15 ideas
| 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] |
| 5049 | Intelligent pleasure is the perception of beauty, order and perfection [Leibniz] |
| 8430 | Causal statements are used to explain, to predict, to control, to attribute responsibility, and in theories [Kim] |
| 8396 | Many counterfactuals have nothing to do with causation [Kim, by Tooley] |
| 8429 | Counterfactuals can express four other relations between events, apart from causation [Kim] |
| 8428 | Causation is not the only dependency relation expressed by counterfactuals [Kim] |
| 4781 | Many counterfactual truths do not imply causation ('if yesterday wasn't Monday, it isn't Tuesday') [Kim, by Psillos] |
| 5048 | Perfection is simply quantity of reality [Leibniz] |
| 5050 | Evil serves a greater good, and pain is necessary for higher pleasure [Leibniz] |