12 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] |
| 304 | Beautiful things must be different from beauty itself, but beauty itself must be present in each of them [Plato] |
| 16120 | Knowing how to achieve immortality is pointless without the knowledge how to use immortality [Plato] |
| 303 | Say how many teeth the other has, then count them. If you are right, we will trust your other claims [Plato] |
| 302 | What knowledge is required to live well? [Plato] |
| 301 | Only knowledge of some sort is good [Plato] |
| 305 | Something which lies midway between two evils is better than either of them [Plato] |
| 7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |