4 ideas
| 19389 | Truth is a characteristic of possible thoughts [Leibniz] |
| 19388 | True and false seem to pertain to thoughts, yet unthought propositions seem to be true or false [Leibniz] |
| 15716 | If axioms and their implications have no contradictions, they pass my criterion of truth and existence [Hilbert] |
| 3016 | Even the gods cannot strive against necessity [Pittacus, by Diog. Laertius] |