[FOM] Mendelson's missing appendix on the consistency of PA

Peter Smith ps218 at cam.ac.uk
Fri Feb 15 13:45:43 EST 2013

Before posting the question here I did search around a bit (probably 
inefficiently and certainly quite ineffectively) to see if I could find an 
email for Elliott Mendelson to ask him directly! But anyway, he picked up 
my query and very kindly wrote to me:

> I was intrigued by your comments about the consistency proof of PA that 
> appeared in the First Edition of my logic book. I omitted it in later 
> editions because I felt that the topic needed a much more thorough 
> treatment than what I had given, a treatment that would require more 
> space than would be appropriate in an introduction to mathematical logic.

I can understand that. Though I think the pointers he gave in that Appendix 
did spur on quite a few readers to find out more, so I still think it was a 
Very Good Thing, and it was perhaps a pity to drop it.

[Prof. Mendelson has kindly allowed me to quote him.]
Dr Peter Smith

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