The eternal question is, of course, how consciousness can possibly arise from non-conscious material (if at all). Harris compares this to the question how the universe could have come into existence out of nothing. Both questions are, in the end, probably unanswerable, but at least engaging to think about. I particularly agree with the fourth paragraph below.
You are not aware of the electrochemical events occurring at each of the trillion synapses in your brain at this moment. But you are aware, however dimly, of sights, sounds, sensations, thoughts, and moods. At the level of your experience, you are not a body of cells, organelles, and atoms; you are consciousness and its ever-changing contents, passing through various stages of wakefulness and sleep, and from cradle to grave.
The term “consciousness” is notoriously difficult to define. Consequently, many a debate about its character has been waged without the participants’ finding even a common topic as common ground. By “consciousness,” I mean simply “sentience,” in the most unadorned sense. To use the philosopher Thomas Nagel’s construction: A creature is conscious if there is “something that it is like” to be this creature; an event is consciously perceived if there is “something that it is like” to perceive it. Whatever else consciousness may or may not be in physical terms, the difference between it and unconsciousness is first and foremost a matter of subjective experience. Either the lights are on, or they are not.
To say that a creature is conscious, therefore, is not to say anything about its behavior; no screams need be heard, or wincing seen, for a person to be in pain. Behavior and verbal report are fully separable from the fact of consciousness: We can find examples of both without consciousness (a primitive robot) and consciousness without either (a person suffering “locked-in syndrome”).
It is surely a sign of our intellectual progress that a discussion of consciousness no longer has to begin with a debate about its existence. To say that consciousness may only seem to exist is to admit its existence in full—for if things seem any way at all, that is consciousness. Even if I happen to be a brain in a vat at this moment—all my memories are false; all my perceptions are of a world that does not exist—the fact that I am having an experience is indisputable (to me, at least). This is all that is required for me (or any other conscious being) to fully establish the reality of consciousness. Consciousness is the one thing in this universe that cannot be an illusion.
The problem, however, is that no evidence for consciousness exists in the physical world. Physical events are simply mute as to whether it is “like something” to be what they are. The only thing in this universe that attests to the existence of consciousness is consciousness itself; the only clue to subjectivity, as such, is subjectivity. Absolutely nothing about a brain, when surveyed as a physical system, suggests that it is a locus of experience. Were we not already brimming with consciousness ourselves, we would find no evidence of it in the physical universe—nor would we have any notion of the many experiential states that it gives rise to. The painfulness of pain, for instance, puts in an appearance only in consciousness. And no description of C-fibers or pain-avoiding behavior will bring the subjective reality into view.
Most scientists are confident that consciousness emerges from unconscious complexity. We have compelling reasons for believing this, because the only signs of consciousness we see in the universe are found in evolved organisms like ourselves. Nevertheless, this notion of emergence strikes me as nothing more than a restatement of a miracle. To say that consciousness emerged at some point in the evolution of life doesn’t give us an inkling of how it could emerge from unconscious processes, even in principle.
I believe that this notion of emergence is incomprehensible—rather like a naive conception of the big bang. The idea that everything (matter, space-time, their antecedent causes, and the very laws that govern their emergence) simply sprang into being out of nothing seems worse than a paradox. “Nothing,” after all, is precisely that which cannot give rise to “anything,” let alone “everything.” Many physicists realize this, of course. Fred Hoyle, who coined “big bang” as a term of derogation, is famous for opposing this creation myth on philosophical grounds, because such an event seems to require a “preexisting space and time.” In a similar vein, Stephen Hawking has said that the notion that the universe had a beginning is incoherent, because something can begin only with reference to time, and here we are talking about the beginning of space-time itself. He pictures space-time as a four-dimensional closed manifold, without beginning or end—much like the surface of a sphere.
To say “Everything came out of nothing” is to assert a brute fact that defies our most basic intuitions of cause and effect—a miracle, in other words. Likewise, the idea that consciousness is identical to (or emerged from) unconscious physical events is, I would argue, impossible to properly conceive—which is to say that we can think we are thinking it, but we are mistaken. We can say the right words, of course—“consciousness emerges from unconscious information processing.” We can also say “Some squares are as round as circles” and “2 plus 2 equals 7.” But are we really thinking these things all the way through? I don’t think so.
Consciousness—the sheer fact that this universe is illuminated by sentience—is precisely what unconsciousness is not. And I believe that no description of unconscious complexity will fully account for it. It seems to me that just as “something” and “nothing,” however juxtaposed, can do no explanatory work, an analysis of purely physical processes will never yield a picture of consciousness. However, this is not to say that some other thesis about consciousness must be true. Consciousness may very well be the lawful product of unconscious information processing. But I don’t know what that sentence means—and I don’t think anyone else does either.