Combining Texts

Ideas for 'The Logic of Boundaryless Concepts', 'Essays on Intellectual Powers 1: Preliminary' and 'thirty titles (lost)'

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2 ideas

9. Objects / B. Unity of Objects / 2. Substance / c. Types of substance
Speusippus suggested underlying principles for every substance, and ended with a huge list [Speussipus, by Aristotle]
     Full Idea: Speusippus suggested principles for each substance, including principles for numbers, magnitude and the soul. He thus arrived at no mean list of substances.
     From: report of Speussipus (thirty titles (lost) [c.367 BCE]) by Aristotle - Metaphysics 1028b
9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects
Vague membership of sets is possible if the set is defined by its concept, not its members [Rumfitt]
     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.
     From: Ian Rumfitt (The Logic of Boundaryless Concepts [2007], p.5)
     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.