You may be able to, but I cannot understand why Many Worlds is deterministic for the reason I said -- why am I in the up-world and not the down-world? What is the deterministic law that makes it such that I experience this world I am in? — Moliere
That's an indexical problem. The answer to that is not a problem for many worlds, it's a problem for ANY multi-consciouness existence, even if many worlds is not true. Why are you you and not me? If you can answer that question coherently, you can also answer why you're this version of you in MWI and not some other version of you.
And the other version of you is wondering the same thing - why is he that version, instead of the version you are?
Imagine putting a conscious being inside my dice program. By the time you roll the dice twice, there's now a person who has seen a 1 and a 1, and ap erson who has seen a 1 and a 2, etc.. all the way to 6 and a 6.
Now you run the program once and the guy who sees a 1 and a 3 wonders aloud, "why am I this one and not the one that saw a 6/6?" and the guy who sees 6/6 says "Wow! Two sixes in a row! I'm so lucky!"
And every time you run the program from scratch, you see it again: the guy who sees a 1 and a 3 wonders aloud, "why am I this one and not the one that saw a 6/6?" and the guy who sees 6/6 says "Wow! Two sixes in a row! I'm so lucky!"
Now you know there's nothing particularly lucky about the 6/6 guy, right? Not from your perspective. From your perspective, outside the program, that's a natural, inevitable consequence of the program running - every time you roll the dice twice, there will ALWAYS be a guy who saw 6 and then 6, and that guy will ALWAYS say "Wow! Two sixes in a row! I'm so lucky!".
And the first guys question is kinda weird too. There's no reason why he's the one who saw 1 and 3 instead of some other one, that question assumes he COULD HAVE seen something else, in some ontologically strong sense of "could", but the reality is his consciousness was in some sense created the moment that window split into the dice roll of 3. He's the one who saw 1 and 3 because he was invented at that moemnt to be the one that saw 1 and 3. He is almost by definition, the version of that consciousness that sees 1 and 3. If he saw something else, he'd just... be somethig else.
So can you answer why you're you and not me? Can you tell me why I'm me and not you? And can you try to apply that answer to many worlds versions of yourself?
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I just realized, it might first be worth clarifying, do you understand why MWI is deterministic if we set aside the problem of conscious experience? Like if you have an MWI-flavor world but just without any experience happening in it, can you accept that THAT world is deterministic?