Thanks for the interesting block of text epepke.
So it seems like our sense of self as an individual is more a necessary fiction generated by the brain?
Maybe, depending on what you mean by "necessary fiction." I'm going to stick with "folk model" because that's the term that George Lakoff uses, and I find it useful.
There are many, many things in brains, and they all interact in hugely complex and approximate ways. Most of the time they seem sort of OK. I say "sort of," because that's also an illusion. People think of proper brain functioning as normative; if you act like other people, you're "ordered," and if you don't, you're "disordered." However, every human being is in constant conflict, and it shifts the balance. Ordinary experiences like anger and sexual excitement can affect decision-making abilities, to the point where under their influence, people can truly believe things that in other states they just as truly believe are wrong. This is an ordinary experience, and I'm convinced that many of the diagnosable "mental disorders" result substantially from these conflicts.
We certainly know of particular gross instances of brain damage that can exacerbate this. There are the split-brain patients, whose corpus callosa have been severed to stop seizures. The halves of their bodies will often act in different ways. The part of their brain that is still connected to the mouth and can do language will often report their other arms reaching for things that they don't want. There are other patients who have damage to the part of the brain that helps them integrate information from audio and visual channels. Oliver Sachs reported that these people love to watch political broadcasts, which they find uproarious, because all the body language is so much in conflict with the words being said as the politicians try to lie and prevaricate. It is an instance where a little bit of a disorder might be better.
[/quote]If some trauma or brain injury were to damage that, then it could well result in 'multiple' personalities?[/QUOTE]
Yes, but it goes beyond that. To a large degree it is normal functioning. This is how the brain basically works. It's not that it works one way, and then trauma or damage breaks it, and then it works (or fails to work) another way. How it works is substantially the same.
As I pointed out, I find it dismaying that skeptics believe so much in logic. That's a kind of Cartesian mistake, which is flat-out wrong: the idea that brains are reasoning engines. It's deceptive, because logic is so simple, and you can list all the rules on a 3 by 5 card. However, the fact remains that brains can do logic. That is what people should be amazed at, that a system originally evolved to provide simple motor control by the engineering hack of having a signal respond on the same side of the body to avoid a stimulus and cross the body to move toward a stimulus should evolve the capability. That is interesting, and it cannot be disregarded.
When you look into how it works, it's fascinating. Almost everything that goes on with respect to learning in the brain involves Hebbian learning. It's simple. There are neurons. They fire, unless they don't. Each runs a lot of axons to other neurons, connected through synapses. When the axons carry signals, it increases the probability that the neurons they are connected to will fire, and then their axons will fire, and so on. When axons fire a lot, they strengthen and eventually split into two. When they don't, they fall apart.
That's it. Where's the logic in that? It's just like wires and resistors and relays. Well, you can see how there is OR and AND capability within them. The more axons coming into a neuron that fire, the more likely it is to fire. That's AND. But you don't need all of them, and maybe one strong signal will do it. That's OR. As any kid who has wired up logic circuits with switches knows, you can do a lot with OR and AND, but not everything. You need a NOT to do a complete logic. But NOTS are expensive. So there has to be a NOT in there somewhere.
It turns out, there are. They are called inhibitory synapses. An axon connected to one will tend to prevent the neuron from firing when the axon fires.
The tricky thing is that these are not fixed. They require neurotransmitters to work. The presence of a neurotransmitter at the synapse will switch it to a NOT.
As most people know (in fact, the issue is far too stressed and oversimplified), neurotransmitters are associated with emotions to some degree. Also, as everybody knows, they're systemic and go everywhere. You can take drugs that change how they work. Not always the level (that's an oversimplification), but things like how long they stick to a receptor, which uses the word "reuptake," or how quickly they are oxidized and excreted to the CSF.
So what happens is that, when an emotional state changes, the whole wiring changes essentially randomly, as NOT gates activate and deactivate here and there. This is very useful; being frustrated at a problem can literally change the logic of the brain. So it can function as kind of a search algorithm. If one state can't find a solution, perhaps another can.
It does mean, though, that people are fluctuating all the time. We don't usually notice it, though, because we normally also learn in all those states and the states between them, and we get memories about what we did, so it all seems pretty fluid.
But an unusually strong emotion from a trauma? Maybe something that's triggered by a particular memory or situation (with that same basic Hebbian mechanism). Well, all bets are off. You're back to randomly flipping switches.
I think that's probably why a lot of therapy involves going back an revisiting the problem. Maybe there's nothing that can actually be done about it to fix it, but maybe it builds a bridge between an unusual state and the usual ones and makes the experience more integrated and easier to connect to everything else.
