15 ideas
20728 | Metaphysics is hopeless with its present epistemology; common-sense realism is needed [Colvin] |
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] |
20726 | We can only distinguish self from non-self if there is an inflexible external reality [Colvin] |
20727 | Common-sense realism rests on our interests and practical life [Colvin] |
20730 | If objects are doubted because their appearances change, that presupposes one object [Colvin] |
20729 | Arguments that objects are unknowable or non-existent assume the knower's existence [Colvin] |
20731 | The idea that everything is relations is contradictory; relations are part of the concept of things [Colvin] |
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] |