13 ideas
| 14970 | Normal system K has five axioms and rules [Cresswell] |
| 14971 | D is valid on every serial frame, but not where there are dead ends [Cresswell] |
| 14972 | S4 has 14 modalities, and always reduces to a maximum of three modal operators [Cresswell] |
| 14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
| 14976 | Reject the Barcan if quantifiers are confined to worlds, and different things exist in other worlds [Cresswell] |
| 5062 | First: there must be reasons; Second: why anything at all?; Third: why this? [Leibniz] |
| 19377 | A monad and its body are living, so life is everywhere, and comes in infinite degrees [Leibniz] |
| 14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
| 14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
| 19353 | 'Perception' is basic internal representation, and 'apperception' is reflective knowledge of perception [Leibniz] |
| 5061 | Animals are semi-rational because they connect facts, but they don't see causes [Leibniz] |
| 19216 | Propositions (such as 'that dog is barking') only exist if their items exist [Williamson] |
| 5063 | Music charms, although its beauty is the harmony of numbers [Leibniz] |