4 ideas
9565 | Zermelo made 'set' and 'member' undefined axioms [Zermelo, by Chihara] |
3339 | For Zermelo's set theory the empty set is zero and the successor of each number is its unit set [Zermelo, by Blackburn] |
16458 | Semantic vagueness involves alternative and equal precisifications of the language [Lewis] |
18284 | Particulars can be verified or falsified, but general statements can only be falsified (conclusively) [Popper] |