The problem of FAI is the problem of figuring out all of humanity’s deepest concerns and preferences, not just the problem of figuring out the ‘moral’ ones (whichever those are)
Those two things turn out to be identical (deepest concerns and preferences=the ‘moral’ ones). Because nothing else can be of greater importance to a decision maker.
Those two things turn out to be identical (deepest concerns and preferences=the ‘moral’ ones). Because nothing else can be of greater importance to a decision maker.