Combining Texts

Ideas for 'fragments/reports', '23: Book of Isaiah' and 'Philosophical Investigations'

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5 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 / E. Structures of Logic / 1. Logical Form
18743 Wittgenstein says we want the grammar of problems, not their first-order logical structure [Wittgenstein, by Horsten/Pettigrew]
     Full Idea: For the later Wittgenstein what we should be after is the grammatical structure of philosophical problems, not the first-order logical structure of such problems.
     From: report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Horsten,L/Pettigrew,R - Mathematical Methods in Philosophy 2
     A reaction: This is the most sympathetic spin I have ever seen put on the apparent rather anti-philosophical later Wittgenstein. I nurse doubts about highly formal approaches to philosophy, and maybe 'grammar' (whatever that is) is our target.
5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names
4139 Naming is a preparation for description [Wittgenstein]
     Full Idea: Naming is a preparation for description.
     From: Ludwig Wittgenstein (Philosophical Investigations [1952], §049)
     A reaction: Something has to be the starting point for a description. And yet a description could turn out to be an elaborate name.
5. Theory of Logic / F. Referring in Logic / 1. Naming / b. Names as descriptive
4946 A name is not determined by a description, but by a cluster or family [Wittgenstein, by Kripke]
     Full Idea: According to Wittgenstein (and Searle) the referent of a name is determined not by a single description but by some cluster or family.
     From: report of Ludwig Wittgenstein (Philosophical Investigations [1952], §079) by Saul A. Kripke - Naming and Necessity lectures Lecture 1
     A reaction: It is because of this characteristically woolly, indeterminate and relativist view of Wittgenstein that I (and most people) find Kripke's notion of a 'baptism' so refreshing. It cuts throught the fog of language, and connects to reality.