15 ideas
| 10282 | Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W] |
| 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] |
| 10289 | Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W] |
| 10288 | Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [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] |
| 14217 | The 'standard' view of relations is that they hold of several objects in a given order [Fine,K] |
| 14216 | The 'positionalist' view of relations says the number of places is fixed, but not the order [Fine,K] |
| 14218 | A block on top of another contains one relation, not both 'on top of' and 'beneath' [Fine,K] |
| 14220 | Explain biased relations as orderings of the unbiased, or the unbiased as permutation classes of the biased? [Fine,K] |
| 14219 | Language imposes a direction on a road which is not really part of the road [Fine,K] |
| 2614 | Modern phenomenalism holds that objects are logical constructions out of sense-data [Ayer] |
| 2615 | The concept of sense-data allows us to discuss appearances without worrying about reality [Ayer] |