The macroeconomic events of the last twelve years are truly breathtaking—a once-in-a-lifetime (we hope) occurrence. While the basics of how economists understand the macroeconomy remain solid, the global financial crisis and the Great Recession took us into waters that, if not uncharted, at least had not been visited in more than half a century. The recovery of the U.S., European, and world economies from these shocks has been remarkably subdued. And, perhaps most troubling of all, the productivity growth that underlies longrun economic performance has been surprisingly slow for more than a decade.过去12年发生的宏观经济事件确实令人惊心动魄——我们希望这是千载难逢的事情。尽管经济学家如何理解宏观经济的基础仍然牢固，但全球金融危机和大萧条将我们带入了一片水域，如果不是未知的话，至少半个多世纪以来从未有人涉足过这片水域。美国、欧洲和世界经济从这些冲击中复苏的势头明显减弱。而且，也许最令人不安的是，作为长期经济表现基础的生产率增长在过去十多年里一直出奇地缓慢。