 Social cooperation on the basis of the difference principle does not  embody the same kind of mutuality. Imagine that citizens are reasoning about their institutions. Starting with an arrangement that creates equal prospects for those born into every starting position, they consider different arrangements that would yield Pareto improvements over the egalitarian  scheme.[20]  Citizens must now choose between different possibilities: one arrangement would maximize the prospects for the least advantaged group; another would maximize the prospects for the second least advantaged group; a third would maximize the prospects for the third least advantaged group; and so on. Given these possibilities, the difference principle requires citizens to choose the arrangement that is best from the standpoint of one group in particular—i.e., those in the least advantaged position.