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Ideas for 'fragments/reports', 'Predest.,God's foreknowledge and contingents' and 'The Limits of Reason'

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3 ideas

5. Theory of Logic / B. Logical Consequence / 5. Modus Ponens

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.

5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle

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.

5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models

18694	Permutation Theorem: any theory with a decent model has lots of models [Button]
	Full Idea: The Permutation Theorem says that any theory with a non-trivial model has many distinct isomorphic models with the same domain.
	From: Tim Button (The Limits of Reason [2013], 02.1)
	A reaction: This may be the most significant claim of model theory, since Putnam has erected an argument for anti-realism on it. See the ideas of Tim Button.