Biological theorists of consciousness hold that consciousness is essentially biological and that no nonbiological system can be conscious.
I guess they have some explanation why, I just can't imagine it.
My best attempt is: The fact that the only known form of consciousness is biological, is an evidence for the hypothesis "consciousness must be biological".
The problem is that it is equally an evidence for hypothesis "consciousness must be human" or "consciousness must be in our Solar system" or even "a conscious being can have at most two legs", which don't sound too plausible.
The biological hypothesis feels more generous that the hypothesis of at most too legs. I am just not aware of any good reason to draw the boundary there. Or even where exactly is the boundary -- for example why the synthetically produced urea is within the "plausible candidates for consciousness" set, but a computer is outside. How exactly does that relate to consciousness?
It feels more generous because it is more generous. First, we encounter people without legs who function apparently close to normally, and cojoined twins with more than two legs. Second, and more seriously, the biological hypothesis here actually involves the brain where pretty much everyone other than a hard-core dualist agrees the actual relevant stuff is occurring. Thus, under some form of the biological hypothesis, if you took a brain and put it in a robot body that that wouldn't be conscious that would still be conscious. So I think there is some real room for being more generous to the biological hypothesis than the alternate hypotheses you propose.
- Eliezer Yudkowsky, "Value is Fragile"
I had meant to try to write a long post for LessWrong on consciousness, but I'm getting stuck on it, partly because I'm not sure how well I know my audience here. So instead, I'm writing a short post, with my main purpose being just to informally poll the LessWrong community on one question: how sure are you that whole brain emulations would be conscious?
There's actually a fair amount of philosophical literature about issues in this vicinity; David Chalmers' paper "The Singularity: A Philosophical Analysis" has a good introduction to the debate in section 9, including some relevant terminology:
So, on the functionalist view, emulations would be conscious, while on the biological view, they would not be.
Personally, I think there are good arguments for the functionalist view, and the biological view seems problematic: "biological" is a fuzzy, high-level category that doesn't seem like it could be of any fundamental importance. So probably emulations will be conscious--but I'm not too sure of that. Consciousness confuses me a great deal, and seems to confuse other people a great deal, and because of that I'd caution against being too sure of much of anything about consciousness. I'm worried not so much that the biological view will turn out to be right, but that the truth might be some third option no one has thought of, which might or might not entail emulations are conscious.
Uncertainty about whether emulations would be conscious is potentially of great practical concern. I don't think it's much of an argument against uploading-as-life-extension; better to probably survive as an up than do nothing and die for sure. But it's worrisome if you think about the possibility, say, of an intended-to-be-Friendly AI deciding we'd all be better off if we were forcibly uploaded (or persuaded, using its superhuman intelligence, to "voluntarily" upload...) Uncertainty about whether emulations would be conscious also makes Robin Hanson's "em revolution" scenario less appealing.
For a long time, I've vaguely hoped that advances in neuroscience and cognitive science would lead to unraveling the problem of consciousness. Perhaps working on creating the first emulations would do the trick. But this is only a vague hope, I have no clear idea of how that could possibly happen. Another hope would be that if we can get all the other problems in Friendly AI right, we'll be able to trust the AI to solve consciousness for us. But with our present understanding of consciousness, can we really be sure that would be the case?
That leads me to my second question for the LessWrong community: is there anything we can do now to to get clearer on consciousness? Any way to hack away at the edges?