Book Review: Readings

The Drunkard's Walk: How Randomness Rules Our Lives

by Leonard Mlodinow
Pantheon, 272 pp., $24.95

"Drunkard's walk" is a mathematical term describing random motion, like that of a molecule floating through space, bouncing haphazardly off this or that other molecule. According to California Institute of Technology physicist Leonard Mlodinow, we are all more like that random molecule than we think. As the son of two Holocaust survivors, Mlodinow has an intimate perspective on randomness. He opens his new book with a story about his father stealing a loaf of bread while imprisoned at Buchenwald. Rather than getting his father killed, the act landed him a job as the baker's assistant. "A chance event," his father called it. "But had it happened differently," he told Mlodinow, "you would never have been born."

The human mind, writes Mlodinow, is designed to find reasons for such things rather than attribute them to chance. It seeks patterns so adeptly that it consistently finds them where they don't exist. When cancer cases cluster in some areas and not others, we naturally seek environmental causes, and when a film company, athlete, CEO, or stockbroker experiences a streak of success, we attribute that streak to skill. But in fact, as Mlodinow painstakingly proves, such things are more consistent with random distribution than with anything else. In many cases, it would be the absence of clusters or streaks that would indicate something amiss, just as, say, the lack of a streak of heads or tails in a long series of coin tosses would be exceptional.

The drunkard's walk, a meandering path that in retrospect may appear purposeful, is representative of the many intuitively sound but nonetheless logically incorrect conclusions we – and our doctors and lawyers, even – draw in everyday life. While we can accept these idiosyncrasies at face value, internalizing them (so that we don't repeat their mistakes) requires understanding a bunch of math. So the book, itself a kind of drunkard's walk through the history of probability, statistics, and chaos theory, covers everything from the ninth century's introduction of the concept of zero to the fashion choices of 17th century mathematician Blaise Pascal, who "wore an iron belt with points on the inside" that would dig into his flesh lest he start feeling too happy.

Along the way, Mlodinow draws direct links from the works of history's greatest minds to the deeds of today's not-so-great ones, explaining phenomena like the prosecutor's fallacy (which helped acquit O.J. Simpson) and the iPod shuffle function (eventually programmed not to be truly random, lest songs hit upon eerie playing streaks). The Drunkard's Walk is, essentially, a math book. It requires at times that you stop and think, or perhaps even break out a pencil. Luckily Mlodinow, most well-known for co-writing A Briefer History of Time with Stephen Hawking and less well-known for penning Star Trek scripts, is equipped for the task of disguising this exercise as a jaunty read worthy of any beach or airplane.