Cerebrally Speaking

Out of Our Heads

By Alva Noë. 214 pp. $25

To be conscious, Alva Noë claims, is to be "awake, aroused, alert," and neuroscientists are wrong to imagine that they can reproduce consciousness in a petri dish.

A philosopher-scientist, Noë aims to replace neuroscience's reductionism. He compares the development of consciousness to a trickle of water that carves a tiny path in the land; with time, the path draws more water to it, eventually making it impossible for other water not to flow down that path. Similarly, cognitive habits grow in response to our needs and interests.

Noë is an alluring writer, though often repetitive (perhaps to lay down paths in the brains of even inattentive readers). One comes away from the book agreeing that an "explanatory gap" separates conscious experience from the simple firing of neurons, that reductionism is indeed dead, yet wondering what accounts for our conscious engagement with the world. Noë's partial answer is summarized in the book's preface: "Only one proposition about how the brain makes us conscious . . . has emerged unchallenged: we don't have a clue."

-- Ruth Levy Guyer