"The high theory debates that she and others conducted with the more orthodox theorists of MIT reached an agreed conclusion when Paul Samuelson was forced to concede that there was no logically consistent way to construct a demand function for capital outside the artificial confines of a one-commodity world (see the symposium on paradoxes in capital theory, Quarterly Journal of Economics, 1966). This, in turn, means that it is not possible to formulate a logically consistent theory of the long-run normal rate of interest; hence no consistent theory of long-run prices or of output and employment is possible either. Building so-called Keynesian models on the basis of market failure no longer makes sense--there cannot be a short-run deviation from a long-run equilibrium that is not there in the first place! In one stroke the critical task in which Keynes had failed was accomplished, and the marginal efficiency of capital schedule was swept away too. What was left was the part of his theory that Keynes himself had regarded as his truly original contribution--the principle of effective demand."