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The Tides of Mind: Uncovering the Spectrum of Consciousness
by david gelernter
liveright, 320 pages, $26.95

Neurobiologists and neuropsychologists have made steady progress in deciphering the anatomy and physiology of the brain, but the essential qualities of the mind—consciousness, self-awareness, feeling—remain as elusive as ever. The organ of subjectivity continues to resist the advances of scientific analysis.

Some brain scientists, confronted with the mind’s recalcitrance, have taken refuge in speculation, spinning elaborate mental theories from sparse empirical evidence. The most influential of these theories, for at least the last half century, has been computationalism, the belief that the brain is an information-processing device, akin to a digital computer. On this model, the functions of the mind are the outputs of some sort of genetically coded software running through the brain’s circuitry. “The mind stands to the brain in much the same way that the program stands to the computer” is how one neuroscientist summed up the idea.

The computationalist creed was given its most expansive and effusive expression in Harvard psychologist Steven Pinker’s popular 1997 book How the Mind Works. Our cognitive functions and even our emotions, Pinker argued, are “well-engineered software modules” executed by the skull-embedded computer we call the brain. “The mind, like the Apollo spacecraft, is designed to solve many engineering problems,” he wrote, “and thus is packed with high-tech systems.” There was an elegance to his argument. By positing mental functions as software programs running on neural hardware, it seemed to bridge the gulf between materialism and dualism. His techie turns of phrase fit the zeitgeist as neatly as a modem cable in a serial port. But even as his book climbed the bestseller list, computationalism’s limitations were coming more clearly into view. Some kinds of thinking could be carried out computationally, through a formal, logical processing of informational inputs, but other kinds could not.

In his 2000 book The Mind Doesn’t Work That Way, Rutgers philosopher of mind Jerry Fodor, one of computationalism’s leading theoreticians, chastised Pinker for overreaching. Fodor argued that certain essential qualities of mind, such as the melding of perception and memory into what we call common sense, lie beyond the theory’s explanatory powers. More recently, Tufts philosopher Daniel Dennett, another prominent computationalist, described the shortcomings of the brain-as-digital-computer analogy in blunt terms: “It doesn’t work.” As with earlier technological metaphors intended to explain the operations of the mind—a hydraulic pump, a self-winding clock, a telephone switchboard, a managerial bureaucracy—the computer analogy is illuminating but reductive. It is, in Dennett’s words, an “inspiring over-simplification.” Whatever the mind may be, a collection of software modules it is not.

“So, how does the mind work?” asked Fodor in a 2005 paper. “I don’t know. You don’t know. Pinker doesn’t know.”

It is against this backdrop of failed description that David Gelernter’s slyly seditious The Tides of Mind: Uncovering the Spectrum of Consciousness appears. A distinguished computer scientist at Yale, ­Gelernter has little patience for the notion that brains work like computers. He traces the idea to a seductive but ultimately misleading tautology: “Scientists designed these machines to carry out tasks for which, ordinarily, they used their minds. So it was perfectly natural to imagine that when machines carried out these tasks, these machines were showing themselves to resemble a mind or brain.” A facile analogy can all too easily be mistaken for fact, particularly when it appeals to professional vanity.

Gelernter’s own approach to investigating the nature of consciousness is not speculative but introspective. Any true understanding of the mind, he suggests, must begin with a rigorous and necessarily subjective examination of the actual experience of thinking and being. What does it feel like to have a mind? What does it feel like to be a person who thinks? What Gelernter discovers, in probing his own patterns of thought, is that the mind is forever in flux. We have not one mind but many. The substance and the texture of thought vary throughout the day in ways that seem tightly linked to the rhythms of the body. “The role of emotion in thought, our use of memory, the nature of understanding, the quality of consciousness—all change continuously throughout the day,” he explains, “as we sweep down a spectrum that is crucial to nearly everything about the mind and thought and consciousness.”

The spectrum of thought is not universal—there are as many variations as there are persons—but it does have a cyclical character, Gelernter argues. Mind and body run a daily round from “doing” to “being.” In the morning, when we are physically refreshed, the mind operates at “the top” of the spectrum. We are in control of our thoughts, concentrating our mental energies on rational, disciplined work while keeping distracting emotions at bay. As the day proceeds, and we tire, our thoughts begin to wander. Memories bubble unbidden into consciousness. We become more emotional, less rational. We drift into reverie and fantasy. Finally, when we fall asleep at the end of the day, we reach “the bottom” of the spectrum, losing conscious control of our thoughts altogether. Flooded with memories, the mind dreams.

Gelernter’s sense of the mind’s workings evokes that of the Romantic poets, whom he quotes frequently and aptly. Particularly resonant are the opening lines of Shelley’s “Mont Blanc”: “The everlasting universe of things/Flows through the mind, and rolls its rapid waves,/Now dark, now glittering . . .”

Creatures of the earth, we have minds attuned to the world around us, capable of dissecting the principles of its construction but also sharing in its restless fluidity. The most remarkable and revealing quality of the human mind is its suppleness. Sometimes we think like mathematicians, sometimes like mystics. No one way of thinking explains us.

Since the dawn of modernity, people have come to place an ever greater emphasis on the high end of the mental spectrum—on rational, practical thinking aimed at solving well-defined problems. The work of the mind is work. The apparently aimless thought that takes place at the lower end of the spectrum, rich with emotion, recollection, and imagination, doesn’t seem like thought at all. It is mere “daydreaming,” an absent-minded indulgence. This “civilized bias,” Gelernter argues, has become so strong in our culture that it has distorted our conception of the mind. It is what paved the way for computationalism, and the attendant assumption that thought is something that can be analyzed in isolation from the physical world and the physical body, and it helps explain why the theory has been so widely embraced. Because computers are adept at replicating the logical procedures characteristic of high-spectrum consciousness, we are drawn to the suggestion that artificial intelligence can encompass all intelligence. We overlook, or dismiss, the inability of software to replicate the more open-ended but nonetheless essential forms of thinking that go on in the lower regions of Gelernter’s spectrum. “Being is not computable,” he reminds us. “Happiness is not computable. Feelings are not computable.”

Though invigorating in its early chapters, The Tides of Mind later grows repetitive, rehashing the contours of the spectrum and offering diffuse observations on human psychology. If instead Gelernter had spent more time testing his observations against contemporary scientific research into the nervous system, this would have been a stronger book. Laboratory experiments have, for example, revealed some of the biological underpinnings of such complex mental phenomena as memory formation, learning, and neuroplasticity. A careful consideration of the findings would have enriched the book’s contentions and amplified their explanatory and critical force. It would also have given Gelernter an opportunity to explain more thoroughly his belief that “the science of mind must be a subjective science.”

What in the end makes The Tides of Mind a brave and exemplary book is not so much Gelernter’s conclusions as his method. It has become fashionable among computationalists and others to argue that subjectivity, consciousness, and selfhood are illusions, the mind a mere side effect of routine neuronal activity. Tortured and narrow, this view is born of hubris—if I don’t understand it, it must not exist—but it speaks to the easy misanthropy of our robotic times. By reminding us of the value and necessity of careful, methodical introspection, of the revelatory power of the subjective eye, Gelernter also returns us to common sense. The Tides of Mind, as he makes clear, takes its inspiration and its approach from the great twentieth-century phenomenologists, such as Edmund Husserl and Maurice Merleau-Ponty, who saw that an understanding of life has to begin with a painstaking examination of the experience of being. Like his intellectual forebears, Gelernter shows us that subjectivity and objectivity need not be antagonists.

Nicholas Carr is the author of Utopia Is Creepy and The Shallows, among other books.