I want to lay down a few constitutive features that, it seems to me, desires must have in order to be desires. I welcome criticisms of the features I mention, and would love to see other suggestions added. I suggest three features (I will address the last two in future posts): conditions of satisfaction, affect, and representational content.
The important distinction, I think, is between occurrent desires (for which the word is normally reserved in ordinary language) and dispositional desires, which are a trickier breed of animal. This is all further complicated by the fact that what we ordinarily mean by “desire” is only one of the many different kinds of pro attitudes. Here I will be using “desire” confusingly to stand for both the narrower and the broader class; that is, I will be taking anything falling under the pro attitude heading as a desire, but will also appeal to the narrower sense. This creates particular complications in light of the argument many have raised against the BDI (belief-desire-intention) theory of action, i.e., the argument that for plenty of actions no desire is needed—the making of a promise, for example, is taken as providing sufficient incentive for keeping it. To say that that incentive itself must be a desire on formal grounds (i.e., because all actions involve desires) would be question-begging. The key, then, is precisely to try to give the constitutive features of desire, such that some such entity can be posited in the etiology of any action without begging the question.
1. Aiming at Satisfaction. Desires necessarily aim at their own satisfaction. I think this is fairly uncontroversial: it is hard to imagine what it would mean to have a desire that does not contain a push toward its fulfillment. Before moving on to this issue, let me note something I think is important: it is in a sense the desire, not the agent, that aims at satisfaction. The agent can, of course, aim at the satisfaction of the desire, but she does so by adopting or incorporating the desire. This is clear from the fact that we have (or can have) plenty of desires that we do not seek to fulfill—violent, fantastic, or incompatible with our other goals. These desires do have their own conditions of satisfaction; but those are not the agent’s conditions unless the agent makes them her own. I will develop this point in a future post, but I think it is important to the literature on the place of agents in event-causal theories of action. Another brief hint at the issue: akrasia clearly involves satisfying some desire; what makes it problematic is the issue of how agents can be taken to commit themselves to actions that aim to satisfy desires the agent has not (or not wholeheartedly) endorsed.
The conditions of satisfaction of occurrent desires are also conditions of their termination: if you have an occurrent desire, and you fulfill it, the desire goes away. If it fails to go away, that means you have not fulfilled the conditions of satisfaction; perhaps you haven’t quite got what those conditions are, or perhaps you’ve only partially satisfied them.
Dispositional desires are more complicated. First off, most of them are not what we would—in everyday language—call desires. Imagine, for example, that whenever I see a chocolate cake, given certain conditions (the cake is not too expensive, I am not already full, etc) I will eat a piece. What this indicates is a reliable disposition toward chocolate cake, but it would be awkward—in ordinary language—to call this a desire. Rather, we might be drawn to another alternative: the disposition is really a disposition toward desiring chocolate cake whenever one is present, namely, a disposition toward developing occurrent desires of a certain kind under certain conditions. But this alternative has serious problems. For one, it is not at all clear that an occurrent desire needs to be present every time I encounter a cake—the disposition alone is sufficient to explain the action, both rationally and causally. Second, this gets even more complicated for non-appetitive things, such as showering regularly (some people really enjoy showering and want to do so as much as possible; I am thinking more of the people who do it just because it is socially required). A disposition to shower regularly provides a good predictor of the behavior of many people, but to say that all people who shower regularly have occurrent desires to shower whenever they do so seems excessive. Similar points for brushing teeth, dressing appropriately for work, and so on.
This latter point is sometimes raised as criticism of the BDI model of action. The idea of the criticisms is something like this: if you assume that occurrent desires are needed to rationalize every action, then you are merely introducing a theoretical element. There are certainly plenty of actions that we undertake without the presence of occurrent desires, and inserting these as premises in a practical syllogism that rationalizes every action simply distorts the nature of action in favor of a theory (externalists about practical reason are particularly prone to such arguments). But the criticism doesn’t work. We can be motivated dispositionally without any occurrent desires taking place. The question is whether these dispositions deserve to be called desires at all; can’t belief alone be enough?
Brandom, for example, argues that we really do not need desire as a premise in the practical syllogism because such syllogisms can involve material, rather than formal, inferences. That is, reasoning from “I am going out today” to “therefore I shall take a shower” is perfectly legitimate; we do not need to insert the extra premise that “I want to be clean around other people”; the premise is already implied, insofar as another premise (e.g., “I want to be dirty around other people”) is lacking. But I don’t think this sort of argument against the BDI theory is right. That the inference goes through in this case shows something about my motivational states (broadly construed), e.g., that I belong to a culture where regular showering is expected. Were I from a culture where it is not, to be sure, my regular showering would require a further explanation. But this does not mean that, in the first case, the postulate of a “desire” is mistaken. It means only that crude BDI theories, ones that take the beliefs and desires that enter into an action as necessarily occurrent states, are mistaken. Dispositional desires may well play a role; it is only that, against a social background in which the disposition in question is assumed, the particular disposition in question is not informative or particularly worth mentioning. But the disposition is still needed as part of the explanation of my action, even though we can easily leave it off when talking to other members of our society. It cannot be eliminated in favor simply of the background existence of social convention, or my recognition of the convention. For one thing, not everyone accepts social conventions; for another, there is no reason to think that just because something is a social convention, it cannot be a desire—many, if not most, of our desires are conventional in nature.
Positing a state—occurrent or dispositional—that is both goal directed and irreducible to either beliefs or social conventions or simply commitments (a disposition to keep my promises, for example, cannot be explained simply by reference to my beliefs that I have made commitments) seems necessary to the explanation of actions.