Keynesian economics is an economic theory named after John Maynard Keynes, a British economist who lived from 1883 to 1946. He is most well-known for his simple explanation for the cause of the Great Depression. His economic theory was based on a circular flow of money, which refers to the idea that when spending increases in an economy, earnings also increase, which can lead to even more spending and earnings. Keynes' ideas spawned numerous interventionist economic policies during the Great Depression.
In Keynes' theory, one person's spending goes towards another person's earnings, and when that person spends his or her earnings, he or she is, in effect, supporting another person's earnings. This cycle continues on and helps support a normal, functioning economy. When the Great Depression hit, people's natural reaction was to hoard their money. Under Keynes' theory, this stopped the circular flow of money, keeping the economy at a standstill.
Keynes' solution to this poor economic state was to "prime the pump." He argued that the government should step in to increase spending, either by increasing the money supply or by actually buying things itself. During the Great Depression, however, this was not a popular solution. It is said, however, that the massive defense spending that United States president Franklin Delano Roosevelt initiated helped revive the U.S. economy.
Keynesian economics advocates for the public sector to step in to assist the economy generally, which is a significant departure from popular economic thought that preceded it — laissez-faire capitalism. Laissez-faire capitalism supported the exclusion of the public sector in the market. The belief was that an unfettered market would achieve balance on its own.
The proponents of free-market capitalism include the Austrian School of economic thought. One of its founders, Friedrich von Hayek, lived in England at the same time as Keynes. The two men had a public rivalry for many years because of their opposing thoughts on the role of the state in the economic lives of individuals.
Keynesian economics warns against the practice of too much saving and not enough consumption, or spending, in an economy. It also supports considerable redistribution of wealth, when needed. Keynesian economics further concludes that there is a pragmatic reason for the massive redistribution of wealth: if the poorer segments of society are given sums of money, they will likely spend it, rather than save it, thus promoting economic growth. Another central idea of Keynesian economics is that trends in the macroeconomic level can disproportionately influence consumer behavior at the micro-level.