Pinker, StevenTHE BLANK SLATE: THE MODERN DENIAL OF HUMAN NATUREViking (528 pp)$26.95Oct. 2002ISBN 0-670-03151-8

The well-published MIT cognitive scientist and linguist (HOW THE MIND WORKS, 1997, etc.) takes on one of philosophy's thorniest problems in this lucid view of what makes humans human.

Against scholars and ideologues of the left and right, Pinker offers a profoundly biological view of human nature, even if his descriptions of what make us tick sometimes sound as if they're straight out of a software manual. Pinker describes the brain, for instance, as a set of data-processing modules, "with many parts cooperating to generate a train of thought or an organized action. It has distinct information-processing systems for filtering out distractions, learning skills, controlling the body, remembering facts, holding information temporarily, and storing and executing rules." Far from a tabula rasa, the brain is hard-wired with genetic information millennia old, governing our responses to events: altruism here, perhaps, or violence there. Psychologists believe that the human personality is variable in only five general dimensions, each governed by genetics: "we are to varying degrees introverted or extroverted, neurotic or stable, incurious or open to experience, agreeable or antagonistic, and conscientious or undirected." (A shy, agoraphobic, narcissistic, and wholly unreliable person, then, can take comfort in blaming his or her unpleasant makeup on generations of ancestors.) The implications of the biological view are many and large, and thus are the subject of fierce debate: if we are but a set of electrochemical circuits heavily programmed to behave according to a simple set of rules, then free choice and moral responsibility go out the window. Yet, Pinker remarks before examining the political and philosophical consequences of this position, "Nothing prevents the godless and amoral process of natural selection from evolving a big-brained social species equipped with an elaborate moral sense:--perhaps too much moral sense, he adds. His conclusions won't please exponents of several camps, Christian conservatives and what he calls "gender feminists" among them, but he ably defends his ground, and with a minimum of jargon and scholarly sophistry.

A rich, sophisticated argument that may leave pious souls a little uneasy.