Stuart—something is not clear in your diagram. Does world Y have twice as many planets as world B, or does it have the same number of planets, but twice as many planets with simple life-forms? (Same question for X and A).
If they have the same number of planets then world B also has an early filter rather than late filter (since it has lower probability of each planet developing life). So you’re not strictly comparing late filter worlds vs early filter worlds.
If they have different numbers of planets, then you have another problem: why would the prior be such as to contain more planets in early-filter worlds, than in late-filter worlds? That seems unreasonable since a priori there is no relationship between size of world and lateness/earliness of filters. Also, we need to take account SIA shifting all the probability weight up to the largest worlds anyway (infinite size if the prior allows that), so we basically ignore the small worlds in any case. If we want to keep things finite to ensure the probability distribution is well-behaved, we should assume that all world models worth thinking about have, say, N = 3^^^3 planets.
Stuart—something is not clear in your diagram. Does world Y have twice as many planets as world B, or does it have the same number of planets, but twice as many planets with simple life-forms? (Same question for X and A).
If they have the same number of planets then world B also has an early filter rather than late filter (since it has lower probability of each planet developing life). So you’re not strictly comparing late filter worlds vs early filter worlds.
If they have different numbers of planets, then you have another problem: why would the prior be such as to contain more planets in early-filter worlds, than in late-filter worlds? That seems unreasonable since a priori there is no relationship between size of world and lateness/earliness of filters. Also, we need to take account SIA shifting all the probability weight up to the largest worlds anyway (infinite size if the prior allows that), so we basically ignore the small worlds in any case. If we want to keep things finite to ensure the probability distribution is well-behaved, we should assume that all world models worth thinking about have, say, N = 3^^^3 planets.