23 ideas
10757 | Henkin semantics has a second domain of predicates and relations (in upper case) [Rossberg] |
10751 | Second-order logic needs the sets, and its consequence has epistemological problems [Rossberg] |
10759 | There are at least seven possible systems of semantics for second-order logic [Rossberg] |
10753 | Logical consequence is intuitively semantic, and captured by model theory [Rossberg] |
10752 | Γ |- S says S can be deduced from Γ; Γ |= S says a good model for Γ makes S true [Rossberg] |
10754 | In proof-theory, logical form is shown by the logical constants [Rossberg] |
10756 | A model is a domain, and an interpretation assigning objects, predicates, relations etc. [Rossberg] |
10758 | If models of a mathematical theory are all isomorphic, it is 'categorical', with essentially one model [Rossberg] |
10761 | Completeness can always be achieved by cunning model-design [Rossberg] |
10755 | A deductive system is only incomplete with respect to a formal semantics [Rossberg] |
18933 | Not-Being obviously doesn't exist, and the five modes of Being are all impossible [Gorgias, by Diog. Laertius] |
12184 | Logical necessity overrules all other necessities [McFetridge] |
15083 | The fundamental case of logical necessity is the valid conclusion of an inference [McFetridge, by Hale] |
15084 | In the McFetridge view, logical necessity means a consequent must be true if the antecedent is [McFetridge, by Hale] |
12180 | Logical necessity requires that a valid argument be necessary [McFetridge] |
12181 | Traditionally, logical necessity is the strongest, and entails any other necessities [McFetridge] |
12183 | It is only logical necessity if there is absolutely no sense in which it could be false [McFetridge] |
12192 | The mark of logical necessity is deduction from any suppositions whatever [McFetridge] |
12182 | We assert epistemic possibility without commitment to logical possibility [McFetridge] |
12187 | Objectual modal realists believe in possible worlds; non-objectual ones rest it on the actual world [McFetridge] |
12186 | Modal realists hold that necessities and possibilities are part of the totality of facts [McFetridge] |
9866 | Gorgias says rhetoric is the best of arts, because it enslaves without using force [Gorgias, by Plato] |
5864 | Destroy seriousness with laughter, and laughter with seriousness [Gorgias] |