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Is Consciousness An Illusion?

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In the NY Review of Books Thomas Nagel reviews a new book by Daniel Dennett (whom I wish had known about back when he started):

From Bacteria to Bach and Back: The Evolution of Minds
by Daniel C. Dennett
Norton, 476 pp., $28.95

For fifty years the philosopher Daniel Dennett has been engaged in a grand project of disenchantment of the human world, using science to free us from what he deems illusions—illusions that are difficult to dislodge because they are so natural. In From Bacteria to Bach and Back, his eighteenth book (thirteenth as sole author), Dennett presents a valuable and typically lucid synthesis of his worldview. Though it is supported by reams of scientific data, he acknowledges that much of what he says is conjectural rather than proven, either empirically or philosophically.

Dennett is always good company. He has a gargantuan appetite for scientific knowledge, and is one of the best people I know at transmitting it and explaining its significance, clearly and without superficiality. He writes with wit and elegance; and in this book especially, though it is frankly partisan, he tries hard to grasp and defuse the sources of resistance to his point of view. He recognizes that some of what he asks us to believe is strongly counterintuitive. I shall explain eventually why I think the overall project cannot succeed, but first let me set out the argument, which contains much that is true and insightful.

The book has a historical structure, taking us from the prebiotic world to human minds and human civilization. It relies on different forms of evolution by natural selection, both biological and cultural, as its most important method of explanation. Dennett holds fast to the assumption that we are just physical objects and that any appearance to the contrary must be accounted for in a way that is consistent with this truth. Bach’s or Picasso’s creative genius, and our conscious experience of hearing Bach’s Fourth Brandenburg Concerto or seeing Picasso’s Girl Before a Mirror, all arose by a sequence of physical events beginning with the chemical composition of the earth’s surface before the appearance of unicellular organisms. Dennett identifies two unsolved problems along this path: the origin of life at its beginning and the origin of human culture much more recently. But that is no reason not to speculate.

The task Dennett sets himself is framed by a famous distinction drawn by the philosopher Wilfrid Sellars between the “manifest image” and the “scientific image”—two ways of seeing the world we live in. According to the manifest image, Dennett writes, the world is

full of other people, plants, and animals, furniture and houses and cars…and colors and rainbows and sunsets, and voices and haircuts, and home runs and dollars, and problems and opportunities and mistakes, among many other such things. These are the myriad “things” that are easy for us to recognize, point to, love or hate, and, in many cases, manipulate or even create…. It’s the world according to us.

According to the scientific image, on the other hand, the world

is populated with molecules, atoms, electrons, gravity, quarks, and who knows what else (dark energy, strings? branes?).

This, according to Dennett, is the world as it is in itself, not just for us, and the task is to explain scientifically how the world of molecules has come to include creatures like us, complex physical objects to whom everything, including they themselves, appears so different.

He greatly extends Sellars’s point by observing that the concept of the manifest image can be generalized to apply not only to humans but to all other living beings, all the way down to bacteria. All organisms have biological sensors and physical reactions that allow them to detect and respond appropriately only to certain features of their environment—“affordances,” Dennett calls them—that are nourishing, noxious, safe, dangerous, sources of energy or reproductive possibility, potential predators or prey.

For each type of organism, whether plant or animal, these are the things that define their world, that are salient and important for them; they can ignore the rest. Whatever the underlying physiological mechanisms, the content of the manifest image reveals itself in what the organisms do and how they react to their environment; it need not imply that the organisms are consciously aware of their surroundings. But in its earliest forms, it is the first step on the route to awareness.

The lengthy process of evolution that generates these results is first biological and then, in our case, cultural, and only at the very end is it guided partly by intelligent design, made possible by the unique capacities of the human mind and human civilization. But as Dennett says, the biosphere is saturated with design from the beginning—everything from the genetic code embodied in DNA to the metabolism of unicellular organisms to the operation of the human visual system—design that is not the product of intention and that does not depend on understanding.

One of Dennett’s most important claims is that most of what we and our fellow organisms do to stay alive, cope with the world and one another, and reproduce is not understood by us or them. It is competence without comprehension. This is obviously true of organisms like bacteria and trees that have no comprehension at all, but it is equally true of creatures like us who comprehend a good deal. Most of what we do, and what our bodies do—digest a meal, move certain muscles to grasp a doorknob, or convert the impact of sound waves on our eardrums into meaningful sentences—is done for reasons that are not our reasons. Rather, they are what Dennett calls free-floating reasons, grounded in the pressures of natural selection that caused these behaviors and processes to become part of our repertoire. There are reasons why these patterns have emerged and survived, but we don’t know those reasons, and we don’t have to know them to display the competencies that allow us to function.

Nor do we have to understand the mechanisms that underlie those competencies. In an illuminating metaphor, Dennett asserts that the manifest image that depicts the world in which we live our everyday lives is composed of a set of user-illusions,

like the ingenious user-illusion of click-and-drag icons, little tan folders into which files may be dropped, and the rest of the ever more familiar items on your computer’s desktop. What is actually going on behind the desktop is mind-numbingly complicated, but users don’t need to know about it, so intelligent interface designers have simplified the affordances, making them particularly salient for human eyes, and adding sound effects to help direct attention. Nothing compact and salient inside the computer corresponds to that little tan file-folder on the desktop screen.

He says that the manifest image of each species is “a user-illusion brilliantly designed by evolution to fit the needs of its users.” In spite of the word “illusion” he doesn’t wish simply to deny the reality of the things that compose the manifest image; the things we see and hear and interact with are “not mere fictions but different versions of what actually exists: real patterns.” The underlying reality, however, what exists in itself and not just for us or for other creatures, is accurately represented only by the scientific image—ultimately in the language of physics, chemistry, molecular biology, and neurophysiology.

Our user-illusions were not, like the little icons on the desktop screen, created by an intelligent interface designer. Nearly all of them—such as our images of people, their faces, voices, and actions, the perception of some things as delicious or comfortable and others as disgusting or dangerous—are the products of “bottom-up” design, understandable through the theory of evolution by natural selection, rather than “top-down” design by an intelligent being. Darwin, in what Dennett calls a “strange inversion of reasoning,” showed us how to resist the intuitive tendency always to explain competence and design by intelligence, and how to replace it with explanation by natural selection, a mindless process of accidental variation, replication, and differential survival.

As for the underlying mechanisms, we now have a general idea of how they might work because of another strange inversion of reasoning, due to Alan Turing, the creator of the computer, who saw how a mindless machine could do arithmetic perfectly without knowing what it was doing. This can be applied to all kinds of calculation and procedural control, in natural as well as in artificial systems, so that their competence does not depend on comprehension. Dennett’s claim is that when we put these two insights together, we see that

all the brilliance and comprehension in the world arises ultimately out of uncomprehending competences compounded over time into ever more competent—and hence comprehending—systems. This is indeed a strange inversion, overthrowing the pre-Darwinian mind-first vision of Creation with a mind-last vision of the eventual evolution of us, intelligent designers at long last.

And he adds: . . .

Continue reading.

Written by LeisureGuy

20 May 2017 at 2:09 pm

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