12 ideas
21757 | Philosophy is the conceptual essence of the shape of history [Hegel] |
19426 | 'Nominal' definitions just list distinguishing characteristics [Leibniz] |
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] |
19424 | Knowledge needs clarity, distinctness, and adequacy, and it should be intuitive [Leibniz] |
19427 | True ideas represent what is possible; false ideas represent contradictions [Leibniz] |
19425 | In the schools the Four Causes are just lumped together in a very obscure way [Leibniz] |