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Ideas for 'Structures and Structuralism in Phil of Maths', 'The Philosopher's Toolkit' and 'Action'

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2 ideas

5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
The principle of bivalence distorts reality, as when claiming that a person is or is not 'thin' [Baggini /Fosl]
     Full Idea: Forcing everything into the straightjacket of bivalence seriously distorts the world. The problem is most acute in the case of vague concepts, such as thinness. It is not straightforwardly true or false that a person is thin.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.03)
     A reaction: Can't argue with that. Can we divide all our concepts into either bivalent or vague? Presumably both propositions and concepts could be bivalent.
5. Theory of Logic / G. Quantification / 5. Second-Order Quantification
Three types of variable in second-order logic, for objects, functions, and predicates/sets [Reck/Price]
     Full Idea: In second-order logic there are three kinds of variables, for objects, for functions, and for predicates or sets.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: It is interesting that a predicate seems to be the same as a set, which begs rather a lot of questions. For those who dislike second-order logic, there seems nothing instrinsically wicked in having variables ranging over innumerable multi-order types.