A Conversation for Logical Completeness

Wrong paradox

Post 1

e to the x

The paradox you speak of is known as Russal's Paradox and was not what Godel used in his proof. Russal's Paradox was used to show that normal Cantorian set theory was incomplete. Godel's therom used (in the propositional calculus) the statement "This statement is not provable in system S". This was the statement that would have to have it (or it's negation) added as an axiom of a logical system. But, then the system would be inconsistant.

Therfore: No system is both consistant (no statements of the form x and not x) and complete (every true statement is in the system)


Wrong paradox

Post 2

The Unmentionable Marauding Pillowcase

Yes, e to the x is right. Clean up this entry a bit, make it real nice, logic is really neat and should not be on the 5 most neglected list!


Wrong paradox

Post 3

Decaf Silicon

I third the motion! Always hated that phrase...


Wrong paradox

Post 4

The mechanical pencils man

Well ii fourth it, so there!


Wrong paradox

Post 5

HenryS

Almost right...but adding the godel sentence or its negation does not make the system inconsistent. I've written a bit on this towards the end of post 59 on http://www.bbc.co.uk/h2g2/guide/F53777&thread=76574&skip=40&show=20


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