The Pragmatic Theory of Truth is, predictably enough, a product of Pragmatism, an American philosophy developed during the early and mid twentieth century. Pragmatists identified the nature of truth with the principle of action. Put simply, truth does not exist in some abstract realm of thought independent of social relationship or actions; instead, truth is a function of an active process of engagement with the world and verification.
Although most closely associated with the work of William James and John Dewey, the earliest descriptions of a Pragmatic Theory of Truth can be found in the writings of Pragmatist Charles S. Pierce, according to whom there is no distinction of meaning so fine as to consist in anything but a possible difference of practice.
The point of the above quote is to explain that one cannot conceive of the truth of a belief without also being able to conceive of how, if true, that belief matters in the world. Thus, the truth of the idea that water is wet cannot be understood or acknowledged without also understanding what wetness means in concert with other objects a wet road, a wet hand, etc.
A corollary of this is that the discovery of truth occurs only through interaction with the world. We dont discover truth by sitting alone in a room and thinking about it. Human beings seek belief, not doubt, and that search takes place when we do scientific research or even just going about our daily business, engaging objects and other people.
William James made a number of important changes to this Pragmatist understanding of truth. The most important was probably the alteration of the public character of truth which Pierce argued for. We must remember that Pierce focused first and foremost on scientific experimentation truth, then, depended upon practical consequences that would be observed by a community of scientists.
James, however, moved this process of belief-formation, application, experimentation, and observation to the very personal level of each individual. Thus, a belief became truth when it proved to have practical utility in the life of a single individual. He expected that a person would take the time to act as if a belief were true and then see what happened if it proved useful, helpful, and productive, then it should indeed be regarded as true after all.
Perhaps his most famous application of this principle of truth was to religious questions, in particular the question of the existence of God. In his book Pragmatism, for example, he wrote: On pragmatic principles, if the hypothesis of God works satisfactorily in the widest sense of the word, it is true. A more general formulation of this principle can be found in The Meaning of Truth: The true is only the expedient in our way of thinking, just as the right is only the expedient in our way of behavior.
There are, of course, a number of obvious objections that can be raised against the Pragmatist Theory of Truth. For one thing, the notion of what works is very ambiguous especially when one expects, as James does, that we seek it in the widest sense of the word. What happens when a belief works in one sense, but fails in another? For example, a belief that one will succeed may give a person the psychological strength needed to accomplish a great deal but in the end, they may fail in their ultimate goal. Was their belief true?
James, it seems, substituted a subjective sense of working for an objective sense of working which Pierce employed. For Pierce, a belief worked when it allowed one to make predictions which could be and were verified thus, the belief that a dropped ball will fall and hit someone works. For James, however, what works seems to mean something like whatever produces results we happen to like.
This is not a bad meaning for what works, but its a radical departure from Pierces understanding and it is not at all clear why this should be a valid means for understanding the nature of truth. When a belief works in this broad sense, why call it true? Why not call it something like useful? But a useful belief is not necessarily the same as a true belief and that is not how people typically use the word true in normal conversation.
For the average person, the statement It is useful to believe that my spouse is faithful does not at all mean the same as It is true that my spouse is faithful. Granted, it may be the case that true beliefs are also usually the ones that are useful, but not always. As Nietzsche argued, sometimes untruth may be more useful than truth.
Now, Pragmatism may be a handy means for distinguishing truth from untruth. After all, that which is true should produce predictable consequences for us in our lives. In order to determine what is real and what is unreal, it would not be unreasonable to focus primarily upon that which works. This, however, is not quite the same as the Pragmatic Theory of Truth as described by William James.