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] |
| 23681 | The first motion or effect cannot be produced necessarily, so the First Cause must be a free agent [Reid] |
| 23676 | A willed action needs reasonable understanding of what is to be done [Reid] |
| 23680 | We are morally free, because we experience it, we are accountable, and we pursue projects [Reid] |
| 23678 | A motive is merely an idea, like advice, and not a force for action [Reid] |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| 23677 | We all know that mere priority or constant conjunction do not have to imply causation [Reid] |
| 23679 | The principle of the law of nature is that matter is passive, and is acted upon [Reid] |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |