The standard economic model shares with ancient Greek philosophy one extremely important underlying assumption that concerns the defining characteristic of the human animal, namely, rationality. This chapter describes the approach of revealed choice utilitarianism (RCU). It discusses the origins of the approach as well as show how it emerged as the theory of decision-making that has dominated not only modern economic theory, but also to spread its influence across the social sciences. The chapter presents an account of the thinness of the theory. This involves a critical review of RCU as well as a review of the attempts to modify, or "thicken", it. Next, the chapter provides a detailed accounting of the understanding of "reason" and "rationality" as it is understood by the ancient thinkers. Finally, it details some ways that contemporary philosophers have up-dated the ancient virtue ethics and suggests briefly how their insights might point the way forward for policy discussion.