5 ideas
18758 | Validity is provable, but invalidity isn't, because the model is infinite [Church, by McGee] |
17697 | The existence of an arbitrarily large number refutes the idea that numbers come from experience [Hilbert] |
17698 | Logic already contains some arithmetic, so the two must be developed together [Hilbert] |
9212 | Possible states of affairs are not propositions; a proposition can't be a state of affairs! [Fine,K] |
9213 | The actual world is a possible world, so we can't define possible worlds as 'what might have been' [Fine,K] |