I’ve never been entirely sure about the whole “it should all add up to normality” thing in regards to MWI. Like, in particular, I worry about the notion of intrusive thoughts. A good 30% of the time I ride the subway I have some sort of weak intrusive thought about jumping in front of the train (I hope it goes without saying that I am very much not suicidal). And since accepting MWI as being reasonably likely to be true, I’ve worried that just having these intrusive thoughts might increase the measure of those worlds where the intrusive thoughts become reality. And then I worry that having that thought will even further increase the measure of such worlds. And then I worry...well, then it usually tapers off, because I’m pretty good at controlling runaway thought processes. But my point is...I didn’t have these kinds of thoughts before I learned about MWI, and that sort of seems like a real difference. How does it all add up to normality, exactly?
Whatever argument you have in mind about “the measure of those worlds” will go through just the same if you replace it with “the probability of the world being that way”. You should be exactly equally concerned with or without MWI.
The question that actually matters to you should be something like: Are people with such intrusive thoughts who aren’t generally suicidal more likely to jump in front of trains? I think I remember reading that the answer is no; if it turns out to be yes (or if you find those thoughts disturbing) then you might want to look into CBT or something; but MWI doesn’t have anything to do with it except that maybe something about it bothers you psychologically.
Okay, fair enough, forget the whole increasing of measure thing for now. There’s still the fact that every time I go to the subway, there’s a world where I jump in front of it. That for sure happens. I’m obviously not suggesting anything dumb like avoiding subways, that’s not my point at all. It’s just...that doesn’t seem very “normal” to me, somehow. MWI gives this weird new weight to all counterfactuals that seems like it makes an actual difference (not in terms of any actual predictions, but psychologically—and psychology is all we’re talking about when assessing “normality”). Probably though this is all still betraying my lack of understanding of measure—worlds where I jump in front of the train are incredibly low measure, and so they get way less magical reality fluid, I should care about them less, etc. I still can’t really grok that though—to me and my naive branch-counting brain, the salient fact is that the world exists at all, not that it has low probability.
and psychology is all we’re talking about when assessing “normality”
I have always taken “it all adds up to normality” to mean not “you should expect everything to feel normal” but “actually, when you work out the physics, all this counterintuitive weird-feeling stuff produces the world you’re already used to, and if it feels weird then you should try to adjust your intuitions if possible”.
I’m not sure there’s much I can say to help—it’s clear from your comments that you understand in theory what’s going on, and it’s just that your “naive branch-counting brain” is naive and cares about the wrong things :-).
Maybe this will help: Suppose you’re visiting a big city. Consider the following two propositions. (1) There is one person in this city who would cheerfully knock you on the head and steal your wallet. (2) Half the people in this city would cheerfully knock you on the head and steal your wallet. I don’t know about you, but I would be really scared to learn #2 and totally unsurprised and unmoved by #1. Similarly: “there are branches in which you jump in front of the train”—well, sure there are, and there are branches where I abruptly decide to declare myself Emperor of the World and get taken off to a mental hospital, and branches where the earth is about to get hit by an asteroid that miraculously got missed by everyone’s observations and we all die. But there aren’t “a lot” of any of these sorts of branch (i.e., the measure is very small). What would worry me is to find that a substantial fraction of branches (reckoned by measure) have me jumping in front of the train. But what it takes to make that true is exactly the same thing as it takes to make it true that “with high probability, you will jump in front of the train”.
You don’t see other people doing so, and I can assure you many more people than jump have such thoughts. Any MWI weirdness would only affect what you recall of your OWN actions in this case.
I’ve never been entirely sure about the whole “it should all add up to normality” thing in regards to MWI. Like, in particular, I worry about the notion of intrusive thoughts. A good 30% of the time I ride the subway I have some sort of weak intrusive thought about jumping in front of the train (I hope it goes without saying that I am very much not suicidal). And since accepting MWI as being reasonably likely to be true, I’ve worried that just having these intrusive thoughts might increase the measure of those worlds where the intrusive thoughts become reality. And then I worry that having that thought will even further increase the measure of such worlds. And then I worry...well, then it usually tapers off, because I’m pretty good at controlling runaway thought processes. But my point is...I didn’t have these kinds of thoughts before I learned about MWI, and that sort of seems like a real difference. How does it all add up to normality, exactly?
Whatever argument you have in mind about “the measure of those worlds” will go through just the same if you replace it with “the probability of the world being that way”. You should be exactly equally concerned with or without MWI.
The question that actually matters to you should be something like: Are people with such intrusive thoughts who aren’t generally suicidal more likely to jump in front of trains? I think I remember reading that the answer is no; if it turns out to be yes (or if you find those thoughts disturbing) then you might want to look into CBT or something; but MWI doesn’t have anything to do with it except that maybe something about it bothers you psychologically.
Okay, fair enough, forget the whole increasing of measure thing for now. There’s still the fact that every time I go to the subway, there’s a world where I jump in front of it. That for sure happens. I’m obviously not suggesting anything dumb like avoiding subways, that’s not my point at all. It’s just...that doesn’t seem very “normal” to me, somehow. MWI gives this weird new weight to all counterfactuals that seems like it makes an actual difference (not in terms of any actual predictions, but psychologically—and psychology is all we’re talking about when assessing “normality”). Probably though this is all still betraying my lack of understanding of measure—worlds where I jump in front of the train are incredibly low measure, and so they get way less magical reality fluid, I should care about them less, etc. I still can’t really grok that though—to me and my naive branch-counting brain, the salient fact is that the world exists at all, not that it has low probability.
I have always taken “it all adds up to normality” to mean not “you should expect everything to feel normal” but “actually, when you work out the physics, all this counterintuitive weird-feeling stuff produces the world you’re already used to, and if it feels weird then you should try to adjust your intuitions if possible”.
I’m not sure there’s much I can say to help—it’s clear from your comments that you understand in theory what’s going on, and it’s just that your “naive branch-counting brain” is naive and cares about the wrong things :-).
Maybe this will help: Suppose you’re visiting a big city. Consider the following two propositions. (1) There is one person in this city who would cheerfully knock you on the head and steal your wallet. (2) Half the people in this city would cheerfully knock you on the head and steal your wallet. I don’t know about you, but I would be really scared to learn #2 and totally unsurprised and unmoved by #1. Similarly: “there are branches in which you jump in front of the train”—well, sure there are, and there are branches where I abruptly decide to declare myself Emperor of the World and get taken off to a mental hospital, and branches where the earth is about to get hit by an asteroid that miraculously got missed by everyone’s observations and we all die. But there aren’t “a lot” of any of these sorts of branch (i.e., the measure is very small). What would worry me is to find that a substantial fraction of branches (reckoned by measure) have me jumping in front of the train. But what it takes to make that true is exactly the same thing as it takes to make it true that “with high probability, you will jump in front of the train”.
You don’t see other people doing so, and I can assure you many more people than jump have such thoughts. Any MWI weirdness would only affect what you recall of your OWN actions in this case.