Keynesianism

This is one of the two leading twentieth-century schools of macroeconomic, which was initiated by John Maynard Keynes. It was first presented in the publication of The General Theory of Employment, Interest and Money in 1939. The new theory quickly gained popularity among the economists who supported the intervention of the state.Its main opponents was Monetarism and Austrian school, including the first Noble Prize Winner in economics Fredrich von Hayek and Ludwig von Mises. 
According to the Keynes , governments should intervene in the market to prevent deep recessions. During a crisis, the drop in demand for goods could cause a serious slump causing the economy to contract and pushing up unemployment. It was the responsibility of the government to kick-start the economy by borrowing cash and spending it, hiring public-sector staff and organizing mass public infrastructure projects-for example building roads,highways,hospitals,schools. The interest-rates cuts should also be done in order to boost the economy.This ''injections' made by the state can raise total economic output by far more than the amount of public money actualy ''injected''
Keynesianism became out of fashion in the 70s only to became popular nowadays in the time of the global crisis.