Still, it’s the beginning of a much needed shift towards fiscal austerity. But now economists and pundits are warning that curbing government spending now, with growth in a rut, is a major mistake. It’s totally obvious by pure economic math, they argue, that lower federal outlays will shrink GDP.

Americans are hearing this argument from New York Times columnist Paul Krugman, his Princeton colleague Alan Blinder, and Fed chief Ben Bernanke, who recently cautioned that quick, severe reductions in government outlays could prove a job and growth killer. Supporters of President Obama, including Howard Fineman of the Huffington Post, worry that when the cuts take hold in 2012, the slowdown they’ll inevitably produce could endanger the President’s prospects for reelection.

But the Keynesian argument that lower government spending automatically hampers GDP growth, right now, is far from the sure thing its champions keep trumpeting. Many eminent economists, from Eugene Fama of the University of Chicago to Allan Meltzer of Carnegie Mellon, take a totally different view. And the utter failure of the $862 billion “stimulus” to produce a robust recovery should encourage Americans to listen carefully to the view that more spending did little or nothing to raise GDP in the past two years, and lowering it will no virtually nothing to hamper expansion going forward.

We have been running an enormous and very expensive experiment for the last three years,” says Kenneth French, a professor at Dartmouth’s Tuck School of Business. “Although the stimulus seems to have produced none of the effects predicted by its Keynesian advocates, they remain as adamant as ever about their policy prescriptions. And more and more of the press and the public seem to be buying their arguments. One wonders what evidence would make people question the conclusion that more government spending will improve economic conditions.”

Indeed, the persistent overconfidence of the “Keynesians” is remarkable for two reasons. The first is the poor results of the stimulus plan. The second is that although Keynes recommended temporarily higher spending and deficits to exit a recession, he never even remotely advocated big increases in government outlays on top of existing, gigantic structural budget deficits.

It’s crucial to understand the logic behind the “spending-equals-growth” argument. GDP has four components: consumer spending, private investment, government outlays, and the excess, or deficit, of exports over imports. The Keynesians believe in something called the “multiplier effect.” It states that every dollar the government borrows and spends raises GDP by more than it would increase in the absence of the new borrowing and spending. For example, if new outlays rise by $1 trillion, and the multiplier effect is 1.2 — and advocates, including the administration, swear the multiple is over 1 — GDP will jump by an extra $1.2 trillion. In that scenario, Americans can have more teachers, solar energy subsidies and bridges without sacrificing a dime in corporate investments or consumer spending.

Moving money around

But that math could be bunk. It certainly doesn’t sound right. In physics, energy can be neither created nor destroyed, it simply changes form. So is it really possible for the government to create money that wouldn’t otherwise exist by borrowing and spending?

The stimulus skeptics come in two categories. The first we’ll call the hard-liners. They include Fama, one of the most influential financial economists of the past half-century, and his University of Chicago colleague John Cochrane, a prominent macroeconomist. Fama and Cochrane essentially argue that the multiplier doesn’t exist, and that by simple accounting, every dollar in government spending must reduce another part of GDP by an equal amount, resulting in a wash.

“The money you lend the government has to come from somewhere,” says Cochrane. “The stimulus is just moving the same money around.”

The hard-liners argue that if Americans buy government bonds, their own spending and savings must fall by an equal amount. What the government lavishes on grants to the states or high-speed trains is precisely offset by lower spending on cars or forklifts. Cochrane emphasizes that savings are all spent. They flow into corporate investments in plants or workstations, or to hire new workers. Simply transferring savings that would be spent on private investment to the government to spend on salaries and subsidies has zero impact on output.

What if the government borrows the money from abroad? It’s the same story, say the hard-liners. If the Japanese buy our bonds, we will use their yen to purchase more Japanese semiconductors or other Japanese products, increasing imports and hence lowering GDP at the same time all the borrowing is supposed to be raising growth.

In effect, the hardliners maintain that government spending doesn’t raise GDP at all, even in the short-term. The second group of economists, call them the “productivity hawks,” acknowledge that higher borrowing and outlays may temporarily raise growth. But they claim that the immediate bump in output is far weaker than its advocates maintain, and that the longer-term effects of the big borrowing and spending are extremely damaging.

Both Robert Lucas, a Nobel Prize winner from the University of Chicago, and Robert Barro of Harvard debunk the power of the multiplier effect, and decry the burden borrowing imposes on future growth. Says Lucas: “The stimulus and multiplier effect were way oversold,” says Lucas. “Germany and Britain are cutting spending, and they’re doing better than we are.”

Another prominent skeptic is Meltzer. For this distinguished monetarist, the reliance on spending is moving America in precisely the wrong direction, boosting consumption when we should be saving far more and plowing those savings into new plants and logistics system. “The borrowing lowers the productive types of spending on capital equipment America needs now,” says Meltzer. “We need to raise our competitiveness and become an export-led economy driven by savings and investment rather than borrowing and consumption.”

The skeptics are an impressive group, and they deserve a prominent place in the debate. If these folks just don’t get it, as the spending advocates loudly proclaim, why hasn’t all the spending resulted in better growth and more jobs? It’s highly probable that Americans were sold a myth, and its champions are now selling still another myth.