PALO ALTO, Calif. — With the American and global economies in the early stages of postrecession recovery, serious questions remain about that recovery's strength and sustainability. In addition to traditional business-cycle concerns, there is a long list of policy tensions threatening to curb growth, including: (1) protectionism, (2) currencies, (3) monetary- and fiscal-stimulus exit strategies and (4) the explosion of public debt.

Recovery from deep recessions is usually strong — the American economy recovered from the two other deep postwar recessions with annual real growth over 6 percent for three years. But nobody forecasts strong growth like that now.

It is worth remembering the real dimensions of the 1930s Great Depression, with which politicians compare this recession in order to justify massive government intervention. From 1929 to 1933, real GDP in the United States fell 30 percent, and the unemployment rate reached almost 25 percent, while the depression itself lasted more than a decade — all large multiples of the recent decline, and of the somewhat larger decline that the intervention helped to avert.