Physicists can only talk to other physicists and economists to economists... sociologists often cannot even understand each other. - Kenneth E. Boulding

One advantage of exhibiting a hierarchy of systems in this way is that it gives us some idea of the present gaps in both theoretical and empirical knowledge. Adequate theoretical models extend up to about the fourth level, and not much beyond. Empirical knowledge is deficient at practically all levels.

The organization of science into disciplines sets up a series of ghettos with remarkable distances of artificial social space between them.

The should not be confused with the profit system. By the profit system, of course, we mean the institution of private property in capital goods and the free private enterprise that goes along with it. There is no reason why the "profit motive" should be necessarily connected with the profit system. In a profit system there is nothing to prevent anyone acting on altruistic lines; there is no law that says a businessman must maximize his profits. If a businessman chose to operate with outputs, prices, and wages that yielded him a smaller profit than the maximum, but which he felt were socially more desirable, there is nothing in the profit system that would prevent him from doing this. Nothing in the profit system would prevent the most ardent liberal from refusing an increase in wages, or from accepting an unpleasant and poorly paid job. At the other extreme, there is nothing in a communist system that would do away with the profit motive, or the "advantage motive."