Ideas of Thoralf Skolem, by Theme

[Norwegian, 1887 - 1963, Professor at the University of Oslo.]

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4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
Axiomatising set theory makes it all relative
     Full Idea: Axiomatising set theory leads to a relativity of set-theoretic notions, and this relativity is inseparably bound up with every thoroughgoing axiomatisation.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.296)
4. Formal Logic / F. Set Theory ST / 8. Critique of Set Theory
Skolem did not believe in the existence of uncountable sets
     Full Idea: Skolem did not believe in the existence of uncountable sets.
     From: Thoralf Skolem (works [1920], 5.3)
     A reaction: Kit Fine refers somewhere to 'unrepentent Skolemites' who still hold this view.
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
If a 1st-order proposition is satisfied, it is satisfied in a denumerably infinite domain
     Full Idea: Löwenheim's theorem reads as follows: If a first-order proposition is satisfied in any domain at all, it is already satisfied in a denumerably infinite domain.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.293)
6. Mathematics / B. Foundations for Mathematics / 1. Foundations for Mathematics
Integers and induction are clear as foundations, but set-theory axioms certainly aren't
     Full Idea: The initial foundations should be immediately clear, natural and not open to question. This is satisfied by the notion of integer and by inductive inference, by it is not satisfied by the axioms of Zermelo, or anything else of that kind.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.299)
     A reaction: This is a plea (endorsed by Almog) that the integers themselves should be taken as primitive and foundational. I would say that the idea of successor is more primitive than the integers.
6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / b. Against mathematical platonism
Mathematician want performable operations, not propositions about objects
     Full Idea: Most mathematicians want mathematics to deal, ultimately, with performable computing operations, and not to consist of formal propositions about objects called this or that.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.300)