What if we also add a requirement that the FAI doesn’t make anyone worse off in expected utility compared to no FAI?
Sounds obviously unreasonable to me. E.g. a situation where a person derives a large part of their utility from having kidnapped and enslaved somebody else: the kidnapper would be made worse off if their slave was freed, but the slave wouldn’t become worse off if their slavery merely continued, so...
The way I said that may have been too much of a distraction from the real problem, which I’ll restate as: considerations of fairness, which may arise from bargaining or just due to fairness being a terminal value for some people, can imply that the most preferred outcome lies on a flat part of the Pareto frontier of feasible expected utilities, in which case such preferences are not VNM rational and the result described in the OP can’t be directly applied.
Sounds obviously unreasonable to me. E.g. a situation where a person derives a large part of their utility from having kidnapped and enslaved somebody else: the kidnapper would be made worse off if their slave was freed, but the slave wouldn’t become worse off if their slavery merely continued, so...
The way I said that may have been too much of a distraction from the real problem, which I’ll restate as: considerations of fairness, which may arise from bargaining or just due to fairness being a terminal value for some people, can imply that the most preferred outcome lies on a flat part of the Pareto frontier of feasible expected utilities, in which case such preferences are not VNM rational and the result described in the OP can’t be directly applied.