51 ideas
| 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] |
| 10455 | Free logic at least allows empty names, but struggles to express non-existence [Bach] |
| 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] |
| 10454 | In first-order we can't just assert existence, and it is very hard to deny something's existence [Bach] |
| 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] |
| 10453 | In logic constants play the role of proper names [Bach] |
| 15409 | All occurrences of variables in atomic formulas are free [Burgess] |
| 10452 | Proper names can be non-referential - even predicate as well as attributive uses [Bach] |
| 10456 | Millian names struggle with existence, empty names, identities and attitude ascription [Bach] |
| 10440 | An object can be described without being referred to [Bach] |
| 10444 | Definite descriptions can be used to refer, but are not semantically referential [Bach] |
| 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] |
| 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] |
| 10446 | Fictional reference is different inside and outside the fiction [Bach] |
| 10447 | We can refer to fictional entities if they are abstract objects [Bach] |
| 10443 | You 'allude to', not 'refer to', an individual if you keep their identity vague [Bach] |
| 10439 | What refers: indefinite or definite or demonstrative descriptions, names, indexicals, demonstratives? [Bach] |
| 10441 | If we can refer to things which change, we can't be obliged to single out their properties [Bach] |
| 10442 | We can think of an individual without have a uniquely characterizing description [Bach] |
| 10445 | It can't be real reference if it could refer to some other thing that satisfies the description [Bach] |
| 10457 | Since most expressions can be used non-referentially, none of them are inherently referential [Bach] |
| 10463 | Just alluding to or describing an object is not the same as referring to it [Bach] |
| 10459 | Context does not create reference; it is just something speakers can exploit [Bach] |
| 10460 | 'That duck' may not refer to the most obvious one in the group [Bach] |
| 10461 | What a pronoun like 'he' refers back to is usually a matter of speaker's intentions [Bach] |
| 10462 | Information comes from knowing who is speaking, not just from interpretation of the utterance [Bach] |
| 10458 | People slide from contextual variability all the way to contextual determination [Bach] |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |