This book is about self-deception and lack of self-control or wishful thinking and acting against one's own better judgement. Steering a course between the skepticism of philosophers, who find the conscious defiance of reason too paradoxical, and the tolerant empiricism of psychologists, it compares the two kinds of irrationality, and relates the conclusions drawn to the views of Freud, cognitive psychologists, and such philosophers as Aristotle, Anscombe, Hare and Davidson.