Another aspect of the second incompleteness theorem that needs to be emphasized is that it does not show that S can only be proved consistent in a system that is stronger than S. To say that S is consistent is not to endorse the axioms of S, and a proof that S is consistent need not use the axioms of S itself.

Ben is not at a philosophy convention the way I am, but he's lazy enough that his comments are being brought to you by a Torkel Franzén quote anyway.