17 ideas
| 13838 | A decent modern definition should always imply a semantics [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] |
| 13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [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] |
| 8967 | Not all predicates can be properties - 'is non-self-exemplifying', for example [Lowe] |
| 8965 | Neither mere matter nor pure form can individuate a sphere, so it must be a combination [Lowe] |
| 9100 | Our intellect only assents to what we believe to be true [William of Ockham] |
| 8968 | If the flagpole causally explains the shadow, the shadow cannot explain the flagpole [Lowe] |
| 9101 | Abstractive cognition knows universals abstracted from many singulars [William of Ockham] |
| 8966 | Properties are facets of objects, only discussable separately by an act of abstraction [Lowe] |