Behavioral economist Dan Ariely is a funny guy on a mission. As director of the Center for Advanced Hindsight, he insists on a commitment to absurdity, but there is nothing cynical about his approach to human behavior. In his previous book, Predictably Irrational, Ariely exposed our false assumptions about the rationality of markets and individuals with plenty of surprising and humorous examples. Our irrationality may be predictable, but our ability to forecast this behavior doesn’t alter the conditions that give rise to it. Recognizing this, he adopts his paradoxical mission: to design better economic and social institutions to protect us from our confident pursuit of rational economic and social institutions.

In The (Honest) Truth about Dishonesty, Ariely applies his experimental approach to how we “lie to everyone — especially ourselves.” The book discusses the powerful ways irrationality affects our lives and begins with a critique of those who think dishonesty is really the result of a rational cost-benefit calculation. In a series of experiments, Ariely neatly shows that neither the size of the reward nor the probability of getting caught substantially affects the likelihood of dishonest behavior. The cost-benefit framework for understanding cheating just doesn’t pay off.

Ariely sees two conflicting motivations at work in dishonest behavior. On the one hand, we want to view ourselves as honorable, and on the other hand we want to get as much stuff as possible. We want the benefits of cheating, and we want to see “ourselves as honest, wonderful people.” So we fudge. We fool ourselves and others. Our “cognitive flexibility” cuts us so much slack that we often don’t even perceive ourselves as getting away with anything. This flexibility keeps the contradictions between our principles and our behavior beyond the horizon of our consciousness.

The (Honest) Truth about Dishonesty is full of examples of how we deceive ourselves about cheating. Somehow it seems to most people less like cheating to favorably reposition a golf ball with one’s foot than to move it with one’s hand. Tapping the ball with your club is best of all! As a rule, “cheating becomes much simpler when there are more steps between us and the dishonest act.” We are more averse to directly taking some cash off the table, but much more likely to behave dishonestly to get a reward that in the end has cash value. Psychological distance is key.

Dishonesty isn’t always so bad. The author describes how doctors and nurses lied to him repeatedly when as a teenager he was recovering from severe burns that almost killed him. If they had told him the brutal truth, he might not have mustered the strength to go on. They didn’t want him anticipating excruciating pain that he was in any case powerless to avoid. The pain was real, but the altruistic dishonesty of his caregivers eased his suffering.

Ariely notes that “we quickly and easily start believing whatever comes out of our own mouths,” which means that once we take credit for something, we are likely to really believe that we deserve it. When students are induced to cheat on tasks in an experimental situation, they start to believe their skill level has increased. They certainly realize they are, say, using an answer key to “solve” a problem. Nonetheless they begin to inflate their perception of their own competence at problem solving. This kills two birds with one stone. They don’t feel guilty for having cheated, and since they’ve forgotten about the cheating, they feel better about their performance.