Here is Scott Sumner explaining the neo-monetarist idea about the Great Recession.
TL;DW:
- Central banks had an unnecessarily tight monetary policy in the lead up to the Financial Crisis.
- The sub-prime mortgage crisis was an issue, but this tight monetary policy made it far worse.
- The Recession, technically, began about six months before the fall of Lehman Brothers.
- Falling NGDP caused the sub-prime issue to inflate.
- The falling NGDP caused a severe drop in aggregate demand, and led to a recession.