19 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] |
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] |
12066 | Aristotelian and Kripkean essentialism are very different theories [Witt] |
12067 | An Aristotelian essence is a nonlinguistic correlate of the definition [Witt] |
12082 | If unity is a matter of degree, then essence may also be a matter of degree [Witt] |
12089 | Essences mainly explain the existence of unified substance [Witt] |
12102 | Essential properties of origin are too radically individual for an Aristotelian essence [Witt] |
9212 | Possible states of affairs are not propositions; a proposition can't be a state of affairs! [Fine,K] |
9213 | The actual world is a possible world, so we can't define possible worlds as 'what might have been' [Fine,K] |
12085 | Reality is directional [Witt] |