One could suppose, as pragmatists believe, a belief is true if it is useful, which is to say it successfully encourages societal action. Pragmatism, which developed following the Civil War, rejects any definition of truth which connotes certainty, individualism, and basic principles in favor of one tied to action, community, and a web of beliefs, any one of which can be subject to questioning [as to its relation to the web] at a given time. There are a few problems with this understanding of truth.
Firstly, pragmatistic commitment to action begs the question as to what sort of action beliefs ought to stimulate. There seems to be a hidden, unsubstantiated ethical principle. If there were no such principle, one could, for example, claim that the very certainty which allegedly stimulated the Civil War was a belief which, since it led to a communal action, was true. On the other hand, adherence to one certain ethical principle over against another would both entail some sort of foundationalism and beg the question as to whether one can be certain said ethical principle should be that according to which one should seek to act.
An even more fundamental problem with the pragmatist’s account of the nature of truth is that it is not clear how the pragmatist can validly claim his understanding of the nature of truth is [more] useful [than another]. It may be the case that belief in a different theory of truth would be a greater stimulant to communal action. In this case, a pragmatistic truth would be self-defeating. A pragmatist would, therefore, need to demonstrate his definition is more useful than all others, which would presuppose the ability to discern a causal relation between [his] beliefs [regarding the nature of truth in particular] and [its] usefulness. A merely correlative relation would not suffice, as any communal action could possibly be attributable to a belief distinct from the pragmatist’s definition of truth. However, as soon as one recognizes Humean disbelief in the ability to demonstrate causation could too be claimed to promote communal action more successfully than belief in causation – and could thus, on the pragmatist’s ground, be true – it becomes evident that the pragmatist cannot justify his theory of truth.