I (now) understand the problem with using a uniform probability distribution over a countably infinite event space. However, I'm kind of confused when you say that the example doesn't exist. Surely, its not logically impossible for such an infinite universe to exist. Do you mean that probability theory isn't expressive enough to describe it?
When I say the probability distribution doesn't exist, I'm not talking about the possibility of the world you described. I'm talking about the coherence of the belief state you described. When you say "The probability of you being in the first 100 rooms is 0", it's a claim about a belief state, not about the mind-independent world. The world just has a bunch of rooms with people in them. A probability distribution isn't an additional piece of ontological furniture.
If you buy the Cox/Jaynes argument that your beliefs must adhere to the probabilit...
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