Richard wrote:

"You go on to talk about "functionally equivalent analogue" neuron replacement which is a different argument. I agree that replacing neurons with functionally equivalent devices makes no odds. My argument is that digital computers cannot achieve functional equivalence with neurons: there is no program that can emulate the brain's functioning."

By "functionally equivalent" I mean that in the first instance external behaviour will be the same. You replace part of the visual cortex of someone who has had a head injury with an electronic visual cortex and he declares that he can see just the same as before and behaves in every way just as before. I would say in that case that he *can* see just as before. The alternative is very weird: that he is a partial zombie and hasn't noticed, or that he is blind and struggling to tell us but observes in horror as his mouth, seemingly of its own accord, declares that everything is fine.

Perhaps you are saying that no computer would even in theory be able to copy the function of a neuron well enough to be equivalent in this sense as a replacement part? Maybe, but conventional belief has it that neurons work using chemistry and chemistry is computable, even if it isn't practically computable with current technology. You need to have a good reason to claim otherwise.

"I remain firmly of the belief that computational functionalism is false and suggest we agree to differ."

That's where this discussion might end but I don't think we're at an impasse yet.

Brent,

I would say that the binding problem and the qualia problem would, mysteriously, be taken care of if the nuts and bolts problem is taken care of. This is why I previously used the example of aliens who have no idea whether or in what way humans are conscious repairing damaged brains. If they do a good job the human will behave as he did before the injury, and he will also be conscious in the same way as he was before the injury (even though the aliens will still have no idea about this).

There are only two ways the above scenario could be wrong. The first way is that neurons incorporates processes that are not computable. The aliens would then only succeed if they replaced like with like; a computer model of a neuron simply wouldn't behave in the same way as the biological original. I think you have indicated you don't believe this, but if you do believe it, on what evidence?

The second way the above scenario could be wrong is if the external behaviour of the human would be the same but the qualia different. That would mean that you could be blind but behave as if you were normally sighted and believe that you were normally sighted. You would be a partial zombie, in other words. But you have indicated that if you were a partial zombie, you would know about it.

The simplest and least weird solution would therefore seem to be that it is possible to emulate brain function, and that the qualia will thus also necessarily be emulated.

Grey wrote,

"Since then I have realized, that mostly this argument is a paper tiger, dependent on the idea that we are going to program a computer system to replace the brain. The computer system we use, will probably either include a Virtual Machine that works differently from the standard software, and thus eliminates any demand that software works only one way, and/or has completely different circuits that work using a completely different architectural approach, which is what I personally am working on.

"Don't worry it will still be implemented in silicon, although I am currently trending towards a hybrid digital/frequency based circuit and away from strict adherence to Digital architectures."

What is a "digital/frequency based circuit"? By the Turing principle, anything that is computable can be computed by a Turing machine, which means effectively it can be computed by a digital computer with enough memory.

John asks what is a digital/frequency circuit and notes that anything that is computable can be computed.

Don't get me wrong, I am not attacking that position (That the brain is computable), I am simply taking a short-cut, via Analog Circuits to implement a specific implicit memory cell architecture.

The question is not "Is it computable" it is.

The question is, is it economic to use software to compute it? I think it might not be all that economical to base the simulation too heavily on parallel processing systems made of sequentially programmable computers and software. But I am still moving in that direction, in case it is.

Usually Hardware is fossilized software, so by skipping the software step, I can go to hardware implimentation, without needing to go through the software implementation stage. If you know someone who wants to simulate my ideas in software, I am willing to talk to them, but face it, with my income limitations it is going to be a while before I can get the simulation programmed.

Of course it is also going to be a while before I can get the circuit I have characterized bread boarded and pattented. Whether that patent is worth anything also depends on whether the patents it depends on , are held by people who want too much for the per-unit licensing.

Oh, the digital/frequency thing, I am using a frequency tag on the individual implicit memory cells, so that they can be filtered. These days you can integrate digital with analog circuits really easily, so I think it might be practical.

Brent says

"The nature has phenomenal properties theory is clearly a subset of the brain identity theory. Within this model, there is not just a 'causal relationship with qualia', you can actually causally detect the cause and effect behavior of whatever it is that also subjectively has the phenomenal properties. The theory also predicts we will even be able to see, causally, and behaviorally, how all this is 'bound together' and abstractly discover how the mind thinks about and answers such a question as "What is red like" and how it knows the difference between red and green and so on."

As IT theory has too many faults to be a viable scientific theory, I suggest we need to expand our concept of the natural world, as Bernard Carr and I do, to include the brain (with its NCCS) and phenomenal consciousness (with its qualia). The investigations you refer to are all about NCCS themselves: they say nothing about the relation about NCCS and qualia—as A.J. Ayer pointed out many years ago.