Wolfgang Schwarz

Descriptive knowledge and shared reference

Some forms of descriptivism say that when I utter a sentence with a proper name in it, communication only succeeds if there is a description, a set of properties, you and I both associate with that name. But often such descriptions are hard to find, so some conclude that instead it suffices if you and I refer to the same object with that name, no matter what properties mediate our reference or if it is mediated by associated properties at all.

In fact, shared reference doesn't quite suffice for successful communication. We should also require that the shared reference is common knowledge. If I tell you that Ljubljana is pretty but you have no idea whether by "Ljubljana" I refer to the town you call "Ljubljana" or whether instead I refer to my neighbour or the moon, you don't understand what I'm trying to tell you.

Moreover, the common knowledge should be resilient. Your belief that I refer to the same object as you by "Ljubljana" should not be undermined merely by the fact that I say something about Ljubljana you take to be false. You should only drop that belief if I say something very odd, like that I've eaten Ljubljana for dinner.

So suppose it is resilient common knowledge between you and me that we refer to the same thing with "Ljubljana". Then in all the possible situations that might, for all you know, be the actual situation, our names corefer. Suppose also that you take "Ljubljana is pretty" to be true in some, but not all these situations. Then, assuming that we agree about the use of "pretty", you can conclude that in my language, too, the sentence is true in exactly this subset of your belief worlds. And by the resilience of your knowledge, that carries over to worlds you assign somewhat lower credence, worlds that are not quite among your belief worlds. Moreover, since you know that I also know that our words corefer, it also carries over to what you take to be my belief worlds and not-quite-belief worlds. That is, in any possible situation that has, for all we know, some chance of being either actual or believed to be actual by one of us, we take our words to corefer and our sentences to make the same distinctions.

Call a possibility that has, for all we know, some chance of being either actual or believed to be actual by one of us "relevant". Each relevant possibility contains an object we (both of us, in that situation) take to be the referent of "Ljubljana". That determines a function from possibilities to objects, in other words, a property -- a property we both associate with "Ljubljana". (If in some of the relevant possibilities, Ljubljana does not exist, no problem: most properties are partial functions.)

So if communication requires resilient common knowledge of shared reference, descriptivism is true. At least a reasonably weak form of it is true.

When we express associated properties as descriptions in English, the amount to which they agree, especially concerning realistic situations, is easily overlooked. For instance, suppose that physicians associate with "arthritis" a certain medical condition, whereas I associate with that name "whatever condition physicians associate with that name". Superficially, these are very different properties and descriptions. But try to imagine a situation where they disagree! All such situations I can think of, e.g. situations in which there are no physicians, are very unlikely to be actual.

For ordinary communication, it doesn't matter how we classify bizarre possibilities. As long as the existence of physicians is taken for granted, we can communicate fairly well even if we disagree about what is true if it turns out that there are no physicians. We don't need conventions about what to do and say in situations that nobody expects to occur. So one might argue that a descriptivism so strong that it demands complete agreement of associated properties -- even for irrelevant, outlandish possibilities -- is over-ambitious anyway.

(Even if we don't take the possibility that there are no physisicans seriously, we can and do talk about such possibilities, saying how life would be if there were no physicians, etc. So it is important that the difference in associated descriptions doesn't show up in such talk about counterfactual possibilities. And it usually doesn't because the descriptions are rigidified: "arthritis" is the condition our physicians actually refer to. So no problem here.

There might be a problem around the corner though. For arguably, some constructions in our language operate not on C- but on A-intensions: "it is a priori that ---" perhaps, or "it is analytic that ---", or "if --- then ---". So if we disagree about the classification of far-fetched possibilities, the disagreement would show up in the evaluation of such sentences. I'm not sure what to say about this. Maybe the fact that this doesn't happen often can be explained, or maybe there's no need for an explanation because that's exactly what we see: people often do disagree about what's a priori and analytic and what would be the case if this or that turned out, and it's not too implausible that often their disagreement is ultimately linguistic disagreement.)