Self-deception does terrible harm to us, to our communities, and to the planet. But if it is so bad for us, why is it ubiquitous? In Useful Delusions, Shankar Vedantam and Bill Mesler argue that, paradoxically, self-deception can also play a vital role in our success and well-being. The lies we tell ourselves sustain our daily interactions with friends, lovers, and coworkers. They can explain why some people live longer than others, why some couples remain in love and others don't, why some nations hold together while others splinter. Filled with powerful personal stories and drawing on new insights in psychology, neuroscience, and philosophy, Useful Delusions offers a fascinating tour of what it really means to be human.