The Middle Ages seem mysterious. The period from the fall of Rome in the 5th century through the 15th century is often—or used to be, anyway—referred to as the Dark Ages. Yet, this period was followed by the Renaissance, the Early Modern period and, in the 18th and 19th century, the Enlightenment, the Industrial Revolution, and (to borrow from Deirdre McCloskey) the “Great Enrichment.” There must have been something in the Middle Ages that was not antithetical to the birth of modernity.

Another enigma, at least from a classical liberal or libertarian perspective, is that the modern, centralized state started growing in the West just after the Late Middle Ages (14th–15th centuries). Is it possible that this powerful state was a condition for the fast economic growth that characterized the Great Enrichment, as claims the so-called “state capacity” theory? If so, this would have weighty consequences for both evaluating the Middle Ages and understanding the modern world.

In their book The Medieval Constitution of Liberty, Texas Tech University economists Alexander William Salter and Andrew T. Young address these broad questions. They believe that “the most important event for social science to explain is the Great Enrichment” and that the High Middle Ages (11th–13th centuries) developed the necessary conditions for the political and economic liberty that ultimately produced Western exceptionalism—that is, classical liberalism and economic growth.

In the authors’ economic jargon, a constitution is “the structure of political property right”—that is, it determines who are the individuals recognized as having the right to govern and in which areas of social life. To understand the written or (as in the Middle Ages) unwritten constitution of a governing apparatus, we need to inquire about the social and economic institutions that guide the behavior of individuals. Institutions represent “the humanly devised constraints that structure the incentives people face and the information they have at their disposal.” This definition is useful except for the “humanly devised,” which could be seen as excluding evolved institutions—which the authors explicitly don’t want to imply.

“Medieval constitution of liberty” invokes Friedrich Hayek’s 1960 book The Constitution of Liberty, which explored the political constitution and institutions of a free society. This does not mean, of course, that the Middle Ages represent a model of individual liberty—far from it—but our authors persuasively argue that many institutions of that era provided the conditions for the later development of classical liberalism.

Polycentric sovereignty / The great benefit of medieval times was the decentralization of power. Around the year 1000, power was so fragmented that French sociologist and historian Jean Baechler wrote, “The expansion of capitalism owes its origins and its raison d’être to political anarchy” (his emphasis). In the 13th century, the invading Mongol hordes were stopped by the “intense armed fragmentation” of Western Europe, where stone castles and fortified cities had to be conquered one at a time and “there was no central government to offer surrender” (quoting Walter Scheidel’s 2019 book Escape from Rome; see “Let’s Travel That Road Again,” Spring 2020).

This fragmentation of political power, where power checked power, seduced a political thinker like Bertrand de Jouvenel. (See his 1945 book On Power, Du Pouvoir in the original French.) The armed capacity of the landed nobility to resist kings’ ambitions may have been what Anthony de Jasay had in mind when he suggested that only “private force” can constrain the state—although he thought that the liberal 19th century was the peak of human civilization. (On de Jasay, see “A Conservative Anarchist? Anthony de Jasay, 1925–2019,” Spring 2019.)

“Polycentric sovereignty” is Salter and Young’s expression to describe the ideal type or model of the decentralized medieval constitution. Its three main constitutive elements were sovereignty, “residual claimancy” (sic), and hierarchical structure of governance. They define sovereignty as power that its holder can enforce and that becomes self-enforcing. Residual claimancy refers to the capacity of a political power holder to be the “residual claimant” (a term borrowed from the economic analysis of private production) of any enrichment that does not immediately flow to the governed. This participation in social enrichment implies that the power holder (the owner of the political rights) has an incentive to improve his flock’s prosperity—because, for example, his tax revenues or rents will increase. This analysis was previously developed by the late economist Mancur Olson. As for the hierarchical structure of governance, it describes different levels of government that are in competition with, and check, each other.

The feudal system recognized cascading and overlapping jurisdictions. Lords offered protection to vassals in exchange for the latter’s services and various contributions. The system comprised the king and the pyramid of noble lords, but also the Church, which exercised some lordship on land. In England, “royal, ecclesiastical, and merchant courts” were available. Kings were under the spiritual authority of the pope and so were their vassals. Lay lords also provided security to bishops and high-ranking clergy. Salter and Young find that the system “resembled what is today known as a federal system of governance.”

The Church was a power in itself. At the end of the 10th century, it started the Peace of God movement to control the armed conflicts that followed the end of Carolingian rule, the proliferation of “banal” lords (sorts of “roving bandits,” to use Olson’s terminology), the fuzziness of jurisdictional boundaries, and “the encastellation of the Western European landscape.” Salter and Young note, however, that the level of “feudal anarchy” violence is contested. “The Peace movement,” they write, “was key to redefining and stabilizing a polycentric structure of governance in Western Europe that would come to characterize the High Middle Ages.”

With only spiritual power and no army of its own, the Church (the First Estate) often won conflicts with nobles (the Second Estate) and even with monarchs. The Third Estate was made of burghers, the residents of cities. Kings needed the consent of the estates, especially to levy unusual taxes.

Besides checking power, another benefit of polycentricity was to allow “greater access to local knowledge” as well as exit options. The latter were limited, of course, especially for the villeins (serfs). Yet a serf could be liberated from his lord if he could “make it to a city and reside there for a year and a day” or if he cleared forest land for cultivation.

From this decentralized system incorporating many divergent interests, Salter and Young claim, a generality norm à la James Buchanan developed. Good governance, defined as “that which furthers general rather than special interests,” was thereby promoted. I would emphasize, perhaps a bit more than Salter and Young, that what we now call individual and equal liberty was only in gestation.

Why Western Europe? / Why did traditions of liberty arise in Western Europe instead of elsewhere, like Asia? Salter and Young note that Western Europe “was not exceptional for most of recorded history.” The Great Divergence of economic growth between Europe and the rest of the world only became obvious in the 18th and 19th centuries and was certainly not the consequence of colonialism. It is without colonies that Sweden and Austria—and we can add Switzerland, Canada, and the United States—rapidly joined European growth, spearheaded by the United Kingdom and the Netherlands.

Like economic historian Joel Mokyr, Salter and Young recognize the importance of the institutional environment for European growth. (See “From the Republic of Letters to the Great Enrichment,” Summer 2018.) The authors of The Medieval Constitution of Liberty examine two other major institutions related to polycentric sovereignty: the medieval assemblies and the self-governing cities.

They argue that medieval assemblies were often characterized by mixed representation and were thus “more resistant to the absolutist ambitions of monarchs than those with estate-based chambers.” They compare France, where assemblies were organized around particular estates, and England, where they tended to be based on local representation. In the latter country, local assemblies had played a role ever since the fall of Rome. Later, Great Councils advising the monarch, renamed Parliaments by the end of the 13th century, had regional representation; in the 1330s, they became a House of Lords and a House of Commons.

Are Salter and Young tempted to exaggerate the role of medieval assemblies? I can’t say, but there seems to be no doubt that the self-governing cities that emerged in the Middle Ages played a major role in the development of liberty. They sprang from “merchant caravans that settled outside fortified towns in the eleventh and twelfth centuries.” Burghers, the cities’ inhabitants, were eventually able to “leverage their wealth and human capital to strike constitutional bargains by playing monarchs, nobles, and clergy off one another. The results of these bargains were various immunities, liberties, and rights codified in cities’ charters.” Merchants, the most important of burghers (others were artisans and laborers), “developed a commercial code (jus mercatorum) for themselves.” Medieval cities became a center of (relative) liberty. A legal maxim circulating in Europe was that “the city air makes you free.” In cities, literacy increased, self-governing universities appeared, and new ideas were discussed.

State capacity / The medieval constitution did not survive long after the High Middle Ages, notably because of the shocks of the 14th century. The Black Death, a plague or viral epidemic, ravaged Europe between 1347 and 1351. Depending on the region, it killed between one-eighth and two-thirds of the population. Another shock was the siege cannon, which produced economies of scale in coercion and eliminated the relative advantage of fortified places. Centralized nation-states rose with “state capacity” for producing what we would now call public goods.

State-capacity scholars believe that the privatization of political authority in the High Middle Ages prevented state centralization and the building of useful state capacity, notably for supporting economic growth. They point to the correlation between high taxes and high economic growth since the Industrial Revolution. (See “A Shackled Leviathan That Keeps Roaming and Growing,” Fall 2021, and “A Fashionable Appeal to a Benevolent State,” Winter 2023–2024.) An example of the perverse effects of decentralized medieval institutions can be found in the guilds, which limited innovation and competition among artisans, and existed from the 11th to the 18th century. Local tolls offer another example. Only the modern central state, goes the argument, was able to abolish these obstacles to the Great Enrichment. Salter and Young consider the state capacity argument “a significant challenge,” which they endeavor to meet.

The state capacity explanation for economic development has been challenged by several scholars such as Peter Boettke, Roselino Candela, Vincent Geloso, Ennio Piano, and Salter and Young themselves. Strong states can be predatory as much as producers of public goods. Historically, state capacity has generally stifled economic development; we only need to think about imperial China or, in recent times, North Korea or the Soviet Union. To support prosperity, state capacity must be limited by the rule of law and a market economy. The state must be constrained in the use of its capacity. Western countries’ march toward the Great Enrichment suggests that something must have prevented state capacity from becoming predatory. Salter and Young argue that this something “was the set of background constraints bequeathed by the constitutional heritage of medieval Europe.”

Thus, we cannot explain “the bounty of modernity” without the conditions that existed in the High Middle Ages. “The rise of the West must be viewed not as an escape from the High Middle Ages,” the authors write, “but a continuation of the proto-liberal traditions that solidified in the High Middle Ages.”

A useful book / Salter and Young’s book confirms that capitalism or, more generally, individual liberty is the daughter of anarchy or, at least, of polycentric and limited political power. Let’s repeat that the Middle Ages were not perfect and mankind had to wait for 19th century classical liberalism to have a glimpse at the bounty that individual liberty can produce.

The Medieval Constitution of Liberty intelligently addresses issues that are essential to understand the development of individual liberty. It provides interesting information on the Middle Ages. And it suggests a healthy skepticism toward the “state capacity” intellectual fad.