19 ideas
| 9208 | Philosophers with a new concept are like children with a new toy [Fine,K] |
| 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] |
| 9210 | Possible objects are abstract; actual concrete objects are possible; so abstract/concrete are compatible [Fine,K] |
| 9211 | A non-standard realism, with no privileged standpoint, might challenge its absoluteness or coherence [Fine,K] |
| 9202 | Objects, as well as sentences, can have logical form [Fine,K] |
| 9206 | We must distinguish between the identity or essence of an object, and its necessary features [Fine,K] |
| 9205 | The three basic types of necessity are metaphysical, natural and normative [Fine,K] |
| 9209 | Metaphysical necessity may be 'whatever the circumstance', or 'regardless of circumstances' [Fine,K] |
| 9200 | Empiricists suspect modal notions: either it happens or it doesn't; it is just regularities. [Fine,K] |
| 2596 | Maybe mind and body are parallel, like two good clocks [Leibniz] |
| 9207 | If sentence content is all worlds where it is true, all necessary truths have the same content! [Fine,K] |
| 2595 | If the universe is a perfect agreement of uncommunicating substances, there must be a common source [Leibniz] |