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2 ideas
| 8078 | Modus ponens is one of five inference rules identified by the Stoics [Chrysippus, by Devlin] |
| Full Idea: Modus ponens is just one of the five different inference rules identified by the Stoics. | |
| From: report of Chrysippus (fragments/reports [c.240 BCE]) by Keith Devlin - Goodbye Descartes Ch.2 | |
| A reaction: Modus ponens strikes me as being more like a definition of implication than a 'rule'. Implication is what gets you from one truth to another. All the implications of a truth must also be true. |
| 20309 | If our ideas are adequate, what follows from them is also adequate [Spinoza] |
| Full Idea: Whatever ideas follow in the mind from ideas which are adequate in the mind are also adequate. | |
| From: Baruch de Spinoza (The Ethics [1675], II Pr 40) | |
| A reaction: This appears to be Modus Ponens, and he calls it (in Sch 1) 'the foundations of our reasoning'. If 'adequate' ideas are knowledge, then this also seems to say that knowledge is closed under known implication. |