How to Test for Truth

It is one thing to say what truth is (= a theory of truth), it is another thing to know when we have found it (= a way of testing for truth).

The correspondence theory of truth says truth is the adequation or conformity between mind and world. This many people consider the common sense theory of truth. Nevertheless, the correspondence theory of truth does not provide a test of truth, only a statement of what truth is. Instead, a test of truth is something like the absence of contradiction in one’s theory. Granted, the mere absence of contradiction doesn’t get us particularly far, since it just tells us our theory may be true, not that it actually is true. So, what else do we have?

This is where we can turn to pragmatism. Many mistake pragmatism as a theory of truth; however, more sophisticated proponents suggest pragmatism as a test for truth. Of course, we use it all the time. Suppose I have two cups before me but cannot see what is in each because they are covered by a lid. Taking an educated guess, I judge the first has coffee in it. However, I discover my judgment is false. How? I tasted it — and it tasted like water, so my action was unsuccessful, insofar as I desired to taste coffee.

Pragmatism as a test for truth obviously assumes the correspondence theory of truth. We are testing to see if what we believe maps onto reality, and that test has to do with whether certain actions are successful or not. So, aside from the absence of contradiction, another way of testing for truth is just to see if certain theories or beliefs result in successful action. If we think our belief maps onto external reality, we might think such a belief will better help us to get around in the world. Simple, right?

Falsification is another test for truth which applies to generalizations, that is, statements using the words “all” or “always.” The test is to look for a negative instance or counterexample. For example, if we observe a black swan, then the theory that all swans are white, is false. Our confidence increases in generalizations that are exposed to potential counterexamples but continually escape them. Granted, we can never be certain that such generalizations are true, only increasingly confident in their probably being true.

We turn now toward coherence or how one’s theory hangs together, which is more of a logical, rather than empirical, test for truth. Here we are looking for points of tension or elements of one’s theory seemingly at odds with one another. Tension can come in degrees. The worst tension is contradiction, which falsifies a theory, since contradictions are impossible. But there can be tensions without contradiction — for example, one might think that there is a tension between one’s religious belief in Adam and Eve and one’s scientific belief in evolution. These commitments are not in strict contradiction, but some think it is difficult to see how they fit together. (FWIW, I think there are resolutions, but that is not our concern today.).

So, incoherence has to do with incompatibility between parts. In some cases, we may just not see how the parts are compatible. In which case, we may be less confident in the truth of our theory, but work toward understanding how the parts fit together, eventually discovering that they do fit together. In other cases, we may see — either immediately or after some investigation — that the parts definitely do not fit together, that there really is some contradiction in our theory. At which point we must either abandon the theory or eliminate whatever elements are resulting in the contradiction, if their elimination is not essential to the theory.