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Single Idea 21693

[filed under theme 4. Formal Logic / F. Set Theory ST / 7. Natural Sets ]

Full Idea

In the case of Russell's antinomy, the tacit and trusted pattern of reasoning that is found wanting is this: for any condition you can formulate, there is a class whose members are the things meeting the condition.

Gist of Idea

Russell's antinomy challenged the idea that any condition can produce a set

Source

Willard Quine (The Ways of Paradox [1961], p.11)

Book Ref

Quine,Willard: 'Ways of Paradox and other essays' [Harvard 1976], p.11


A Reaction

This is why Russell's Paradox is so important for set theory, which in turn makes it important for the foundations of mathematics.


The 10 ideas with the same theme [which sets are natural, rather than conventional]:

What physical facts could underlie 0 or 1, or very large numbers? [Frege on Mill]
Russell's proposal was that only meaningful predicates have sets as their extensions [Russell, by Orenstein]
Russell's antinomy challenged the idea that any condition can produce a set [Quine]
A class is natural when everybody can spot further members of it [Quinton]
We can have a series with identical members [Tait]
Zermelo allows ur-elements, to enable the widespread application of set-theory [Hallett,M]
Maddy replaces pure sets with just objects and perceived sets of objects [Maddy, by Shapiro]
The master science is physical objects divided into sets [Maddy]
ZFU refers to the physical world, when it talks of 'urelements' [Chihara]
A flock of birds is not a set, because a set cannot go anywhere [Brown,JR]