35 ideas
| 10476 | The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W] |
| 10282 | Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W] |
| 10478 | Since first-order languages are complete, |= and |- have the same meaning [Hodges,W] |
| 10477 | |= in model-theory means 'logical consequence' - it holds in all models [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] |
| 10474 | |= should be read as 'is a model for' or 'satisfies' [Hodges,W] |
| 10473 | Model theory studies formal or natural language-interpretation using set-theory [Hodges,W] |
| 10475 | A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W] |
| 10481 | Models in model theory are structures, not sets of descriptions [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] |
| 10480 | First-order logic can't discriminate between one infinite cardinal and another [Hodges,W] |
| 10286 | A 'set' is a mathematically well-behaved class [Hodges,W] |
| 20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
| 8143 | Self is the rider, intellect the charioteer, mind the reins, and body the chariot [Anon (Upan)] |
| 8147 | We have an apparent and a true self; only the second one exists, and we must seek to know it [Anon (Upan)] |
| 8155 | Without speech we cannot know right/wrong, true/false, good/bad, or pleasant/unpleasant [Anon (Upan)] |
| 8142 | The wise prefer good to pleasure; the foolish are drawn to pleasure by desire [Anon (Upan)] |
| 8151 | Let your teacher be a god to you [Anon (Upan)] |
| 8153 | By knowing one piece of clay or gold, you know all of clay or gold [Anon (Upan)] |
| 8154 | Originally there must have been just Existence, which could not come from non-existence [Anon (Upan)] |
| 8148 | Brahma, supreme god and protector of the universe, arose from the ocean of existence [Anon (Upan)] |
| 8144 | Brahman is the Uncaused Cause [Anon (Upan)] |
| 8152 | Earth, food, fire, sun are all forms of Brahman [Anon (Upan)] |
| 8156 | The gods are not worshipped for their own sake, but for the sake of the Self [Anon (Upan)] |
| 8157 | A man with desires is continually reborn, until his desires are stilled [Anon (Upan)] |
| 8159 | Damayata - be self-controlled! Datta - be charitable! Dayadhwam - be compassionate! [Anon (Upan)] |
| 8145 | Those ignorant of Atman return as animals or plants, according to their merits [Anon (Upan)] |
| 8149 | Charity and ritual observance distract from the highest good of religion [Anon (Upan)] |
| 8158 | Do not seek to know Brahman by arguments, for arguments are idle and vain [Anon (Upan)] |
| 8146 | The immortal in us is the part that never sleeps, and shapes our dreams [Anon (Upan)] |
| 8150 | The immortal Self and the sad individual self are like two golden birds perched on one tree [Anon (Upan)] |