15 ideas
| 18261 | A simplification which is complete constitutes a definition [Kant] |
| 22275 | Logic gives us the necessary rules which show us how we ought to think [Kant] |
| 14249 | Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley] |
| 10830 | Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos] |
| 10829 | A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos] |
| 10832 | '∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos] |
| 10834 | Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos] |
| 13841 | Why should compactness be definitive of logic? [Boolos, by Hacking] |
| 10833 | Many concepts can only be expressed by second-order logic [Boolos] |
| 13857 | Truth-functional possibilities include the irrelevant, which is a mistake [Edgington] |
| 13853 | It is a mistake to think that conditionals are statements about how the world is [Edgington] |
| 13855 | A conditional does not have truth conditions [Edgington] |
| 13859 | X believes 'if A, B' to the extent that A & B is more likely than A & ¬B [Edgington] |
| 13854 | Conditionals express what would be the outcome, given some supposition [Edgington] |
| 18260 | If we knew what we know, we would be astonished [Kant] |