19 ideas
10282 | Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W] |
14620 | Theories in logic are sentences closed under consequence, but in truth discussions theories have axioms [Fine,K] |
10283 | A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W] |
10284 | There are three different standard presentations of semantics [Hodges,W] |
10285 | I |= φ means that the formula φ is true in the interpretation I [Hodges,W] |
10288 | Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W] |
10289 | Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W] |
10287 | If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W] |
10286 | A 'set' is a mathematically well-behaved class [Hodges,W] |
10735 | Abstraction from objects won't reveal an operation's being performed 'so many times' [Geach] |
14530 | The role of semantic necessity in semantics is like metaphysical necessity in metaphysics [Fine,K, by Hale/Hoffmann,A] |
10732 | If concepts are just recognitional, then general judgements would be impossible [Geach] |
10731 | For abstractionists, concepts are capacities to recognise recurrent features of the world [Geach] |
10733 | The abstractionist cannot explain 'some' and 'not' [Geach] |
10734 | Only a judgement can distinguish 'striking' from 'being struck' [Geach] |
14618 | Semantics is either an assignment of semantic values, or a theory of truth [Fine,K] |
14621 | Semantics is a body of semantic requirements, not semantic truths or assigned values [Fine,K] |
14622 | Referential semantics (unlike Fregeanism) allows objects themselves in to semantic requirements [Fine,K] |
14619 | The Quinean doubt: are semantics and facts separate, and do analytic sentences have no factual part? [Fine,K] |