Re: what makes it true?

grubb@xxxxxxxxxxxxxxxxx (Daniel Grubb) writes:

> I can understand, given a formal system, whether I have a well formed
> formula, a proof, etc because I can apply whatever rules are given
> for forming formulae or for deriving new strings from the ones already
> obtained. However, without a set theory, I can't talk about the set of
> statements or prove anything about proofs. So my understanding of
> formal systems would be purely local if not for some type of set theory.

All of this sounds very strange. I don't see how it relates to
anything that actually happens. To begin with, what do you mean by
being given a formal system? In the real world, this means being
given such explanations as "A->(B->A) is an axiom for all formulas
A and B". We understand such explanations perfectly well without
any set theory whatsoever, and I can't imagine by which procedure
one would first introduce a set theory and then somehow use that
set theory to elucidate the explanation.
.

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