Why Nations Fail: The Origins of Power, Prosperity, and Poverty by Daron Acemoglu and James A. Robinson Crown, 529 pp., $30.00

The fence that divides the city of Nogales is part of a natural experiment in organizing human societies. North of the fence lies the American city of Nogales, Arizona; south of it lies the Mexican city of Nogales, Sonora. On the American side, average income and life expectancy are higher, crime and corruption are lower, health and roads are better, and elections are more democratic. Yet the geographic environment is identical on both sides of the fence, and the ethnic makeup of the human population is similar. The reasons for those differences between the two Nogaleses are the differences between the current political and economic institutions of the US and Mexico.

This example, which introduces Why Nations Fail by Daron Acemoglu and James Robinson, illustrates on a small scale the book’s subject.* Power, prosperity, and poverty vary greatly around the world. Norway, the world’s richest country, is 496 times richer than Burundi, the world’s poorest country (average per capita incomes $84,290 and $170 respectively, according to the World Bank). Why? That’s a central question of economics.

Different economists have different views about the relative importance of the conditions and factors that make countries richer or poorer. The factors they most discuss are so-called “good institutions,” which may be defined as laws and practices that motivate people to work hard, become economically productive, and thereby enrich both themselves and their countries. They are the basis of the Nogales anecdote, and the focus of Why Nations Fail. In the authors’ words:

The reason that Nogales, Arizona, is much richer than Nogales, Sonora, is simple: it is because of the very different institutions on the two sides of the border, which create very different incentives for the inhabitants of Nogales, Arizona, versus Nogales, Sonora.

Among the good economic institutions that motivate people to become productive are the protection of their private property rights, predictable enforcement of their contracts, opportunities to invest and retain control of their money, control of inflation, and open exchange of currency. For instance, people are motivated to work hard if they have opportunities to invest their earnings profitably, but not if they have few such opportunities or if their earnings or profits are likely to be confiscated.

The strongest evidence supporting this view comes from natural experiments involving borders: i.e., division of a uniform environment and initially uniform human population by a political border that eventually comes to separate different economic and political institutions, which create differences in wealth. Besides Nogales, examples include the contrasts between North and South Korea and between the…