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<p>On Fri, Jan 10, 2020 at 3:50 AM Ben Zaiboc via extropy-chat <a
class="moz-txt-link-rfc2396E"
href="mailto:extropy-chat@lists.extropy.org"><extropy-chat@lists.extropy.org></a>
wrote:<br>
<br>
Brent:<br>
I think I have a way to disprove your idea about physical
substances in<br>
the brain producing qualia,<br>
<br>
Is your position that specific types of molecule in the brain
(e.g. the infamous glutamate) are what produce specific qualia
(e.g. the infamous 'red'), and that this mapping is one-to-one
(e.g. glutamate and only glutamate produces the 'red' quale and
only that)?<br>
<br>
>Yes<br>
<br>
The consequence of this would be that if you removed glutamate
from someone's brain (without killing them somehow), that person
would be incapable of experiencing 'red'.<br>
<br>
>Exactly<br>
</p>
<p><br>
OK, good.<br>
<br>
My original idea turned out to be more difficult to verify than I
expected, but it also gave me two other ideas, that are better,
and easier.</p>
<p>Only one is necessary, so I'll talk about the easiest one to
explain and understand, and just mention the other one<br>
</p>
<p>I'm going to call this the 'availability argument'.</p>
<p>If a specific type of molecule produces a specific quale as you
claim, then that type of molecule must be deployed or activated
somehow, for the quale to become active. The example you always
give, of glutamate, is a neurotransmitter, that's released at the
pre-synaptic membrane, which is when it does its job of
transmitting data from one neuron to another. If this is also when
it somehow causes the 'red' quale to become active, we have an
impossible situation.</p>
<p>That's because of the very large number of qualia that can exist.
We know that humans are capable of distinguishing several million
different colours, and that's only a tiny fraction of all the
qualia that can be experienced. There are probably at least
hundreds of millions of qualia that are possible. By your own
claim, each of them must be produced by a different type of
molecule. This means we must have hundreds of millions of distinct
types of molecule at the ready to be activated when needed. If we
assume that most of these molecules are proteins (because there
aren't enough varieties of any other kind of molecule, and and
other type would have to be made by proteins anyway),
theoretically there is no problem in creating them, we know that
given enough amino acids, an arbitrarily large number of different
proteins can be created. The problem is in having them available
to be deployed when they are needed.</p>
<p>Neurotransmitters are created in the neuronal cell body and
transported down the axon, then stored in vesicles just inside the
pre-synaptic membrane. Generally, one neuron uses one
neurotransmitter (although that is being called into question now,
it doesn't really matter for this argument, because the number of
different neurotransmitters any one neuron uses is certainly low).
When needed (when an action potential depolarises the synaptic
membrane), a set of molecules on the inner surface of the membrane
links the vesicles to the membrane, fusing them and releasing the
contents of the vesicles into the synaptic cleft.</p>
<p>We have identified somewhere between one hundred and two hundred
different signalling molecules that can be used as
neurotransmitters. Let's be generous and say a thousand exist.
That's far short of the number of 'quale-producing' molecules we
need, so it's obvious that it can't just be neurotransmitters that
are involved.</p>
<p>Let's assume, then, that some other, currently unknown system is
responsible for the production of qualia, via these hundreds of
millions of different types of molecule.</p>
<p>The core of my argument is that these molecules can't possibly be
pre-existing, ready to be deployed within a fraction of a second
in the way that neurotransmitters are, because we would see them.
We would know about the ridiculously huge numbers of different
molecules just hanging around in our nervous system waiting for an
appropriate signal to release them, or activate them, or whatever.
We don't see this, we see a comparatively small number of
signalling molecules instead.</p>
<p>If they can't be stored ready for use, maybe they can be created
when needed?</p>
<p>That doesn't work either. Protein synthesis is not quick. it
takes a few seconds to translate each amino acid, so a large
protein (necessary, if we are to have hundreds of millions of
distinct ones) will take minutes to produce at least. Then there's
the transport of the proteins from the endoplasmic reticulum where
they're made to the site/s where they are needed. For
neurotransmitters, this means a trip down an axon, which is even
slower.</p>
<p>So on-demand synthesis is not an option either.</p>
<p>There's also a parsimony issue. Why would our brains make and
keep ready a vast set of molecules for qualia that we may never
use? A native of a tropical forest is very unlikely to ever
experience snow. Why keep all the molecules needed for this in his
brain ready for use? We know that if such a native is exposed to
snow, he will instantly experience a new set of qualia, without
having to wait for a set of new molecules to be produced. With all
the overhead involved in creating and maintaining a very large
number of unused molecules, I'm sure evolution would have weeded
out any such profligacy a long time ago.<br>
</p>
<p>The upshot of all this is that there is an availability problem.
Hundreds of millions of different types of molecule simply can't
be made available for the production of qualia on the milliseconds
timescale that we need. So the production of qualia can't be
something that relies on a one-to-one correspondence with specific
types of molecule.</p>
<p><br>
</p>
<p>Another argument involves possible mechanisms for activating or
deploying these molecules (assuming it was possible for them to be
ready and waiting), and how any individual neuron or collection of
neurons could know just which molecule to pick. I'm not going to
unravel this argument here, but essentially it leads right back to
what we currently know about how our nervous system works, and
makes an enormous set of specific types of molecule redundant.<br>
</p>
<p><br>
</p>
<p>If you, or anyone else, can see any flaws in the 'availability
argument' above, please let me know.</p>
<p><br>
</p>
<p>Oh, and PS: <i>Please stop Cc'ing my email address in your
replies to the list</i>. I don't want to have to create a filter
to automatically delete any emails from you.</p>
<p>Thanks.<br>
</p>
<pre class="moz-signature" cols="72">--
Ben Zaiboc
</pre>
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