8 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] |
21687 | It seems obvious to prefer the simpler of two theories, on grounds of beauty and convenience [Quine] |
21688 | There are four suspicious reasons why we prefer simpler theories [Quine] |
9425 | Lewis later proposed the axioms at the intersection of the best theories (which may be few) [Mumford on Lewis] |