20 ideas
13838 | A decent modern definition should always imply a semantics [Hacking] |
13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
8956 | What is a singleton set, if a set is meant to be a collection of objects? [Szabó] |
13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
8953 | Abstract entities don't depend on their concrete entities ...but maybe on the totality of concrete things [Szabó] |
14637 | Only individuals have essences, so numbers (as a higher type based on classes) lack them [McMichael] |
14636 | Essences are the interesting necessary properties resulting from a thing's own peculiar nature [McMichael] |
14640 | Maybe essential properties have to be intrinsic, as well as necessary? [McMichael] |
14638 | Essentialism is false, because it implies the existence of necessary singular propositions [McMichael] |
8954 | Geometrical circles cannot identify a circular paint patch, presumably because they lack something [Szabó] |
8955 | Abstractions are imperceptible, non-causal, and non-spatiotemporal (the third explaining the others) [Szabó] |
14639 | Individuals enter into laws only through their general qualities and relations [McMichael] |