Dana Milbank of the Washington Post wrote this weekend that critics of Keynesianism are somewhat akin to those who believe the earth is flat. He specifically cites the presumably malignant influence of the Cato Institute.

Keynes was right, and in this case it’s probably for the better: Keynes didn’t live to see the Republicans of 2010 portray him as some sort of Marxist revolutionary. …These men get their economic firepower from conservative think tanks such as the Cato Institute… What’s with the hate for Maynard? Perhaps these Republicans don’t realize that some of their tax-cut proposals are as “Keynesian” as Obama’s program. There’s a fierce dispute about how best to respond to the economic crisis — Tax cuts? Deficit spending? Monetary intervention? — but the argument is largely premised on the Keynesian view that government should somehow boost demand in a recession. …With so much of Keynesian theory universally embraced, Republican denunciation of him has a flat-earth feel to it. …There is an alternative to such “Keynesian experiments,” however. The government could do nothing, and let the human misery continue. By rejecting the “Keynesian playbook,” this is what Republicans are really proposing.

Milbank makes some good points, particularly when noting the hypocrisy of Republicans. Bush’s 2001 tax cuts were largely Keynesian in their design, which is one of the reasons why the economy was sluggish until the supply-side tax cuts were implemented in 2003. Bush pushed through another Keynesian package in 2008, and many GOPers on Capitol Hill often erroneously use Keynesian logic even when talking about good policies such as lower marginal tax rates.

But the thrust of Milbank’s column is wrong. He is wrong in claiming that Keynesian economics works, and he is wrong is claming that it is the only option. Regarding the first point, there is no successful example of Keynesian economics. It didn’t work for Hoover and Roosevelt in the 1930s. It didn’t work for Japan in the 1990s. It didn’t work for Bush in 2001 or 2008, and it didn’t work for Obama. The reason, as explained in this video, is that Keynesian economics seeks to transform saving into consumption. But a recession or depression exists when national income is falling. Shifting how some of that income is used does not solve the problem.

This is why free market policies are the best response to an economic downturn. Lower marginal tax rates. Reductions in the burden of government spending. Eliminating needless regulations and red tape. Getting rid of trade barriers. These are the policies that work when the economy is weak. But they’re also desirable policies when the economy is strong. In other words, there is no magic formula for dealing with a downturn. But there are policies that improve the economy’s performance, regardless of short-term economic conditions. Equally important, supporters of economic liberalization also point out that misguided government policies (especially bad monetary policy by the Federal Reserve) almost always are responsible for downturns. And wouldn’t it be better to adopt reforms that prevent downturns rather than engage in futile stimulus schemes once downturns begin?

None of this means that Keynes was a bad economist. Indeed, it’s very important to draw a distinction between Keynes, who was wrong on a couple of things, and today’s Keynesians, who are wrong about almost everything. Keynes, for instance, was an early proponent of the Laffer Curve, writing that, “Nor should the argument seem strange that taxation may be so high as to defeat its object, and that, given sufficient time to gather the fruits, a reduction of taxation will run a better chance than an increase of balancing the budget.”

Keynes also seemed to understand the importance of limiting the size of government. He wrote that, “25 percent taxation is about the limit of what is easily borne.” It’s not clear whether he was referring to marginal tax rates or the tax burden as a share of economic output, but in either case it obviously implies an upper limit to the size of government (especially since he did not believe in permanent deficits).

If modern Keynesians had the same insights, government policy today would not be nearly as destructive.