If only "Your zombie brain" had been the title of this book. Pantheon could've had a marketing smash if only they'd latched onto the quasi-human chimera du jour. (Not that the book has necessarily done that badly--a number of people have mentioned hearing the author on NPR.) And there wouldn't have been anything cheap or sleazy about a title like that, since it comes from the text almost verbatim.

Almost--actually the author refers to "alien subroutines" and "zombie programs" in the brain, but the point is the same: our consciousness is not in control to the extent we like to think it is. The author uses "zombie" to signify a "lack of conscious access" to brain activity. And to read him, when it comes to brain activity, far and away the most of it is in the undead category.

Even though Eagleman is nowhere near as flip with his rhetoric, delving down into the zombie metaphor works pretty well with his analysis. Essentially what happens is that many things--reading for example--used to be very much "alive" in the sense that they were governed by conscious effort while we were learning to read. Once we learned, reading became second nature--spun off from the conscious effort of evaluating the shapes in front of us--and now when we read, we shamble down the road with a glazed look in our eyes and our arms outstretched. In a manner of speaking.

Eagleman's choice of metaphor for the conscious, directing function is "chief executive." He suggests that a conscious life form is one that is able to choose between competing instinctual urges--that is something that humans do better than lab rats.

But not always. Eagleman parades a number of pathological conditions--frontal lobe dementia, for example--that prevent people from being able to make the "right" choice, let's say, between wearing clothes in public as opposed to nakedness. (For now let's just imagine that there's no such place as San Francisco.)

Eagleman expands the pathological model to the entire human population. We may not all be demented, but we all have to decide whether or not to go naked in public, and this is the job of the chief executive. Whom, by the way, we cannot fire. So what if the chief executive lets us eat too much, drink too much, shoplift, or kill? It all amounts to the same thing: it represents a conflict in the brain among competing, natural tendencies. What determines our own idiosyncratic response to the world around us depends on a complex interaction between our inherited selves and environmental factors.

For this reason (lawyers take note!) Eagleman favors discarding the whole concept of culpability as a factor to be used in judging the severity of criminal behavior. Because of advances in psychology and brain science, we no longer judge a schizophrenic, epileptic, or manic depressive to be as blameworthy as we used to. Eagleman says we should expect the exculpatory list to grow: "Technology will continue to improve, and as we grow better at measuring problems in the brain ... problems that are now opaque will open up to examination by new techniques, and we may someday find that certain types of bad behavior will have a meaningful biological explanation" (p. 176). To be preferred, when it comes to determining corrective (or correctional) action, is a scheme that replaces the frame of mind at the time of the crime with one that predicts the likelihood of future transgressions.

Eagleman is fond of saying that all seeing happens in the brain. After reading his book, it becomes more obvious why, when we say we understand something, we use the expression "I see."

[Postscript: In vino veritas: on p. 103 of this book, it says "The Roman historian Tacitus claimed that the Germanic peoples always drank alcohol while holding councils to prevent anyone from lying." Let's make that a requirement for all future televised presidential debates.]