20 ideas
| 16123 | Whenever you perceive a community of things, you should also hunt out differences in the group [Plato] |
| 21546 | We can't sharply distinguish variables, domains and values, if symbols frighten us [Russell] |
| 16125 | To reveal a nature, divide down, and strip away what it has in common with other things [Plato] |
| 16124 | No one wants to define 'weaving' just for the sake of weaving [Plato] |
| 13201 | ∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton] |
| 13204 | The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [Enderton] |
| 13206 | A 'linear or total ordering' must be transitive and satisfy trichotomy [Enderton] |
| 13200 | Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ [Enderton] |
| 13199 | The empty set may look pointless, but many sets can be constructed from it [Enderton] |
| 13203 | The singleton is defined using the pairing axiom (as {x,x}) [Enderton] |
| 13202 | Fraenkel added Replacement, to give a theory of ordinal numbers [Enderton] |
| 13205 | We can only define functions if Choice tells us which items are involved [Enderton] |
| 21531 | Common sense agrees with Meinong (rather than Russell) that 'Pegasus is a flying horse' is true [Lackey on Russell] |
| 21545 | I prefer to deny round squares, and deal with the difficulties by the theory of denoting [Russell] |
| 5961 | The soul gets its goodness from god, and its evil from previous existence. [Plato] |
| 283 | The question of whether or not to persuade comes before the science of persuasion [Plato] |
| 282 | Non-physical beauty can only be shown clearly by speech [Plato] |
| 281 | The arts produce good and beautiful things by preserving the mean [Plato] |
| 22559 | Democracy is the worst of good constitutions, but the best of bad constitutions [Plato, by Aristotle] |
| 279 | Only divine things can always stay the same, and bodies are not like that [Plato] |