14 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] |
| 12312 | The real essence of a thing is its powers, or 'dispositional properties' [Copi] |
| 10937 | Essential properties are the 'deepest' ones which explain the others [Copi, by Rami] |
| 12308 | In modern science, nominal essence is intended to be real essence [Copi] |
| 12303 | Within the four types of change, essential attributes are those whose loss means destruction [Copi] |
| 468 | Musical performance can reveal a range of virtues [Damon of Ath.] |
| 12307 | Modern science seeks essences, and is getting closer to them [Copi] |
| 12310 | Real essences are scientifically knowable, but so are non-essential properties [Copi] |