From the protests in Hong Kong to the increasing power of ethnonationalist governments in India and Europe and the troubling overreach of leaders like President Jair Bolsonaro in Brazil and President Trump in the United States, our global crisis of democracy has never been more apparent or urgent. In their latest book, “The Narrow Corridor: States, Societies, and the Fate of Liberty,” political economists Daron Acemoglu and James A. Robinson hark back to an earlier tradition of postwar social science, asking a fundamental question: What explains the rise and fall of democracy and dictatorship? In so doing, they offer a provocative framework for analyzing our current moment of democratic crisis.