Last week I reread Hartry Field’s “Tarski’s Theory of Truth” and John McDowell’s response, “Physicalism and Primitive Denotation: Field on Tarski”, and realized I hadn’t understood the McDowell at all before. Field’s point seems straightforward enough – Tarski gave a materially adequate characterization of truth that was not explanatory of the concept any more than a listing of the net gravitational force on every pair of objects in the universe explains gravity. Field argues that in order to get a proper explanation, we should be able to explain why a word means what it does, which would presumably involve something like Kripke’s causal theory of names, together with various psychophysical explanations of how we acquire meanings for words.
However, McDowell seems to think that such a story is impossible, and that Tarski’s theory is adequate for what actually is possible. Until I read some Davidson, this didn’t make much sense. But now I think I understand Davidson’s basic idea – that mental events are all identical with physical events, but we can never be satisfied with any lawlike explanation of which mental events correspond to which physical events unless we stop regarding people as rational agents and seeking to interpret them with a principle of charity. Thus, explaining truth merely in terms of truth-conditions, and truth-conditions merely extensionally, is all that we can do, and it is in fact a useful project. For McDowell, it seems that the point of the concept “true” is to allow us to interpret other speakers, so that whenever someone says something, I can say “What she said is true iff x”, where x is some set of conditions expressed in my language. My theory of truth will have to be different for each new speaker I encounter, because I have to understand each of them slightly differently. This is clearest when they’re speaking non-English languages, but even if both speak English languages, they’ve almost certainly got subtle differences in their usage of particular words.
However, for Field, it seems that the purpose of a theory of truth is not just to understand speakers of other languages, but to understand even my own language. That is, I can understand people speaking my language directly, but if I want to understand how it is that language hooks up with the world, then I need the concept of truth.
And of course, this all links back up to Dummett in “Truth” wondering just what the point of truth is. He suggests that it has something to do with the fact that a speaker “usually seeks to make true statements”, but notes that this picture is far from complete. Davidson and Field are just giving two competing pictures of what more it is we might want.