This book is a provocative contribution to contemporary ethical theory challenging foundational conceptions of character that date back to Aristotle. John Doris draws on behavioral science, especially social psychology, to argue that we misattribute the causes of behavior to personality traits and other fixed aspects of character rather than to the situational context. More often than not it is the situation not the nature of the personality that really counts. The author elaborates the philosophical consequences of this research for a whole array of ethical theories and shows that, once rid of the misleading conception of motivation, moral psychology can support more robust ethical theories and more humane ethical practices.