1. Keynesian economics argues that governments should intervene in the economy to boost aggregate demand and mitigate economic downturns, unlike classical liberal economics which favors laissez-faire policies. 2. Keynes advocated for policies like increasing government spending, reducing taxes and interest rates, and borrowing to stimulate the economy and achieve full employment during recessions. 3. Although Keynesian policies fell out of favor in the 1980s-1990s, some viewed the economic response to the 2008 financial crisis as a return to Keynesian ideas through similar stimulus measures.