Mercier and Sperber (M&S) suggest that human reasoning is reflective and has evolved to support social interaction. Cognitive agents benefit from being able to reflect on their beliefs whether they are acting alone or socially. A formal framework for argumentation that has emerged from research on artificial cognitive systems that parallels M&S's proposals may shed light on mental processes that underpin social interactions.

I will discuss those epistemic accounts of truth that say, roughly and at least, that the truth is what all ideally rational people, with maximum evidence, would in the long run come to believe. They have been defended on the grounds that they can solve sceptical problems that traditional accounts cannot surmount, and that they explain the value of truth in ways that traditional (and particularly, minimal) accounts cannot; they have been attacked on the grounds that they collapse into idealism. (...) I show that all these claims are mistaken. The system of statements accepted by an adherent of an epistemic account who also accepts the equivalence scheme is the same as that accepted by an adherent of a traditional account who also accepts a remarkably strong thesis of epistemic optimism. The singling out of one rather than another claim within this system as defining 'true' cannot make as much difference as to imply idealism or refute scepticism. However, it can make all the difference when it is a matter of explaining the value of truth. For a crucial point in such explanation depends on what can be soundly substituted for what in intensional contexts; above all those governed by such verbs as 'know', 'hope', 'believe', 'value'. That is, it depends on what expressions are intensionally equivalent. And one point of singling out one formulation as definitional can be to settle just this. But though some epistemic theorists have deemed ability to explain the value of truth a merit of their account (and lack of this ability a fatal defect of traditional accounts, of minimal accounts in particular), it turns out that minimal accounts of 'true' fit a sound account of our valuing of truth in a way that epistemic accounts do not. In the course of this argument I rebut related positions: e.g. Dummett's, that minimal definitions fail because they cannot account for the point of having a notion of truth, and that an account of the practice of assertion is what would fill this lacuna. I argue to the contrary that if the point of the notion could not be explained on the basis of a traditional definition, it could not be explained at all. (shrink)