Difference between revisions of "Russell's Paradox"

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The '''Russell's Paradox''', credited to Bertrand Russell, was one of those which forced the axiomatization of set theory.  
 
The '''Russell's Paradox''', credited to Bertrand Russell, was one of those which forced the axiomatization of set theory.  
  
==Paradox==
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Paradox
We start with the property <math>P</math>: (<math>x</math> does not belong to <math>x</math>). We define <math>C</math> to be the collection of all <math>x</math> with the property <math>P</math>. Now comes the question: does <math>C</math> have the property <math>P</math>? Assuming it does, it cannot be in itself, in spite of satisfying its own membership criterion, a contradiction. Assuming it doesn't, it must be in itself, in spite of not satisfying its own membership criterion. This is the paradox.
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We start with the property P: (x does not belong to x). We define C to be the collection of all x with the property P. Now comes the question: does C have the property P? Assuming it does, it cannot be in itself, in spite of satisfying its own membership criterion, a contradiction. Assuming it doesn't, it must be in itself, in spite of not satisfying its own membership criterion. This is the paradox.
  
==See Also==
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See Also
 
*[[Set]]
 
*[[Set]]
  
 
[[Category:Set theory]]
 
[[Category:Set theory]]

Latest revision as of 17:57, 12 May 2023

The Russell's Paradox, credited to Bertrand Russell, was one of those which forced the axiomatization of set theory.

Paradox We start with the property P: (x does not belong to x). We define C to be the collection of all x with the property P. Now comes the question: does C have the property P? Assuming it does, it cannot be in itself, in spite of satisfying its own membership criterion, a contradiction. Assuming it doesn't, it must be in itself, in spite of not satisfying its own membership criterion. This is the paradox.

See Also