I think this makes more sense than initial appearances.
If A+ is the current world and B is possible, then the well-off people in A+ have an obligation to move to B (because B>A).
If A is the current world, A+ is possible but B impossible, then the people in A incur no new obligations by moving to A+, hence indifference.
If A is the current world and both A+ and B are possible, then moving to A+ saddles the original people with an obligation to further move the world to B. But the people in A, by supposition, don’t derive any benefit from the move to A+ and the obligation to move to B harms them. On the other hand, the new people in A+ don’t matter because they don’t exist in A. Thus A+>A in this case.
Basically: options create obligations, and when we’re assessing the goodness of a world we need to take into account welfare + obligations (somehow).
I think this makes more sense than initial appearances.
If A+ is the current world and B is possible, then the well-off people in A+ have an obligation to move to B (because B>A).
If A is the current world, A+ is possible but B impossible, then the people in A incur no new obligations by moving to A+, hence indifference.
If A is the current world and both A+ and B are possible, then moving to A+ saddles the original people with an obligation to further move the world to B. But the people in A, by supposition, don’t derive any benefit from the move to A+ and the obligation to move to B harms them. On the other hand, the new people in A+ don’t matter because they don’t exist in A. Thus A+>A in this case.
Basically: options create obligations, and when we’re assessing the goodness of a world we need to take into account welfare + obligations (somehow).