19 ideas
| 1542 | Diogenes of Apollonia was the last natural scientist [Diogenes of Apollonia, by Simplicius] |
| 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] |
| 489 | Each thing must be in some way unique [Diogenes of Apollonia] |
| 483 | Start a thesis with something undisputable [Diogenes of Apollonia] |
| 1544 | Perception must be an internal matter, because we can fail to perceive when we are preoccupied [Diogenes of Apollonia, by Theophrastus] |
| 24042 | The older Diogenes said the soul is air, made of the smallest particles [Diogenes of Apollonia] |
| 468 | Musical performance can reveal a range of virtues [Damon of Ath.] |
| 5995 | Diogenes of Apollonia offered the first teleological account of cosmology [Diogenes of Apollonia, by Robinson,TM] |
| 488 | Air is divine, because it is in and around everything, and arranges everything [Diogenes of Apollonia] |
| 484 | Everything is ultimately a variation of one underlying thing [Diogenes of Apollonia] |
| 486 | Plants and animals can only come into existence if something fixes their species [Diogenes of Apollonia] |
| 485 | Things must retain their essential nature during change, or mixing would be impossible [Diogenes of Apollonia] |