[ExI] The relevance of glutamate in color experience

[Rafal Smigrodzki]

On Sun, May 1, 2022 at 10:07 PM Brent Allsop via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

>
> Hi Jason,
>
> Yes, this is the Neuro Substitution Argument for functionalism
> <https://canonizer.com/topic/79-Neural-Substitn-Argument/1-Agreement> Stathis,
> I and others have been rehashing, forever, trying to convince the other
> side..  Stathis, Chalmers, and other functionalists
> <https://canonizer.com/topic/88-Theories-of-Consciousness/18-Qualia-Emerge-from-Function>
> believe they must accept functionalism because of this argument.  This is a
> specific example of the 'dancing qualia' contradiction (one of many) which
> results if you accept this argument.
>
> I like to point out that this argument is dependent on two assumptions.
> 1., that all the neurons do is the same thing discrete logic gates do in
> abstract computers.  2. That the neuro substitution will succeed.  If
> either of these two fail, the argument doesn't work.
>

### This is not true. The argument is valid regardless of the mechanism of
computation in the device that is substituting for a part of the brain.
Only requirement for the substitution argument is that the substituted
device must not change the way the rest of the recipient brain works (i.e.
the overall pattern of neural activity and behavior controlled by the
brain).

By way of illustration, instead of using a digital device for substitution,
we may consider a genetically engineered brain that has the identical
functional organization as a normal human brain but substitutes e.g.
D-glutamate for L-glutamate as the transmitter. This would require
re-engineering the structure of the relevant glutamate receptors, adding a
glutamate isomerase to make D-glutamate out of L-glutamate and perhaps
other minor tweaks but it would not change the functional aspects of
neurotransmission in the modified brain or its parts.

Obviously, if the chemical structure of glutamate somehow determined
qualia, then such a modified brain would have different qualia. If however
the modified D-glutamate brain is able to substitute for a part of the
standard L-glutamate brain without changing the overall patterns of neural
activation and without changing behavior then the substitution would prove
that glutamate has nothing to do with qualia.

Rafal
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