Thomas asked:

How are we to tell which of the theories of truth (e.g. pragmatism, correspondence) is true? Surely we
would already have to be within one of these systems to discern truth?

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Your question is a very reasonable one; circularity of this sort does hamper many fundamental
enquiries in philosophy. However, this isn't one of them.

Theories of truth are concerned with what truth is,not with what is true. Hence proponents of different
theories need not disagree over which propositions are true and which false (apart from the
propositions which articulate their competing theories, of course). Rather, they disagree over what it
means to say of a proposition that it is true.

Correspondence theorists believe that 'p is true' means that p corresponds to the facts; pragmatists
believe that 'p is true' means that p is a useful thing to believe; coherentists believe that 'p is true'
means that p is consistent with all the other true things; and disquotationalists (aka minimalists)
believe that 'p is true' is just another way of saying p.

It is no part of the responsibility of a theory of truth to help us to identify true and false propositions.
Indeed, proponents of the competing theories are often in agreement about the sort of methods we
use to do that. Should these methods identify one theory as true and its competitors as false (by no
means the most likely outcome) their different theories of truth need not prevent them from
recognising this.

Andrew Aberdein