12 ideas
16519 | No one can conceive of a possible substance, apart from those which God has created [Arnauld] |
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] |
6866 | It is disturbing if we become unreal when we die, but if time is unreal, then we remain real after death [Le Poidevin] |
6867 | Existentialism focuses on freedom and self-making, and insertion into the world [Le Poidevin] |
6865 | A-theory says past, present, future and flow exist; B-theory says this just reports our perspective [Le Poidevin] |