Joy is appropriate when you learn that something happens that you *really really* want. Despair is appropriate when you learn that something happens that you *really really* don’t want to happen. Emotional indifference is appropriate when you learn that something happens which you neither want nor don’t want–which is null for you. And there are grades of appropriate emotional responses—from joy to happiness, to neutrality, to sadness, to despair. I take it that we all know the differences in the intensity of the feeling in each case, and have no trouble distinguishing the valence as positive or negative.
More than just level and intensity of desire matters to the appropriateness of an emotional response. You might not feel joy in something you already took for granted, for example. Belief-like as well as desire-like states matter when we assess an overall pattern of belief/desire/emotional states as to whether they “hang together” in an appropriate way–whether they are rationally coherent. But levels and intensities of desire obviously matter (I think).
Suppose you were charged with interpreting a person about whose psychology you knew nothing beforehand. I tell you what they choose out the options facing them in a wide variety of circumstances, in response to varying kinds of evidence. This is a hard task for you, even given the rich data, but if you assumed the personal is rational you could make progress. But if *all* you did was attribute beliefs and desires which (structrurally) rationalize the choices and portray the target as responding rationally to the evidence, then there’d be a distintive kind of in-principle limit built into the task. If you attributed utility and credences which make the target’s choices maximize expected utility, and evolve by conditionalization on evidence, then you’d get a fix on what the target prefers to what, but not, in any objective sense, how much more they prefer one thing to another, or whether they are choosing x over y because x is the “lesser or two evils” or the “greater of two goods”. If you like, think of two characters facing the same situation–an enthusiast who just really likes the way the world is going, but mildly prefers some future developments to others, and the distraught one, who thinks the world has gone to the dogs, but regards some future developments as even worse than others. You can see how the the choice-dispositions of the two given the same evidence could match despite their very different attitudes. So given *only* information about the choice-dispositions of a target, you wouldn’t know whether to interpret the target as an enthusiast or their distraight friend.
While the above gloss is impressionistic, it reflects a deep challenge to the attempt to operationalize or otherwise reduce belief-desire psychology to patterns of choice-behaviour. It receives its fullest formal articulation in the claim that positive affine transformations of a utility function will preserve the “expected utility property”. (Any positive monotone transformation of a utility function will preserve the same ordering over options. The mathetically interesting bit here is that the positive affine transformations of utility function guarantee that the pattern between preferences over outcomes and preferences over acts that bring about those outcomes, mediated by credences in the act-outcome links, are all preserved).
One reaction to this in-principle limitation is to draw the conclusion that really, there are no objective facts about the level of desire we each have in an outcome, or how much more desirable we find one thing than another. A famous consequence of drawing that conclusion is that no objective sense could be made out of questions like: do I desire this pizza slice more or less than you do? Or questions like: does the amount by which I desire the pizza more than the crisps exceed the amount you desire the pizza more than the crisps? And clearly if desires aren’t “interpersonally comparable” in this sort of ways, certain ways of appealing to them within accounts of how its appropriate to trade off one person’s desires against another’s won’t make sense. A Rawlsian might say: if there’s pizza going spare, give it to the person for whom things are going worst (for whom the current situation, pre-pizza, is most undesirable). A utilitarian might say: if everyone is going to get pizza or crisps, and everyone prefers pizza to crisps, give the pizza to the person who’ll appreciate it the most (i.e. prefers pizza over crisps more than anyone else). If the whole idea of interpersonal comparisons of level and differences of desirability are nonsense, however, then those proposals write cheques that the metaphysics of attitudes can’t pay.
(As an aside, it’s worth noting at this point that you could have Rawlsian or utilitarian distribution principles that work with quantities other than desire—some kind of objective “value of the outcome for each person”. It seems to me that if the metaphysics of value underwrites interpersonally comparable quantities like the levels of goodness-for-Sally for pizza, and goodness-difference-between-pizza-and-crisps-for-Harry, then the metaphysics of desires should be such that Sally and Harry’s desire-state will, if tuned in correctly, reflect these levels and differences.)
It’s not only the utilitarian and Rawlsian distribution principles (framed in terms of desires) that have false metaphysical presuppositions if facts about levels and differences in desire are not a thing. Intraindividual ties between intensities of emotional reaction and strength of desire, and between type of emotional reaction and valence of desire, will have false metaphysical presuppositions if facts about an individual’s desire are invariant under affine tranformation. Affine transformations can change the “zero point” on the scale on which we measure desirability, and shrink or grow the differences between desirabilities. But we can’t regard zero-points or strengths of gaps as merely projections of the theorist (“arbitrary choices of unit and scale”) if we’re going to tie to them to real rational constraints on type and intensity of emotional reaction.
However. Suppose in the interpretive scenario I gave you, you knew not only the choice-behaviour of your target in a range of varying evidential situations, but also their emotional responses to the outcome of their acts. Under the same injunction to find a (structurally) rationalizing interpretation of the target, you’d now have much more to go on. When they have emotional reactions rationally linked to indifference, you would attribute a zero-point in the level of desirability. When an outcome is met with joy, and another with mere happiness, you would attribute a difference in desire (of that person, for that outcome) that makes sense of both. Information about emotions, together with an account of the rationality of emotions, allow us to set the scale and unit in interpreting an individual, in a way choice-behaviour alone struggles to. As a byproduct, we would then have a epistemic path to interpersonal comparability of desires. And in fact, this looks like an epistemic path that’s pretty commonly available in typical interpersonal situations–the emotional reactions of others are not *more* difficult to observe than the intentions with which they act or the evidence that is available to them. Emotions, choices and a person’s evidence are all interestingly epistemically problematic, but they are “directly manifestable” in a way that contrasts with the beliefs and desires that mesh with them.
The epistemic path suggests a metaphysical path to grounding levels and relative intensities of desires. Just as you can end up with a metaphysical argument against interpersonal comparability of desires by commiting oneself to grounding facts about desires in patterns of choice-behaviour, and then noting the mathematical limits of that project, you can get, I think, a metaphysical vindication of interpersonal comparabiilty of desire by including in the “base level facts” upon which facts about belief and desire are grounded facts about, type, intensity and valence of intentional emotional states. As a result, the metaphysical presuppositions of the desire-based Rawlsian and utilitarian distribution principles are met, and our desires have the structure necessary to capture and reflect level and valence of any good-for-x facts that might feature in a non-desire based articulation of those kind of principles.
In my book The Metaphysics of Representation I divided the task of grounding intentionality into three parts. First, grounding base-level facts about choice and perceptual evidence (I did this by borrowing from the teleosemantics literature). Then grounding belief-desire intentional facts in the base-level facts, via a broadly Lewisian metaphysical form of radical interpretation. (The third level concerned representational artefacts like words, but needn’t concern us here). In these terms, what I’m contemplating is to add intensional emotional states to the base level, using that to vindicate a richer structure of belief and desire.
Now, this is not the only way to vindicate levels and strength of desires (and their interpersonal comparability) in this kind of framework. I also argue in the book that the content-fixing notion of “correct interpretation” should use a substantive conception of “rationality”. The interpreter should not just select any old structurally-rationalizing interpretation of their target, but will go for the one that makes them closest to an ideal, where the ideal agent responds to their reasons appropriately. If an ideal agent’s strength and levels of desire are aligned, for example, to the strength and level of value-for-the-agent present in a situation, then this gives us a principled way to select between choice-theoretically equivalent interpretations of a target, grounding choices of unit and scale and interpersonal comparisons. I think that’s all good! But I think that including emotional reactions as constraining factors in interpretation can help motivate the hypothesis that there will be facts about the strength and level of desire *of the ideal agent*, and gives a bottom-up data-based constraint on such attributions that complements the top-down substantive-rationality constraint on attributions already present in my picture.
I started thinking about this topic with an introspectively-based conviction that *of course* there are facts about how much I want something, and whether I want it or want it not to happen. I still think all this. But I hope that I’ve now managed to identify how those convinctions to their roles in a wider theoretical edifice–their rational interactions with *obvious* truths about features of our emotional lives, the role of these in distribution principles, which give a fuller sense of what is at stake if we start denying that the metaphysics of attitudes has this rich structure. I can’t see much reason to go against this, *unless* you are in the grip of a certain picture of how attitudes get metaphysically grounded in choice-behaviour. And I like a version of that picture! But I’ve also sketched how the very links to emotional states give you a version of that kind of metaphysical theory that doesn’t have the unwelcome, counterintuitive consequences its often associated with.