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Ideas for 'fragments/reports', 'Cratylus' and 'On the spiritual perfection of life'

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6 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 / F. Referring in Logic / 1. Naming / a. Names

13777	A name is a sort of tool [Plato]
	Full Idea: A name is a sort of tool.
	From: Plato (Cratylus [c.377 BCE], 388a)
	A reaction: Idea 13775 gives a background for this metaphor, from earlier in the text. Wittgenstein has a famous toolkit metaphor for language. The whole of this text, 'Cratylus', is about names.

13790	A name-giver might misname something, then force other names to conform to it [Plato]
	Full Idea: The name-giver might have made a mistake at the beginning and then forced the other names to be consistent with it.
	From: Plato (Cratylus [c.377 BCE], 436c)
	A reaction: Lovely. This is Gareth Evans's 'Madagascar' example. See Idea 9041.

13791	Things must be known before they are named, so it can't be the names that give us knowledge [Plato]
	Full Idea: If things cannot be learned except from their names, how can we possibly claim that the name-givers or rule-setters have knowledge before any names had been given for them to know?
	From: Plato (Cratylus [c.377 BCE], 438b)
	A reaction: Running through this is a hostility to philosophy of language, so I find it very congenial. We are animals who relate to the world before language takes a grip. We have full-blown knowledge of things, with no intervention of words.

5. Theory of Logic / F. Referring in Logic / 1. Naming / c. Names as referential

13789	Anyone who knows a thing's name also knows the thing [Plato]
	Full Idea: The simple truth is that anyone who knows a thing's name also knows the thing.
	From: Plato (Cratylus [c.377 BCE], 435d)
	A reaction: A nice slogan, but it seems to be blatantly false. The best example is Gareth Evans's of joining in a conversation about a person ('Louis'?), and only gradually tuning in to the person to which the name refers.