15 ideas
9358 | There are several logics, none of which will ever derive falsehoods from truth [Lewis,CI] |
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] |
9357 | Excluded middle is just our preference for a simplified dichotomy in experience [Lewis,CI] |
9364 | Names represent a uniformity in experience, or they name nothing [Lewis,CI] |
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] |
17555 | 'One' can mean undivided and not a multitude, or it can add measurement, giving number [Aquinas] |
9362 | Necessary truths are those we will maintain no matter what [Lewis,CI] |
9365 | We can maintain a priori principles come what may, but we can also change them [Lewis,CI] |
9361 | We have to separate the mathematical from physical phenomena by abstraction [Lewis,CI] |
9363 | Science seeks classification which will discover laws, essences, and predictions [Lewis,CI] |