Combining Texts

Ideas for 'On the Question of Absolute Undecidability', 'The Concept of Logical Consequence' and 'Meditations'

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4 ideas

5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
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.
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 / C. Ontology of Logic / 3. If-Thenism
Arithmetic and geometry achieve some certainty without worrying about existence [Descartes]
     Full Idea: Arithmetic, geometry and sciences of that kind only treat of things without taking any great trouble to ascertain whether they are actually existent or not, and contain some measure of certainty.
     From: René Descartes (Meditations [1641], §1), quoted by Alan Musgrave - Logicism Revisited §4
     A reaction: This is Musgrave's earliest quotation which seems to take the if-thenist view.
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
We have no argument to show a statement is absolutely undecidable [Koellner]
     Full Idea: There is at present no solid argument to the effect that a given statement is absolutely undecidable.
     From: Peter Koellner (On the Question of Absolute Undecidability [2006], 5.3)