On 8/2/2011 2:08 PM, Stephen P. King wrote:
On 8/2/2011 4:04 PM, meekerdb wrote:
On 8/2/2011 12:43 PM, Craig Weinberg wrote:
On Aug 2, 2:06 pm, "Stephen P. King"<stephe...@charter.net>  wrote:

The point is that there is a point where the best possible model or computational simulation of a system is the system itself. The fact that it is impossible to create a model of a weather system that can predict
*all* of its future behavior does not equal to a proof that one cannot
create an approximately accurate model of a weather system. One has to
trade off accuracy for feasibility.
I agree that's true, and by that definition, we can certainly make
cybernetic systems which can approximate the appearance of
consciousness in the eyes of most human clients of those systems for
the scope of their intended purpose. To get beyond that level of
accuracy, you may need to get down to the cellular, genetic, or
molecular level, in which case it's not really worth the trouble of re-
inventing life just to get a friendlier sounding voicemail.


So now you agree that a simulation of a brain at the molecular level would suffice to produce consciousness (although of course it would be much more efficient to actually use molecules instead of computationally simulating them). This would be a good reason to say 'no' to the doctor, since even though you could simulate the molecules and their interactions, quantum randomness would prevent you from controlling their interactions with the molecules in the rest of your brain. Bruno's argument would still go through, but the 'doctor' might have to replace not only your brain but a big chunk of the universe with which it interacts. However, most people who have read Tegmark's paper understand that the brain must be essentially classical as a computer and so a simulation, even one of molecules, could be quasi-classical, i.e. local.


Hi Brent,

I wonder if you would make a friendly wager with me about the veracity of Tegmark's claims about the brain being "essentially classical"? I bet $1 US (payable via Paypal) that he is dead wrong *and* that the proof that the brain actively involves quantum phenomena that are discounted by Tegmark will emerge within two years. We already have evidence that the photosynthesis process in plants involves quantum coherence, there is an experiment being designed now to test the coherence in the retina of the human eye.


Those are not really to the point. Of course the brain involves quantum processes and some of these involve coherence for short times. But Tegmark argues that the times are too short to be relevant to neural signaling and information processing. There's an implicit assumption that neural activity is responsible for thought - that the 'doctor' could substitute at the neuron level. I think this is right and it is supported by evolutionary considerations. We wouldn't want an intelligent Mars Rover to make decisions based on quantum randomness except in rare circumstance (like Buridan's ass) and it wouldn't be evolutionarily advantageous for an organism on Earth. I'm glad to accept your bet; except that I'm not sure how to resolve it. It don't think finding something like the energy transfer involving coherence in photosynthesis or photon detection is relevant.

As to your post here. Craig's point is that the simulated brain, even if simulated down to the molecular level, will only be a simulation and 'think simulate thoughts'. If said simulated brain has a consiousness it will be its own, not that some other brain.

Craig's position seems to be more a blur than a point. He has said that only biological neurons can instantiate consciousness and only a conscious being can act like a conscious being. That would imply that a being with an artificial, e.g. silicon chip based, brain cannot act like a conscious being.

A consciousness can no more be copied than the state of a QM system.

That's the point in question.  If Tegmark is right, it can.




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