For the past six years, the West has believed that monetary policy can save the day. The crisis led to huge budget deficits and rising debt, and the need for deleveraging, the thinking goes, means that fiscal policy must be shunted aside.

The problem is that low interest rates will not motivate firms to invest if there is no demand for their products. Nor will low rates inspire individuals to borrow to consume if they are anxious about their future (which they should be). What monetary policy can do is create asset-price bubbles. It might even prop up the price of government bonds in Europe, thereby forestalling a sovereign-debt crisis. But it is important to be clear: the likelihood that loose monetary policies will restore global prosperity is nil.