The title is a reference to the correspondence theory of truth. This is not a post about letter writing.
When asked what they mean by “true” people often mention the correspondence theory. However, I find the common descriptions of the correspondence theory to be unsatisfactory. So this post will be an attempt to make sense of the idea of correspondence.
The correspondence theory is sometime said to say that a sentence is true if it corresponds to the facts. I always saw this as puzzling, because to me the term “fact” was just another name for a true statement. Described that way, the correspondence theory of truth seemed to just say that true statements are true and false statements are false. Of course, I did not disagree with that, except that it did not say anything at all.
It is sometimes suggested that facts are metaphysical things, and that correspondence to facts means correspondence to these metaphysical entities. I have trouble trying to understand what a metaphysical fact might be. Several hundred years ago, it would have been taken to be a metaphysical fact that the earth is fixed and the sun goes around the earth. Today, we instead say that the earth goes around the the sun.
Another way of presenting it, that I sometime see, is to say that a sentence is true if it expresses what is the case. But, once again, “what is the case” just seems to be another word for “true”, so we are again left with the correspondence theory saying that true statements are true and false statements are false.
Truth as a property of syntactic expression
There’s an intuitive idea, that a statement is true if it corresponds to reality. But it usually isn’t defined that way because of the difficulty of explaining “corresponds to reality”.
Part of the problem, I think, is that truth is typically taken as a property of propositions. So I’ll go a different route, and take truth to be a property of syntactic expressions. Here, a syntactic expression is a sequence of word with perhaps some requirements that the sequence is grammatical. This contrasts with the idea of a proposition which is not the sequence of words, but what that sequence of words are taken to mean.
Logic is usually said to be truth preserving. But logic itself is based on the form of the argument rather than on the meanings of the premises. For sure, we follow meanings when setting premises. But the logic starts after that, and uses only the form. So the use of truth in logic seems to fit with truth as applied to syntactic expression.
Computers are usually seen as doing logic. And, once again, computers work with the form of arguments. So the use of truth in computers also seems consistent with the idea of truth applied to syntactic expression.
So what does it mean to say that a syntactic expression corresponds to reality? This seems to suggest that there are some rules of correspondence that connect our words to reality. And there are. That’s roughly what we call “meaning”. We can think of our meanings as a system of mappings between reality and the words we use.
It is usually understood that language is conventional. That is to say, our language is based on a system of social conventions. Meanings are included, and people talk of meaning conventions. Looked at this way, we see that a statement is true if it conforms with our system of rules, where in this case the rules are the meaning convention.
What about rules of correspondence?
Those rules of correspondence, are they true?
This question is similar to one we saw in my earlier post on mathematics. There, we saw that ordinary statements are true if they conform to our axioms. But the question of whether axioms are true cannot be answered in the same way. Now we see that truth by correspondence is similar, a matter of conforming to conventional rules of correspondence. But the rules themselves cannot be evaluated in the same way. There are no rules of correspondence for the the rules of correspondence. I tend to see those as neither true nor false. They fall outside our system for evaluating truth by correspondence.
If we go back to the time when there was a debate over geocentrism vs. heliocentrism, that’s a case where I’m inclined to see truth as not actually involved. This was more a question of which should become the accepted social convention. And society went with heliocentrism, really on pragmatic grounds. That was a good decision, but I don’t see it as a true/false decision. Once decided, and once that became the conventional view, then most people agreed with it. That is to say, we now tend to see it as true just as we treat axioms in mathematics as true.
Scientific theories
I tend to see scientific theories as neither true nor false. Those theories are usually establishing rules of correspondence for scientific observations. The actual observation or measurements made under a theory are then true because they conform to the rules of the theory. But the rules of the theory are themselves outside of any pre-existing rules of correspondence.
A final note
Overall, this suggests that truth itself is a social construct. And it pretty much has to be. It is part of language, part of how we use language to coordinate our activities. It could not work if it were not social.
The Heretical Philosopher 