We present a model of the creation of social networks, such as political parties, trade unions, religious coalitions, or political action committees, through discussion and mutual persuasion among their members. The key idea is that people are influenced by those inside their network, but not by...

When world trade is not free and costless, a less developed country can profitably industrialize only if its domestic markets are large enough. In such a country, for increasing returns technologies to break even, sales must be high enough to cover the set-up costs, This paper studies some...

This paper explores Rosenstein-Rodman's (1943) idea that simultaneous industrialization of many sectors of the economy can be profitable for all of them, even when no sector can break even industrializing alone. We analyze this ides in the context of an imperfectly competitive economy with...

We compare "real business cycle" and increasing returns models of economic fluctuations. In these models, business cycles are driven by productivity changes resulting either from technology shocks or from crucial building blocks that give both types of models hope of fitting the data. These...

A country's most talented people typically organize production by others, so they can spread their ability advantage over a larger scale. When they start firms, they innovate and foster growth, but when they become rent seekers, they only redistribute wealth and reduce growth. Occupational...

We describe an economy where a durable good is produced with an increasing returns to scale technology. Equilibria in this economy take the form of business cycles in which consumption fluctuates too much and is too low on average. A 2-sector version of this economy with imperfect credit and...

We present a model of trade in which similar countries trade more with each other than very different countries. The reason is that high human capital countries have a comparative advantage at producing high quality goods, but are also rich enough to want to consume high quality. As a result,...

Watching TV and other forms of media consumption represent, after sleeping and working, the main activity that adults perform in developed countries. We present a dynamic theory of commercial broadcasting where the media trade utility-raising goods (programs, information, and services) with...

We consider three questions related to the choice between war in Iraq and a continuation of the pre-war containment policy. First, in terms of military resources, casualties and expenditures for humanitarian assistance and reconstruction, is war more or less costly for the United States than...

This paper concentrates on both the positive and normative effects of punishments that enforce laws to make production and consumption of particular goods illegal, with illegal drugs as the main example. Optimal public expenditures on apprehension and conviction of illegal suppliers obviously...