13 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] |
| 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] |
| 5122 | Maybe consequentialism is a critique of ordinary morality, rather than describing it [Harman] |
| 5123 | Maybe there is no such thing as character, and the virtues and vices said to accompany it [Harman] |
| 5124 | If a person's two acts of timidity have different explanations, they are not one character trait [Harman] |
| 5125 | Virtue ethics might involve judgements about the virtues of actions, rather than character [Harman] |
| 14014 | Space alone, and time alone, will fade away, and only their union has an independent reality [Minkowski] |