The aim of the research project is to explore the relationship between Darwinian evolution and the theory of rational choice, from an overarching philosophical perspective. There exist deep and interesting links, both conceptual and formal, between evolutionary theory and rational choice theory. These arise because a notion of optimization, or maximization, is central to both bodies of theory. Evolutionary biologists typically assume that because of natural selection, animals will behave as if they are trying to maximize their Darwinian fitness (for some appropriate measure of fitness). This is the guiding assumption in much work on animal behaviour. Rational choice theorists typically assume that humans will behave as if they are trying to maximize a utility function. This is the guiding assumption in much work in social science. Thus there is a close parallel between the notion of fitness in evolutionary theory and the notion of utility in the theory of rationality. This parallel has been noted before, by workers in a number of fields, but has never been systematically explored from a philosophical perspective, and has been the source of considerable confusion in the literature.The research project has three inter-related strands. The first is to explore the thematic links between rational choice theory and Darwinian evolution, focusing on the fitness/utility parallel. The second is to examine whether there is an evolutionary foundation for the norms of traditional rational choice theory, such as expected utility maximization, Bayesian updating, and transitivity of preference. The third is to study the tension between individual self-interest and group welfare as it arises in both an evolutionary and a rational-choice context.The research will be carried out by the PI, a team member, two post-docs and a PhD student, using an innovative inter-disciplinary methodology. Research outputs will include a series of articles in leading journals and a monograph.