On Oct 17, 8:56 pm, Stathis Papaioannou <stath...@gmail.com> wrote:
> On Tue, Oct 18, 2011 at 11:31 AM, Craig Weinberg <whatsons...@gmail.com> 
> wrote:
> > On Oct 17, 7:45 pm, Stathis Papaioannou <stath...@gmail.com> wrote:
> >> On Sun, Oct 16, 2011 at 11:44 PM, Craig Weinberg <whatsons...@gmail.com> 
> >> wrote:
> >> >> As an engineering problem as well as for the purpose of the thought
> >> >> experiment, we replace a part at a time and, as with the mechanic and
> >> >> the car, see whether it works the same. If the subject says they have
> >> >> gone blind or feel weird or something then the replacement part is not
> >> >> working properly. If they say they feel normal and they seem to you to
> >> >> behave normally then the replacement part is working properly.
> >> > I agree that would be a decent way of finding out. I'm saying that
> >> > they will not feel normal though, and they will most likely not behave
> >> > normally over time.
> >> But they have to say they feel normal since the speech centres of
> >> their brain receives the same electrical input and the neurons there
> >> fire in the same sequence as they normally would. Only if the neurons
> >> are affected by non-physical inputs (which would by assumption be
> >> missing if the artificial neurons are installed) would the subject be
> >> able to say that something was awry.
> > They wouldn't have to say that they feel normal, because the 'speech
> > centers' are not controlled by the artificial neurons. The speech
> > centers are used by the conscious areas of the brain so they can
> > vocalize anything that the subject cares to vocalize. If you were
> > colorblind and you replaced part of a computer monitor with an area of
> > pixels which looked like a perfect physical match to you, the user
> > would still be able to see the difference if they were the wrong
> > colors or monochrome.
> The speech centres must, through a relay of neurons, receive
> information from the visual centres if the subject is to make any
> statement about what he sees.

What makes you think that's the case? That's a blatant fallacy, isn't
it? "The windshield wipers must, through a relay of mechanical parts,
receive music from the from the radio station"

Visual centers don't talk, and speech centers don't see. People see
and talk.

> If the visual centres are artificial,
> but producing the same neural outputs to the rest of the brain,

They probably won't though. They can't because they don't feel the
appropriate qualia to repspond to events in the same way over time. It
depends how close they are to natural neurons, maybe even the neurons
which are genetically specific to that individual.

> then
> the rest of the brain will respond as if vision is normal:

If there is some part of the natural visual centers there, they may
very well be able to use the artificial ones as a substitute - like a
cane, but you can't use a cane as a substitute for your whole arm.

> the subject
> will say everything looks normal, he will grasp things normally with
> his hands, he will paint or write poetry about what he sees normally.
> His motor cortex cannot be aware that the visual cortex has changed,
> since the only awareness of the outside world the motor cortex can
> have must come through the surrounding tissue.

I understand how you are thinking about it, but I think that would
make sense if there were a such thing as functional equivalence of
qualia, but qualia has no function. There is no way to know if you can
make something that feels just like a neuron unless it is in fact a
natural neuron.

> > Since we know absolutely that we have experiences which cannot be
> > observed directly in the tissue of the brain, there is no sense in
> > imagining that replicating what we observe in the brain will not be
> > missing crucial capacities which we can't anticipate. Even replacing
> > simpler organs with actual human organs have a risk of rejection. Why
> > would the brain, which is presumably infinitely more sensitive than a
> > kidney, have no problem with a completely theoretical and unrealizably
> > futuristic artificial device?
> We assume that the artificial device reproduces the pattern of neural
> firing and nothing else. Do you think that is *impossible*? Why?

Sure, it might be impossible. Because the pattern is context
dependent. If you have a bunch of separate heart cells, they will all
beat regularly but not synchronized. So you make an artificial heart
cell that beats regularly at the same interval as any of the other
heart cells. When you put all of the separate heart cells in a dish
together, they all will synchronize - except the artificial ones. If
you were to put enough artificial heart cells in a living heart, you
would cause an arrhythmia and kill the person who is using that heart
to live.

Neurons are orders of magnitude more interconnected than that. The
idea that there is a fixed 'pattern of neural firing' which can be
derived from a single neuron in isolation that can be extrapolated out
to the brain as a whole is just factually incorrect. It's not some
exotic wackiness that I dreamed up, it's actually not at all the way
that the brain, or any living organism works. Neurons aren't just
miniature brains, and brains aren't just a pile of neurons. It's like
assuming that if you make a mannequin that acts like a nomadic hunter
gatherer, you should have no trouble repopulating New York, London,
and Hong Kong with a large group of them.


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