Neoclassical economics is based on the following two basic postulates, one at the individual level and the other at the aggregate level. First, individuals are rational, i.e., they make wise decisions taking all the available alternatives into account. Second such individual rationality is carried over to the aggregates, i.e., the aggregate behaviour never errs systematically. In other words, a million sages always make a great sage. The Keynesian counterparts of these postulates, in contrast, are, first, that individuals may not be so rational, and second, that even if they are, a million sages can make a great fool.