This book offers a sustained critique of individualism in psychology, a view that has been the subject of debate between philosophers such as Jerry Fodor and Tyler Burge for many years. The author approaches individualism as an issue in the philosophy of science and by discussing issues such as computationalism and the mind's modularity he opens the subject up for non-philosophers in psychology and computer science. Professor Wilson carefully examines the most influential arguments for individualism and identifies the main metaphysical assumptions underlying them. Since the topic is so central to the philosophy of mind, a discipline generating enormous research and debate, the book has implications for a very broad range of philosophical issues including the naturalisation of intentionality, psychophysical supervenience, the nature of mental causation, and the viability of folk psychology.