Why has Argentina been unable to sustain a democracy? Why has establishing Iraq’s been particularly dicey? According to the Harvard economist Edward Glaeser, it comes down to schools. If we want stable democracies, he writes, we need to invest in education. Being a numbers guy, though, he doesn’t just argue the case philosophically. He’s got data to back him up.

What kind of data? The kind that shows that the more educated a country is, the…

Why has Argentina been unable to sustain a democracy? Why has establishing Iraq’s been particularly dicey? According to the Harvard economist Edward Glaeser, it comes down to schools. If we want stable democracies, he writes, we need to invest in education. Being a numbers guy, though, he doesn’t just argue the case philosophically. He’s got data to back him up.

What kind of data? The kind that shows that the more educated a country is, the…