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] |
15312 | We get the idea of power by abstracting from ropes, magnets and electric shocks [Priestley] |
13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
15311 | Attraction or repulsion are not imparted to matter, but actually constitute it [Priestley] |
20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |