Global Demographic Trends Can’t Be Predicted by a Single Theory

If you start reading scholarly articles on trends in marriage, fertility, and family issues, it won’t be long before you run into the phrase “second demographic transition” (SDT). Coined more than 30 years ago, the term describes the emergence of several interrelated markers produced by a cultural shift toward individualism. Those markers are a high age at first marriage; high rates of divorce, cohabitation, and nonmarital births; and most importantly, fertility rates below 2.1 children per woman. Sounds like a pretty fair description of how families are evolving in most Western and many non-Western countries, right?

Yes and no, say Batool Zaidi and S. Philip Morgan in the 2017 Annual Review of Sociology. Most of the trends that theorists of the second demographic transition sought to explain (and predict) have indeed become apparent on a wide scale. People around the globe are getting married later and later (and becoming more likely to skip marriage entirely) and having fewer children, to such an extent that almost half of all people live in a country with a fertility rate below the replacement level of 2.1. Similarly, divorce and having children outside of marriage have generally become more prevalent since the mid-twentieth century. But the data do not support the idea that these changes are inevitable, irreversible, or inextricable—and attributing them mainly to postmodern values is likewise unjustified, Zaidi and Morgan argue.

Consider, for instance, ongoing differences between countries in the markers that characterize the SDT. The two scholars note:

It is hard to find a consistent pattern across countries, beyond perhaps the spread of cohabitation. Several studies show that even within Europe there is growing evidence of divergence rather than convergence between countries…

Of special importance is the failure of SDT to predict or account for the variation in low fertility. In some countries, fertility continues to fall, and it is recuperating in others. Further, some countries leading the fertility decline, such as Japan, are lagging behind in cohabitation and non-marital childbearing rates. While countries that were late to transition, like those in Southern Europe and some in East Asia, now have some of the lowest fertility rates but have seen slow increases in cohabitation, divorce, and non-marital fertility.

Nor do theorists of the second demographic transition adequately explain why patterns of marriage and childbearing vary considerably within some countries, such as the U.S.

Another weakness in the SDT framework is the claim that recent demographic trends are driven primarily (though not only) by a societal move from altruistic values to more individualistic ones, a move evident in secularization and an increasing emphasis on autonomy. Indeed, according to Ron Lesthaeghe and Dirk van de Kaa, the two scholars who formulated the theory of the SDT, it was a transformation in norms that distinguishes the second demographic transition from the first. The first demographic transition refers to the shift from high rates of birth and death—the pattern that prevailed for most of human history—to relatively low rates of birth and death. (This transition began by 1800 in wealthier countries, and it is still playing out in some of the world’s poorer countries.) There is no doubt that cultural norms have altered in the past few decades and that they affect whether and when people marry and have children; however, national survey data do not reveal a consistent correlation between postmodern values and rates of fertility or nonmarital births.

More fundamentally, Zaidi and Morgan believe the “search for developmental stages and irreversible transitions is wrongheaded.” One problem is this: the original explanations of the SDT “were clearly an exercise in examining cross-sectional data and interpreting differences observed as if they represented longitudinal change.” Based on information from a single point in time, in other words, countries are classified as falling into a certain stage of development. The related assumption that social and demographic changes are driven by similar forces across different cultures, locations, and points in time is not a safe one.

Finally, Zaidi and Morgan think that the SDT framework may rely on ethnocentric biases. The theory “was based upon White-European family experience,” and in it, “the end state of the development process is best exemplified by the country most accepting of postmodern values.” It seems plausible to conclude that wishful thinking (the values and family arrangements of the Nordic countries are poised to triumph worldwide!) plays some role in the idea of the second demographic transition.

If we throw out the grand narrative of the SDT, how should we account for the developments it tried to explain? In short, Zaidi and Morgan argue, we need a more complex framework that can account for demographic disparities between and within countries. As other scholars have pointed out, SDT theorists understate the importance of changing gender roles and economic globalization—two revolutions with varying effects on people in different countries and social classes. And the effects of globalization, in particular, are also linked to national systems of welfare, employment, and education. A new framework that accounts for all of these factors won’t be as tidy as the idea of the second demographic transition—but it will capture reality more accurately.

Anna Sutherland is a writer and editor living in Michigan. 

Editor's Note: The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or views of the Institute for Family Studies.