This chapter focuses an ongoing critical debate between Jan Narveson and Peter Danielson over the role of two models the games of prisoner's dilemma (PD) and chicken of the state of nature in contractarian political philosophy. If Narveson finds the PD preferable to chicken, there are likely two reasons, one based on rationality, the other on morality, respectively. Following David Gauthier, Narveson assumes that there is a way for rational agents to coordinate on the second-best outcome in the PD. The chapter focuses on Narveson's claim to bring rational choice to bear on ethics. It explores the link between rational choice, ethical theory and real-world behaviour. Evolutionary game theory (EGT) shifts the focus from single complex rational agents choosing strategies, to populations of simpler agents exemplifying strategies. The rational choice/game-theoretic approach tempts one to oversimplify and see the world in its terms.