Why should morality be based on group decision-making principles? Why should I care about VNM rationality of the group?
It doesn’t have to be the group, it can be an impartial observer with their own social welfare function, as long as it is increasing with individual expected utility, i.e. satisfies ex ante Pareto. Actually, that’s how it was originally stated.
EDIT: woops, condition 2 is weaker than ex ante Pareto; it’s just vNM rationality with respect to outcomes for social/ethical preferences/views. It’s condition 3 that connects individual vNM utility and social/ethical vNM utility.
It doesn’t have to be the group, it can be an impartial observer with their own social welfare function, as long as it is increasing with individual expected utility, i.e. satisfies ex ante Pareto. Actually, that’s how it was originally stated.
EDIT: woops, condition 2 is weaker than ex ante Pareto; it’s just vNM rationality with respect to outcomes for social/ethical preferences/views. It’s condition 3 that connects individual vNM utility and social/ethical vNM utility.