On 29 Feb 2012, at 21:05, meekerdb wrote:

On 2/29/2012 10:59 AM, Bruno Marchal wrote:

Comp says the exact contrary: it makes matter and physical processes not completely Turing emulable.

But it makes them enough TE so that you can yes to the doctor who proposes to replace some part of your brain (which is made of matter) with a Turing emulation of it?

The doctor does not need to emulate the "matter" of my brain. This is completely not Turing *emulable*. It is only (apparently) Turing simulable, that is emulable at some digital truncation of my brain. Indeed matter is what emerges from the 1p indeterminacy on all more fine grained computations reaching my current states in arithmetic/UD.

Ah, Quentin already said this. Let me copy his reply and your reply to it:

[Quentin] The turing emulation is not of the matter but of the mind... Computationalism, is the theory that the mind is some sort of information processor... the brain made of matter is just an UTM... any UTM could do the job, the emulation is not of the brain made of matter but of the consciousness.

[Brent]: But suppose I'm only replacing a small part of my brain. There's on reason to suppose that part, by itself, is conscious.

OK. A priori. Assuming that part being rather small.

Consciousness is supposed to be realized by the computation that the brain is doing.

But here we might have to be cautious. Natural language can fails to describe what is going on. My consciousness is not really realized by the computation made by the brain, it is only the content of my belief (computer generated) as far as it corresponds to some truth. It is not associated with any singular brain, but with the infinity of equivalent state reached by infinity of computations. The material brain is a sort of first (plural) person moiré effect due to the statistical interference of all those computations.

So the question becomes, at what level of fidelity must I emulate that piece of brain I'm going to replace. One answer would be at the lowest possible level, i.e. emulate the quarks and electrons and vacuum field fluctuations, then I'll be sure to survive with consciousness unchanged.

I am not sure you can ever be sure, but you might find a reasonable level. Already with the actual physics, I am not sure you can get all the vacuum field fluctuations, because there are infinities of them. Given that the artifficial brain is digital, you will have to make a truncation (unless you believe in a *locally* digital physics, but this should not be possible with comp). In fact comp entails that matter has no lowest level, if we want all decimals exact.

But that's emulating the matter of that piece of my brain, which Bruno says is not completely emulable. If that can't be done, why should I believe there is any level that I should say 'yes' to?

You should not believe in it 100% rationally. That's why you will need some act of faith, and just hope you bet on the comp right level. If comp is true, it cannot be entirely justified. It can only be refuted, or hope for. You *can* believe in it, if you want extend your life, or get a new brain expected to be better performing.

With the future first artificial brains, there will be bugs, and objective reasons to be anxious. The first people with artificial brain will complain on many things. They will say, I did survive, but I feel something is different, it is very hard to sleep, and my dreams seems more weird and a bit frightening. They will lose some biological rythmic cycles related to the metabolism, they might suffer headache. Worst, some people will say that they survive very well, but outsider will disagree, because they will not behave normally, etc. Artificial brains will be an evolving technology.



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