If it helps, I've read Nagel, and would have gotten the bat allusion. (Dan Dennett does a very entertaining riff on "What is it like to bat a bee?" in response.)
But I consider the physics of qualia to be kind of irrelevant to the conversation we're having.
I mean, I'm willing to concede that in order for a computer program to be a person, it must be able to feel things in italics, and I'm happy to posit that there's some kind of constraint -- label it X for now -- such that only X-possessing systems are capable of feeling things in italics.
Now, maybe the physics underlying X is such that only systems made of protoplasm can possess X. This seems an utterly unjustified speculation to me, and no more plausible than speculating that only systems weighing less than a thousand pounds can possess X, or only systems born from wombs can possess X, or any number of similar speculations. But, OK, sure, it's possible.
So what? If it turns out that a computer has to be made of protoplasm in order to possess X, then it follows that for an upload to be able to feel things in italics, it has to be an upload running on a computer made of protoplasm. OK, that's fine. It's just an engineering constraint. It strikes me as a profoundly unlikely one, as I say, but even if it turns out to be true, it doesn't matter very much.
That's why I started out by asking you what you thought a computer was. IF people have to be made of protoplasm, AND IF computers can't be made of protoplasm, THEN people can't run on computers... but not only do I reject the first premise, I reject the second one as well.
"IF people have to be made of protoplasm, AND IF computers can't be made of protoplasm, THEN people can't run on computers... but not only do I reject the first premise, I reject the second one as well."
Does it matter?
What if we can run some bunch of algorithms on a computer that pass the turing test but are provably non-sentient? When it comes down to it we're looking for something that can solve generalized problems willingly and won't deliberately try to kill us.
It's like the argument against catgirls. Some people would prefer to have human girls/boys but trust me sometimes a catgirl/boy would be better.
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