3 ideas
| 18758 | Validity is provable, but invalidity isn't, because the model is infinite [Church, by McGee] |
| Full Idea: Church showed that logic has a proof procedure, but no decision procedure. If an argument is invalid, there is a model with true premises and false conclusion, but the model will typically be infinite, so there is no way to display it concretely. | |
| From: report of Alonzo Church (A Note on the entscheidungsproblem [1936]) by Vann McGee - Logical Consequence 5 |
| 490 | Everything happens by reason and necessity [Leucippus] |
| Full Idea: Nothing happens at random; everything happens out of reason and by necessity. | |
| From: Leucippus (fragments/reports [c.435 BCE], B002), quoted by (who?) - where? |
| 6231 | There is a self-determing power in each person, which makes them what they are [Cudworth] |
| Full Idea: This hegemonicon (self-power) always determines the passive capability of men's nature one way or other, either for better or for worse; and has a self-forming and self-framing power by which every man is self-made into what he is. | |
| From: Ralph Cudworth (Treatise of Freewill [1688], §X) | |
| A reaction: The idea that we can somehow create our own selves seems to me the core of existentialism, and the opposite of the Aristotelian belief in a fairly fixed human nature. See Stephen Pinker's 'The Blank Slate' for a revival of the old view. |