Monetary Theories of the Trade Cycle Are Generally Regarded as “Exogenous” (Instead of “Endogenous”) Theories

If we are to understand the present status of monetary theories of the trade cycle, we must pay special attention to the assumptions upon which they are based. At the present day, monetary theories are generally regarded as falling within the class of so-called “exogenous” theories, i.e., theories that look for the cause of the cycle not in the interconnections of economic phenomena themselves but in external interferences. Now it is, no doubt, often a waste of time to discuss the merits of classifying a theory in a given category. But the question of classification becomes important when the inclusion of a theory in one class or another implies, at the same time, a judgment as to the sphere of validity of the theory in question. This is undoubtedly the case with the distinction, very general today, between endogenous and exogenous theories—a distinction introduced into economic literature some twenty years ago by Bouniatian. Endogenous theories, in the course of their proof, avoid making use of assumptions that cannot either be decided by purely economic considerations, or regarded as general characteristics of our economic system—and hence capable of general proof. Exogenous theories, on the other hand, are based on concrete assertions whose correctness has to be proved separately in each individual case. As compared with an endogenous theory, which, if logically sound, can in a sense lay claim to general validity, an exogenous theory is at some disadvantage, inasmuch as it has, in each case, to justify the assumptions on which its conclusions are based.

Now as far as most contemporary monetary theories of the cycle are concerned, their opponents are undoubtedly right in classifying them, as does Professor Lowe in his discussion of the theories of Professors Mises and Hahn, among the exogenous theories; for they begin with arbitrary interferences on the part of the banks. This is, perhaps, one of the main reasons for the prevailing skepticism concerning the value of such theories. A theory that has to call upon the deus ex machina of a false step by bankers, in order to reach its conclusions is, perhaps, inevitably suspect. Yet Professor Mises himself—who is certainly to be regarded as the most respected and consistent exponent of the monetary theory of the trade cycle in Germany—has, in his latest work, afforded ample justification for this view of his theory by attributing the periodic recurrence of the trade cycle to the general tendency of central banks to depress the money rate of interest below the natural rate.

—F. A. Hayek, “The Fundamental Cause of Cyclical Fluctuations,” in Prices and Production and Other Works: F. A. Hayek on Money, the Business Cycle, and the Gold Standard, ed. Joseph T. Salerno (Auburn, AL: Ludwig von Mises Institute, 2008), 75-76.