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Is It Possible to Explain How Consciousness Works?

이강기 2021. 11. 3. 21:42

Is It Possible to Explain How Consciousness Works?

 

By Jim Holt

New York Times

Nov. 2, 2021

 

 

FEELING & KNOWING
Making Minds Conscious
By Antonio Damasio

 

 

We all know what it means to be conscious. Consciousness is what distinguishes being awake from being in a coma or a state of dreamless sleep. I am now conscious, and so (presumably) are you. Many animals — probably all mammals — have conscious minds, but plants and bacteria do not. Nor do computers (so far). Nor do stars, or rocks.

 

Why is consciousness important? Well, in a way, it’s the basis of everything that’s important. Without consciousness, there would be no pleasure or pain; no good or evil; no experiences of beauty, or of love. In a universe that never evolved conscious minds, nothing would matter.

 

Intimately familiar though we are with it, consciousness confronts us with a mystery. It doesn’t readily fit into our scientific conception of the world. Consciousness seems to be caused by neural firings in our brains. But how can these objective electrochemical events give rise to ineffable qualitative experiences, like the smell of a rose, the stab of a pain or the transport of joy? Why, when a physical system attains a certain degree of complexity, is it “like something” to be that system?

 

This is the “hard problem” of consciousness: the problem of how subjective mind arises from brute matter. (There is also an “easy problem,” that of determining what role consciousness plays in the information-processing economy of the mind. But one thing at a time.)

 

In the last few decades, the mystery of consciousness has exercised thinkers of all stripes, sometimes driving them to rather desperate-sounding devices. Philosophers (Thomas Nagel, David Chalmers) have flirted with “panpsychism,” the idea that consciousness might be a fundamental ingredient of all matter, right down to the atomic level. The Nobel-laureate physicist Roger Penrose has speculated that some kind of quantum magic might be behind it. In his mega-best-selling “Gödel, Escher, Bach,” the computer scientist Douglas Hofstadter argued that consciousness arises when the brain becomes intricate enough to form self-referential “strange loops” — neural equivalents of Gödel’s notorious formula that says, “I am not provable.”

 

Meanwhile, neuroscientists have tried to understand consciousness as a biological phenomenon — like, say, digestion. Using brain-imaging and other empirical techniques, they have sought out the neural signatures of conscious thought within the gray spongy matter in our skulls. Among them have been the Nobel laureates Francis Crick and Gerald Edelman, each of whom produced a book outlining his own favored take on consciousness. Today, one of the most distinguished researchers working along these lines is Antonio Damasio, a Portuguese American who holds a chair in neuroscience at the University of Southern California.

 

“Feeling & Knowing” represents a distillation of themes Damasio has explored in earlier books, which include “Descartes’ Error” (1994) and “Self Comes to Mind” (2010). The most prominent of his preoccupations is the importance of feeling. It is feeling, he thinks, that can bridge the conceptual abyss between the physical body and the conscious mind.

 

Before getting down to substance, a word about style. In a prologue, Damasio tells us that readers of his earlier books often missed the key ideas amid all the scientific details. So he set out to write “a focused and very brief book on consciousness.” Brief the new book is: It consists of 40-odd sections, some less than a page long, surrounded by ample white space. Each of these mini-chapters reads rather like a prose poem — often soaring to lyrical heights, though sometimes weighted down by bits of neuroscientific argot. “Focused,” though, is not the mot juste for it: Despite its brevity, it can be meandering and repetitious (“Feelings again, must we? We must indeed”). Crucial ideas often lie enshrouded in an elegant mist of metaphor. Still, the quality of the author’s mind, the boldness of his aims and the suspense of his argument propelled me through the book.

 

Put with brutal succinctness, Damasio’s brief goes like this: Mental activity consists of a stream of “images” that map aspects of the world around us. But these images, by themselves, cannot be conscious. For that, they must be related to a perspective, an “owner,” a self — this, after all, is what subjectivity means. And here is where feeling comes in. As Damasio uses the term, “feelings” are “the hybrid, interactive processes of the interior, at once mental and physical.” They register how well or badly its various subsystems are doing at maintaining homeostasis, at keeping the organism alive and flourishing. So feelings point within, to the interior; images point without, to the world. And when feelings and images come together in the brain, the result is conscious thought. To adapt a simile of Damasio’s, feelings are like a musical score that, when added to the silent reel of images in the mind, produces cinematic consciousness.

 

This is Damasio’s solution to the mystery of consciousness. What’s not to like? Plenty!

 

First, Damasio has adroitly dodged the “hard problem.” An image of (say) a bear is, in his account, a pattern of neural firing in the brain. A feeling of (say) fear is another such pattern. Put them together and you’ve just got a bigger and more complicated pattern of neural firing. Why should it be accompanied by qualitative consciousness? For Damasio to use the terms “images” and “feelings” to refer to these electrochemical events is to make them sound already conscious — which might be called the fallacy of tendentious nomenclature.

 

Second, for Damasio consciousness requires possessing a sense of self, an ability to entertain “me-ish” thoughts. But most mammals seem to have no such sense of self. They are incapable of recognizing themselves in a mirror. This is also true of human children in the first months of life — are we to suppose that they are not conscious? This might be called the “Unfair to babies!” objection.

 

Third, Damasio’s category of “feeling” is too capacious. It encompasses not only emotions, but also desires, and states of pleasure and pain. Is all of this really necessary for consciousness? Might not rational thought plus value-based goals be enough? Call this the “Unfair to Mr. Spock!” objection.

 

I could go on.

 

But if Damasio’s account of consciousness is not an unqualified success, that merely puts him in the company of all the other distinguished scientists and philosophers who have tried to crack this conundrum. And happily, “Feeling & Knowing” has supplementary virtues that make it well worth reading.

 

Chief among these is how beautifully Damasio expatiates on the theme of feeling — on how feelings “arise in the interior of organisms, in the depth of viscera and fluids where the chemistry responsible for life in all its aspects reigns supreme.” Here the master scientist unites with the silken prose-stylist to produce one thrilling insight after another. For instance: The neural channels that convey feeling, in contrast to those tasked with other mental functions, are uninsulated from the cells that environ them, and from the blood itself. This biochemical nakedness permits “intimate cross talk between body structures and nervous system.” (D. H. Lawrence’s “thinking with the blood” is not, alas, a pure metaphor.)

 

Damasio may not have dispelled the mystery of consciousness in this book. But he has succeeded brilliantly in narrowing the gap between body and mind.