For a while though, it looked like a recovery was afoot: growth did rebound from the depths of the Great Recession, and very quickly compared to the Great Depression (though slowly when compared to Post-WWII recessions).
Clearly the scale of government spending, and the enormous increase in Base Money by Bernanke, had some impact—but nowhere near as much as they were hoping for. However the main factor that caused the brief recovery—and will also cause the dreaded “double dip”—is the Credit Accelerator.
I’ve previously called this the “Credit Impulse” (using the name bestowed by Michael Biggs et al., 2010), but I think “Credit Accelerator” is both move evocative and more accurate. The Credit Accelerator at any point in time is the change in the change in debt over previous year, divided by the GDP figure for that point in time. From first principles, here is why it matters
Related book (October release): Debunking Economics - Revised and Expanded