This is that wonderful time of year when a roly-poly, white-bearded fellow descends from the North Pole to lavish us with presents. So when President Obama follows suit, maybe it's just his way of getting into the spirit of the season.

He sounded uncannily like Santa Claus the other day in a speech taking credit for creating and saving 1.6 million jobs and vowing to do even more. The recent uptick in the economy and dip in unemployment, the president announced, came about because of the $787 billion economic stimulus package he signed last February.

But with unemployment still at 10 percent, Obama perceives a need for the government to generate additional jobs -- which he plans to do with a new collection of tax cuts, public works expenditures, subsidies to homeowners for energy-saving investments, and a partridge in a pear tree. Though he stressed his commitment to fiscal responsibility, the president studiously avoided putting a price tag on this plan.

Like a certain jolly old elf, he doesn't want us to worry about the cost. After all, fiscal stimulus is supposed to more than pay for itself by goosing consumption expenditures to unleash a new surge of jobs, economic activity and tax revenue. It's a Christmas that will go on for months or even years.

If only it were true. In fact, there is no reason to believe the American Recovery and Reinvestment Act has done anything to revive the economy. Economist John Taylor of the Hoover Institution at Stanford University reports that the economic data show "no noticeable impact of the temporary tax rebates and one-time payments on consumption." No impact, by the way, is pretty much what we got when President Bush tried a stimulus in 2008.

The administration's allies crow that in the six months before the package was approved, the economy shrank, and in the six months after, the economy grew. But just because football season follows baseball season, that doesn't prove baseball causes football. Just because the economy grew after the stimulus passed doesn't mean the stimulus deserves the credit.

Considering the claims of stimulus supporters, John Cochrane, a macroeconomist at the University of Chicago Booth School of Business, says, "There is just as much evidence that Valentine's Day saved the economy." What the advocates disregard, he notes, is that every dollar spent on federal programs is a dollar that is not invested or spent elsewhere. An extravagant program can create jobs in one place only by endangering them in another.

Even by the administration's logic, the success story doesn't hold up. The contraction of the economy slowed sharply in the first month after the passage of the stimulus -- before any appreciable amounts of federal cash had been spent. Which suggests that the economy, far from requiring huge injections of federal cash to avert a depression, was already bouncing back on its own, something economies did for eons before Keynesian prescriptions came along.

What has happened since then doesn't make the case for buying a second round. Apparently the recession has already ended and unemployment has begun to fall -- despite the fact that most of that $787 billion is doing about as much stimulating as the gold in Fort Knox. Only about one-third of the money has actually gone out the door.

If one-third of the stimulus spending was potent enough to rekindle growth, shouldn't the other two-thirds be even more effective? Why do we need to throw more tens or hundreds of billions on the fire when it's already starting to blaze? On the other hand, if the first stimulus fizzled, as the evidence suggests, it makes no sense to do a sequel.

Either way, there's precious little to be said for opening the throttle of a federal spending machine that is already hurtling out of control. But there's a lot to be said against it. Every big new appropriation represents money that has to be paid back with interest, on top of the $12 trillion we already owe.

Whatever else it may do, piling up more debt brings us closer to the day when the government will have to choose among such dire options as vastly increasing taxes, resorting to inflation and defaulting on its obligations. If that day comes, Santa Claus may be hard to find.