65 ideas
| 12274 | Begin examination with basics, and subdivide till you can go no further [Aristotle] |
| 12260 | Dialectic starts from generally accepted opinions [Aristotle] |
| 12291 | There can't be one definition of two things, or two definitions of the same thing [Aristotle] |
| 12292 | Definitions are easily destroyed, since they can contain very many assertions [Aristotle] |
| 12272 | We describe the essence of a particular thing by means of its differentiae [Aristotle] |
| 12279 | The differentia indicate the qualities, but not the essence [Aristotle] |
| 12283 | In definitions the first term to be assigned ought to be the genus [Aristotle] |
| 12289 | The genera and the differentiae are part of the essence [Aristotle] |
| 12261 | Differentia are generic, and belong with genus [Aristotle] |
| 12263 | 'Genus' is part of the essence shared among several things [Aristotle] |
| 12285 | The definition is peculiar to one thing, not common to many [Aristotle] |
| 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] |
| 11261 | Puzzles arise when reasoning seems equal on both sides [Aristotle] |
| 15428 | The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut' [Burgess] |
| 12273 | Unit is the starting point of number [Aristotle] |
| 12267 | There are ten categories: essence, quantity, quality, relation, place, time, position, state, activity, passivity [Aristotle] |
| 12282 | An individual property has to exist (in past, present or future) [Aristotle] |
| 12264 | An 'accident' is something which may possibly either belong or not belong to a thing [Aristotle] |
| 12280 | Genus gives the essence better than the differentiae do [Aristotle] |
| 13269 | In the case of a house the parts can exist without the whole, so parts are not the whole [Aristotle] |
| 12284 | Everything that is has one single essence [Aristotle] |
| 12262 | An 'idion' belongs uniquely to a thing, but is not part of its essence [Aristotle] |
| 12290 | Destruction is dissolution of essence [Aristotle] |
| 12286 | If two things are the same, they must have the same source and origin [Aristotle] |
| 12266 | 'Same' is mainly for names or definitions, but also for propria, and for accidents [Aristotle] |
| 12287 | Two identical things have the same accidents, they are the same; if the accidents differ, they're different [Aristotle] |
| 12288 | Numerical sameness and generic sameness are not the same [Aristotle] |
| 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] |
| 12259 | Reasoning is when some results follow necessarily from certain claims [Aristotle] |
| 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] |
| 19540 | Don't confuse justified belief with justified believers [Dougherty/Rysiew] |
| 19539 | If knowledge is unanalysable, that makes justification more important [Dougherty/Rysiew] |
| 12271 | Induction is the progress from particulars to universals [Aristotle] |
| 12293 | We say 'so in cases of this kind', but how do you decide what is 'of this kind'? [Aristotle] |
| 19538 | Entailment is modelled in formal semantics as set inclusion (where 'mammals' contains 'cats') [Dougherty/Rysiew] |
| 12277 | Friendship is preferable to money, since its excess is preferable [Aristotle] |
| 12276 | Justice and self-control are better than courage, because they are always useful [Aristotle] |
| 12275 | We value friendship just for its own sake [Aristotle] |
| 12281 | Man is intrinsically a civilized animal [Aristotle] |
| 12265 | All water is the same, because of a certain similarity [Aristotle] |
| 12278 | 'Being' and 'oneness' are predicated of everything which exists [Aristotle] |