Stalnaker on Reinterpreting Assertions
On page 305 of "Assertion Revisited" (in the latest issue of Phil.Studies), Robert Stalnaker suggests that the information conveyed by an utterance is the diagonal proposition associated with the utterance iff it is unclear in the relevant context which horizontal proposition the utterance expresses:
[T]he relevant maxim is that speakers presume that their addressees understand what they are saying. In terms of the two-dimensional apparatus, this presumption will be satisfied if and only if the propositional concept for the utterance [a function that assigns to every relevant possible context the horizontal proposition expressed by the utterance in that context] is constant, relative to the possible worlds that are compatible with the context. Our problematic example [of saying "Hesperus is Phosphorus" to O'Leary who doesn't yet know that Hesperus is Phosphorus], and all cases of necessary truths that would be informative (in the sense that the addressee does not already know that they are true) will be prima facie counterexamples to this maxim, and so will require reinterpretation [so that what is said is the diagonal, not the horizontal proposition].
Three comments:
1. It seems possible that in some community the propositional concepts are hardly ever constant. Suppose we are such a community. Then according to Stalnaker, what our utterances convey is always the (relevant) diagonal proposition. Isn't it then just a matter of terminology and theoretical elegance whether we call the diagonal proposition the default content right from the beginning? (Or a function from contexts to diagonal propositions if the latter are as flexible as Stalnaker seems to think.) But then it can't be right that this question of what to count as the default content is tied to the debate between internalism and externalism about mental content, as Stalnaker argues later in the paper. Externalists would hardly grant that internalism would be true if only in communicative contexts it were usually unclear what proposition our utterances express.
2. Isn't our community in fact one in which the propositional concepts are mostly variable? Suppose I say to O'Leary, who doesn't know that Hesperus is Phosphorus, "the diameter of Hesperus is 12'000 km". Presumably the contextually relevant worlds then also contain worlds where the planet we call "Hesperus" is not the planet we call "Phosphorus". For according to Stalnaker, these worlds would have been relevant if I had said "Hesperus is Phosphorus" instead, and how could what I said about the diameter of Hesperus rule out these worlds? But in some of those worlds where "Hesperus" and "Phosphorus" denote different planets, "Hesperus" does not denote Venus. (Otherwise "Phosphorus" doesn't denote Venus in any of the worlds, and I can make the example with "Phosphorus" instead. But there seems to be no reason to assume such an asymmetry between "Hesperus" and "Phosphorus".) Hence in all these worlds, the proposition I express is not the proposition I actually express. Hence the propositional concept is not constant, and what I said must be reinterpreted as conveying the diagonal proposition. So generally, whenever somebody says "A is F" to someone who does not know that A corefers with another name B, the content of the utterance is the diagonal. But this situation is very common.
Moreover, isn't there just a gradual difference between O'Leary and me? O'Leary is agnostic about whether "Hesperus" and "Phosphorus" corefer. I'm not, but I'm not dead certain that they corefer either. Sufficient empirical information would convince me that they don't. So why are the worlds where they don't corefer only relevant in conversations with O'Leary and not in conversations with me?
3. Even if diagonal intensions are only needed as semantic values in exceptional cases, they are still needed. So Stalnaker can't say, as he does later, that diagonal intensions can't do the job of semantic values because they are too speaker-relative and holistic. (He also complains about them being "indirect" and "abstract", but I don't understand that complaint.)