Single Idea 14428

[catalogued under 4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / b. Axiom of Extensionality I]

Full Idea

There is only one class having a given set of members, whereas there are always many different characteristics by which a given class may be defined.

Gist of Idea

Members define a unique class, whereas defining characteristics are numerous

Source

Bertrand Russell (Introduction to Mathematical Philosophy [1919], II)

Book Reference

Russell,Bertrand: 'Introduction to Mathematical Philosophy' [George Allen and Unwin 1975], p.13

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