Combining Texts

Ideas for 'Parmenides', 'Set Theory and its Logic' and 'Briefings on Existence'

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3 ideas

4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
There is 'transivity' iff membership ∈ also means inclusion ⊆ [Badiou]
     Full Idea: 'Transitivity' signifies that all of the elements of the set are also parts of the set. If you have α∈Β, you also have α⊆Β. This correlation of membership and inclusion gives a stability which is the sets' natural being.
     From: Alain Badiou (Briefings on Existence [1998], 11)
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
The axiom of choice must accept an indeterminate, indefinable, unconstructible set [Badiou]
     Full Idea: The axiom of choice actually amounts to admitting an absolutely indeterminate infinite set whose existence is asserted albeit remaining linguistically indefinable. On the other hand, as a process, it is unconstructible.
     From: Alain Badiou (Briefings on Existence [1998], 2)
     A reaction: If only constructible sets are admitted (see 'V = L') then there is a contradiction.
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / p. Axiom of Reducibility
Reducibility undermines type ramification, and is committed to the existence of functions [Quine, by Linsky,B]
     Full Idea: Quine charges that the axiom of Reducibility both undoes the effect of the ramification, and commits the theory to a platonist view of propositional functions (which is a theory of sets, once use/mention confusions are cleared up).
     From: report of Willard Quine (Set Theory and its Logic [1963], p.249-58) by Bernard Linsky - Russell's Metaphysical Logic 6.1