Using psychology, philosophy, and the theory of evolution, this book examines whether egoism is the rule, or whether altruism plays a key role in both nature and human psychology. A strong argument for the existence and importance of both psychological and evolutionary altruism is built. A separate case for each of these ideas is made and the relationship between them is explored. In order to support the idea of evolutionary altruism, it is shown that Darwin's once discredited idea of group selection has been a significant force in evolution. In order to make the case for psychological altruism, the idea that altruistic actions generally conceal self-serving motives is challenged.