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] |
22465 | We see a moral distinction between doing and allowing to happen [Foot] |
22466 | We see a moral distinction between our aims and their foreseen consequences [Foot] |
22467 | Acts and omissions only matter if they concern doing something versus allowing it [Foot] |
22470 | A good moral system benefits its participants, and so demands reciprocity [Foot] |
22468 | Virtues can have aims, but good states of affairs are not among them [Foot] |
22469 | Some virtues imply rules, and others concern attachment [Foot] |
13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |