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Brent Allsop <a class="moz-txt-link-rfc2396E" href="mailto:brent.allsop@gmail.com"><brent.allsop@gmail.com></a> wrote:<br>
><br>
> Ben, let me ask you this. What do you think your knowledge of
a strawberry is composed of?<br>
<br>
<br>
The same thing as my knowledge of anything is composed of. The same
thing my, or anyone else's, experience (and any other mental
phenomena you care to mention) of anything is composed of:<br>
<br>
Patterns of neural activation in my brain.<br>
<br>
What are they composed of?<br>
<br>
An enormous number of spike-trains (sets of action potentials in a
bewildering array of combinations) in an enormous number of axons,
interacting in various ways (neural circuits involving lots of
feedback loops, reinforcement, cancellation, etc.) via summation
functions in neural hillocks and dynamic connections mediated by
synapses, and modified by various enzymes in synaptic gaps and the
properties of synaptic membranes.<br>
<br>
Plus a few other things not worth mentioning here.<br>
(this is as far as we know to date (as far as I know)).<br>
<br>
And what are all those things composed of?<br>
<br>
Probably the best answer to that, if anyone really wants to know, is
to study biology, and especially neurology, to at least
degree-level.<br>
<br>
Probably not the kind of answer you're looking for, but expecting
simple answers to complex questions is rarely going to make anyone
happy (except perhaps those of a religious disposition), and
certainly isn't going to lead to any useful knowledge.<br>
<br>
One thing that is quite clear to me, though, is that no amino acid
possesses an intrinsic 'quality' that has nothing to do with its
chemical composition, but relates directly to mental phenomena like
the perception of a colour. In fact, that makes no sense whatsoever.
Glutamate in particular, is one of the most common amino acids in
our bodies, is present in most proteins, and its use in the brain as
a neurotransmitter is of no real significance. Anything else would
be just as good, as long as there were corresponding receptors for
it.<br>
<br>
If glutamate really did possess 'elemental red' (pretending for a
minute that that means something), why would it be present in our
fingernails? Our hair? and a hundred other places in our bodies
apart from the brain?<br>
<br>
Someone else has remarked that its role in the brain as a
neurotransmitter could be taken by glycine instead, with the
relevant receptors changed to glycine receptors, with no change in
any mental phenomena at all. I'd go further than that, and say it
could just as well be exchanged for, say, sodium iodide, with NaI
receptors, and the required metabolic pathways for its synthesis and
breakdown, and it would make <i>absolutely no difference whatever</i>.
If this exchange was made in your brain, you would have no way of
telling, apart from doing a chemical analysis of your brain tissue.
Any other substance would do as well, as long as it was biologically
plausible. It certainly would not affect your experience of the
colour red, or anything else.<br>
<br>
You could even replace all the glutamate circuits with a dozen
different neurotransmitter/receptor pairs, anywhere you like in the
brain. It would make things unnecessarily complicated, biochemically
(as if the brain wasn't complicated enough!), but wouldn't make any
subjective difference. All the neural circuits would work exactly
the same as before.<br>
<br>
Which brings me back to my statement, "the concept of 'elemental
red' is sheer nonsense". Experiencing a colour is very far from
'elemental', it's a complex process involving thousands of neural
events. Apart from anything else, just think of some of the many
different things that "Experiencing a colour" can mean! How many
different varieties of Red can you picture or apprehend? See?
Remember? Imagine? What do they have in common? Anything? Perhaps a
category label, very abstract, that we can articulate as the word
"red". I say 'perhaps', because one man's red can be another man's
orange (or purple).<br>
<br>
And as far as strawberries are concerned, what if my 'knowledge of a
strawberry' doesn't even consider the colour? Having seen yellow and
green strawberries, I might conclude that their colour is
irrelevant. Do our brains possess an amino acid that is 'elemental
strawberry'?<br>
<br>
I'm confident that they don't.<br>
<br>
Ben Zaiboc<br>
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