In the 25 years before the Great Recession of 2008-2009, the United States experienced two brief, mild recessions and two strong, long expansions. Globally, incomes grew briskly; inflation abated; and stock markets boomed. Moreover, the recovery from the last major slump, in the early 1980s, brought about a quarter-century of unprecedentedly strong and stable macroeconomic performance. This time, however, the return to growth has been much more difficult.

America's recovery since the Great Recession, has been inconsistent, with growth repeatedly picking up and then sputtering out. In fact, the U.S. has not experienced three consecutive quarters of 3 percent growth in a decade. Though lower oil prices are helping consumers, this gain is partly offset by less energy investment, and the effects of the stronger dollar will be even larger.

The U.S. is not alone. Though most European economies are now growing again, aided by lower oil prices and currency depreciation, the pace of expansion remains anemic. Similarly, Japan's recovery remains fragile, despite strong efforts by the government. Even the major emerging economies, which were supposed to serve as global growth engines in the years ahead, are struggling: China and India have downshifted, and Brazil and Russia are contracting.