Belief and Desire as Commitment

According to a common view, beliefs suffer a coherence constraint that desires do not. If I believe that p, then I'm very unlikely, at the very same time, to believe that not-p -- and if I do, that's a clear rational failing. But desiring various contradictory things is commonplace.

I don't want to dispute that the English statement of the common view just given can often express a truth. But I think it's a mistake to infer from this that there's something interestingly different between the natures of belief and desire. The words 'belief' and 'desire' are used loosely to refer to a few different kinds of things. And the ones that are of most interest in a lot of philosophy, I think, are structurally much more similar than the common view would lead one to think.

Particular Beliefs and Belief-Desire Psychology

Let us suppose that Dmitri knows how to sing the "Il balen" cadenza from Verdi's Il Trovatore.

There's a debate about whether Dmitri's knowing how to sing the cadenza amounts to knowing some proposition. According to 'intellectualists', knowing how to X just is (to an approximation), knowing, for some w, that w is a way to X. I don't mean to weigh in on that debate just now, but one of the moves in it is relevant for an issue concerning imagination, which is my current research topic du jour. The move is, on its face, an argument against the thesis that knowing how is knowing that -- it argues that in some cases in which know-how is clearly present, the relevant know-that is not present, because the requisite beliefs are absent or even disbelieved. For example, Dmitri may, consistent with his knowing how to sing the cadenza, have entirely erroneous beliefs about how he does it. Maybe he thinks that he clenches his abdominal muscles, when what he really does is expand his ribcage. He thinks that he opens his mouth widely, but what he actually does is lift his soft palate. The way he sings the cadenza is by expanding his ribcage and lifting his soft palate, but he doesn't know that, because he doesn't believe it. Charles Wallace offers a version of this argument. (This was brought to my attention in a forthcoming paper by my new colleague Ephraim Glick.)

Inference in Imagination, Belief, and Desire

Shaun Nichols writes:

In addition to a pretense box, Stich and I propose a mechanism that supplies the pretense box with representations that initiate or embellish an episode of pretense, the “Script Elaborator”. This is required to explain the bizarre and creative elements that are evident in much pretend play. However, there are also much more staid and predictable elaborations in pretend play. This too is well illustrated by Leslie’s experiment. Virtually all of the children in his experiment responded the same way when asked to point to the “empty cup”. How are these orderly patterns to be explained? In everyday life when we acquire new beliefs, we routinely draw inferences and update our beliefs. No one knows how this process works, but no one disputes that it does work. There must be some set of mechanisms subserving inference and updating, and we can simply use another functional grouping to collect these mechanisms under the heading “Inference Mechanisms”. Now, to explain the orderly responses of the children in Leslie’s experiment, we propose that the representations in the pretense box are processed by the same inference mechanisms that operate over real beliefs. Of course, to draw these inferences the child must be able to use real world knowledge about the effects of gravity and so forth, and so Stich and I also suppose that the inferences the child makes during pretense can somehow draw on the child’s beliefs.

This is, I think, a fairly typical statement of one important respect in which belief is often said to be similar to imagination: each is subject to the same inference mechanisms. Nichols includes this chart:



Notice the 'inference mechanisms' that act on beliefs and imaginings alike.

Now I can see well enough that pretense and belief inferences tend to go in the same way. If I know full well that p only if q, and believe p, I'll often come to infer to a belief that q, just as, if I imagine p, I'll often come to infer to imagine q. (Modulo various familiar complications: sometimes I give up the previous belief, etc.) But doesn't just the same thing happen with desire? If I desire that p, and know full well that p only if q, I'll very often, through a very ordinary sort of means-end reasoning, come to desire that q, modulo various familiar complications like the possibility that I'll stop desiring p.

Take a background situation where I know that nothing funny is going on with the cups; gravity is normal, the water is liquid, etc.

Suppose I believe the cup had water in it and has been turned over. Then I'll believe that the cup is now empty.

Suppose I imagine or pretend that the cup had water in it and has been turned over. Then I'll imagine or pretend that the cup is now empty.

Suppose I desire that the cup had water in it and has now been turned over. Then I'll desire that the cup is now empty.

This suggests to me that the similarities between imagination and belief, in contrast with desire, are exaggerated by, e.g., the diagram above. Those inference mechanisms apply to desires just as well as to beliefs and pretenses. Are there similarities in inference mechanisms that distinguish beliefs and pretenses/imaginings from propositional attitudes more generally?

New draft paper on modals and modal epistemology

I've just completed a draft of a new paper on modals and modal epistemology, developing some of the ideas in my last few blog posts, and engaging with Timothy Williamson's discussion of counterfactuals and modal epistemology. Here's the abstract:

Modals and Modal Epistemology

Abstract. I distinguish (§§1-2) two projects in modal epistemology, and suggest (§3) that Timothy Williamson’s treatment of modal epistemology, relating truths of modality to counterfactual conditionals, is best understood as a way of addressing the mystery of why we should have developed cognitive access to facts of metaphysical modality. I offer (§4) a reconstruction of his argument, so interpreted. I compare Williamson’s counterfactual-based approach to metaphysical modality with a treatment in terms of quotidian modals (§§5-6), relating each to the dominant linguistic treatments of modals and conditionals (§§7-8). The insights offered by these linguistic treatments will emphasize the similarity of the counterfactual approach with the quotidian modals approach—in particular, they will demonstrate that the counterfactuals approach does not enjoy the advantage over the latter that Williamson claims for it. The ultimate lesson to be drawn (§9) is that there is a respect in which investigation into metaphysical modality is sui generis; but this is not a respect that renders modal epistemology implausibly mysterious.

The draft is online here. Comments are definitely very welcome -- feel free to email me, or leave a comment to this blog post, or get in touch with me in whatever other way seems like a good idea.

Williamson on modal epistemology and counterfactuals

This post is an exercise in Williamson exegesis. I'm looking primarily at chapter five -- the modal epistemology chapter -- of The Philosophy of Philosophy. (That chapter substantially overlaps a couple of earlier papers as well.) As many readers will know, Williamson emphasises the equivalence of claims of metaphysical modality with particular counterfactuals (such as the ones discussed in my recent post here), and suggests, therefore, that our ordinary imagination-based capacity for the evaluation of counterfactual conditionals brings along with it a capacity for knowledge of metaphysical modality. As Williamson says, "the epistemology of metaphysical thinking is tantamount to a special case of the epistemology of counterfactual thinking."

There are important interpretive questions that are too easily overlooked. The question I'm after right now is just: what in particular is Williamson trying to accomplish in this material? I think that many people are not always clear about this question. (Williamson is one of these people.)

One candidate project is to answer what I'll call the 'how' question:

How do we have modal knowledge?

A possible answer to the how question suggested by Williamson's work, which emphasizes the equivalence of modal claims with certain counterfactuals, is that we acquire modal knowledge by coming to have counterfactual knowledge, and exploiting the connection between counterfactual truths and modal truths. I think understanding Williamson's project in this way would be a mistake.

Counterfactuals and Modals

I like the approach to counterfactuals that treats them as modals. The sentence 'if A were the case, C would be the case' says that, out of some restricted class of possibilities, all the A possibilities are C possibilities. Which restricted class is in play is of course in part a context-sensitive matter. The relevant class of possibilities is relevant for other modal language, too. I've argued, controversially, that this is the case for 'knows'. But there are much less contentious cases, too. Consider bare modals like 'might' and 'must'; these definitely take context-sensitive domains, and those domains look to play central roles in the interpretation of counterfactual conditionals, too.

There is a kind of conflict between sentences like these, uttered back to back in a given conversational context:

(1) If he were to break thorough his chains, he would save the girl.

(2) He couldn't possibly break through his chains.

The 'kind of conflict' here isn't necessarily a matter of semantic inconsistency. (The approach to modals and counterfactuals I have in mind has the second entailing the first -- if there's no possibility of his breaking his chains, then, trivially, all possibilities in which he breaks through his chains are ones in which he kills his captors.) It's rather something like a pragmatic tension. The 'couldn't possibly' claim requires the modal base to be devoid of cases in which he breaks through his chains; such a base renders the counterfactual trivial -- so the counterfactual strongly prefers a context in which there are some chain-breaking possibilities among the modal base. (Compare: "There's nothing in this bottle." "All the air in the bottle is musty.")

Given this connection between bare modals and counterfactual conditionals, it's pretty straightforward to see that certain equivalences will hold as well. In particular, these two sentences will, in any given context, have the same truth value:

(3) He can't phi.

(4) If he were to phi, then p and not-p.

Varieties of Modality

We all know that metaphysical possibility isn't the same thing as physical possibility, or other 'restricted' notions.

It is sometimes suggested that the modifiers ‘metaphysically’, ‘physically’, ‘epistemically’, etc., in phrases like ‘metaphysically possible’ act as restrictors on the more general, univocal, property of possibility. (Compare: someone can be surprisingly wealthy, unjustly wealthy, or extremely wealthy — these are all just more specific ways of being wealthy.) On this model, there is a property — possibility — and modal language attributes it, often specifying the way in which the relevant situation is said to be possible. When we say that it is physically possible that a man should run the 100m-dash in 9.50 seconds, we say that this achievement is among a particular subset of the possible: the physically possible.

This isn't exactly how I think about possibility language, but it's not too far off.

One question raised by this approach concerns just what the unrestricted modality includes. It’s clear enough that the physically possible is a restriction on the metaphysically possible. One might continue to suggest that the metaphysically possible is a subset of the conceptual or logically possible—and perhaps further into various logically impossible ‘possibilities’. Or one might somewhere draw the line. George Bealer, in his contribute to the Gendler & Hawthorne Conceivability and Possibility anthology, draws the line at the metaphysically possible. He writes:

[S]ome people insist on distinguishing logical possibility and metaphysical possibility and so are led to the following: p is logically possible iff p is merely consistent with the laws of logic (i.e., not ruled out by logic alone). This usage, however, invites confusion. There are many logically consistent sentences that express obvious impossibilities (e.g., ‘Bachelors are necessarily women’, ‘Triangles are necessarily circles’, ‘Water contains no hydrogen’). If you buy into calling mere logical consistency a kind of possibility, why not keep going? For example: p is ‘sententially possible’ iff p is consistent with the laws of sentential logic. Then, since ‘Everything is both F and not F’ is not ruled out by sentential logic (quantifier logic is what rules it out), would it be possible in some sense (i.e., sententially possible) that everything is both F and not F?! Certainly not my ear! (78-79)

I don't think this comprises a very good argument, for at least two reasons.

First, the logical structure of the argument for drawing the line at metaphysical possibility is suspect. It follows a particular erroneous form of a slippery slope argument: if you permit X (which doesn’t seem too bad), then what’s to stop you from going on to permit Y (which seems terrible)? The difference in felt terribleness, if there is one, would provide just the needed traction between X and Y in order to avoid the slip. Remember that drawing the line at metaphysical possibility represents a substantive choice; one might try draw it even more narrowly — at physical possibility, say. Imagine a philosopher who refuses to countenance those ‘metaphysical possibilities’ which violate the laws of physics; he will insist that they’re in no sense possible. Against someone like Bealer, who believes in such physically impossible possibilities, he might offer just the same retort: “if you buy into calling mere metaphysical consistency a kind of possibility, then why not keep going?” If there is reason to countenance metaphysical possibilities—and I agree with Bealer that there is—then presumably, we will justify it by reference to the useful work to which thinking about metaphysical modality can be put. But for all Bealer has said, it may well be that further conceptual or logical possibilities can be put to similar work. (This seems to me very plausible.)

The second reason to be concerned with Bealer’s argument is that he makes an insufficient case for the undesirability of the bottom of his slippery slope. Bealer apparently finds the suggestion that there is a sense in which this contradiction is possible implausible. He doesn’t say why, but the invocation of how it strikes his ear suggests it may be based in a linguistic intuition; it just sounds terrible, perhaps, to say that there’s a sense in which it is possible that everything is both F and not F. But that there is some sense in which it possible does not, of course, imply that it’s a very interesting sense, or one that ordinary speakers are used to thinking about. Bealer ostends a notion of ‘sentential possibility’, abstracting away from any use to which thinking about it might be put. It shouldn’t come as any surprise, then, that, so presented, we shouldn’t have any interest in thinking about such ‘possibilities’. That doesn’t mean they’re not there, ready for us to take them up if and when the course of inquiry demands it. (Again, a philosopher who thought of physical possibility the way Bealer feels about metaphysical possibility might respond just the same way Bealer does, in response to what is conventionally recognized as the physically impossible metaphysically possible. "It's just not possible in any sense for humans to travel faster than light." Actually, I suspect that most people who haven't studied metaphysics are likely to respond this way.)