59 ideas
| 16512 | Semantic facts are preferable to transcendental philosophical fiction [Wiggins] |
| 15413 | With four tense operators, all complex tenses reduce to fourteen basic cases [Burgess] |
| 15415 | The temporal Barcan formulas fix what exists, which seems absurd [Burgess] |
| 15430 | Is classical logic a part of intuitionist logic, or vice versa? [Burgess] |
| 15431 | It is still unsettled whether standard intuitionist logic is complete [Burgess] |
| 15429 | Relevance logic's → is perhaps expressible by 'if A, then B, for that reason' [Burgess] |
| 15404 | Technical people see logic as any formal system that can be studied, not a study of argument validity [Burgess] |
| 15405 | Classical logic neglects the non-mathematical, such as temporality or modality [Burgess] |
| 15427 | The Cut Rule expresses the classical idea that entailment is transitive [Burgess] |
| 15421 | Classical logic neglects counterfactuals, temporality and modality, because maths doesn't use them [Burgess] |
| 15403 | Philosophical logic is a branch of logic, and is now centred in computer science [Burgess] |
| 15407 | Formalising arguments favours lots of connectives; proving things favours having very few [Burgess] |
| 15424 | Asserting a disjunction from one disjunct seems odd, but can be sensible, and needed in maths [Burgess] |
| 15409 | All occurrences of variables in atomic formulas are free [Burgess] |
| 15414 | The denotation of a definite description is flexible, rather than rigid [Burgess] |
| 15406 | 'Induction' and 'recursion' on complexity prove by connecting a formula to its atomic components [Burgess] |
| 15425 | The sequent calculus makes it possible to have proof without transitivity of entailment [Burgess] |
| 15426 | We can build one expanding sequence, instead of a chain of deductions [Burgess] |
| 15408 | 'Tautologies' are valid formulas of classical sentential logic - or substitution instances in other logics [Burgess] |
| 15418 | Validity (for truth) and demonstrability (for proof) have correlates in satisfiability and consistency [Burgess] |
| 15412 | Models leave out meaning, and just focus on truth values [Burgess] |
| 15411 | We only need to study mathematical models, since all other models are isomorphic to these [Burgess] |
| 15416 | We aim to get the technical notion of truth in all models matching intuitive truth in all instances [Burgess] |
| 15428 | The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut' [Burgess] |
| 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] |
| 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] |
| 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] |
| 16496 | Singling out extends back and forward in time [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] |
| 16509 | Natural kinds are well suited to be the sortals which fix substances [Wiggins] |
| 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] |
| 16503 | 'What is it?' gives the kind, nature, persistence conditions and identity over time of a thing [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] |
| 16497 | Leibniz's Law (not transitivity, symmetry, reflexivity) marks what is peculiar to identity [Wiggins] |
| 16502 | Identity is primitive [Wiggins] |
| 16498 | Identity cannot be defined, because definitions are identities [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] |
| 16494 | We want to explain sameness as coincidence of substance, not as anything qualitative [Wiggins] |
| 15420 | De re modality seems to apply to objects a concept intended for sentences [Burgess] |
| 15419 | General consensus is S5 for logical modality of validity, and S4 for proof [Burgess] |
| 15417 | Logical necessity has two sides - validity and demonstrability - which coincide in classical logic [Burgess] |
| 15422 | Three conditionals theories: Materialism (material conditional), Idealism (true=assertable), Nihilism (no truth) [Burgess] |
| 15423 | It is doubtful whether the negation of a conditional has any clear meaning [Burgess] |
| 16522 | It is hard or impossible to think of Caesar as not human [Wiggins] |
| 16525 | Our sortal concepts fix what we find in experience [Wiggins] |
| 16518 | We conceptualise objects, but they impinge on us [Wiggins] |
| 16511 | A 'conception' of a horse is a full theory of what it is (and not just the 'concept') [Wiggins] |
| 11945 | In addition to laws, God must also create appropriate natures for things [Leibniz] |
| 19348 | All that is real in motion is the force or power which produces change [Leibniz] |