This work examines the principle of economic man as presented by Simon Blackburn in Ruling Passions. The principle of economic man states that rational agents always act in ways that maximize their utility. Blackburn suggests that this principle can be interpreted in three ways. First, it could be taken to be an empirical claim, where utility is a measure of empirical benefit to the agent and all agents aim (self-interestedly) to maximize this benefit to themselves. Second, it could be taken to be a normative recommendation, where utility is a measure of empirical benefit to the agent and it is suggested that agents act in ways that maximize this benefit to themselves. Blackburn rejects these two interpretations in favor of a third analytic interpretation. Under this interpretation utility is a mathematical representation of preference orderings, which are in turn mathematical representations of actual choices. This makes it true by definition that all choices maximize utility. Blackburn's analytic interpretation, however, has problems of its own. I show that the theoretical assumptions Blackburn employs to render his interpretation a useful scientific tool fail, and so too the usefulness of his interpretation. I suggest a fourth alternative interpretation, one that combines the strengths of the analytic interpretation with the strengths of the empirical interpretation Blackburn hastily rejected. This new interpretation brings with it its own theoretical assumptions, and I attempt to elucidate these assumptions and show that they are minimally controversial. Finally, I acknowledge that the useful scientific application of my proposed interpretation is threatened by the epistemic worry of access to other minds. However, I attempt to show that a greater unification of empirical social science can greatly help avoid these epistemic difficulties, thus allowing empirical application of the principle of economic man.