Propositions , What Are They Good For ? Stephen Schiffer

Our propositional-attitude concepts are indispensable to us; our very survival depends on the ways we use those concepts to exploit others as sources of information about the extra-cranial world and to predict and explain our own and other people’s behavior. If, as many suppose, to have a propositional attitude is to stand in a propositional-attitude relation to a proposition, then we should find that propositions play an essential role in enabling propositional-attitude concepts to perform the jobs they perform for us, and if we found that things of some other kind—say, linguistic entities of some stripe or other—could do what propositions do better than, or even as well as, propositions, then we should doubt whether propositional attitudes really are relations to propositions. In this article I inventory the jobs that our propositional-attitude concepts do for us and explain how propositions enable them to do those jobs and why things of no other kind could enable them to do those jobs nearly as well as propositions do. I also show that, among propositions, fine-grained material-object-dependent propositions are much better enablers than propositions of any other kind. If my arguments are correct, then Davidsonians and others should give up trying to hold that propositional attitudes are relations to linguistic entities, and Stalnakerians and others should give up trying to hold that the propositions we believe and assert can be represented as sets of possible worlds. Although there is a vast literature on whether propositional attitudes are relations to propositions, a crucial question that ought to lie at the heart of this debate is not often enough seriously addressed. This is the question of the contribution propositions make to the ways in which we benefit from having our propositional-attitude concepts, if those concepts are concepts of relations to propositions. Unless propositions can be shown to confer a benefit that no non-propositions could provide, we should probably doubt whether propositional attitudes really are relations to propositions. I believe that propositional attitudes are relations to propositions and that the role played by them in our conceptual economy cannot be played by things of any other kind, and in this article I try to say why. This article, in other words, offers my answer to the question posed by my title. A. Sharpening the Question Let’s start by asking what important jobs our propositional-attitude concepts do for us. There is a lot we can say in answer to this question, whether or not propositional attitudes are relations to propositions. Once we are reminded of what important jobs those concepts perform, we can ask how they are able to perform them, and here we can ask what role propositions play in answer to that question, if propositional attitudes are relations to propositions. There are at least three important roles our propositional-attitude concepts play in our conceptual economy. 1 This paper is a reconceptualization and clearer and improved version of the answer given in my (2003), chapter 8. The information-acquisition role. We exploit the beliefs of others to gain information about the extra-cranial world. If I know that you are in London and that you now believe that it’s raining in London, then I will believe that it’s raining in London. I will take the fact that you believe that it’s raining in London to be extremely good evidence that it is raining in London. If I know that you believe that your department just hired Professor So-and-So, then I will take that to be good evidence that your department did hire her. It would be difficult to overemphasize the importance of our ability to exploit the beliefs of others to gain information about the world, since it underlies our use of language to convey information. A friend in London utters the sentence ‘It’s raining’ and you straightway know that it’s raining in London. There are unresolved questions about whether knowledge by testimony is inferential, but whether or not it is, it seems clear that you cannot be justified in believing something you were told unless you’re also justified in believing that the speaker believes it, too. Of course, it is no mystery how you can be justified in believing that it’s raining in London on the basis of knowing that your friend believes that it’s raining in London, since we know enough about how normal people acquire such beliefs to enable us to know that they typically wouldn’t have them if they weren’t true. The predictive role. Just as we can sometimes infer that such-and-such from the fact that so-andso believes that such-and-such, so, too, we can sometimes infer that so-and-so believes that such-andsuch from the fact that such-and-such. Knowing what a person believes often enables us to draw new conclusions about what she wants, and, besides, just as certain kinds of extra-cranial facts provide evidence of what a person believes, so others provide evidence of what a person wants. One reason this epistemic access to the beliefs and desires of others is important is that we are very often able to exploit it to predict what they will do. Thanks to the ways in which non-mental facts of certain kinds provide good evidence of what others believe and desire, we have wide-ranging access to what others believe and desire, and we’re often positioned to make reliable predictions about what people will do based on our beliefs about what they believe and desire. The explanatory role. We exploit the beliefs and desires of others to explain both intentional and non-intentional facts: Herbert came to Manhattan because he wanted to find his wife and believed that she was hiding in Manhattan; Jane is stretched out on the floor like that because she is looking for her child and thinks he may be hiding under the bed. The claim that our propositional-attitude concepts play an explanatory role might seem more contentious than the claim that they play either an information-acquisition or a predictive role. This is because no one doubts that our propositionalattitude concepts can be wielded to use others as a source of information or to predict their behavior, but various philosophers have produced various arguments to show that propositional-attitude facts are incapable of playing a genuinely explanatory role. I don’t think any of these arguments are sound, and in (2003) I try to say why. But we can skirt these issues, because I don’t think anyone can reasonably doubt that our common-sense propositional-attitude because-statements—e. g. ‘Leroy divorced his wife because he wanted to be a rabbi and believed that rabbis had to be single’—play some important role in our lives, whether or not it’s to provide correct propositional-attitude explanations, and we can ask what that role is and what propositions contribute to it. In some sense, a common-sense propositional-attitude because-statement may be correct or incorrect, and knowledge of correct such statements are valuable at least because they help to enable us both to affect the behavior of others and to predict what they will do. In this regard, two features of them are crucial. First, they have counterfactual value: if someone did something because she had such-and-such propositional attitudes, then, all other things being equal, she would not have done what she did if she hadn’t had those propositional attitudes. Second, they have predictive value: we have epistemic access to the propositional attitudes of others, and we can often predict what they will do on the basis of knowing what they believe and want. Roughly speaking, the more we know about why someone did what she did in propositional-attitude terms, the better we are able to predict what she will do on other occasions. Since the predictive value is already in play, the explanatory role of our propositional-attitude concepts introduces just their counterfactual value to be accounted for, although accounting for this isn’t something I can attempt in this article (I do try to account for it in [2003]). If our propositional-attitude concepts play the roles just cited, then it’s legitimate to ask what explains the ability of those concepts to play those roles. But that isn’t quite the question I set for myself. That question is about the role propositions play in enabling propositional-attitude concepts to play those roles, and this question needs itself to be narrowed before we can profitably try to deal with it. In (2003) I argue that believing is a triadic relation expressed by the open sentence