12 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] |
| 15533 | We can quantify over fictions by quantifying for real over their names [Lewis] |
| 15534 | We could quantify over impossible objects - as bundles of properties [Lewis] |
| 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] |
| 15532 | 'Allists' embrace the existence of all controversial entities; 'noneists' reject all but the obvious ones [Lewis] |
| 15535 | We can't accept a use of 'existence' that says only some of the things there are actually exist [Lewis] |
| 18424 | If two people can have phenomenally identical experiences, they can't involve the self [Brogaard] |