The goal of this book is to present the science behind decision-making in humans. In particular, one of the main concepts the author puts forward in the book is that, if our brain is a decision-making machine, then that machine can break down; it can have a "failure" or "vulnerabilities." And that it is possible to understand that machinery (even to understand that it is a machinery), without losing the potential to appreciate all the things that make us human (including our decision-making ability). Here the author brings together cutting edge research in psychology, robotics, economics, neuroscience, and the new fields of neuroeconomics and computational psychiatry, to offer a unified theory of human decision-making. Most importantly, he shows how vulnerabilities, or "failure-modes," in the decision-making system can lead to serious dysfunctions, such as irrational behavior, addictions, problem gambling, and PTSD. Ranging widely from the surprising roles of emotion, habit, and narrative in decision-making, to the larger philosophical questions of how mind and brain are related, what makes us human, the nature of morality, free will, and the conundrum of robotics and consciousness, this work offers fresh insight into one of the most complex aspects of human behavior.