 The two parts of the argument for justice as fairness above occur at the first stage of the original position. At this first stage, the parties also agree to a principle of just savings to regulate how much each generation must save for future generations. Since the parties do not know which era the citizens they represent live in, it is rational for them to choose a savings principle that is fair to all generations. Rawls says that the parties need not choose a savings principle that requires endless economic growth. Rather, the parties may prefer a Millian “steady state” of zero real growth, once a generation has been reached in which the two principles are satisfied.