The brilliant odd lots podcast had Richard Koo on to discuss his theory of a balance sheet recession. The central idea is that when a credit bubble bursts and the private sector and consumers both start to deleverage it causes the economy to go into a demand loss spiral, which is a counterintuitive result. If excess leverage caused the bubble then deleveraging and repairing your balance sheet is the most rational individual choice, but this de-levering in aggregate is the wrong choice for the economy as a whole. I would highly recommend reading this paper that goes into some details and also reading his book.
