Keynesian Revolution in the context of "Neo-Keynesian economics"

John Maynard Keynes, 1st Baron Keynes CB, FBA (/keɪnz/ KAYNZ; 5 June 1883 – 21 April 1946), was an English economist whose ideas fundamentally changed the theory and practice of macroeconomics and the economic policies of governments. Originally trained in mathematics, he built on and greatly refined earlier work on the causes of business cycles. One of the most influential economists of the 20th century, he produced writings that are the basis for the school of thought known as Keynesian economics, and its various offshoots. His ideas, reformulated as New Keynesianism, are fundamental to mainstream macroeconomics. He is known as the "father of macroeconomics".

Keynes was educated at King's College at the University of Cambridge, where he graduated in 1904 with a B.A. in mathematics. During the Great Depression of the 1930s, Keynes spearheaded a revolution in economic thinking, challenging the ideas of neoclassical economics that held that free markets would, in the short to medium term, automatically provide full employment, as long as workers were flexible in their wage demands. He argued that aggregate demand (total spending in the economy) determined the overall level of economic activity, and that inadequate aggregate demand could lead to prolonged periods of high unemployment, and since wages and labour costs are rigid downwards the economy will not automatically rebound to full employment. Keynes advocated the use of fiscal and monetary policies to mitigate the adverse effects of economic recessions and depressions. After the 1929 crisis, Keynes also turned away from a fundamental pillar of neoclassical economics: free trade. He criticized Ricardian comparative advantage theory (the foundation of free trade), considering the theory's initial assumptions unrealistic, and became definitively protectionist. He detailed these ideas in his magnum opus, The General Theory of Employment, Interest and Money, published in early 1936. By the late 1930s, leading Western economies had begun adopting Keynes's policy recommendations. Almost all capitalist governments had done so by the end of the two decades following Keynes's death in 1946. As a leader of the British delegation, Keynes participated in the design of the international economic institutions established after the end of World War II but was overruled by the American delegation on several aspects.

The General Theory of Employment, Interest and Money is a book by English economist John Maynard Keynes published in February 1936. It caused a profound shift in economic thought, giving macroeconomics a central place in economic theory and contributing much of its terminology – the "Keynesian Revolution". It had equally powerful consequences in economic policy, being interpreted as providing theoretical support for government spending in general, and for budgetary deficits, monetary intervention and counter-cyclical policies in particular. It is pervaded with an air of mistrust for the rationality of free-market decision-making.

Keynes denied that an economy would automatically adapt to provide full employment even in equilibrium, and believed that the volatile and ungovernable psychology of markets would lead to periodic booms and crises. The General Theory is a sustained attack on the classical economics orthodoxy of its time. It introduced the concepts of the consumption function, the principle of effective demand and liquidity preference, and gave new prominence to the multiplier and the marginal efficiency of capital.