121 ideas
3240 | There is more insight in fundamental perplexity about problems than in their supposed solutions [Nagel] |
3269 | If your life is to be meaningful as part of some large thing, the large thing must be meaningful [Nagel] |
3242 | Philosophy is the childhood of the intellect, and a culture can't skip it [Nagel] |
3241 | It seems mad, but the aim of philosophy is to climb outside of our own minds [Nagel] |
16325 | Analysis rests on natural language, but its ideal is a framework which revises language [Halbach] |
1489 | Modern philosophy tends to be a theory-constructing extension of science, but there is also problem-solving [Nagel] |
3248 | Realism invites scepticism because it claims to be objective [Nagel] |
20989 | Views are objective if they don't rely on a person's character, social position or species [Nagel] |
22354 | Things cause perceptions, properties have other effects, hence we reach a 'view from nowhere' [Nagel, by Reiss/Sprenger] |
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] |
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] |
15650 | Axiomatic theories of truth need a weak logical framework, and not a strong metatheory [Halbach] |
16322 | CT proves PA consistent, which PA can't do on its own, so CT is not conservative over PA [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] |
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] |
15655 | Should axiomatic truth be 'conservative' - not proving anything apart from implications of the axioms? [Halbach] |
15648 | Instead of a truth definition, add a primitive truth predicate, and axioms for how it works [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] |
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] |
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] |
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] |
4242 | Pure supervenience explains nothing, and is a sign of something fundamental we don't know [Nagel] |
3291 | Emergent properties appear at high levels of complexity, but aren't explainable by the lower levels [Nagel] |
16346 | Maybe necessity is a predicate, not the usual operator, to make it more like truth [Halbach] |
3249 | Modern science depends on the distinction between primary and secondary qualities [Nagel] |
22429 | We achieve objectivity by dropping secondary qualities, to focus on structural primary qualities [Nagel] |
3296 | Sense-data are a false objectification of what is essentially subjective [Nagel] |
3247 | Epistemology is centrally about what we should believe, not the definition of knowledge [Nagel] |
3271 | We can't control our own beliefs [Nagel] |
3270 | Justifications come to an end when we want them to [Nagel] |
3252 | Scepticism is based on ideas which scepticism makes impossible [Nagel] |
1490 | You would have to be very morally lazy to ignore criticisms of your own culture [Nagel] |
3251 | Observed regularities are only predictable if we assume hidden necessity [Nagel] |
3295 | Inner v outer brings astonishment that we are a particular person [Nagel] |
2957 | Brain bisection suggests unity of mind isn't all-or-nothing [Nagel, by Lockwood] |
3286 | An organism is conscious if and only if there is something it is like to be that organism [Nagel] |
3285 | We may be unable to abandon personal identity, even when split-brains have undermined it [Nagel] |
3293 | If you assert that we have an ego, you can still ask if that future ego will be me [Nagel] |
3244 | Personal identity cannot be fully known a priori [Nagel] |
3245 | The question of whether a future experience will be mine presupposes personal identity [Nagel] |
3246 | I can't even conceive of my brain being split in two [Nagel] |
3292 | The most difficult problem of free will is saying what the problem is [Nagel] |
3288 | Can we describe our experiences to zombies? [Nagel] |
4883 | Nagel's title creates an impenetrable mystery, by ignoring a bat's ways that may not be "like" anything [Dennett on Nagel] |
3287 | We can't be objective about experience [Nagel] |
4989 | Physicalism should explain how subjective experience is possible, but not 'what it is like' [Kirk,R on Nagel] |
4001 | The meaning of a word contains all its possible uses as well as its actual ones [Nagel] |
16298 | We need propositions to ascribe the same beliefs to people with different languages [Halbach] |
6479 | Noninterference requires justification as much as interference does [Nagel] |
6450 | Morality must be motivating, and not because of pre-moral motives [Nagel] |
3284 | There is no one theory of how to act (or what to believe) [Nagel] |
3257 | Total objectivity can't see value, but it sees many people with values [Nagel] |
3265 | We don't worry about the time before we were born the way we worry about death [Nagel] |
3263 | If our own life lacks meaning, devotion to others won't give it meaning [Nagel] |
3256 | Pain doesn't have a further property of badness; it gives a reason for its avoidance [Nagel] |
3272 | Moral luck can arise in character, preconditions, actual circumstances, and outcome [Nagel] |
6447 | Game theory misses out the motivation arising from the impersonal standpoint [Nagel] |
3261 | Something may be 'rational' either because it is required or because it is acceptable [Nagel] |
3258 | If cockroaches can't think about their actions, they have no duties [Nagel] |
6446 | In ethics we abstract from our identity, but not from our humanity [Nagel] |
3282 | The general form of moral reasoning is putting yourself in other people's shoes [Nagel] |
3294 | As far as possible we should become instruments to realise what is best from an eternal point of view [Nagel] |
3254 | If we can decide how to live after stepping outside of ourselves, we have the basis of a moral theory [Nagel] |
3264 | We should see others' viewpoints, but not lose touch with our own values [Nagel] |
6477 | I can only universalise a maxim if everyone else could also universalise it [Nagel] |
3255 | We find new motives by discovering reasons for action different from our preexisting motives [Nagel] |
3262 | Utilitarianism is too demanding [Nagel] |
3268 | If a small brief life is absurd, then so is a long and large one [Nagel] |
3278 | An egalitarian system must give priority to those with the worst prospects in life [Nagel] |
6448 | A legitimate system is one accepted as both impartial and reasonably partial [Nagel] |
3275 | Equality was once opposed to aristocracy, but now it opposes public utility and individual rights [Nagel] |
3281 | The ideal of acceptability to each individual underlies the appeal to equality [Nagel] |
3277 | In judging disputes, should we use one standard, or those of each individual? [Nagel] |
3274 | Equality can either be defended as good for society, or as good for individual rights [Nagel] |
3273 | Equality nowadays is seen as political, social, legal and economic [Nagel] |
6478 | Democracy is opposed to equality, if the poor are not a majority [Nagel] |
3276 | A morality of rights is very minimal, leaving a lot of human life without restrictions or duties [Nagel] |
3290 | Given the nature of heat and of water, it is literally impossible for water not to boil at the right heat [Nagel] |
1513 | The Egyptians were the first to say the soul is immortal and reincarnated [Herodotus] |