9 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] |
22320 | An 'object' is just what can be referred to without possible non-existence [Wittgenstein] |
18283 | Language pictures the essence of the world [Wittgenstein] |
18282 | You can't believe it if you can't imagine a verification for it [Wittgenstein] |
468 | Musical performance can reveal a range of virtues [Damon of Ath.] |