The length of a business cycle is the period of time containing a single boom and contraction in sequence. Business cycles are usually measured by considering the growth rate of real gross domestic product. Despite the often-applied term cycles, these fluctuations in economic activity do not exhibit uniform or predictable periodicity. The common or popular usage boom-and-bust cycle trade life cycle in investment banking pdf to fluctuations in which the expansion is rapid and the contraction severe.
The first systematic exposition of periodic economic crises, in opposition to the existing theory of economic equilibrium, was the 1819 Nouveaux Principes d’économie politique by Jean Charles Léonard de Sismondi. Prior to that point classical economics had either denied the existence of business cycles, blamed them on external factors, notably war, or only studied the long term. Sismondi found vindication in the Panic of 1825, which was the first unarguably international economic crisis, occurring in peacetime. Sismondi and his contemporary Robert Owen, who expressed similar but less systematic thoughts in 1817 Report to the Committee of the Association for the Relief of the Manufacturing Poor, both identified the cause of economic cycles as overproduction and underconsumption, caused in particular by wealth inequality.
They advocated government intervention and socialism, respectively, as the solution. This work did not generate interest among classical economists, though underconsumption theory developed as a heterodox branch in economics until being systematized in Keynesian economics in the 1930s. Sismondi’s theory of periodic crises was developed into a theory of alternating cycles by Charles Dunoyer, and similar theories, showing signs of influence by Sismondi, were developed by Johann Karl Rodbertus.