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Single Idea 14117

[from 'The Principles of Mathematics' by Bertrand Russell, in 6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / c. Fregean numbers ]

Full Idea

Numbers are to be regarded as properties of classes.

Gist of Idea

Numbers are properties of classes

Source

Bertrand Russell (The Principles of Mathematics [1903], §109)

Book Reference

Russell,Bertrand: 'Principles of Mathematics' [Routledge 1992], p.113


A Reaction

If properties are then defined extensionally as classes, you end up with numbers as classes of classes.