Turning numbers into mumbo-jumbo lies

The Dark Arts
of Mathematical Deception
By Charles Seife

Viking. 295 pp. $25.95

Seife describes the lawyer's line of reasoning like this: "[Only] one in a thousand wife-beaters winds up murdering his spouse. One in a thousand! Such a small probability means that O.J. Simpson almost certainly isn't the murderer, right?"

The proper statistic to consider is the percentage of murdered abused women whose killer was also their abuser - 50 to 80 percent. But the defense team had successfully used a technique that Seife calls "risk mismanagement," putting valid data in the wrong context. It was "tantamount to turning Simpson's wife-beating . . . into exculpatory evidence," and it gave a sympathetic jury a way to dismiss Simpson's past violence.

"Risk mismanagement" is one of many coined words and phrases Seife includes under the umbrella term "proofiness: the art of using bogus mathematical arguments to prove something that you know in your heart is true - even when it's not."

Seife's coinages, humor, and curious tidbits keep readers engaged as the book gradually moves from a description of techniques to their practical application. He begins with a chapter on "Phony Facts, Phony Figures," in which he describes made-up "Potemkin numbers" and a set of techniques he calls collectively "fruit-packing" (apple-polishing, cherry-picking, and comparing apples to oranges).

He then moves on to "Rorschach's Demon," where practitioners of proofiness rely on the human mind's proclivity to see patterns, even when none exist. They transform casuistry, "the art of making a misleading argument through seemingly sound principles," into "causuistry" (with an extra u) in order to turn correlation into causation. They rely on the misunderstanding of random distributions ("randumbness"). They use "regression to the moon," or the misapplication of mathematical curve fitting (regression to the mean), to produce nonsense, such as a formula for "Callipygianness . . . derived by a team of academic psychologists after many hours of serious research into the female derriere."