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9390
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Logic guides thinking, but it isn't a substitute for it [Rumfitt]
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Full Idea:
Logic is part of a normative theory of thinking, not a substitute for thinking.
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From:
Ian Rumfitt (The Logic of Boundaryless Concepts [2007], p.13)
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A reaction:
There is some sort of logicians' dream, going back to Leibniz, of a reasoning engine, which accepts propositions and outputs inferences. I agree with this idea. People who excel at logic are often, it seems to me, modest at philosophy.
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16655
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Different genera are delimited by modes of predication, which rest on modes of being [Aquinas]
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Full Idea:
Being is delimited into different genera in accord with different modes of predicating, which depend on different modes of being.
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From:
Thomas Aquinas (On Aristotle's 'Metaphysics' [1266], V.9.890), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 12.3
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A reaction:
I like this. When people say that predication is the way we divide things up, and go all linguistic-relativist about things, they forget how closely language not only describes reality, but arises out of, or is even caused by, reality. 'Grue' is silly.
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9389
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Vague membership of sets is possible if the set is defined by its concept, not its members [Rumfitt]
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Full Idea:
Vagueness in respect of membership is consistency with determinacy of the set's identity, so long as a set's identity is taken to consist, not in its having such-and-such members, but in its being the extension of a concept.
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From:
Ian Rumfitt (The Logic of Boundaryless Concepts [2007], p.5)
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A reaction:
I find this view of sets much more appealing than the one that identifies a set with its members. The empty set is less of a problem, as well as non-existents. Logicians prefer the extensional view because it is tidy.
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