This is an iconoclastic volume on the causes and effects of irrational behaviour. Why do doctors, army generals, high-ranking government officials, and other people in positions of power make bad decisions that cause harm to others? On the other hand, why do people insist on sitting through an awful play or film just because the tickets were expensive? Irrational beliefs and behaviour are virtually universal. It is not only gamblers and parapsychologists that fall into simple statistical traps to do with sample sizes or simple assumptions, but experts of all types, selection committees, and everyday people. "Irrationality" is an iconoclastic volume that draws on a mass of intriguing research to examine why we are irrational, the different types of irrationality, the damage it does us, and the possible cures. It also argues that we could significantly reduce irrationality and its effects - but only if we first recognize just how irrational we really are.