Greenspan and "The Crisis"

In a detailed review of the causes of the financial crisis, former Federal Reserve Chairman Alan Greenspan acknowledged a range of regulatory failures but strongly disputed the widely held view that the Fed left interest rates too low for too long...

Mr. Greenspan's reputation has been tarnished by the crisis. Widely hailed when he left office in January 2006 as one of the greatest central bankers ever, he is now blamed by many for advocating deregulation and low interest rates during the 1990s and 2000s.

WSJ article

Barry Ritholtz responds:
his incompetence as a regulator made his incompetence as a central banker even worse.

source

here is the Greenspan paper: The Crisis