Conditional Comparative Statics James A. Robinsony Ragnar Torvikz August 15, 2010 Abstract Why was the Black Death followed by the decline of serfdom in Western Europe but its’ intensi…cation in Eastern Europe? What explains why involvement in Atlantic trade in the Early Modern pe- riod was positively correlated with economic growth in Britain but negatively correlated in Spain? Why did frontier expansion in the 19th Century Americas go along with economic growth in the United States and economic decline in Latin America? Why do natural re- source booms seem to stimulate growth in some countries, but lead to a ‘curse’in others, and why does foreign aid sometimes seem to encour- age, other times impede economic growth? In this paper we argue that the response of economies to shocks or innovations in economic oppor- tunities depends on the nature of institutions. When institutions are strong, new opportunities or windfalls can have positive e¤ects. But when institutions are weak they can have negative e¤ects. We present a simple model to illustrate how comparative statics are conditional on the nature of institutions and show how this perspective helps to unify a large number of historical episodes and empirical studies. Keywords: JEL: Paper prepared for the 2010 World Congress of the Econometic Society. We are grateful to Marco Battaglini for his incisive comments. yHarvard University, Department of Government and Institute for Quanti- tative Social Science, 1737 Cambridge St., Cambridge MA02138. E-mail:
[email protected]. zNorwegian University of Science and Technology, Department of Economics, Dragvoll, N-7491 Trondheim, Norway.