It is predictable enough that any popular social science book will inspire antipathy among academic social scientists—for being too simple, too fun, too easily understood. After all, what do university intellectuals offer the general public if not sweaty handfuls of painstakingly gathered arcana? And here is the successful crossover author just giving the stuff away between four-color covers!

So it is with some wistful jealousy that the tower-bound academic, staring down another “revise and resubmit” notice from a peer-reviewed journal, contemplates the immense popularity of a book like Freakonomics. Well, she thinks, how did the authors roost on the best-seller list in a season of beach reads? How did they get the subtitular “hidden side of everything” to thrill like an airport mystery or an addiction-recovery memoir? Your students are already slack-jawed over their suspiciously crisp copies of The Protestant Ethic; maybe this is something they could get excited about.

The coauthors—one gathers that Steven Levitt does the thinking, while Stephen Dubner does the glossing—begin by shuffling their feet in self-deprecation. Levitt, they claim, despite being a University of Chicago economist, is practically an ingénue when it comes to his chosen field. “‘I just don’t know very much about the field of economics,’” Levitt tells journalist Dubner at their first meeting, “swiping the hair from his eyes.” “‘I’m not good at math. . . . [I]f you ask me about taxes—I mean, it would be total fakery if I said I knew anything about any of those things.’” Economics needn’t be dismal, they seem to be saying, or a science. This ostensible mistrust of obscurantist expertise is doubtless partly responsible for the book’s sales and its expansion into a Times Magazine column. In a society where most people understand only two things about economics—that they don’t understand it, and that it dictates their lives—Levitt and Dubner promise plain talk, along with a fund of offbeat anecdotes.

It’s true that the book dispenses with the model-building and analysis of structural features (such as business cycles and monetary policy) that usually characterize macroeconomic research. Levitt focuses instead on individual decision-making. The strategy, repeated in each chapter, is to find a situation with colorful particulars (sumo wrestling! crack dealing in the projects!) and then to shake these off to reveal the core rationality that alone animates all players. Surface eclecticism belies an elemental monomania. The authors claim that “incentives are the cornerstone of modern life. And understanding them—or, often, ferreting them out—is the key to solving just about any riddle, from violent crime to sports cheating to online dating.” Levitt’s arguments are all based on the idea that human action is oriented toward achieving positive incentives and avoiding negative sanctions. The authors describe the doctrine of incentives as Fem>Freakonomics’s unifying theme: a self—your self, my self, anyone’s—is driven by a calculative rationality, bent on achieving some version of the good life. Fellow Chicago professor Gary Becker bequeathed this meager conception of human nature to economics in the 1970s.