There's a general consensus that the massive monetary easing, fiscal stimulus and support of the financial system undertaken by governments and central banks around the world prevented the deep recession of 2008-2009 from devolving into the Second Great Depression.
Policy-makers were able to avoid a depression because they had learned from the policy mistakes made during the Great Depression of the 1930s and Japan's near depression of the 1990s. As a result, policy debates have shifted to arguments about what the recovery will look like: V-shaped (rapid return to potential growth), U-shaped (slow and anemic growth) or even W-shaped (a double dip). During the global economic free fall between last fall and this spring, an L-shaped economic and financial Armageddon was still firmly in the mix of plausible scenarios.
But the crucial policy issue ahead is how to time and sequence the exit strategy from this massive monetary and fiscal easing. Clearly, the current fiscal path being pursued in most advanced economies - the reliance of the United States, the euro zone, the United Kingdom, Japan and others on very large budget deficits and rapid accumulation of public debt - is unsustainable.
These deficits have been partly monetized by central banks, which, in many countries, have pushed their interest rates down to 0 per cent (in Sweden's case, to below that), and sharply increased the monetary base through unconventional quantitative and credit easing. In the United States, for example, the monetary base more than doubled in a year.
If not reversed, this combination of very loose fiscal and monetary policy will lead to a fiscal crisis and runaway inflation, together with another dangerous asset and credit bubble. So the key issue for policy-makers is to decide when to mop up the excess liquidity and normalize policy rates - and when to raise taxes and cut government spending, and in which combination.
The biggest policy risk is that the exit strategy from monetary and fiscal easing is somehow botched, because policy-makers are damned if they do and damned if they don't. If they have built up large, monetized fiscal deficits, they should raise taxes, reduce spending and mop up excess liquidity sooner rather than later.
The problem is that most economies are now barely bottoming out, so reversing the fiscal and monetary stimulus too soon - before private demand has recovered more robustly - could tip these economies back into deflation and recession. Japan made that mistake between 1998 and 2000, just as the United States did between 1937 and 1939.
But if governments maintain large budget deficits and continue to monetize them as they have been doing, at some point - after the current deflationary forces become more subdued - bond markets will revolt. When that happens, inflationary expectations will mount, long-term government bond yields will rise, mortgage rates and private market rates will increase, and one would end up with stagflation (inflation and recession).
So how should we square the policy circle?
First, different countries have different capacities to sustain public debt, depending on their initial deficit levels, existing debt burden, payment history and policy credibility. Smaller economies - like some in Europe - that have large deficits, growing public debt and banks that are too big to fail and too big to be saved may need fiscal adjustment sooner to avoid failed auctions, rating downgrades and risk of a public-finance crisis.
Second, if policy-makers credibly commit to raise taxes and reduce public spending (especially entitlement spending), say, in 2011 and beyond, when the economic recovery is more resilient, the gain in market confidence would allow a looser fiscal policy to support recovery in the short run.
Third, monetary policy authorities should specify the criteria they will use to decide when to reverse quantitative easing, and when and how fast to normalize policy rates. Even if monetary easing is phased out later rather than sooner - when the recovery is more robust - markets and investors need clarity in advance on the parameters that will determine the timing and speed of the exit. Preventing another asset and credit bubble by including the price of assets such as housing in determining monetary policy is also important.
Getting the exit strategy right is crucial: Serious policy mistakes would significantly heighten the threat of a double-dip recession. Moreover, the risk of such a mistake is high, because the political economy of countries such as the United States may lead officials to postpone tough choices about unsustainable fiscal deficits.
In particular, the temptation for governments to use inflation to reduce the real value of public and private debts may become overwhelming. In countries where asking a legislature for tax increases and spending cuts is politically difficult, monetization of deficits and eventual inflation may become the path of least resistance.
Nouriel Roubini is professor of economics at New York University's Stern School of Business and chairman of RGE Monitor.