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4 ideas
12342 | Topos theory explains the plurality of possible logics [Badiou] |
Full Idea: Topos theory explains the plurality of possible logics. | |
From: Alain Badiou (Briefings on Existence [1998], 14) | |
A reaction: This will because logic will have a distinct theory within each 'topos'. |
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. |
12341 | Logic is a mathematical account of a universe of relations [Badiou] |
Full Idea: Logic should first and foremost be a mathematical thought of what a universe of relations is. | |
From: Alain Badiou (Briefings on Existence [1998], 14) |
6023 | Every proposition is either true or false [Chrysippus, by Cicero] |
Full Idea: We hold fast to the position, defended by Chrysippus, that every proposition is either true or false. | |
From: report of Chrysippus (fragments/reports [c.240 BCE]) by M. Tullius Cicero - On Fate ('De fato') 38 | |
A reaction: I am intrigued to know exactly how you defend this claim. It may depend what you mean by a proposition. A badly expressed proposition may have indeterminate truth, quite apart from the vague, the undecidable etc. |