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] |
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] |
23026 | We know mathematical axioms, such as subtracting equals from equals leaves equals, by a natural light [Leibniz] |
13189 | A necessary feature (such as air for humans) is not therefore part of the essence [Leibniz] |
19432 | Intelligible truth is independent of any external things or experiences [Leibniz] |
19430 | We know objects by perceptions, but their qualities don't reveal what it is we are perceiving [Leibniz] |
19431 | There is nothing in the understanding but experiences, plus the understanding itself, and the understander [Leibniz] |
20440 | Art is a referential activity, hence indefinable, but it has a set of symptoms [Goodman] |
20439 | Artistic symbols are judged by the fruitfulness of their classifications [Goodman, by Giovannelli] |
20438 | A performance is only an instance of a work if there is not a single error [Goodman] |
20437 | A copy only becomes an 'instance' of an artwork if there is a system of notation [Goodman] |