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excreationist,

Yes, I did read your last post, but it didn't seem like you were speaking to what I was saying.
Agreed.
What do you mean by the "best" decision?
I don't really see a distinction here. Although only one outcome is possible under deterministic physics, I don't see how it is any different for non-deterministic physics. Since we cannot know the future, the MWI branches out from all the possibilities of the current situation. As you agree when you say, "but in most parallel histories, the decision would be about the same if the timespan was short," this means that in the near future no major changes are likely to occur, or, one's momentum should remain roughly the same, which is equivalent to deterministic physics.
You're missing the point here. It is not a decision. This is how Mexicola and I both saw how the experience of fatalism would be like, if it were true. However, this is not what our experiences suggest. It feels like we actually do make decisions and have control over our own actions.

excreationist

spacer1:
The decision that (according to currently recalled information) seems to maximize our expected (or present) pleasure and/or minimize pain.
I think all of our "good"/"bad" (pleasure/pain, etc) emotions are summed together to find an overall result.
e.g.
say you were driving slowly along a busy freeway and you saw lots of money lying around. But you were late for an important meeting.
You could either hop out of the car and start picking up money or not get out of the car.
You initial thoughts might be (approximately)

a) Getting out of the car:
Being more late for meeting (-70), having lots of money (+100), holding up the traffic (-20)

b) Staying in car:
Missing out on money (-30)

So for (a), overall it would be +10 but you'd simultaneously feel various pleasures and "pains" that would be based on fundamental drives.
(b) would be -30 overall so you'd choose option (a).
Then while hopping out the car you might hesitate (rethink) a little and realize that you should hand that money into the police in case somebody claims it or it was stolen. That could sway your decision the other way. But you'd be aware of the potential pleasure of the money and perhaps remember that if no-one claims the money after a few months it's yours. So you might reverse your decision again, but then remember your meeting and maybe remember that this meeting could get you a promotion so you just forget about the money and keep driving. This would also involve the overall values for possible decisions to change, possibly making the "best" decision change.
An analogy could be a chess computer. Let's say you gave it a few seconds to make its "decision" as to what piece it will move and where it will move it. This might be enough time for it to look 3 moves into the future. Then if you gave it some more time - so that it could look 5 moves into the future, its decision might change.

Over long timespans though, quantum randomness in alternate histories would make the processes of their brain and external environment (which is the input to their brain) diverge and so over the course of their lives people would have different lives. (Rather than be doomed to live one possible life by fate)

I'm saying the areas involved with our top-level decision-making activities ARE involved with our consciousness (they are intimately related). And we DO make decisions... I mean, even chess computers make decisions... though they are preprogrammed, and we learn most of our problem-solving strategies.

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excreationist,
Does this apply equally to each person?
What about two different chess computers which give different weightings to certain outcomes? One might change its mind while the other may not, and they both might play different moves anyway. Which move is the best?
Who's to say that the same outcome wasn't determined all along?
Yes, and since we are not pre-programmed, and have evolved naturally from inanimate matter which does not exhibit any form of consciousness in itself, why do we make decisions? (Tough question, I know, but it follows on from my earlier points.)

excreationist

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I think the basic process is the same, but the details are different. (e.g. people may have developed some inappropriate fetishes/phobias by associating pleasure/pain with things too much)

By choosing the "best" decision I just mean choosing whatever decision fits the selection criteria the best - based on priorities, etc. e.g. if your only selection criteria as far as buying a car is what goes the fastest, then the fastest car is the best. If your selection criteria involves a combination of the cheapest initial price plus the cheapest running costs, then another car would be the "best" car.

It depends if MWI is true and whether it meant that the alternate lives of people would diverge over time... Maybe, according to MWI(?), a researcher might look at an electron that was in an indeterminate state. There would be two possible outcomes which would turn into two different realities (according to MWI?). The researcher would have slightly different thoughts based on what they saw and that would affect their future thoughts.

You seem to be asking two questions here... "WHY" do people make decisions and why do "WE" (the conscious we) make those decisions. It should be obvious why people make decisions. In the wild, we'd be faced with complex situations with competing priorities like looking for food, avoiding danger, mating, staying popular with the group (maybe fighting rivals), etc.
As far as why the conscious "I" is involved... well *something* needs to be involved which simultaneously processes relevant data such as priorities (based on fundamental drives), and hypothetical options. There are also areas of the brain that associate different elements of experience together to learn patterns and so make future decisions. e.g. we can associate sounds or smells with the sight of objects. We can associate the sound "red" with a certain pattern of visual sensation. So our learning involves having all the senses interlinked. And learning is connected to our decision-making. I think that the processing system (which may be spread out) for decision making and/or learning is what our consciousness is. As for why the data (qualia) that these systems (our "consciousness") are processing seems so real and immediate... well you didn't ask about that and that is quite a difficult question anyway.

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excreationist,
How do these "inappropriate fetishes/phobias" arise if, as you propose, we "maximize our expected (or present) pleasure and/or minimize pain."
What determines the "selection criteria" or "priorities"?
I only intended to ask one question, which was: Why do we make decisions? It is obvious that people make decisions to help them survive. My point is, how does inanimate matter come to have a desire to survive in the first place?

excreationist

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Well our expectations (or beliefs about the future) can be flawed. When they are really flawed subconscious beliefs about seeking pleasure or avoiding pain, then they are "inappropriate". Perhaps a better thing to contrast with phobias are "good luck" superstitions? Fetishes may be a different concept altogether. Maybe I'll just be concerned with phobias. So anyway, if you have an extreme phobia of something - like mice - then your beliefs as far as the danger it poses are flawed. Perhaps people might think the mice are dirty or contaminated?
Assuming their subconscious beliefs about mice (which they might have learnt as an infant or child) are true (which their brain does assume), them taking extreme measures to avoid mice does involve minimizing pain (aka discomfort).

I think we have many hardwired fundamental drives, which I partially listed earlier. The intensity of the desires (e.g. "newness", sweet tastes, muscle relaxation, etc) would vary over time and from person to person. (Some people would crave more newness than others)

Well according to mainstream science, billions of years ago some chemicals came together to form single-celled organisms. I don't think there is any answer to "why" they did this - the chemicals just did that. I mean I don't think some God made it happen as part of some big plan he thought up. These single-celled organisms had DNA, and this DNA was copied as the cells copied themselves. Sometimes the DNA mutated and the child cells therefore changed. Sometimes that change was fatal and sometimes it gave them an advantage over the others and so they copied themselves more and dominated the planet more. Eventually there were things like worms and trilobytes and later insects, reptiles and birds... they make decisions - to varying degrees, like how it can be said that chess computers make decisions.
"My point is, how does inanimate matter come to have a desire to survive in the first place?"
What do you mean by "come to"? Do you mean how inanimate matter has developed over billions of years to get to this point? Or how during our lifetime we turn from inanimate matter to decision-making people? BTW, most animals wouldn't have an explicit desire to live. I mean they probably wouldn't be able to imagine themselves not being alive. They'd want to avoid physical pain though. People can learn that it is possible for them to not be alive (be dead) and so want to survive. But I don't think we have a hardwired desire to avoid death. Our avoidance of physical pain to varying degrees would be hardwired though. That's why people sometimes actively choose death in order to avoid things like physical pain or feelings of alienation (lack of "connectedness"). I think when people learn about their own possible death, they usually feel a connectedness pleasure (familiarity/attachment) with their life and so a lack of connectedness (unfamiliarity/loss) with death. They might also think that death would hurt (involve physical pain).

tronvillain

Uh, keep in mind that the phobia doesn't necessarily require incorrect beliefs, it could as easily be that the basic response to certain stimuli are simply "innapropriate." In that case, mice associated stimuli would be incorrectly wired to trigger fear or nausea, without anything accurately described as a "belief" about mice (though it might be the basis of negative beliefs about mice later).

excreationist

Maybe.... or maybe "belief" could be taken in a very vague way - e.g. that mice *are* incredibly dangerous or disgusting. These beliefs would be handled subconsciously - taken for granted as being true and are not always critically analysed by us. Maybe all beliefs are like it - in that they just involves things being associated together. Though phobias can involve extreme reactions from us (a pounding heart, etc) so do other more rational (though near-instant) stimuli - e.g. being pushed near a cliff edge (babies don't have a fear of heights) or having a gun pointed at you. Perhaps beliefs are normally thought not to involve immediate emotional responses like that. But I think they can be called beliefs. BTW, phobias would be learnt and can often be unlearnt... that would be my best reason why they could be called beliefs. Instinctual responses we have on the other hand, aren't learnt - though we can suppress them.