This paper, an extension of the Presidential Address to the International Economic Association, evaluates alternative strands of macro-economics in terms of the three basic questions posed by deep downturns: What is the source of large perturbations? How can we explain the magnitude of...

Most recessions are a result of some shock to the economic system, typically amplified by financial accelerators, and leading to large balance sheet effects of households and firms, which result in the effects persisting. But, over time, the balance sheets get restored. Even banks recover. But...