26 ideas
| 5784 | In its primary and formal sense, 'true' applies to propositions, not beliefs [Russell] |
| 5777 | The truth or falsehood of a belief depends upon a fact to which the belief 'refers' [Russell] |
| 5783 | Propositions of existence, generalities, disjunctions and hypotheticals make correspondence tricky [Russell] |
| 7798 | There are three axiom schemas for propositional logic [Girle] |
| 7786 | Propositional logic handles negation, disjunction, conjunction; predicate logic adds quantifiers, predicates, relations [Girle] |
| 7799 | Proposition logic has definitions for its three operators: or, and, and identical [Girle] |
| 7797 | Axiom systems of logic contain axioms, inference rules, and definitions of proof and theorems [Girle] |
| 7794 | There are seven modalities in S4, each with its negation [Girle] |
| 7793 | ◊p → □◊p is the hallmark of S5 [Girle] |
| 7795 | S5 has just six modalities, and all strings can be reduced to those [Girle] |
| 7787 | Possible worlds logics use true-in-a-world rather than true [Girle] |
| 7796 | Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle] |
| 7788 | Modal logic has four basic modal negation equivalences [Girle] |
| 7789 | Necessary implication is called 'strict implication'; if successful, it is called 'entailment' [Girle] |
| 7790 | If an argument is invalid, a truth tree will indicate a counter-example [Girle] |
| 7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
| 7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
| 7792 | A world has 'access' to a world it generates, which is important in possible worlds semantics [Girle] |
| 5780 | The three questions about belief are its contents, its success, and its character [Russell] |
| 7458 | The reliability of witnesses depends on whether they benefit from their observations [Laplace, by Hacking] |
| 3441 | If a supreme intellect knew all atoms and movements, it could know all of the past and the future [Laplace] |
| 5778 | If we object to all data which is 'introspective' we will cease to believe in toothaches [Russell] |
| 5779 | There are distinct sets of psychological and physical causal laws [Russell] |
| 5781 | Our important beliefs all, if put into words, take the form of propositions [Russell] |
| 5782 | A proposition expressed in words is a 'word-proposition', and one of images an 'image-proposition' [Russell] |
| 5776 | A proposition is what we believe when we believe truly or falsely [Russell] |