It's been a while, so I wanted to reply to at least one comment:
Post: Observer selection effects from scratch
Comment: here
I’m not sure it makes sense to assume that nothing about your observation X favors any of these observers over any other (out of the 101 possible observers distributed among W1 and W2)...
For instance, let’s say... observation B is externally focused (i.e. that apples appear to fall downward). For observation B, it seems that some relevant factors would be how available you think the information is to make that observation (i.e. are there apple trees near others), how likely it is that other people are paying attention, etc. If it seems reasonable that others could be observers too, it seems like that should tilt you more towards believing that you are in W2. I’m not sure, but it seems plausible to me that you should think it’s more than 100 times more likely that you’re in W2 than W1.Thanks for this! I'm not sure that I understand it, though. As far as I can tell, you're saying that some facts about observation B and world W2 could tell us about how likely each observer in W2 is to observe B, right? Like if almost all of the observers in W2 are near apple trees and B is that apples fall downward, it's likely that many observers in W2 will observe B, but if all of W2's observers are in the middle of the ocean, probably few of them will observe B. Is that right?
If so, I totally agree, and I think it's saying the same thing as my post. In my post, I'm not talking about all observers in W1 and W2, but only about those that do actually observe X. In your example, that'd mean there is 1 observer in W1 who sees an apple fall, and 100 in W2 who see the apple fall. That would be in part because of how many observers total there are in each world, but also largely because of where those observers are placed, whether they're paying attention, etc, and it'd be consistent with W1 having millions of observers far from apple trees, asleep, etc -- W2 would still be favored, even with millions of sleeping observers.
Let me know if I've made a mistake, but I think we're on the same page?
Thanks! I think I’m saying something slightly different, though I’m not sure. I think it’s possible that the difference is baked into some potentially faulty implicit assumptions I’m making, so let me lay those out.
ReplyDeleteI’m assuming that:
(1) You don’t know how many people (aside from yourself) do actually observe X. (If you knew that someone else did, that seems like it should persuade you that you are in W2, with similar logic as used initially to eliminate W0 — if there are 2 observers of X, you can’t be in W1).
(2) That either W1 or W2 actually exists, but not both. (This could definitely be a faulty assumption, and where things are coming apart)
(3) You know some facts about the world you are in.
I’m saying that, given that you don’t know how many people do actually observe X (my assumption 1), some facts about observation B and some facts about the world (which is either W1 or W2 but not both) could persuade you to think that your are more likely to be in one of the worlds than the other.
So, to the apple example: you observe an apple falling, you don’t know if any other people observe an apple falling, you know some facts about the world you are in, and you are either in W1 where you are the only falling apple observer or in W2 where you are one out of 100 falling apple observers. You want to determine which world you are more likely to be in. It seems like the probability that someone else observed an apple falling is (a) a relevant factor for thinking about whether you are in W1 or W2 (given that if someone else observers an apple falling, you are in W2) and (b) something that some facts you know about the world you are actually in (i.e. where observers are placed, the abundance or lack of other apple trees) may have bearing on.
I think this is saying something slightly different, but it’s definitely possible I’m misunderstanding.
Ah, you're right! Thanks for your persistence, this seems correct to me. Some observations should give you evidence about whether you're in W1 or W2 in the way you describe. I'll be more careful about this in the future.
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