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Single Idea 10109

[filed under theme 4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / a. Sets as existing ]

Full Idea

Sets, unlike extensions, fail to correspond to all concepts. We can prove in ZFC that there is no set corresponding to the concept 'set' - that is, there is no set of all sets.

Gist of Idea

ZFC can prove that there is no set corresponding to the concept 'set'

Source

A.George / D.J.Velleman (Philosophies of Mathematics [2002], Ch.4)

Book Ref

George,A/Velleman D.J.: 'Philosophies of Mathematics' [Blackwell 2002], p.90


A Reaction

This is rather an important point for Frege. However, all concepts have extensions, but they may be proper classes, rather than precisely defined sets.


The 8 ideas with the same theme [commitment to sets as really existint entities]:

Classes are a host of ethereal, platonic, pseudo entities [Goodman]
The use of plurals doesn't commit us to sets; there do not exist individuals and collections [Boolos]
If singletons are where their members are, then so are all sets [Lewis]
A huge part of Reality is only accepted as existing if you have accepted set theory [Lewis]
Set theory isn't innocent; it generates infinities from a single thing; but mathematics needs it [Lewis]
Are sets part of logic, or part of mathematics? [Shapiro]
The set theorist cannot tell us what 'membership' is [Chihara]
ZFC can prove that there is no set corresponding to the concept 'set' [George/Velleman]