  The dispute between Schroeder and Morillo over how to interpret the neural structure that is the unique common cause of phenomena such as action and pleasure highlights one way in which scientific research can become important to philosophical theories of desire. The dopamine-releasing reward system is said by Schroeder to be a cause of pleasure, but by Morillo to be the neural realization of pleasure (when active). Evidence that the reward system realizes pleasure comes principally from the fact that its activity coincides with pleasure (reviewed in Berridge 2003), and from the fact that stimulating the reward system (via drugs or electrodes) is known to cause pleasure (classics of this literature are reviewed in Stellar and Stellar 1985). But this evidence is also compatible with the theory that the reward system is one normal cause of pleasure. Evidence for this latter view has come in the form of evidence that some pleasure-causing drugs work independently of the reward system (reviewed in Berridge 2003), in the form of evidence that rats deprived of their reward systems can still experience gustatory pleasure (Berridge and Robinson 1998), and in the form of reasonable candidates for neural realizers of pleasure that are located causally “downstream” from the reward system (reviewed in Berridge 2003 in support of one candidate structure; a different candidate is defended in Schroeder 2004).