17 ideas
| 13201 | ∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton] |
| 13206 | A 'linear or total ordering' must be transitive and satisfy trichotomy [Enderton] |
| 13204 | The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [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] |
| 468 | Musical performance can reveal a range of virtues [Damon of Ath.] |
| 21332 | We don't get a love of 'order' from nature - which is thoroughly chaotic [Mill] |
| 21335 | Belief that an afterlife is required for justice is an admission that this life is very unjust [Mill] |
| 21334 | No necessity ties an omnipotent Creator, so he evidently wills human misery [Mill] |
| 21333 | Evil comes from good just as often as good comes from evil [Mill] |
| 21329 | Nature dispenses cruelty with no concern for either mercy or justice [Mill] |
| 21328 | Killing is a human crime, but nature kills everyone, and often with great tortures [Mill] |
| 21331 | Hurricanes, locusts, floods and blight can starve a million people to death [Mill] |
| 21330 | Nature makes childbirth a miserable experience, often leading to the death of the mother [Mill] |