Epstein’s historical evidence came from medieval Italy. Late medieval Italy was highly urbanized and prosperous by pre-industrial standards. According to Broadberry’s estimates, per capita GDP in Italy in 1450 was not matched by England until 1750. Like growth elsewhere in the premodern world, it was Smithian growth, driven by trade, market integration, and the division of labor. But unlike in England, this Smithian growth did not continue and blossom into modern growth. Epstein’s explanation for why this did not take place was that late medieval Italy suffered an “integration crisis”.
He saw the late medieval period as characterized by new opportunities for growth and innovation. Urbanization increased. Capital markets expanded and deepened. Interregional trade developed. Proto-industrialization took place. But Epstein contended these opportunities were only seized in areas where political authority was centralization.
In reference to proto-industrialization, he observed that
“Crucially, the success of regional crafts was inversely proportional to the concentration of economic and institutional power in the hands of a dominant city.”
With respect to the establishment of permanent fairs, he noted that
In fifteenth-century Lombardy, new fairs proliferated only after the balance of power shifted decisively from the former city-states to the territorial prince with Francesco Sforza’s victory in 1447.
Market integration was complemented and perhaps driven by political integration. Integrated urban hierarchies were themselves the product of political centralization.
“Centralisation underlies all the major institutional changes to market structures previously described. It lowered domestic transport costs, made it easier to enforce contracts and to match demand and supply, intensified economic competition between towns and strengthened urban hierarchies, weakened urban monopolies over the countryside, and stimulated labour mobility and technological diffusion.”
The more centralized parts of Italy — notably Lombardy — were better able to benefit from these trends than was Tuscany. But in general, political fragmentation and regional diversity were “distinctive features of pre-modern Italy” in general and an impediment to its long-run growth prospects.
Unlike in his analysis of interest rates, Epstein brought little data to bear on these claims and I am unaware of subsequent research on late medieval Italy. As such, the thesis of a late medieval integration crisis laid out in Freedom and Growth remains speculative. Epstein would no doubt have fill in the details had he lived longer. Subsequent research has mostly focused on early modern rather than medieval Europe (see here). But the larger message: the importance of the state for premodern economic development has been central to subsequent research, including my own work (e.g. here).