22 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] |
11115 | 'All horses' either picks out the horses, or the things which are horses [Jubien] |
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] |
11116 | Being a physical object is our most fundamental category [Jubien] |
11117 | Haecceities implausibly have no qualities [Jubien] |
11119 | De re necessity is just de dicto necessity about object-essences [Jubien] |
11118 | Modal propositions transcend the concrete, but not the actual [Jubien] |
11108 | Your properties, not some other world, decide your possibilities [Jubien] |
11111 | Modal truths are facts about parts of this world, not about remote maximal entities [Jubien] |
11105 | We have no idea how many 'possible worlds' there might be [Jubien] |
11107 | If there are no other possible worlds, do we then exist necessarily? [Jubien] |
11106 | If all possible worlds just happened to include stars, their existence would be necessary [Jubien] |
11112 | Possible worlds just give parallel contingencies, with no explanation at all of necessity [Jubien] |
11109 | If other worlds exist, then they are scattered parts of the actual world [Jubien] |
11113 | Worlds don't explain necessity; we use necessity to decide on possible worlds [Jubien] |
11110 | We mustn't confuse a similar person with the same person [Jubien] |
3448 | Do new ideas increase the weight of the brain? [Dance] |