[ExI] How the brain builds sentences, neuron by neuron

[Ben Zaiboc]

I just wanted to reiterate that nothing physical, like for instance a neurotransmitter, has the kind of 'qualities' we talk about when referring to colours (e.g. redness, etc.).

This should be obvious when you consider how many types of red there are (many, many more than the number of neurotransmitters our brains use), then how many different types of green, and blue, and yellow, etc., etc. Then there are all the other sensations we are capable of experiencing.

There are probably more different types and variations of possible qualia than there are atoms in the universe, so they cannot possibly be inherent in or dependent on specific pieces of matter. There simply isn't enough of it /in the entire universe/, let alone in a single brain.

If you come up with some way for a small number of molecules to combine together in different ways, though, things are very different. Molecule x in molecular aggregate A can signify something entirely different from the same molecule in aggregate B. This is how an atronomical number of different proteins can be made from 22 amino acids

Unending complexity can be, and is, built from small numbers of simple things. We know this from physics, from biochemistry, and from biology. It's a pattern we see again and again in nature.

So rather than asking "what molecules have what physical qualities that are equivalent or relevant to mental states?" (which leads to the above problem of there not being enough molecules in existence), we need to ask "what simple processes in the brain can be combined in endless ways to produce the vast variety of mental states that brains can experience?". The answer is glaringly obvious, when you know how neurons work.

To drive this point home, imagine that in the early days of computing, instead of using holes punched in cards or tape to represent zeros and ones which can be combined in various ways to produce a hierarchy of codes that could be assigned to an endless variety of meanings, we instead started with the meanings themselves, and used chemicals in small areas on the cards, with each meaning being assigned to a different chemical compound. Waving away the problems of producing and reading the different chemicals, how far would computing have got? Would "sodium borate = homesickness, silver nitrate = black with the faintest tinge of crimson, etc., etc., etc..." actually be practical?

Complex things are made of simpler things. All the ordinary matter in the universe is made of neutrons, protons and electrons. All the staggering complexity of physical things boils down to that.

In the same way, all mental states, no matter how complex, are made of two pieces of information, ON and OFF, combined together in a huge variety of ways. This is what red is, this is what homesickness is. The infinitely large space of possible thoughts boils down to ON and OFF, nothing else. The physical properties of molecules are not only unnecessary, but totally insignificant in comparison.

-- 
Ben