5 ideas
7791 | The simplest of the logics based on possible worlds is Lewis's S5 [Lewis,CI, by Girle] |
9390 | Logic guides thinking, but it isn't a substitute for it [Rumfitt] |
9389 | Vague membership of sets is possible if the set is defined by its concept, not its members [Rumfitt] |
11002 | Equating necessity with informal provability is the S4 conception of necessity [Lewis,CI, by Read] |
4871 | A thing is free if it acts only by the necessity of its own nature [Spinoza] |