34 ideas
15063 | Some sentences depend for their truth on worldly circumstances, and others do not [Fine,K] |
10775 | The axiom of choice now seems acceptable and obvious (if it is meaningful) [Tharp] |
10766 | Logic is either for demonstration, or for characterizing structures [Tharp] |
10767 | Elementary logic is complete, but cannot capture mathematics [Tharp] |
10769 | Second-order logic isn't provable, but will express set-theory and classic problems [Tharp] |
10762 | In sentential logic there is a simple proof that all truth functions can be reduced to 'not' and 'and' [Tharp] |
10776 | The main quantifiers extend 'and' and 'or' to infinite domains [Tharp] |
10774 | There are at least five unorthodox quantifiers that could be used [Tharp] |
10773 | The Löwenheim-Skolem property is a limitation (e.g. can't say there are uncountably many reals) [Tharp] |
10777 | Skolem mistakenly inferred that Cantor's conceptions were illusory [Tharp] |
10765 | Soundness would seem to be an essential requirement of a proof procedure [Tharp] |
10763 | Completeness and compactness together give axiomatizability [Tharp] |
10770 | If completeness fails there is no algorithm to list the valid formulas [Tharp] |
10772 | Compactness blocks infinite expansion, and admits non-standard models [Tharp] |
10771 | Compactness is important for major theories which have infinitely many axioms [Tharp] |
10764 | A complete logic has an effective enumeration of the valid formulas [Tharp] |
10768 | Effective enumeration might be proved but not specified, so it won't guarantee knowledge [Tharp] |
15078 | There are levels of existence, as well as reality; objects exist at the lowest level in which they can function [Fine,K] |
15072 | Bottom level facts are subject to time and world, middle to world but not time, and top to neither [Fine,K] |
15071 | Tensed and tenseless sentences state two sorts of fact, which belong to two different 'realms' of reality [Fine,K] |
15075 | Modal features are not part of entities, because they are accounted for by the entity [Fine,K] |
15065 | What it is is fixed prior to existence or the object's worldly features [Fine,K] |
15076 | Essential features of an object have no relation to how things actually are [Fine,K] |
15073 | Self-identity should have two components, its existence, and its neutral identity with itself [Fine,K] |
15074 | We would understand identity between objects, even if their existence was impossible [Fine,K] |
15064 | Proper necessary truths hold whatever the circumstances; transcendent truths regardless of circumstances [Fine,K] |
15070 | It is the nature of Socrates to be a man, so necessarily he is a man [Fine,K] |
15069 | Possible worlds may be more limited, to how things might actually turn out [Fine,K] |
15068 | The actual world is a totality of facts, so we also think of possible worlds as totalities [Fine,K] |
1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
15077 | It is said that in the A-theory, all existents and objects must be tensed, as well as the sentences [Fine,K] |
15067 | A-theorists tend to reject the tensed/tenseless distinction [Fine,K] |
15066 | B-theorists say tensed sentences have an unfilled argument-place for a time [Fine,K] |
5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |