12 ideas
| 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] |
| 8502 | Realism doesn't explain 'a is F' any further by saying it is 'a has F-ness' [Devitt] |
| 8503 | The particular/universal distinction is unhelpful clutter; we should accept 'a is F' as basic [Devitt] |
| 8501 | Quineans take predication about objects as basic, not reference to properties they may have [Devitt] |
| 19384 | Space and time are the order of all possibilities, and don't just relate to what is actual [Leibniz] |