It's become a dreary ritual. Every six months, the International Monetary Fund (IMF) forecasts the global economy — and cuts its previous forecast. Despite an army of economists, all of its forecasts since 2011 have been too optimistic. The latest, released last week, shaved 0.4 percentage points off the growth estimate made in April.

The world economy is now expected to expand only 3.3 percent in 2014, down from a respectable 5.4 percent in 2010. The feeble growth raises the specter of a global recession.

IMF Managing Director Christine Lagarde — her agency makes loans to financially troubled countries — calls the outlook "the new mediocre." Maybe worse. In August, manufacturing output fell in China, Japan, South Korea and much of Europe, report economists at JPMorgan Chase. A 4.3 percent month-to-month drop in Germany was especially ominous.