A school of economic thought founded by the UK economist John Maynard Keynes (1883-1946) and developed by his followers. In 1936, at the height of the great depression, Keynes' landmark book The General Theory Of Employment, Interest And Money caused a paradigm shift for economics: it suddenly replaced their emphasis on study of the economic behavior of individuals and companies (microeconomics) to the study of the behavior of the economy as a whole (macroeconomics).
The main plank of his revolutionary theory is the assertion that the aggregate demand created by households, businesses and the government and not the dynamics of free markets is the most important driving force in an economy. This theory further asserts that free markets have no self-balancing mechanisms that lead to full employment. Keynesian economists urge and justify a government's intervention in the economy through public policies that aim to achieve full employment and price stability. Their ideas have greatly influenced governments the world-over in accepting their responsibility to provide full or near-full employment through measures (such as deficit spending) that stimulate aggregate demand. See also classical economics, neo-classical Economics, new classical economics and supply side economics.