One Reason I'm Worried About My Concept of Consciousness
Consciousness must, it seems, be a vague phenomenon. The newly formed zygote has no conscious experience; the two-year-old child has conscious experience. I find it hard to believe that consciousness suddenly pops in, in a quantum leap. Even if it emerges fairly suddenly, it must still spread out across some stretch of time (a day, a second, a hundred milliseconds?) such that at a narrow enough temporal resolution it is gradual. Actually, I suspect the transitional period is fairly long: I know of no sudden neural or behavioral change (even at birth) that suggests anything other than an extended gradualism. In the transitional period, by definition, it will be a vague matter whether the organism is conscious, such that it's not quite right simply to say it's conscious and not quite right to say it's not, except perhaps as governed by flexible practical norms. (Compare going bald.)
The same considerations apply phylogenetically: Humans clearly have consciousness. Viruses clearly do not (unless you go panpsychist and say that everything is conscious -- that would clear up the zygote problem too -- but I assume we don't want to do that!). Why think there will be a sharp line across the phylogenetic tree? The only plausible place, it seems, for a sharp line would be between human beings and all others. But then evolutionary history becomes a problem: Modern humans, early homo sapiens, homo erectus, homo habilis, australopithecus, etc., which of these have conscious experience?
And yet I can't get my head around this vagueness. I can imagine what it is like for it to be a vague matter whether one is bald; I can picture the gradual transition. I can imagine what it is for it to be a vague matter whether a bottle is in a backpack (perhaps the bottle is partly melted or hanging half out). But how can it be a vague matter whether a particular being has conscious experience or whether a particular state is conscious?
Consider visual experience: I can imagine a very small speck of visual experience, with the visual field limited to one second of arc. But that's still straightforwardly a case of conscious experience, even if it's very limited. It wouldn't be a matter of convention or pragmatics whether to regard such a case as qualifying as conscious experience. I can imagine a very hazy visual experience, or a gappy experience, or one fading out toward medium gray; but all these too are straightforwardly cases of experience, however impoverished that experience is. They are discretely different in kind from lacking visual experience. So what then would it be to be partway between having visual experience and lacking it, so that it's a vague matter, so that it would be a pragmatic decision like with baldness or the water bottle half hanging out of the pack? As soon as there's the itsiest bit of visual consciousness, there's visual consciousness, end of story -- right?
You might point to cases of organisms with barely any sensory capacities as plausibly having perceptual consciousness so limited that it would be a vague case. But what would those organisms be? Not snails or ants, surely, who have complex sensory systems; the most extremely limited perceptual manifold must belong to the simplest of the mutlicellular animals, maybe even single celled organisms. That seems rather far down the phylogenetic tree to find vague cases of consciousness, doesn't it? And if such simple organisms are conscious, why not also the personal computer you're viewing this post on, or the nation in which you live, which is in some ways as complicated in its reactions? If simple reactivity to the environment is sufficient for consciousness, why not go wholly panpsychist? If it takes more than simple reactivity, then there will be organisms with complex perceptual manifolds but for which it is transitional, vague, indeterminate, a pragmatic decision about the application of terms, whether they are conscious. So there would be complex perceptual not-quite-experience-not-quite-non-experience. Huh?
Theoretically, it seems to me that there must be vague cases, and that those cases must be reasonably far along the developmental and phylogenetic spectrum, to the point where the organism's reactivity is fairly richly structured. But I cannot imagine such vague cases. I can't make sense of them. I can't understand what they would be like.
And that seems to indicate that there's something fundamentally flawed in my concept of consciousness.