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Nisan comments on The two insights of materialism - Less Wrong
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The former might believe that consciousness arises from particular physical interactions — interactions that might exist in the brain but not in a computer.
Wouldn't such a person believe that you can't fully simulate a person at all with a conventional computer though?
I think Phil Goetz is using the term "simulate" in its computational or mathematical sense: The materialist of the first kind would agree that if you had a pretty good algorithmic model of a brain, you could simulate that model in a computer and it would behave just like the brain. But they would not agree that the simulation had consciousness.
ETA: Correct me if I'm wrong, but a materialist of the first kind would be one who is open to the possibility of p-zombies.
No, p-zombies are supposed to be indistinguishable from the real thing. You can tell apart a simulation of consciousness from an actual conscious being, because the simulation is running on a different substrate.
Basically, yes. But I think it's worthwhile to distinguish between physically (the original definition), functionally, and behaviorally identical p-zombies, where materialists reject the possibility of the first, and functionalists reject the first and second (each is obviously a superset of the former).
NB: "Functionally identical" is handwaving, absent some canonical method of figuring out what computation a physical system implements (the conscious-rocks argument).
Do people holding this view who call themselves materialists actually exist? It seems an incoherent position to hold and I can't recall seeing anyone express that belief. It seems very similar to the dualist position that consciousness has some magic property that can't be captured outside of a human brain.
John Searle, David Pearce (see the last question), presumably some of the others listed under "Criticism" here.
As far as I can tell from looking at those links both Searle and Pearce would deny the possibility of simulating a person with a conventional computer. I understand that position and while I think it is probably wrong it is not obviously wrong and it could turn out to be true. It seems that this is also Penrose's position.
From the Chinese Room Wikipedia entry for example:
From the Pearce link you gave:
So I still wonder whether anyone actually believes that you could simulate a human mind with a computer but that it would not be conscious.
They would deny that a conventional computer simulation can create subjective experience. However, the Church-Turing thesis implies that if physicalism is true then conscious beings can be simulated. AFAICT, it is only Penrose who would deny this.
Do you mean the Church-Turing-Deutsch principle? It appears to me that Pearce at least in the linked article is making a claim which effectively denies that principle - his claim implies that physics is not computable.
Why? Pearce is a physicalist, not a computationalist; he ought to accept the possibility of a computation which is behaviorally identical to consciousness but has no conscious experience.
What sense of 'ought' are you using here? That seems like a very odd thing to believe to me. If you think that's what he actually believes you're going to have to point me to some evidence.
Basically, what bogus said.
I'm confused about what you mean by "simulating a person". Presumably you don't mean simulating in a way that is conscious/has mental states (since that would make the claim under discussion trivially, uninterestingly inconsistent), so presumably you do mean just simulating the physics/neurology and producing the same behavior. While AFAIK neither explicitly says so in the links, Searle and Pearce both seem to me to believe the latter is possible. (Searle in particular has never, AFAIK, denied that an unconscious Chinese Room would be possible in principle; and by "strong AI" Searle means the possibility of AI with an 'actual mind'/mental states/consciousness, not just generally intelligent behavior.)
Yes. Equivalently, is uploading possible with conventional computers?
It seems to me that both Searle and Pearce would answer no to both questions. Pearce in particular seems to be saying that consciousness depends on quantum properties of brains that cannot be simulated by a conventional computer. It appears to me that this is equivalent to a claim that physics is not computable but I'm not totally confident of that equivalence. I have trouble reading any other conclusion from anything in those links. Can you point to a quote that makes you think otherwise?
I don't think Pearce or Searle would agree with this, and it sounds like you might be projecting your belief onto them. We already know of philosophers who explicitly endorse the possibility of zombies, so it's not surprising for philosophers to endorse positions that imply the possibility of zombies.
Afraid not, but I think if they thought physics were uncomputable (in the behavioral-simulation sense) they would say so more explicitly.
Way back at the beginning of this thread I was trying to establish whether anybody who calls themselves a materialist actually believes the statement "you can't fully simulate a person without the simulation being conscious" to be false. I still don't feel I have an answer to that question. It seems that bogus might believe that statement to be false but he is frustratingly evasive when it comes to answering any direct questions about what he actually believes. It seems we are not currently in a position to say definitively what Pearce or Searle believe.
The only reason I asked in the first place is that I've tended to assume someone who self-describes as a materialist would also believe that statement to be true. I guess the moral of this thread is that I can't assume that and should ask if I want to know.
To the best of our knowledge, any "quantum property" can be simulated by a classical computer with approx. exponential slowdown. Obviously, a classical computer is not going to instantiate these quantum properties.
Is that obvious?
I don't know about consciousness, but the position that subjective experience has some magic property is common sense. Materialism is just a reasonable attempt to ground that magic property in the physical world.
You could fully simulate the person's consciousness. The simulation won't have any subjective experience, and it might also be very inefficient from a computational perspective. Compare running an executable program on a computer vs. running the same program in an interpreted VM.