Traditional welfare economics shows that there are certain of these combinations that will be preferred by all the voters, which permits us to elimin… - Kenneth Arrow

Not only is it possible to devise complete models of the economy on hypotheses other than rationality, but in fact virtually every practical theory of macroeconomics is partly so based. The price- and wage- rigidity elements of Keynesian theory are hard to fit into a rational framework, though some valiant efforts have been made. … But if the Keynesian model is a natural target of criticism by the upholders of universal rationality, it must be added that monetarism is no better. I know of no serious derivation of the demand for money from a rational optimization. … The use of rationality in these arguments is ritualistic, not essential.

The slippery role of information as an economic good is of deep significance to economic behavior, especially in the relatively information-rich modern economy. It is an economic good in the traditional sense; it is valuable, and it is costly. But it has a peculiar algebra. Adding one ton of steel to another permits more to be done; repeating the same item of information does not add anything useful. On the other hand, supplying a ton of steel to another reduces the steel available to the supplier; supplying information to another does not reduce the information available to the supplier.

We find that capitalism, like any very complex system, contains within itself contradictory tendencies, but there is no reason to suppose they are fatal, at least in the foreseeable future. We do find implied in these contradictions some social tasks: the completion of the tasks involved in the achievement of macroeconomic stability, the redistribution of income and power to improve the sense of justice in the arrangements of society, by which I mean the inseparable elements of the liberty and equality of individuals, and, perhaps hardest, the increase in the sense of individual and local control over one's destiny in the workplace and the small society. These aims are mutually reinforcing, not competitive.