[FOM] The Derivability Conditions, Again

Richard Heck rgheck at brown.edu
Tue Oct 2 09:26:13 EDT 2012

On 10/02/2012 08:47 AM, Harry Deutsch wrote:
> Isn't your proof of G2 in your first post on this subject pretty much the same as the provability logical proof Boolos gives at the end of "Goedel's Second Incompleteness Theorem Explained in Words of One Syllable"...?
> Harry
Similar, no doubt---though Boolos's proof seems more complicated at the 
end than the one I gave. In any event, the interesting observation here 
is Visser's: that there is a way of structuring this kind of proof of G2 
that makes its relationship to the standard proof of Löb's Theorem 
clear, but doesn't make it just what you get by giving the proof of 
Löb's Theorem for the special case in which the "key sentence" is 
provably refutable.


Richard G Heck Jr
Romeo Elton Professor of Natural Theology
Brown University

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