Liberal economists think we should reduce the deficit. Just not yet.

When it comes to the national debt, says Paul Krugman, the best advice may come from St. Augustine: "Grant me chastity and continence—but not yet." That was the rough consensus among the economists who convened Wednesday at the Washington Court Hotel for a conference held by the Center for American Progress and the Center for Budget and Policy Priorities: We absolutely have to do something about this deficit. Just not right now.

Their advice is on the merits, but it just so happens to be politically convenient. We wanted to reduce the deficit, the White House and congressional Democrats can say, but the experts told us not to! In economics as in politics, timing is everything.

Before the economists gave the politicians permission not to act right away, however, they established the need to do something eventually. Right now, CBPP President Robert Greenstein said, the annual deficit is about 8 percent of gross domestic product, while the national debt—the sum of all past deficits—is about 70 percent of GDP, or $10 trillion. If current policy persists, the deficit will inflate to become 20 percent of GDP by 2050, with a total national debt of 300 percent of GDP. (The main reason for the ballooning deficit is Medicare and Medicaid spending, but Social Security plays a role, too.)

If those numbers don't scare you, maybe the practical consequences will. Princeton professor Alan Blinder explored the possibilities. Inflation? "I don't think we're going to see that in the United States," he said, even though it happens all the time in other countries when debt mounts. Skyrocketing interest rates? That's a "very obvious candidate." But the most likely risk, he said, is a weakening dollar: "If the economy cracks, it cracks on the dollar." A plummeting dollar means less economic influence in the global market, less purchasing power when it comes to foreign investment, and, above all, unhappy creditors. China, which currently has some $2 trillion invested in American dollars, would probably refinance in some other currency.

Another possibility, said Blinder, is that the political system cracks first. He cited the New Deal as an example of a good political crackup. What a mountain of debt could mean for our political system, he said, "I wouldn't even begin to forecast." A questioner, however, did just that. Recall 1992, he said, when Ross Perot ran on a platform of deficit reduction. Perot didn't win, but his influence—he drew enough votes to allow Bill Clinton to become president—produced a bipartisan obsession with deficit reduction, which occupied much of Clinton's first term. "It's highly likely we're about to see that happen again," he said.

So if the stakes are so high and the future so dire, why wait? Why not eliminate the deficit now, while we're talking about it? Because the economy is still fragile. The recession is officially over, sure, but unemployment is still high—it rose to 9.8 percent in September—and a full recovery will take time. As Berkeley economist Laura Tyson put it, "We have two risks: If we do something too precipitously fast, we undermine recovery … but if we don't do something," we risk the dystopian future described above.