3 ideas
17750 | The first clear proof of the consistency of the first order predicate logic was in 1928 [Hilbert/Ackermann, by Walicki] |
18810 | Aristotle's proofs give understanding, so it can't be otherwise, so consequence is necessary [Smiley, by Rumfitt] |
1513 | The Egyptians were the first to say the soul is immortal and reincarnated [Herodotus] |