6 ideas
6564 | To affirm 'p and not-p' is to have mislearned 'and' or 'not' [Quine] |
10163 | Propositional modal logic has been proved to be complete [Kripke, by Feferman/Feferman] |
10760 | With possible worlds, S4 and S5 are sound and complete, but S1-S3 are not even sound [Kripke, by Rossberg] |
16189 | The variable domain approach to quantified modal logic invalidates the Barcan Formula [Kripke, by Simchen] |
15132 | The Barcan formulas fail in models with varying domains [Kripke, by Williamson] |
8754 | Logic is dependent on mathematics, not the other way round [Heyting, by Shapiro] |