45 ideas
1597 | Thales was the first western thinker to believe the arché was intelligible [Roochnik on Thales] |
8092 | Logic was merely a branch of rhetoric until the scientific 17th century [Devlin] |
17713 | After 1903, Husserl avoids metaphysical commitments [Mares] |
18781 | Inconsistency doesn't prevent us reasoning about some system [Mares] |
8081 | 'No councillors are bankers' and 'All bankers are athletes' implies 'Some athletes are not councillors' [Devlin] |
8085 | Modern propositional inference replaces Aristotle's 19 syllogisms with modus ponens [Devlin] |
8086 | Predicate logic retains the axioms of propositional logic [Devlin] |
18789 | Intuitionist logic looks best as natural deduction [Mares] |
18790 | Intuitionism as natural deduction has no rule for negation [Mares] |
18787 | Three-valued logic is useful for a theory of presupposition [Mares] |
8091 | Situation theory is logic that takes account of context [Devlin] |
8087 | Golden ages: 1900-1960 for pure logic, and 1950-1985 for applied logic [Devlin] |
8089 | Montague's intensional logic incorporated the notion of meaning [Devlin] |
18793 | Material implication (and classical logic) considers nothing but truth values for implications [Mares] |
18784 | In classical logic the connectives can be related elegantly, as in De Morgan's laws [Mares] |
8082 | Where a conditional is purely formal, an implication implies a link between premise and conclusion [Devlin] |
18786 | Excluded middle standardly implies bivalence; attacks use non-contradiction, De M 3, or double negation [Mares] |
18780 | Standard disjunction and negation force us to accept the principle of bivalence [Mares] |
8072 | Sentences of apparent identical form can have different contextual meanings [Devlin] |
18782 | The connectives are studied either through model theory or through proof theory [Mares] |
18783 | Many-valued logics lack a natural deduction system [Mares] |
18792 | Situation semantics for logics: not possible worlds, but information in situations [Mares] |
18785 | Consistency is semantic, but non-contradiction is syntactic [Mares] |
8075 | Space and time are atomic in the arrow, and divisible in the tortoise [Devlin] |
17715 | The truth of the axioms doesn't matter for pure mathematics, but it does for applied [Mares] |
17716 | Mathematics is relations between properties we abstract from experience [Mares] |
18788 | For intuitionists there are not numbers and sets, but processes of counting and collecting [Mares] |
3013 | Nothing is stronger than necessity, which rules everything [Thales, by Diog. Laertius] |
17703 | Light in straight lines is contingent a priori; stipulated as straight, because they happen to be so [Mares] |
17714 | Aristotelians dislike the idea of a priori judgements from pure reason [Mares] |
17705 | Empiricists say rationalists mistake imaginative powers for modal insights [Mares] |
17700 | The most popular view is that coherent beliefs explain one another [Mares] |
8088 | People still say the Hopi have no time concepts, despite Whorf's later denial [Devlin] |
17704 | Operationalism defines concepts by our ways of measuring them [Mares] |
17710 | Aristotelian justification uses concepts abstracted from experience [Mares] |
17706 | The essence of a concept is either its definition or its conceptual relations? [Mares] |
8073 | How do we parse 'time flies like an arrow' and 'fruit flies like an apple'? [Devlin] |
18791 | In 'situation semantics' our main concepts are abstracted from situations [Mares] |
17701 | Possible worlds semantics has a nice compositional account of modal statements [Mares] |
8076 | The distinction between sentences and abstract propositions is crucial in logic [Devlin] |
17702 | Unstructured propositions are sets of possible worlds; structured ones have components [Mares] |
1494 | Thales said water is the first principle, perhaps from observing that food is moist [Thales, by Aristotle] |
1713 | Thales must have thought soul causes movement, since he thought magnets have soul [Thales, by Aristotle] |
17708 | Maybe space has points, but processes always need regions with a size [Mares] |
1742 | Thales said the gods know our wrong thoughts as well as our evil actions [Thales, by Diog. Laertius] |