 An important step away from a narrow understanding of Humean moral psychology is taken if one recognizes the existence of what Rawls has called “principle-dependent desires” (Rawls 1996, 82–83; Rawls 2000, 46–47). These are desires whose objects cannot be characterized without reference to some rational or moral principle. An important special case of these is that of “conception-dependent desires,” in which the principle-dependent desire in question is seen by the agent as belonging to a broader conception, and as important on that account (Rawls 1996, 83–84; Rawls 2000, 148–152). For instance, conceiving of oneself as a citizen, one may desire to bear one’s fair share of society’s burdens. Although it may look like any content, including this, may substitute for Ψ in the Humean conception of desire, and although Hume set out to show how moral sentiments such as pride could be explained in terms of simple psychological mechanisms, his influential empiricism actually tends to restrict the possible content of desires. Introducing principle-dependent desires thus seems to mark a departure from a Humean psychology. As Rawls remarks, if “we may find ourselves drawn to the conceptions and ideals that both the right and the good express … , [h]ow is one to fix limits on what people might be moved by in thought and deliberation and hence may act from?” (1996, 85). While Rawls developed this point by contrasting Hume’s moral psychology with Kant’s, the same basic point is also made by neo-Aristotelians (e.g., McDowell 1998). 