38 ideas
| 22285 | Impredicative definitions are circular, but fine for picking out, rather than creating something [Potter] |
| 22301 | The Identity Theory says a proposition is true if it coincides with what makes it true [Potter] |
| 22324 | It has been unfortunate that externalism about truth is equated with correspondence [Potter] |
| 7786 | Propositional logic handles negation, disjunction, conjunction; predicate logic adds quantifiers, predicates, relations [Girle] |
| 7798 | There are three axiom schemas for propositional logic [Girle] |
| 7799 | Proposition logic has definitions for its three operators: or, and, and identical [Girle] |
| 7797 | Axiom systems of logic contain axioms, inference rules, and definitions of proof and theorems [Girle] |
| 7794 | There are seven modalities in S4, each with its negation [Girle] |
| 7793 | ◊p → □◊p is the hallmark of S5 [Girle] |
| 7795 | S5 has just six modalities, and all strings can be reduced to those [Girle] |
| 7787 | Possible worlds logics use true-in-a-world rather than true [Girle] |
| 7788 | Modal logic has four basic modal negation equivalences [Girle] |
| 7796 | Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle] |
| 22279 | Frege's sign |--- meant judgements, but the modern |- turnstile means inference, with intecedents [Potter] |
| 7789 | Necessary implication is called 'strict implication'; if successful, it is called 'entailment' [Girle] |
| 22291 | Deductivism can't explain how the world supports unconditional conclusions [Potter] |
| 7790 | If an argument is invalid, a truth tree will indicate a counter-example [Girle] |
| 22295 | Modern logical truths are true under all interpretations of the non-logical words [Potter] |
| 22310 | The formalist defence against Gödel is to reject his metalinguistic concept of truth [Potter] |
| 22298 | Why is fictional arithmetic applicable to the real world? [Potter] |
| 22287 | If 'concrete' is the negative of 'abstract', that means desires and hallucinations are concrete [Potter] |
| 22284 | 'Greater than', which is the ancestral of 'successor', strictly orders the natural numbers [Potter] |
| 7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
| 7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
| 22281 | A material conditional cannot capture counterfactual reasoning [Potter] |
| 7792 | A world has 'access' to a world it generates, which is important in possible worlds semantics [Girle] |
| 21515 | Incoherence may be more important for enquiry than coherence [Olsson] |
| 21514 | Coherence is the capacity to answer objections [Olsson] |
| 21496 | Mere agreement of testimonies is not enough to make truth very likely [Olsson] |
| 21499 | Coherence is only needed if the information sources are not fully reliable [Olsson] |
| 21502 | A purely coherent theory cannot be true of the world without some contact with the world [Olsson] |
| 21512 | Extending a system makes it less probable, so extending coherence can't make it more probable [Olsson] |
| 22327 | Knowledge from a drunken schoolteacher is from a reliable and unreliable process [Potter] |
| 22273 | Traditionally there are twelve categories of judgement, in groups of three [Potter] |
| 22290 | The phrase 'the concept "horse"' can't refer to a concept, because it is saturated [Potter] |
| 22283 | Compositionality should rely on the parsing tree, which may contain more than sentence components [Potter] |
| 22282 | 'Direct compositonality' says the components wholly explain a sentence meaning [Potter] |
| 22296 | Compositionality is more welcome in logic than in linguistics (which is more contextual) [Potter] |