THE U.S. ECONOMY is in the doldrums, as June’s disappointing employment figures showed. Europe and China, the world’s other two economic engines, are also sputtering. Time for the Federal Reserve to administer another dose of monetary stimulus, to head off a potentially disastrous global downturn?

That’s the advice of many experts, including the presidents of the Chicago, Boston and San Francisco Federal Reserve banks. The Federal Reserve’s Open Market Committee holds its next policy-making meeting at the end of this month: Chairman Ben S. Bernanke will be under some pressure to heed the calls for a third round of “quantitative easing.” His problem is that it’s not clear whether that’s the right course.

To be sure, the risk of inflation in the short run is minimal, as pro-QE3 economists argue. Yet it is also true that the economy is achieving paltry growth despite having absorbed a phenomenal amount of stimulus, fiscal and monetary, since the crisis hit in 2008. The annual federal deficit has averaged more than 9 percent of gross domestic product (GDP) over the past three years. It is on course to be 7 percent of GDP in fiscal 2012. The Fed has cut interest rates to near zero and purchased $2 trillion in mortgage-backed securities and Treasury debt, a figure equal to roughly 13 percent of GDP. And last month the Fed expanded its so-called “twist” program, announcing that it would hold down long-term interest rates by swapping an additional $267 billion in short-term notes for long-term bonds.

As Mr. Bernanke himself has said many times, these policy innovations, while necessary, also put the Fed in uncharted territory; the risks and benefits of the actions already taken, let alone those of further balance-sheet expansion, are hard to specify. The Fed may also need to save ammunition to help deal with a financial collapse in Europe.

If QE3 works at all, it would be by reducing the cost of investment capital and by boosting asset prices, so as to make consumers feel wealthier — and thus more free-spending. Yet with well over $1 trillion sitting on corporate balance sheets and mortgage rates at all-time lows, it’s not clear that the economy’s problem is a lack of cheap money. Rather, slow growth may reflect structural factors, such as the huge household debt burden, which is declining but still equal to 83.6 percent of GDP. Then there’s the federal government’s out-of-whack tax and entitlement policies, and the uncertainty they generate.

By effectively transferring much private and government debt onto its own balance sheet, the Fed bought time for the U.S. economy to rebalance under relatively benign conditions. Companies and households have used the time so far to deleverage significantly. More monetary easing now might buy the economy even more time to heal. But soon it will be government’s turn to adjust; the Fed can prop up growth, not engineer a permanent escape from fiscal reality.

More on the Federal Reserve from The Post editorial board:

The Fed eases out

Nailing down the ‘Volcker Rule’

Two for the money

Ben Bernanke’s wise words