Combining Texts

Ideas for 'fragments/reports', 'Nominalism' and 'The Identity of Indiscernibles'

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2 ideas

4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets
What is a singleton set, if a set is meant to be a collection of objects? [Szabó]
     Full Idea: The relationship between an object and its singleton is puzzling. Our intuitive conception of a set is a collection of objects - what are we to make of a collection of a single object?
     From: Zoltán Gendler Szabó (Nominalism [2003], 4.1)
     A reaction: The ontological problem seems to be the same as that of the empty set, and indeed the claim that a pair of entities is three things. For logicians the empty set is as real as a pet dog, but not for me.
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
The Axiom of Choice needs a criterion of choice [Black]
     Full Idea: Some mathematicians seem to think that talk of an Axiom of Choice allows them to choose a single member of a collection when there is no criterion of choice.
     From: Max Black (The Identity of Indiscernibles [1952], p.68)