Good Riddance to the Roman Empire: Maybe Rome needed to disintegrate before the West could grow wealthy.

• Author: Davies, Stephen

ALTER SCHEIDEL MAKES a dramatic claim in Escape From Rome: The collapse of the Roman Empire made the modern world possible. The release from imperial governance, he argues, had an outcome in Europe that was not replicated elsewhere. That in turn explains why Europe became the birthplace of modernity.

Scheidel, a Stanford-based historian, argues this thesis with an amazing erudition and a sweeping synthesis of scholarship. There is just one major weakness in his analysis, and it can be addressed without abandoning the main argument. Indeed, addressing it strengthens the already compelling case.

Escape From Rome belongs to what is by now a well-established genre of historiography: books that try to explain the nature and origins of the modern world. Works of this kind all have to account for the central feature that distinguishes modernity from previous human history--the enormous and unprecedented increase in wealth produced by sustained intensive economic growth. Since roughly the middle of the 18th century, ever larger numbers of human beings, over more and more of the planet, have escaped the constraints that had bound their ancestors since the advent of agriculture. Scheidel calls this "the Great Escape."

The challenge for every author in this genre is to explain why this process of liberation started when and where it did. Most recent accounts point to the ways Western Europe became strikingly different from other major civilizations in the later 17th and early 18th centuries--what the historian Kenneth Pomeranz calls "the Great Divergence." But Scheidel thinks the real divergence happened much earlier.

SCHEIDEL'S ARGUMENT HAS three main elements. First, he attributes the sustained intensive growth of the Great Escape to innovation of all kinds. This, he says, was made possible--indeed, was encouraged--by a political order of polycentrism.

In Scheidel's usage, this means a system in which major densely populated geographical regions are divided into a large number of smaller and competing territorial states rather than being ruled or dominated by large and long-lived empires. Those states, in turn, are relatively decentralized, with many competing centers of power. This competition provides both space and incentive for experimentation and diversity, and it limits elites' ability to stop them. Large empires, by contrast, can provide stable government but have a strong impetus to smother innovation and variety. (This is the almost exact...