Long before economics turned to psychology, environmentalists were nudging and framing and pushing their cause like highly gifted amateur psychologists. Their interventions seem to have changed behavior by altering beliefs, norms and preferences, but because psychological interventions are often...

Warfare is enormously destructive, and yet countries regularly initiate armed conflict against one another. Even more surprisingly, wars are often quite popular with citizens who stand to gain little materially and may lose much more. This paper presents a model of warfare as the result of...

We revisit the debate over whether political institutions cause economic growth, or whether, alternatively, growth and human capital accumulation lead to institutional improvement. We find that most indicators of institutional quality used to establish the proposition that institutions cause...

Using a sample of Harvard undergraduates, we analyze trust and social capital in two experiments. Trusting behavior and trustworthiness rise with social connection; differences in race and nationality reduce the level of trustworthiness. Certain individuals appear to be persistently more...

Using theory, case studies, and cross-country evidence, we investigate the factors behind the concentration of a nation's urban population in a single city. High tariffs, high costs of internal trade, and low levels of international trade increase the degree of concentration. Even more clearly,...

Could urbanization lead to more democracy and better government for the mega-cities of the developing world? This paper reviews three channels through which urbanization may generate political change. First, cities facilitate coordinated public action and enhance the effectiveness of uprisings....

How do the different elements in the standard bundle of property rights, including those of possession and transfer, influence the shape of cities? This paper incorporates insecure property rights into a standard model of urban land prices and density, and makes predictions about investment in...

We examine a new data set of laws and practices governing public procurement, as well as procurement outcomes, in 187 countries. We measure regulation as restrictions on discretion of the procuring agents. We find that laws and practices are highly correlated with each other across countries,...