18 ideas
14600 | Analysis aims at secure necessary and sufficient conditions [Schaffer,J] |
14603 | 'Reification' occurs if we mistake a concept for a thing [Schaffer,J] |
14607 | T adds □p→p for reflexivity, and is ideal for modeling lawhood [Schaffer,J] |
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] |
14604 | If a notion is ontologically basic, it should be needed in our best attempt at science [Schaffer,J] |
14599 | Three types of reduction: Theoretical (of terms), Definitional (of concepts), Ontological (of reality) [Schaffer,J] |
14605 | Tropes are the same as events [Schaffer,J] |
14601 | Individuation aims to count entities, by saying when there is one [Schaffer,J] |
14606 | Only ideal conceivability could indicate what is possible [Schaffer,J] |
1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |