Gerald M.Edelmann A UNIVERSE OF CONSCIOUSNESS Basic 2000

The World Knot ________________________________________________________ When I turn my gaze skyward I see the flattened dome of the sky and the sun's brilliant disc and a hundred other visible things underneath it. What are the steps which bring this about? A pencil of light from the sun enters the eye and is focussed there on the retina. It gives rise to a change, which in turn travels to the nerve layer at the top of the brain. The whole chain of these events, from the sun to the top of mv brain, is physical. Each step is an electrical reaction. But now there succeeds a change wholly unlike any that led up to it, and wholly inexplicable bv us. A visual scene presents itself to the mind: I see the dome of the sky and the sun in it, and a hundred other visual things beside. In fact, I perceive a picture of the world around me.' With this simple example, in 1940, the great neurophysiologist Charles Sherrington illustrated the problem of consciousness and his belief that it was scientifically inexplicable.  A few years earlier, Bertrand Russell used a similar example to express his skepticism about the ability of philosophers to arrive at a solution: We suppose that a physical process starts from a visible object, travels to the eye, there changes into another phvsical process, causes yet another physical process in the optic nerve, and finally produces some effects in the brain, simultaneously with which we see the object from which the process started, the seeing being something "mental," totally different in character from the physical processes, which precede and accompany it. This view is so queer that metaphysicians have invented all sorts of theories designed to substitute something less incredible. No matter how accurate the description of the physical processes underlying it, it is hard to conceive how the world of subjective experience ?the seeing of blue and the feeling of warmth?springs out of mere physical events.  And yet, in an age in which brain imaging, general anesthesia, and neurosurgery are becoming commonplace, we are aware that the world of conscious experience depends all too closely on the delicate workings of the brain.  We are aware that consciousness, in all its glory, can be annihilated by a minuscule lesion or a slight chemical imbalance in certain parts of the brain. In fact, our conscious life is annihilated every time the mode of activity in our brain changes and we fall into dreamless sleep.  We are also aware that our own private consciousness is, in a profound sense, all there is. The flattened dome of the sky and the hundred other visible things underneath, including the brain itself?in short, the entire world?exist, for each of us, only as part of our consciousness, and they perish with it.  This enigma wrapped within a mystery of how subjective experience relates to certain objectively describable events is what Arthur Schopenhauer brilliantly called the "world knot." Despite the appearance of mystery, the best hope of disentangling this knot will come from a scientific approach that combines testable theories and well-designed experiments. This book is dedicated to this end.

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