But episodically, the "shock" is deeper. It is structural. Among advanced countries, the movement from agricultural to manufacturing in the last century, and the more recent movement from manufacturing to the service sector reflect such a large economic transformation. The associated downturns...

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...