First and foremost, Keynesian economics is a theory of aggregate demand and of the effects of aggregate demand on real output and inflation.

Keynesian economics at a minimum provides a license for welfare state measures and other government efforts towards redistribution of wealth. The license is the faith that macroeconomic stabilization and prosperity are compatible with a wide range of social policies, that modern capitalism and democracy are robust enough to prosper and progress while being humane and equitable. That faith conflicts with the visions of extreme Right and Left, which agree that extremes of wealth and poverty, of security and insecurity, are indispensable to the functioning of capitalism. Keynesian policies helped to confound those dismal prophecies in the past; I think they will do so again.

Keynesian economics is the economics of nominal rigidities basically, nominal rigidities everywhere. Fully anticipated money does affect output. Everybody can see that! So, it's right. The fact that it's not as theoretically tidy as Lucas's 1972 Journal of Economic Theory paper is not a reason to throw it away. That's become a minority view in this profession, unfortunately. It wouldn't have been in the '60s.

Broadly speaking, [Keynesianism means] that the government has a specific responsibility for the behavior of the economy, that it doesn't work on its own autonomous course, but the government, when there's a recession, compensates by employment, by expansion of purchasing power, and in boom times corrects by being a restraining force. But it controls the great flow of demand into the economy, what since Keynesian times has been the flow of aggregate demand. That was the basic idea of Keynes so far as one can put it in a couple of sentences.

I still think Keynesian economics is extremely important, and if anybody didn’t think so, this crisis should have made them rethink.

The legacy of Keynesian economics — the misdiagnosis of unemployment, the fear of saving, and the unjustified faith in government intervention — affected the fundamental ideas of policy makers for a generation and altered such basic institutions of our economy as the tax laws, the social insurance programs and the financial system. Changing these deeply ingrained aspects of economic life can happen only slowly. But the economics profession has undoubtedly begun to re-examine and re-evaluate the Keynesian notions that have been so dominant for the past 35 years. There is a return to older and more basic economic truths and an attempt to adapt these ideas to the changing conditions of technology and affluence. From this is emerging a new view of unemployment, of saving, and of the role of government.

The word ‘Keynesian’ means many things to many people. Decades ago, it was a carelessly applied label for economic liberals and interventionists in general. For a while in the late 1970s and early 1980s it became a pejorative term more or less synonymous with old-fashioned.

For a period of roughly 35 years, Keynesian theory provided a central paradigm for macroeconomists, and considerable progress was made on several empirical fronts. It was widely recognized that some of the ingredients of Keynesian economics (e.g. money illusion and/or nominal wage rigidity) rested on slender to non-existent microtheoretic foundations; and there were always dissenters. But, thought of as a collection of empirical regularities that fit together into a coherent whole, the theory worked tolerably well. In the 1970s, however, the Keynesian paradigm was rejected by a great many academic economists, especially in the United States, in favour of what we now call new classical economics. By about 1980, it was hard to find an American academic macroeconomist under the age of 40 who professed to be a Keynesian. That was an astonishing intellectual turnabout in less than a decade, an intellectual revolution for sure.

In a crisis we are all Keynesians.

Keynes was no revolutionary, but his ideas revolutionized 20th-century economics.

Today, Keynesian theorizing does not inspire whispers and giggles from the audience. There are many economists under the age of forty who do not take offense when their work is called ‘Keynesian’, and I count myself as one of them. If Keynesian economics was dead in 1980, then today it has been reincarnated.

Keynesian economics was, in the context of those times, essentially conservative. The message was that capitalism was not doomed; its major failing, chronic large-scale unemployment, could be remedied fairly easily, by intelligent use of the fiscal and monetary instruments governments already had at their disposal. This message was not welcome news to Marxists committed to the view that the system was no longer structurally capable of prosperity and progress.

It is impossible indeed not to look with considerable uneasiness at the type of the "modern economist" as he developed after Keynes' revolutionary book, whom Keynes himself regarded with alarm at the end of his days. It is the type of man who is obsessed by one thing, i.e. "effective demand," which he thinks must be kept up at whatever cost, while he forgets the working of the mechanism of prices, wages, interest and exchange rates.

Keynesian economics — the go - to theory for those who like government at the controls of the economy — is in the forefront of the ongoing debate on fiscal - stimulus packages. For example, in true Keynesian spirit, Agriculture Secretary Tom Vilsack said recently that food stamps were an "economic stimulus" and that "every dollar of benefits generates $1.84 in the economy in terms of economic activity." Many observers may see how this idea—that one can magically get back more than one puts in — conflicts with what I will call "regular economics." What few know is that there is no meaningful theoretical or empirical support for the Keynesian position.