I disagree with this part—if Harry does the quantum equivalent of flipping an unbiased coin, then there’s a branch of the universe’s wavefunction in which Harry sees heads and says “gee, isn’t it interesting that I see heads and not tails, I wonder how that works, hmm why did my thread of subjective experience carry me into the heads branch?”, and there’s also a branch of the universe’s wavefunction in which Harry sees tails and says “gee, isn’t it interesting that I see tails and not heads, I wonder how that works, hmm why did my thread of subjective experience carry me into the tails branch?”. I don’t think either of these Harrys is “preferred”.
This is how it works in MWI without additional postulates. But if you postulate the probability that you will find yourself somewhere, then you are postulating the difference between the case where you have found yourself there, and the case where you haven’t. Having a number for how much you prefer something is the whole point of indexical probabilities. And as probability of some future “you” goes to zero, this future “you” goes to not being the continuation of your subjective experience, right? Surely that would make this “you” dispreferred in some sense?
This is how it works in MWI without additional postulates. But if you postulate the probability that you will find yourself somewhere, then you are postulating the difference between the case where you have found yourself there, and the case where you haven’t. Having a number for how much you prefer something is the whole point of indexical probabilities. And as probability of some future “you” goes to zero, this future “you” goes to not being the continuation of your subjective experience, right? Surely that would make this “you” dispreferred in some sense?
I wrote “flipping an unbiased coin” so that’s 50⁄50.