Tim Schroeder, “Desire”:http://compass.bw.semcs.net/subject/philosophy/article_view?parent=browse&sortby=date&last_results=&browse_id=635179&article_id=phco_articles_bpl047 in “Philosophy Compass”:http://compass.bw.semcs.net/subject/philosophy/.

bq. Desires move us to action, give us urges, incline us to joy at their satisfaction, and incline us to sorrow at their frustration. Naturalistic work on desire has focused on distinguishing which of these phenomena are part of the nature of desire, and which are merely normal consequences of desiring. Three main answers have been proposed. The first holds that the central necessary fact about desires is that they lead to action. The second makes pleasure the essence of desire. And the third holds that the central necessary fact about desires is that they open us to reward-based learning.