Book Review: David Berreby on Dan Ariely's 'Predictably Irrational'

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By David Berreby
Published: March 14, 2008

For years, the ideology of free markets bestrode the world, bending politics as well as economics to its core assumption: market forces produce the best solution to any problem. But these days, even Bill Gates says capitalism’s work is “unsatisfactory” for one-third of humanity, and not even Hillary Clinton supports Bill Clinton’s 1990s trade pacts.

Another sign that times are changing is “Predictably Irrational,” a book that both exemplifies and explains this shift in the cultural winds. Here, Dan Ariely, an economist at M.I.T., tells us that “life with fewer market norms and more social norms would be more satisfying, creative, fulfilling and fun.” By the way, the conference where he had this insight wasn’t sponsored by the Federal Reserve, where he is a researcher. It came to him at Burning Man, the annual anarchist conclave where clothes are optional and money is banned. Ariely calls it “the most accepting, social and caring place I had ever been.”

Obviously, this sly and lucid book is not about your grandfather’s dismal science. Ariely’s trade is behavioral economics, which is the study, by experiments, of what people actually do when they buy, sell, change jobs, marry and make other real-life decisions.

To see how arousal alters sexual attitudes, for example, Ariely and his colleagues asked young men to answer a questionnaire – then asked them to answer it again, only this time while indulging in Internet pornography on a laptop wrapped in Saran Wrap. (In that state, their answers to questions about sexual tastes,, violence and condom use were far less respectable.) To study the power of suggestion, Ariely’s team zapped volunteers with a little painful electricity, then offered fake pain pills costing either 10 cents or $2.50 (all reduced the pain, but the more expensive ones had a far greater effect). To see how social situations affect honesty, they created tests that made it easy to cheat, then looked at what happened if they reminded people right before the test of a moral rule. (It turned out that being reminded of any moral code – the Ten Commandments, the non-existent “M.I.T. honor system” – caused cheating to plummet.)

These sorts of rigorous but goofy-sounding experiments lend themselves to a genial, gee-whiz style, with which Ariely moves comfortably from the lab to broad social questions to his own life (why did he buy that Audi instead of a sensible minivan?). He is good-tempered company – if he mentions you in this book, you are going to be called “brilliant,” “fantastic” or “delightful” – and crystal clear about all he describes. But “Predictably Irrational” is a far more revolutionary book than its unthreatening manner lets on. It’s a concise summary of why today’s social science increasingly treats the markets-know-best model as a fairy tale.

At the heart of the market approach to understanding people is a set of assumptions. First, you are a coherent and unitary self. Second, you can be sure of what this self of yours wants and needs, and can predict what it will do. Third, you get some information about yourself from your body – objective facts about hunger, thirst, pain and pleasure that help guide your decisions. Standard economics, as Ariely writes, assumes that all of us, equipped with this sort of self, “know all the pertinent information about our decisions” and “we can calculate the value of the different options we face.” We are, for important decisions, rational, and that’s what makes markets so effective at finding value and allocating work. To borrow from H. L. Mencken, the market approach presumes that “the common people know what they want, and deserve to get it good and hard.”

What the past few decades of work in psychology, sociology and economics has shown, as Ariely describes, is that all three of these assumptions are false. Yes, you have a rational self, but it’s not your only one, nor is it often in charge. A more accurate picture is that there are a bunch of different versions of you, who come to the fore under different conditions. We aren’t cool calculators of self-interest who sometimes go crazy; we’re crazies who are, under special circumstances, sometimes rational.

Ariely is not out to overthrow rationality. Instead, he and his fellow social scientists want to replace the “rational economic man” model with one that more accurately describes the real laws that drive human choices. In a chapter on “relativity,” for example, Ariely writes that evaluating two houses side by side yields different results than evaluating three – A, B and a somewhat less appealing version of A. The subpar A makes it easier to decide that A is better – not only better than the similar one, but better than B. The lesser version of A should have no effect on your rating of the other two buildings, but it does. Similarly, he describes the “zero price effect,” which marketers exploit to convince us to buy something we don’t really want or need in order to collect a “free” gift. “FREE! gives us such an emotional charge that we perceive what is being offered as immensely more valuable than it really is,” Ariely writes. None of this is rational, but it is predictable.

What the reasoning self should do, he says, is set up guardrails to manage things during those many, many moments when reason is not in charge. (Though one might ask why the reasoning self should always be in charge, an assumption Ariely doesn’t examine too closely.) For example, Ariely writes, we know our irrational self falls easily into wanting stuff we can’t afford and don’t need. So he proposes a credit card that encourages planning and self-control. After $50 is spent on chocolate this month – pfft, declined! He has in fact suggested this to a major bank. Of course, he knew that his idea would cut into the $17 billion a year that American banks make on consumer credit-card interest, but what the heck: money isn’t everything.

David Berreby is the author of “Us and Them: Understanding your Tribal Mind,” which will be published in paperback this fall.