In Chapter 4 of The Philosophy of Philosophy, “Epistemological Conceptions of Analyticity”, Williamson argues against epistemologies of analytic truths based on epistemological conceptions of analytic truths, which, in turn, are based on “understanding-assent” links. An understanding-assent link is a sentence like:
(1) Necessarily, whoever understands “All bachelors are unmarried” will assent to it.
I think the idea is that understanding links hold between object-level sentences corresponding to metalinguistic semantic facts, on the one hand, and assent to the content of the object-level sentences, on the other. If an understanding-assent link like (1) is supposed to provide the basis on which I know that “All bachelors are unmarried” is true, then this could be on the basis of a corresponding understanding-knowledge link:
(2) Necessarily, whoever understands “All bachelors are unmarried” knows that it is true.
Knowledge is factive. So, (2) entails:
(3) Necessarily, someone understands “All bachelors are unmarried” only if it is true.
But then, Williamson observes, it is unclear how to proceed with understanding-assent links related to several sorts of terms. I’ll just deal with “phlogiston” and other special theoretical terms from discredited theories, although what I have to say applies to the other sorts of terms he talks about.
It seems that fans of understanding-assent links will have to say that there are some even for “phlogiston”. Intuitively, part of the meaning of "phlogiston" is captured by its role in phlogiston theory. This commits us to:
(4) Necessarily, whoever understands “Phlogiston has the role R” will assent to it.
But phlogiston does not have the role R, because nothing plays the role that phlogiston plays in phlogiston theory. However, it follows from (4) that whoever does not assent to “Phlogiston has the role R” doesn’t understand it. Then it follows that people who think that nothing has role R don’t understand “Phlogiston has the role R”. Intuitively, this is not the case. So fans of understanding-assent links will have to accept something that is intuitively not the case.
I’m sure there are all sorts of ways around the problem Williamson is trying to set up for epistemologies of analytic truths based on understanding-assent links, but I’d like to propose just one.
First, excluding bizarre cases involving private codes, we understand sentences only relative to languages (or, if you like, idiolects). Second, sentences have their truth-values relative to languages (or idiolects). Assume, contrary to Williamson, that assent is generally metalinguistic – to assent to “All bachelors are unmarried” is, generally, to assent to the metalinguistic fact that “All bachelors are unmarried” is true, not to assent the corresponding object-level fact that all bachelors are unmarried. So, fully unpacked, (4) means something like:
(4`) Necessarily, whoever understands “Phlogiston has the role R” in L will assent to the metalinguistic fact that “Phlogiston has the role R” is true in L.
In a theoretically important sense, phlogiston theory is stated in a different language from our current chemical theory. (I think this is the sense in which languages classically do not contain their own truth predicate, and probably the sense in which sentences of a language have determinate logical forms.) When doing chemical theory today, we do not speak the L mentioned in (4`). We are not speaking L even when we say that phlogiston theory is false, or that nothing has the role R. If a fully-spelled out description of R invokes other special theoretical terms of phlogiston theory, perhaps a good interpretation of “Nothing has the role R” is “We should not speak a language in which a sentence of the form ‘x has the role R’ is true, for some name substituted for ‘x’.”
The problem with words like “phlogiston” and “tonk” (and, an eliminativist might say, “believes”) is that it is a bad idea to use them at all (except, perhaps, to say something like that phlogiston doesn’t exist). It is a bad idea to use them because it is a bad idea to use languages that countenance them - languages which commit us to parts of phlogiston theory, or in which everything is true or nothing is true. Still, I think we can endorse understanding-assent links for even these sorts of words by relativizing the understanding and the assent in question to languages that we do not use.
File under: Applied Carnap.
Update: This is a pretty bad objection, now that I look at it again. That's because (4`) is false. If people don't know what language L is - and most people don't, on the ontology of languages necessary to make this work - then they won't (or shouldn't) assent to statements mentioning it, including (4`). And the business about the ellipticality of "Nothing has the role R" seems pretty implausible.