ABSTRACT
This chapter begins the exposition of the various theories of the business cycle, some remarks may be advisable on the general logical nature of any explanation of the cycle, and on the mutual relation between various possible explanations (theories). Such a complex phenomenon as the business cycle, which embraces almost all parts of the economic system, does not easily lend itself to explanation by any one factor. Normally, a complex phenomenon such as the business cycle is caused and conditioned by a large number of factors and circumstances. The considerations suggest that it is useful to distinguish certain types of causal factors. One may draw a distinction, for instance, between active and passive factors or, in other words, between causes and conditions or between conditions per quam and conditions sine qua non. Closely connected with the distinction between economic and non-economic factors and causes is the distinction between "exogenous" and "endogenous" theories of the business cycle.
