# 4

You find yourself in a room. You know there are only two possible ways you could have gotten into the room, and just a moment earlier you considered them both equally likely:

A: I make 8 identical copies of you and put them in totally identical rooms. A minute passes, then I instantly kill 7 of the copies. (Also, I don't think it matters but your cognition is deterministic, so you know all 8 copies of you stay perfectly in sync until I kill 7 of them.)

B: I make one copy of you and put it in a room. A minute passes, then I do something that has a 7/8 chance of instantly killing the copy.

Now you've appeared in the room, but a minute hasn't passed yet. Regardless of whether A or B is true, you'd experience the same thing either way. Does your estimation of the odds of A:B change?

Now a minute passes and you're still alive. Des your estimation of the odds of A:B change now?.

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# 3 Answers sorted by top scoring

JBlack

### Sep 17, 2021

40

The number of observers in the possible worlds given their observations are 8 for A and 1 for B (with weighting 1/2 each) before 1 minute passes. So SIA says that the odds are 8:1 in favour of A at that time. The weighted number of observers who survive more than a minute is 1/2 for A and 1/16 for B, so the odds remain unchanged at 8:1 in favour of A.

Under SSA there are equal odds of scenarios A and B, which don't change in the first minute since they are observationally indistinguishable. After a minute, scenario B(i) in which the clone lives and scenario A are still indistinguishable, with weightings 1/2 and 1/16 respectively. B(ii) is ruled out, so the updated odds are 8:1 in favour of A.

This analysis is unchanged if you replace "is killed" by "is told which scenario they're in" and condition on a minute passing and not being told which scenario you were in.

Measure

### Sep 16, 2021

00

Immediately upon finding myself in the room, I could be the single copy in scenario B or any of the 8 copies in scenario A. I think I would have to assign 8:1 odds for A:B. Either way, I have a 7/8 chance of dying after a minute. After 1 minute, there is 1 clone in scenario A and 1/8 of a clone in scenario B, so I'm still at 8:1 odds for A:B.

Pablo Repetto

### Sep 17, 2021

-10

No and no.

When I appear in the room I observe that I exist, but I couldn't have observed that I didn't exist, thus I don't update.

When a minute passes I observe that I survived, but I couldn't have observed that I didn't survive, thus I don't update.