Combining Texts

Ideas for 'Function and Concept', 'Conditionals (Stanf)' and 'Letters to Descartes'

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2 ideas

4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic

18806	Frege thought traditional categories had psychological and linguistic impurities [Frege, by Rumfitt]
	Full Idea: Frege rejected the traditional categories as importing psychological and linguistic impurities into logic.
	From: report of Gottlob Frege (Function and Concept [1891]) by Ian Rumfitt - The Boundary Stones of Thought 1.2
	A reaction: Resisting such impurities is the main motivation for making logic entirely symbolic, but it doesn't follow that the traditional categories have to be dropped.

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / c. Derivation rules of PL

14273	Conditional Proof is only valid if we accept the truth-functional reading of 'if' [Edgington]
	Full Idea: Conditional Proof seems sound: 'From X and Y, it follows that Z. So from X it follows that if Y,Z'. Yet for no reading of 'if' which is stronger that the truth-functional reading is CP valid, at least if we accept ¬(A&¬B);A; therefore B.
	From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.2)
	A reaction: See the section of ideas on Conditionals (filed under 'Modality') for a fuller picture of this issue. Edgington offers it as one of the main arguments in favour of the truth-functional reading of 'if' (though she rejects that reading).