[ExI] Mental Phenomena

[Ben Zaiboc]

On Fri, Jan 10, 2020 at 3:50 AM Ben Zaiboc via extropy-chat 
<extropy-chat at lists.extropy.org> wrote:

Brent:
I think I have a way to disprove your idea about physical substances in
the brain producing qualia,

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)?

 >Yes

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'.

 >Exactly


OK, good.

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.

Only one is necessary, so I'll talk about the easiest one to explain and 
understand, and just mention the other one

I'm going to call this the 'availability argument'.

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.

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.

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.

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.

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.

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.

If they can't be stored ready for use, maybe they can be created when 
needed?

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.

So on-demand synthesis is not an option either.

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.

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.


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.


If you, or anyone else, can see any flaws in the 'availability argument' 
above, please let me know.


Oh, and PS: /Please stop Cc'ing my email address in your replies to the 
list/. I don't want to have to create a filter to automatically delete 
any emails from you.

Thanks.

-- 
Ben Zaiboc

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