simon2 comments on The Cartoon Guide to Löb's Theorem - Less Wrong
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Comments (90)
We don't have PA + X proving anything for any X.
It seems to me that we do have (PA + "?(◻C -> C)" |- "?C")
from which the deduction theorem gives: (PA |- "?(◻C -> C) -> ?C") which is Löb's Theorem itself.