 16297 | Semantic theories avoid Tarski's Theorem by sticking to a sublanguage [Halbach] |
| 16337 | Disquotational truth theories are short of deductive power [Halbach] |
| 16322 | CT proves PA consistent, which PA can't do on its own, so CT is not conservative over PA [Halbach] |
| 16294 | Axiomatic truth doesn't presuppose a truth-definition, though it could admit it at a later stage [Halbach] |
| 16326 | The main semantic theories of truth are Kripke's theory, and revisions semantics [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] |
| 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] |
| 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] |
| 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] |
| 16332 | The KF theory is useful, but it is not a theory containing its own truth predicate [Halbach] |
| 16331 | The KF is much stronger deductively than FS, which relies on classical truth [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] |
| 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] |
| 14684 | A world is 'accessible' to another iff the first is possible according to the second [Salmon,N] |
| 14669 | For metaphysics, T may be the only correct system of modal logic [Salmon,N] |
| 14667 | System B has not been justified as fallacy-free for reasoning on what might have been [Salmon,N] |
| 14668 | In B it seems logically possible to have both p true and p is necessarily possibly false [Salmon,N] |
| 14692 | System B implies that possibly-being-realized is an essential property of the world [Salmon,N] |
| 14671 | What is necessary is not always necessarily necessary, so S4 is fallacious [Salmon,N] |
| 14686 | S5 modal logic ignores accessibility altogether [Salmon,N] |
| 14691 | S5 believers say that-things-might-have-been-that-way is essential to ways things might have been [Salmon,N] |
| 14693 | The unsatisfactory counterpart-theory allows the retention of S5 [Salmon,N] |
| 14670 | Metaphysical (alethic) modal logic concerns simple necessity and possibility (not physical, epistemic..) [Salmon,N] |
| 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] |
| 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] |
| 16310 | A theory is some formulae and all of their consequences [Halbach] |
| 16342 | You cannot just say all of Peano arithmetic is true, as 'true' isn't part of the system [Halbach] |
| 16341 | Normally we only endorse a theory if we believe it to be sound [Halbach] |
| 16344 | Soundness must involve truth; the soundness of PA certainly needs it [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] |
| 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] |
| 16345 | That Peano arithmetic is interpretable in ZF set theory is taken by philosophers as a reduction [Halbach] |
| 14678 | Any property is attached to anything in some possible world, so I am a radical anti-essentialist [Salmon,N] |
| 16346 | Maybe necessity is a predicate, not the usual operator, to make it more like truth [Halbach] |
| 14680 | Logical possibility contains metaphysical possibility, which contains nomological possibility [Salmon,N] |
| 14690 | In the S5 account, nested modalities may be unseen, but they are still there [Salmon,N] |
| 14677 | Metaphysical necessity is said to be unrestricted necessity, true in every world whatsoever [Salmon,N] |
| 14679 | Bizarre identities are logically but not metaphysically possible, so metaphysical modality is restricted [Salmon,N] |
| 14688 | Without impossible worlds, the unrestricted modality that is metaphysical has S5 logic [Salmon,N] |
| 14685 | Metaphysical necessity is NOT truth in all (unrestricted) worlds; necessity comes first, and is restricted [Salmon,N] |
| 14681 | Logical necessity is free of constraints, and may accommodate all of S5 logic [Salmon,N] |
| 14676 | Nomological necessity is expressed with intransitive relations in modal semantics [Salmon,N] |
| 14689 | Necessity and possibility are not just necessity and possibility according to the actual world [Salmon,N] |
| 14674 | Impossible worlds are also ways for things to be [Salmon,N] |
| 14682 | Denial of impossible worlds involves two different confusions [Salmon,N] |
| 14687 | Without impossible worlds, how things might have been is the only way for things to be [Salmon,N] |
| 14683 | Possible worlds rely on what might have been, so they can' be used to define or analyse modality [Salmon,N] |
| 14672 | Possible worlds are maximal abstract ways that things might have been [Salmon,N] |
| 14675 | Possible worlds just have to be 'maximal', but they don't have to be consistent [Salmon,N] |
| 14673 | You can't define worlds as sets of propositions, and then define propositions using worlds [Salmon,N] |
| 3654 | The pineal gland links soul to body, and unites the two symmetrical sides of the body [Descartes, by PG] |
| 4015 | For Descartes passions are God-given preservers of the mind-body union [Descartes, by Taylor,C] |
| 4313 | Are there a few primary passions (say, joy, sadness and desire)? [Descartes, by Cottingham] |
| 23989 | There are six primitive passions: wonder, love, hatred, desire, joy and sadness [Descartes, by Goldie] |
| 16298 | We need propositions to ascribe the same beliefs to people with different languages [Halbach] |
| 20037 | Merely willing to walk leads to our walking [Descartes] |
| 16763 | We don't die because the soul departs; the soul departs because the organs cease functioning [Descartes] |
| 4016 | Descartes makes strength of will the central virtue [Descartes, by Taylor,C] |