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Single Idea 18190

[filed under theme 6. Mathematics / A. Nature of Mathematics / 5. The Infinite / d. Actual infinite ]

Full Idea

The line of development that finally led to a coherent foundation for the calculus also led to the explicit introduction of completed infinities: each real number is identified with an infinite collection of rationals.

Gist of Idea

Completed infinities resulted from giving foundations to calculus

Source

Penelope Maddy (Naturalism in Mathematics [1997], I.3)

Book Ref

Maddy,Penelope: 'Naturalism in Mathematics' [OUP 2000], p.51


A Reaction

Effectively, completed infinities just are the real numbers.


The 11 ideas with the same theme [treating an infinite collection as a complete thing]:

If there were real infinities, you could add two together, which is ridiculous [Locke]
I strongly believe in the actual infinite, which indicates the perfections of its author [Leibniz]
I don't admit infinite numbers, and consider infinitesimals to be useful fictions [Leibniz]
Actual infinities are not allowed in mathematics - only limits which may increase without bound [Gauss]
Cantor proposes that there won't be a potential infinity if there is no actual infinity [Cantor, by Hart,WD]
Poincaré rejected the actual infinite, claiming definitions gave apparent infinity to finite objects [Poincaré, by Lavine]
The idea of an infinite totality is an illusion [Hilbert]
Cantor and Dedekind brought completed infinities into mathematics [Maddy]
Completed infinities resulted from giving foundations to calculus [Maddy]
Infinite cuts and successors seems to suggest an actual infinity there waiting for us [Read]
The classical mathematician believes the real numbers form an actual set [George/Velleman]