"The glitch arises from the possibility that the average number of people living in the preposthuman phase might be different in civilizations that produce ance

"The glitch arises from the possibility that the average number of people living in the preposthuman phase might be different in civilizations that produce ancestor simulations than in civilizations that do not." No, that's not the problem. The simulation argument essentially depends on the fact that a universe that reaches simulation-capability ends up simulating more rational beings than half of the beings that exist in the universe itself. But it's possible that the simulations themselves are so limited that they can only simulate some fraction of the universes' number of rational beings. In fact, that seems likely: it seems that any simulation of this universe which obeys the same laws as this universe must be smaller than this universe. "How much smaller?" is the glitch. The simulated universes have to be sufficiently large (as measured by the number of rational minds they ultimately simulate) to exceed an average of 0.5 simulated minds per real mind in order for the simulation argument to hold.