When it comes to human nature, it’s no secret that smart people do stupid shit. But why, exactly, do people find an expensive pill more efficient than a cheaper equivalent? Why do people keep stuffing their faces at all-you-can-eat buffets when they’re already full? And what the hell makes people decide to engage in unprotected sex with strangers when they’ve got a condom? MIT Professor of Behavioral Economics Dan Ariely sets out to answer such questions and more in his latest book, Predictably Irrational: The Hidden Forces That Shape Our Decisions. Sure, Ariely wants to assist you in improving your life by identifying patterns of misguided behavior, but Predictably Irrational isn’t some New Age self-help book: It’s a scientific experiment–laden look into why members of what is supposedly Earth’s most intelligent species so often act like complete idiots. Ariely discusses and signs copies of his work at 7 p.m. at Politics and Prose, 5015 Connecticut Ave. NW. Free. (202) 364-1919.