17 ideas
15842 | An ad hominem refutation is reasonable, if it uses the opponent's assumptions [Harte,V] |
15841 | Mereology began as a nominalist revolt against the commitments of set theory [Harte,V] |
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] |
15858 | Traditionally, the four elements are just what persists through change [Harte,V] |
15848 | Mereology treats constitution as a criterion of identity, as shown in the axiom of extensionality [Harte,V] |
15837 | What exactly is a 'sum', and what exactly is 'composition'? [Harte,V] |
15839 | If something is 'more than' the sum of its parts, is the extra thing another part, or not? [Harte,V] |
15838 | The problem with the term 'sum' is that it is singular [Harte,V] |
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] |