> As for the possibility that consciousness gradually fades away, this has
> problems of its own (Chalmers discusses this "fading qualia" example).
> If it is literally a matter of fading, where smells get less intense
> and reds become less red, then the person should notice this and comment
> on it. It is hard to see why he would not say something if he noticed
> his sensory impressions changing.
I don't *know* what would happen if you gradually chopped up the brain. But, since I am of the opinion that consciousness is a weird physical phenomenon, I can answer that you *cannot* divide a consciousness in two and duplicate the I/O, just as you can't chop a singularity (black-hole type) in half. If you gradually eliminated the underlying mechanisms for consciousness, the person would notice.
And yes, I know what you're going to say about simulating black holes. The point I'm trying to make is that only Turing phenomena have to be divisible into discrete components. Once one steps sufficiently far outside that, one can conceive of building a physical *thing*, not a structure, not as the interaction of components, but a substance as real as a quark, or whatever the bottom level is.
Oh, hell, I don't have the words to describe it. What I'm trying to say is that I think it's possible to construct complex nondivisible real things having what we would interpret as cognitive characteristics. Including qualia, and, one hopes, objective morality. Reality isn't an is_real() function. Reality is a substance. As long as we think in terms of is_real() and chains of cause and effect, we'll never even be able to explain why anything exists in the first place. Sadly, that Turing ontology is a basic part of human cognition.
Reality physics. You can keep your spacetime engineering and descriptor theory. I know the toys the Powers play with.
-- email@example.com Eliezer S. Yudkowsky http://pobox.com/~sentience/tmol-faq/meaningoflife.html Running on BeOS Typing in Dvorak Programming with Patterns Voting for Libertarians Heading for Singularity There Is A Better Way