88 ideas
18835 | Logic doesn't have a metaphysical basis, but nor can logic give rise to the metaphysics [Rumfitt] |
18819 | The idea that there are unrecognised truths is basic to our concept of truth [Rumfitt] |
18826 | 'True at a possibility' means necessarily true if what is said had obtained [Rumfitt] |
18803 | Semantics for propositions: 1) validity preserves truth 2) non-contradition 3) bivalence 4) truth tables [Rumfitt] |
12204 | The logic of metaphysical necessity is S5 [Rumfitt] |
18814 | 'Absolute necessity' would have to rest on S5 [Rumfitt] |
18798 | It is the second-order part of intuitionistic logic which actually negates some classical theorems [Rumfitt] |
18799 | Intuitionists can accept Double Negation Elimination for decidable propositions [Rumfitt] |
18830 | Most set theorists doubt bivalence for the Continuum Hypothesis, but still use classical logic [Rumfitt] |
18843 | The iterated conception of set requires continual increase in axiom strength [Rumfitt] |
18836 | A set may well not consist of its members; the empty set, for example, is a problem [Rumfitt] |
18837 | A set can be determinate, because of its concept, and still have vague membership [Rumfitt] |
18845 | If the totality of sets is not well-defined, there must be doubt about the Power Set Axiom [Rumfitt] |
11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
18815 | Logic is higher-order laws which can expand the range of any sort of deduction [Rumfitt] |
9390 | Logic guides thinking, but it isn't a substitute for it [Rumfitt] |
18804 | The case for classical logic rests on its rules, much more than on the Principle of Bivalence [Rumfitt] |
18805 | Classical logic rules cannot be proved, but various lines of attack can be repelled [Rumfitt] |
18827 | If truth-tables specify the connectives, classical logic must rely on Bivalence [Rumfitt] |
12195 | Soundness in argument varies with context, and may be achieved very informally indeed [Rumfitt] |
12199 | There is a modal element in consequence, in assessing reasoning from suppositions [Rumfitt] |
12201 | We reject deductions by bad consequence, so logical consequence can't be deduction [Rumfitt] |
18813 | Logical consequence is a relation that can extended into further statements [Rumfitt] |
18808 | Normal deduction presupposes the Cut Law [Rumfitt] |
18840 | When faced with vague statements, Bivalence is not a compelling principle [Rumfitt] |
12194 | Contradictions include 'This is red and not coloured', as well as the formal 'B and not-B' [Rumfitt] |
11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
18802 | In specifying a logical constant, use of that constant is quite unavoidable [Rumfitt] |
11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
12198 | Geometrical axioms in logic are nowadays replaced by inference rules (which imply the logical truths) [Rumfitt] |
18800 | Introduction rules give deduction conditions, and Elimination says what can be deduced [Rumfitt] |
18809 | Logical truths are just the assumption-free by-products of logical rules [Rumfitt] |
18807 | Monotonicity means there is a guarantee, rather than mere inductive support [Rumfitt] |
18842 | Maybe an ordinal is a property of isomorphic well-ordered sets, and not itself a set [Rumfitt] |
17462 | A single object must not be counted twice, which needs knowledge of distinctness (negative identity) [Rumfitt] |
18834 | Infinitesimals do not stand in a determinate order relation to zero [Rumfitt] |
18846 | Cantor and Dedekind aimed to give analysis a foundation in set theory (rather than geometry) [Rumfitt] |
17461 | Some 'how many?' answers are not predications of a concept, like 'how many gallons?' [Rumfitt] |
9389 | Vague membership of sets is possible if the set is defined by its concept, not its members [Rumfitt] |
18839 | An object that is not clearly red or orange can still be red-or-orange, which sweeps up problem cases [Rumfitt] |
18838 | The extension of a colour is decided by a concept's place in a network of contraries [Rumfitt] |
14532 | A distinctive type of necessity is found in logical consequence [Rumfitt, by Hale/Hoffmann,A] |
18816 | Metaphysical modalities respect the actual identities of things [Rumfitt] |
12193 | Logical necessity is when 'necessarily A' implies 'not-A is contradictory' [Rumfitt] |
12200 | A logically necessary statement need not be a priori, as it could be unknowable [Rumfitt] |
18825 | S5 is the logic of logical necessity [Rumfitt] |
12202 | Narrow non-modal logical necessity may be metaphysical, but real logical necessity is not [Rumfitt] |
18824 | Since possibilities are properties of the world, calling 'red' the determination of a determinable seems right [Rumfitt] |
18828 | If two possibilities can't share a determiner, they are incompatible [Rumfitt] |
12203 | If a world is a fully determinate way things could have been, can anyone consider such a thing? [Rumfitt] |
18821 | Possibilities are like possible worlds, but not fully determinate or complete [Rumfitt] |
18831 | Medieval logicians said understanding A also involved understanding not-A [Rumfitt] |
18820 | In English 'evidence' is a mass term, qualified by 'little' and 'more' [Rumfitt] |
4363 | The word 'person' is useless in ethics, because what counts as a good or bad self-conscious being? [Hursthouse] |
18817 | We understand conditionals, but disagree over their truth-conditions [Rumfitt] |
18829 | The truth grounds for 'not A' are the possibilities incompatible with truth grounds for A [Rumfitt] |
11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
4355 | There may be inverse akrasia, where the agent's action is better than their judgement recommends [Hursthouse] |
4325 | Must all actions be caused in part by a desire, or can a belief on its own be sufficient? [Hursthouse] |
4351 | It is a fantasy that only through the study of philosophy can one become virtuous [Hursthouse] |
4340 | You are not a dishonest person if a tragic dilemma forces you to do something dishonest [Hursthouse] |
4329 | After a moral dilemma is resolved there is still a 'remainder', requiring (say) regret [Hursthouse] |
4330 | Deontologists resolve moral dilemmas by saying the rule conflict is merely apparent [Hursthouse] |
4341 | Involuntary actions performed in tragic dilemmas are bad because they mar a good life [Hursthouse] |
4358 | Virtue may be neither sufficient nor necessary for eudaimonia [Hursthouse] |
4337 | Teenagers are often quite wise about ideals, but rather stupid about consequences [Hursthouse] |
4324 | Animals and plants can 'flourish', but only rational beings can have eudaimonia [Hursthouse] |
4359 | When it comes to bringing up children, most of us think that the virtues are the best bet [Hursthouse] |
20195 | Eudaimonia first; virtue is a trait which promotes it; right acts are what virtues produce [Hursthouse, by Zagzebski] |
4336 | Any strict ranking of virtues or rules gets abandoned when faced with particular cases [Hursthouse] |
4334 | Virtue ethics is open to the objection that it fails to show priority among the virtues [Hursthouse] |
4361 | Good animals can survive, breed, feel characteristic pleasure and pain, and contribute to the group [Hursthouse] |
4349 | Virtuous people may not be fully clear about their reasons for action [Hursthouse] |
4352 | Performing an act simply because it is virtuous is sufficient to be 'morally motivated' or 'dutiful' [Hursthouse] |
4353 | If moral motivation is an all-or-nothing sense of duty, how can children act morally? [Hursthouse] |
4346 | The emotions of sympathy, compassion and love are no guarantee of right action or acting well [Hursthouse] |
4339 | According to virtue ethics, two agents may respond differently, and yet both be right [Hursthouse] |
4354 | Maybe in a deeply poisoned character none of their milder character traits could ever be a virtue [Hursthouse] |
4364 | Being unusually virtuous in some areas may entail being less virtuous in others [Hursthouse] |
4356 | We are puzzled by a person who can show an exceptional virtue and also behave very badly [Hursthouse] |
4327 | Deontologists do consider consequences, because they reveal when a rule might apply [Hursthouse] |
4335 | 'Codifiable' morality give rules for decisions which don't require wisdom [Hursthouse] |
4328 | Preference utilitarianism aims to be completely value-free, or empirical [Hursthouse] |
4343 | We are torn between utilitarian and deontological views of lying, depending on the examples [Hursthouse] |
4338 | Deontologists usually accuse utilitarians of oversimplifying hard cases [Hursthouse] |
4365 | We are distinct from other animals in behaving rationally - pursuing something as good, for reasons [Hursthouse] |
4350 | If people are virtuous in obedience to God, would they become wicked if they lost their faith? [Hursthouse] |
1513 | The Egyptians were the first to say the soul is immortal and reincarnated [Herodotus] |