Imagine that an outside observer uses a fair coin to observe one of two rooms (assuming merging in the red room has happened). They will observe either a red room or a green room, with a copy in each. However, the observer who was copied has different chances of observing the green and red rooms.
Well obviously. The observer and the person being copied participate in non-isomorphic experiments with different sampling. There is nothing surprising about it. On the other hand, if we make the experiments isomorphic:
Two coins are tossed and the observer is brought into the green room if both are Heads, and is brought to the red room, otherwise
Then both the observer and the person being copied will have the same probabilities.
Even without merging, an outside observer will observe three rooms with equal 1⁄3 probability for each, while an insider will observe room 1 with 1⁄2 probability.
Likewise, nothing is preventing you from designing an experimental setting where an observer have 1⁄2 probability for room 1 just as the person who is being copied.
When I spoke about the similarity with the Sleeping Beauty problem, I meant its typical interpretation.
I’m not sure what use is investigating a wrong interpretation. It’s a common confusion that one has to reason about problems involving amnesia the same way as about problems involving copying. Everyone just seem to assume it for no particular reason and therefore got stuck.
However, I have an impression that this may result in a paradoxical two-thirder solution: In it, Sleeping Beauty updates only once – recognizing that there are two more chances to be in tails. But she doesn’t update again upon knowing it’s Monday, as Monday-tails and Tuesday-tails are the same event. In that case, despite knowing it’s Monday, she maintains a 2⁄3 credence that she’s in the tails world.
This seems to be the worst of both worlds. Not only you update on a completely expected event, you then keep this estimate, expecting to be able to guess a future coin toss better than chance. An obvious way to lose all your money via betting.
Well obviously. The observer and the person being copied participate in non-isomorphic experiments with different sampling. There is nothing surprising about it. On the other hand, if we make the experiments isomorphic:
Two coins are tossed and the observer is brought into the green room if both are Heads, and is brought to the red room, otherwise
Then both the observer and the person being copied will have the same probabilities.
Likewise, nothing is preventing you from designing an experimental setting where an observer have 1⁄2 probability for room 1 just as the person who is being copied.
I’m not sure what use is investigating a wrong interpretation. It’s a common confusion that one has to reason about problems involving amnesia the same way as about problems involving copying. Everyone just seem to assume it for no particular reason and therefore got stuck.
This seems to be the worst of both worlds. Not only you update on a completely expected event, you then keep this estimate, expecting to be able to guess a future coin toss better than chance. An obvious way to lose all your money via betting.