Overview: In the 15 years to mid-2007 the world economy enjoyed unparalleled stability (the so-called "Great Moderation"), with steady growth and low inflation. But the period since mid-2007 ("the Great Recession") has seen the worst macroeconomic turmoil since the 1930s. A dramatic plunge in trade, output and employment in late 2008 and 2009 has been followed by an unconvincing recovery. How is the lurch from stability to instability to be explained?...