14 ideas
| 11022 | Gentzen introduced a natural deduction calculus (NK) in 1934 [Gentzen, by Read] |
| 11065 | The inferential role of a logical constant constitutes its meaning [Gentzen, by Hanna] |
| 11023 | The logical connectives are 'defined' by their introduction rules [Gentzen] |
| 11213 | Each logical symbol has an 'introduction' rule to define it, and hence an 'elimination' rule [Gentzen] |
| 10067 | Gentzen proved the consistency of arithmetic from assumptions beyond arithmetic [Gentzen, by Musgrave] |
| 15567 | Some events involve no change; they must, because causal histories involve unchanges [Lewis] |
| 15561 | The events that suit semantics may not be the events that suit causation [Lewis] |
| 15565 | Events have inbuilt essences, as necessary conditions for their occurrence [Lewis] |
| 15566 | Events are classes, and so there is a mereology of their parts [Lewis] |
| 15564 | An event is a property of a unique space-time region [Lewis] |
| 15563 | Properties are very abundant (unlike universals), and are used for semantics and higher-order variables [Lewis] |
| 15562 | Causation is a general relation derived from instances of causal dependence [Lewis] |
| 16713 | Philosophers are the forefathers of heretics [Tertullian] |
| 6610 | I believe because it is absurd [Tertullian] |