4 ideas
19404 | Necessities rest on contradiction, and contingencies on sufficient reason [Leibniz] |
17743 | De Morgan introduced a 'universe of discourse', to replace Boole's universe of 'all things' [De Morgan, by Walicki] |
4038 | Properties are sets of their possible instances (which separates 'renate' from 'cordate') [Lewis, by Mellor/Oliver] |
19403 | Each of the infinite possible worlds has its own laws, and the individuals contain those laws [Leibniz] |