What are the theoretical obstacles to abandoning expected utility calculations regarding extremities like x-risk from a rogue AI system in order to avoid biting the bullet on Pascal’s Mugging? Does Bayesian epistemology really require that we assign a credence to any proposition at all and if so - shouldn’t we reject this framework in order to avoid fanaticism? It does not seem rational to me that we should assign credences to e.g. the success of specific x-risk mitigation interventions when there are so many unknown unknowns governing the eventual outcome.
I hope you can help me sort out this confusion.
In principal I agree, although in practice there are other mitigating factors which means it doesn't seem to be that relevant.
This is partly because the 10^52 number is not very robust. In particular, once you start postulating such large numbers of future people I think you have to take the simulation hypothesis much more seriously, so that the large size of the far future may in fact be illusory. But even on a more mundane level we should probably worry that achieving 10^52 happy lives might be much harder than it looks.
It is partly also because at a practical level the interventions long-termists consider don't rely on the possibility of 10^52 future lives, but are good even over just the next few hundred years. I am not aware of many things that have smaller impacts and yet still remain robustly positive, such that we would only pursue them due to the 10^52 future lives. This is essentially for the reasons that asolomonr gives in their comment.