Classical economics believes that free markets are self-regulating and that government intervention harms the economy. In contrast, Keynesian economics emerged after the Great Depression to argue that markets are imperfect, unemployment and low growth can occur in equilibrium, and the government should intervene to stimulate demand when the economy is lacking growth. Keynes argued for government policies to boost consumer income and demand to promote economic growth, unlike classical economists who felt the economy would automatically adjust on its own.