By endowing his agents with simple forecasting models, or representations, M. Woodford (“Learning to Believe in Sunspots,” Econometrica 58, 277–307, 1990) found that finite state Markov sunspot equilibria may be stable under learning. We show that common factor representations generalize to all sunspot equilibria the representations used by Woodford. We find that if finite state Markov sunspots are stable under learning then all sunspots are stable under learning, provided common factor representations are used.

High degrees of relative risk aversion induce indeterminacy in cash-in-advance economies. This paper finds that Taylor-style policies can preempt such sunspot equilibria. Specific policy recommendations depend on the fundamentals of the economy, i.e. the empirically true value of coefficient of relative risk aversion.

David Cass is undoubtedly one of the central contributors to modern dynamic economics. His fundamental contributions include work on optimal growth problems, overlapping-generations models, sunspot equilibria, and general equilibrium models with incomplete markets. His research has shaped in profound ways the manner in which we do both micro- and macroeconomics. From laying the foundations of real business-cycle theory via the Cass-Koopmans model, to providing us with general tools and techniques to analyze dynamic economic models, to furthering our understanding of monetary economics, to making fundamental contributions to the economics of extrinsic uncertainty, Cass's work has played a major part in the development of much of modern macroeconomic theory. In addition to being a first-class scholar, Cass is also truly his own man and a free spirit of the highest order.

In this interview, we tried to gain some insights into the story of David Cass and his approach to economic theory. Also, given the title as well as the intended readership of Macroeconomic Dynamics, we made a real effort to get him to discuss modern macroeconomics and the influence his work has had on its development. We edited out some parts of the discussion in the interests of space, but what remains is essentially unedited. As most readers will know, David Cass has collaborated extensively with Karl Shell over the years. We talked to Shell a few weeks after talking to Cass, and that interview is scheduled to appear in a future issue.

We met with Dave in his office at the University of Pennsylvania's Economics Department just before noon. Amid the boxes and piles of articles, books and CD's, he sat in his standard jeans and T-shirt, looking about as disheveled as he usually does. We chatted there for a while, went out and continued over lunch, and then returned to complete the interview several hours later. It was an unseasonably warm day in February, and Friday the 13th to be exact. That is traditionally an unlucky day, but one that turned out in this case to be a real treat, at least for us! We hope that you get as much out of this conversation with Dave as we did.