By Alva Noë
(Hill and Wang/Farrar, Straus and Giroux; 214 pages; $25)
The most mysterious thing about the human brain is that the more we know about it, the deeper our own mystery becomes. On the one hand, scientists tell us that we are nothing but 3 pounds of electrical flesh inside the skull, a trillion synapses exchanging squirts of neurotransmitter.
And yet we feel like more than the sum of these cells. We feel self-conscious, endowed with a mind that experiences the taste of a peach, and the redness of red, and the thrill of romantic love. The question of how the brain creates the mind - how these subjective experiences emerge from a piece of pale gray meat - is one of the essential questions of modern science. And yet, despite decades of research, we aren't remotely close to an answer.
Alva Noë, a philosopher at UC Berkeley, argues that consciousness remains a mystery because we've been looking in the wrong place. In his provocative and lucid new book, Noë writes that scientists have been so eager to locate the mind in the brain that they've neglected to consider the possibility that our mind might not be inside our head.
Then where is it? Don't worry, Noë isn't an old-fashioned Cartesian dualist: He doesn't believe that our consciousness is some metaphysical gift from God. Instead, he suggests that who we are and what we know is inseparable from where we are and what we're doing: "Consciousness is not something the brain achieves on its own," Noë writes. "Consciousness requires the joint operation of the brain, body and world. ... It is an achievement of the whole animal in its environmental context."
Noë sells this audacious idea with a series of effective metaphors. For instance, he begins the book by comparing consciousness to a dollar bill. He notes that it would be silly to search for the physical correlates of "monetary value." After all, the meaning of money isn't in the paper, or the green ink, or the picture of George Washington. Instead, it exists in the institutions and practices that give the paper meaning. Similarly, our awareness of reality doesn't depend entirely on what's happening inside the brain, but is a side effect of how we, as individuals, interact with the wider world.
Although Noë is a philosopher, his argument is carefully built on scientific evidence, as he considers everything from studies of cells in the visual cortex to examples of neural plasticity. In each instance, he interprets the data in a startlingly original fashion, such as when he uses experiments showing that ferrets can learn to "see" with cells in their auditory cortex as proof that "there isn't anything special about the cells in the so-called visual cortex that makes them visual. Cells in the auditory cortex can be visual just as well. There is no necessary connection between the character of experience and the behavior of certain cells."
Certainly, many of the scientists cited by Noë would disagree with his interpretations, but that's part of what makes this book so important: It's an audacious retelling of the standard story, an exploration of the mind that questions some of our most cherished assumptions about what the mind is.
In many respects, Noë's ideas mark a return to an earlier tradition of American philosophy, represented by people like William James and John Dewey. These thinkers insisted that the attempt to reduce the mind to its fleshy source was inherently flawed: The brain is part of an organism, and that organism is part of a culture. "Man is more than a psychical machine," Dewey wrote. "His life is bound up with the life of society." For the most part, modern scientists brushed aside such skepticism, as they embarked on an epic search for the cellular circuits that give rise to our conscious mind. Although much has been learned, little has been found. Perhaps, as Noë argues, that's because we're searching on our inside for something that doesn't exist.