Marriage Made the West WEIRD
Some of the differences between “modern” and “developing” nations are visible at a glance, in the former’s scientific and technological culture, centralized and (professedly) democratic nation-states, and fluid social organization of nuclear families and voluntary associations. Modernity, however, extends not just to our machines, but also to our minds. In an influential 2010 paper (“The weirdest people in the world?”), the anthropologist Joseph Henrich and his co-authors pointed out that those of us who are “Western, Educated, Industrialized, Rich, and Democratic” are psychologically “WEIRD” as well, outliers among not only among past civilizations, but also among other populations around the world today. We are “individualists” rather than “collectivists,” and are unusually disposed to “impersonal” rather than “inter-personal pro-sociality,” and to inward-oriented guilt rather than other-oriented shame, among other traits.
Henrich’s 2010 article mapped some key differences between WEIRD populations and the rest of the world. In the decade that followed, he turned his attention to the problem of cultural origins, first in The Secret of Our Success (2015), which describes our species’ transition to “cumulative cultural evolution” and “gene-culture evolution,” and most recently in The WEIRDest People in the World (2020), which “examines how and why a broad array of psychological differences emerged in western Europe, and what their implications are for understanding modern economic prosperity, innovation, law, democracy, and science.”
This latest book is thus an addition to the crowded shelf of “genealogies of modernity.” The entries in this genre which enjoy the greatest popularity among philosophers and theologians—whether plaintive declension narratives or upbeat “Whig histories”—tend to follow a common pattern, tracing the ripple effects of intellectual shifts among philosophers and theologians in late-medieval or early-modern Europe. In these stories, modernity appears as the rightful heir or bastard child of, variously and among others, John Duns Scotus, Martin Luther, or René Descartes.
Henrich’s genealogy, by contrast, locates our turn toward WEIRDness in the Western Church's implementation (between ca. 500-1500 AD) of what he calls the “Marriage and Family Plan (MFP),” a loose package of social policies which eventually destroyed Europe’s tribes and replaced them with societies of nuclear families, voluntary associations, and impersonal markets. Henrich—now a professor at Harvard and plainly without much personal sympathy for organized religion—mounts an impressive empirical and even quantitative case that the social transformation wrought by the MFP was a crucial factor in the rise of the “WEIRD” psychology that characterizes the modern West in particular.
Medieval manuscript of a wedding
The MFP incorporated some longstanding “social technologies,” notably the pro-social effects of belief in a future judgment by an all-knowing, all-powerful, and good God. Nonetheless, it profoundly undermined other ancient social forms, particularly the networks of extended kinship which structure most densely-settled human societies. These extended kindreds are sustained in turn by marriage practices—notably “cousin-marriage,” polygamy, easy divorce and remarriage, etc.—that reinforce family ties and maximize the odds that the dominant lineage in a given kin-network will produce an heir.
In tribal or clan-based societies, an individual’s social and professional world is dominated by extended relatives, an arrangement which fosters high levels of “interpersonal prosociality” (which applies different norms for the treatment of insiders and outsiders). Success in such settings, Henrich notes, requires a distinctive psychology, one which favors “conformity to peers, deference to traditional authorities, sensitivity to shame, and an orientation toward the collective (e.g., the clan) over oneself.”
The MFP undermined the entire social order of extended kinship by attacking the marriage practices which sustained it. As Henrich shows, the late-ancient Western Church began to enforce a package of social policies for its members which insisted on lifelong monogamy with little scope for remarriage after divorce; banned marriages between even distant relatives, including in-laws and godsiblings; and eroded customary inheritance laws. Taken together, the MFP profoundly undermined Europe’s tribes “by (1) establishing a pan-tribal social identity (Christian), (2) compelling individuals to look far and wide to find unrelated Christian spouses, and (3) providing a new set of norms about marriage, inheritance, and residence that would have set a foundation on which diverse tribal communities could begin to interact, marry, and coordinate.” In short, the MFP made it impossible to sustain tight-knit communities based on extended kinship, and so gradually transformed the West into a society of nuclear families cooperating via impersonal markets and voluntary societies.
As an evolutionary anthropologist, Henrich likes to stress the creative role of apparently random cultural “tinkering,” which results in incremental social changes. These changes are conserved and diffused because they happen to serve some valuable purpose which no one really understands. (For instance, it turns out that spicy foods are anti-microbial.) Nonetheless, this Darwinian (we might even say Burkean) impulse perhaps causes him to understate the extent to which the MFP was a deliberate undertaking (in a letter to Augustine of Canterbury, for example, Pope Gregory the Great stressed the adverse health effects of cousin marriage) and even a natural culmination of the Church’s ambition to overthrow and overshadow the idolatrous social order it met in its mission fields.
After all, Henrich himself acknowledges, “With the weakening of kinship and dissolution of tribes, Christians seeking security could more fully dedicate themselves to the Church and other voluntary associations.” Where St. Boniface hacked down the sacred oak of the Druids to demonstrate that Christ had conquered the old gods, the MFP uprooted converts from a seamless and sacralized fabric of family, politics, and religion, and allowed (compelled?) them to reconstitute their social worlds in immediate and pervasive relation to the Church. In the process, the Church acquired not only converts’ allegiance, but increasingly also their bequests—by 1200, as Henrich notes, the Church owned approximately one-third of the land in Europe.
Whatever the precise motivations for the MFP, Henrich makes a strong case that it had profound effects, not only on the social organization, but also on the psychology of those subject to it. Where extended kindreds foster deference to tradition and attunement to honor and shame, “success in individual-centered worlds favors” the cultivation of WEIRD traits, such as “greater independence, less deference to authority, more guilt, and more concern with personal achievement.” Instead of the “inter-personal prosociality” of extended kindreds, medieval Europe’s trade-centered cities encouraged “impersonal prosociality,” since success in an “impersonal market” requires (at least the appearance of) adherence to uniform norms of fairness and honesty. In turn, these requirements foster a heightened internal sense of guilt over transgressions.
The gradual diffusion of the Western Church offers a natural experiment which Henrich brilliantly exploits for testing the hypothesis that the MFP caused WEIRD psychology, rather than merely preceding it. The gradual diffusion of bishoprics in communion with the Pope acted “as a time-release dosage of the MFP, measured in centuries of exposure to the Church.” “The stronger the MFP dosage ingested by a population,” Henrich shows, “the weaker their kin-based institutions,” and the WEIRDer their psychology today.
The results are truly striking, although space only permits me to draw a thimbleful from the ocean of evidence Henrich assembles. “A millennium of MFP exposure,” he notes, “is associated with nearly a 20-percentile-point drop in people’s willingness to go along with the group to give the same wrong answer in the Asch Conformity Task,” and also “increases voluntary blood donations fivefold, cuts people’s willingness to exaggerate their die rolls [in an experiment testing honesty] by half, and reduces the number of unpaid parking tickets from nearly seven per member in a diplomatic delegation to only one ticket for every 10 members.”
The MFP at least partly explains not only divergences of “the West from the rest,” but also intra-European variation in psychology and social structure, as in the divide between prosperous northern Italy and Mafia-ridden southern Italy. As Henrich writes, “Southern Italy . . . wasn’t fully incorporated under the papal hierarchy until after the Norman conquests of the 11th and 12th centuries. Prior to this, Sicily had been under Muslim rule for roughly two and a half centuries.” Unsurprisingly, rates of cousin marriage are 10x higher in southern Italy than in the north, and “in southern Italy, including almost all of Sicily, the rates of blood donations are near zero. In some northern provinces, they reach 105 donations . . . per 1000 people per year.”
Henri Rousseau, ‘Le Douanier’ The Wedding Party, c.1905
Though the MFP’s full effects have only become evident in recent centuries, it can be seen at work as far back as Thomas Aquinas’s understanding of marriage, which reflects a decidedly WEIRD individualism. “Slaves are not bound to obey their masters,” he wrote, “nor children their parents, in the question of contracting marriage or of remaining in the state of virginity or the like.” Henrich’s story might not explain the modern West on its own; these developments are always massively over-determined. Nonetheless, his magisterial account of the rise of the modern world shows that much of what we take to be typically modern habits of mind—individualism, impersonal prosociality, an acute sense of guilt—were already deeply imbedded in the Western psyche by the High Middle Ages. Given that, those portraying Scotus, Luther, or Descartes as the fathers of modernity—of WEIRD habits and institutions, from individualism and capitalism, to the scientific method and democracy—should consider that all of these men were already distinctive products of the world the MFP wrought.
Dr. Brendan Case (Th.D., Duke Divinity School) is the Associate Director for Research of the Human Flourishing Program at Harvard University, and author of The Accountable Animal: Justice, Justification, & Judgment (T&T Clark, 2021).