If an agent is to be moved to action, then two requirements have to be fulfilled: first, the agent must possess beliefs about the way things actually are, about the actions possible given the way things are, and about the likely effects of those actions on how things are; and, second, the agent must have or form desires to change the way things are by resorting to this or that course of action. The beliefs tell the agent about how things are and about how they can be altered; the desires attract the agent to how things are not but can be made to be.

This rough sketch of beliefs and desires is widely endorsed in contemporary philosophy; it derives in many ways from the seminal work of the eighteenth century Scottish philosopher David Hume. The striking thing about it, from the point of view of desire, is that it characterizes desire by the job desire does in collaborating with belief and thereby generating action: it characterizes desire by function, not by the presence of any particular feeling. The account raises a host of questions. Is desire an entirely different sort of state from belief, for example, and from belief-related states like habits of inference? Does desire have to answer to the considerations of evidence and truth that are relevant to belief and inference? How does desire relate to preference and choice? And how does desire relate to the values that we ascribe to different courses of action and that influence us in what we do?

Citing this article:
Pettit, Philip. 'Desire'. Routledge Encyclopedia of Philosophy 1998: Accessed (May 30, 2015).
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