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Ideas for 'fragments/reports', 'Proslogion' and 'The Concept of Logical Consequence'

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3 ideas

5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
14181 Validity is where either the situation or the interpretation blocks true premises and false conclusion [Etchemendy, by Read]
     Full Idea: The Representational account of validity says an argument is valid if there is no situation where the premises are true and the conclusion false. The Interpretation account says the premises are true and conclusion false under no interpretations.
     From: report of John Etchemendy (The Concept of Logical Consequence [1999]) by Stephen Read - Formal and Material Consequence 'Inval'
     A reaction: My immediate instinct is to want logic to be about situations, rather than interpretations. Situations are more about thought, where interpretations are more about language. I think our account of logic should have some applicability to animals.
14180 Etchemendy says fix the situation and vary the interpretation, or fix interpretations with varying situations [Etchemendy, by Read]
     Full Idea: In Etchemendy's Interpretational Semantics (perhaps better called 'Substitutional') we keep the situation fixed and vary the interpretation; in Representational Semantics ('Modal'?) we keep interpretations fixed but consider varying situations.
     From: report of John Etchemendy (The Concept of Logical Consequence [1999]) by Stephen Read - Formal and Material Consequence 'Inval'
     A reaction: [compressed] These are semantic strategies for interpreting logic, so they are two ways you might go about assessing an argument.
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.