this is a very sobering read. main thesis is in section 5:
> Our conjecture is that a modern society makes the third child expensive and childlessness cheap, even when GDP per capita is only a fraction of the frontier (i.e., the U.S. level). Children are expensive because a child must be equipped to function in a world of formal knowledge and credentials, which takes years of costly investment (Restuccia and Vandenbroucke, 2013, Doepke and Zilibotti, 2019). At the same time, children are no longer productive in the household, not even for smaller chores, having been replaced by “engines of liberation” such as the electric appliances now available even to poor households (this idea extends the intuition in Greenwood et al., 2005). Modernity also imposes tight career schedules, set by large-scale organizations, that collide with the biological clock and with the kin networks that used to share the work of raising children (Adda et al., 2017, Compton and Pollak, 2014). And modernity makes childlessness cheap, because an impersonal society imposes next to no penalty on those who have no children: pensions and health care do the work that sons and daughters once did (Boldrin et al., 2015), and lineage counts for little.
> Goldin (2026) pushes this line further with an argument about a growing mismatch between genders. Modernity also changes gender roles unevenly. Women’s opportunities expand rapidly through education, work, and greater independence, while expectations about housework and childcare often change more slowly (Goldin and Katz, 2002, Goldin, 2021). This is particularly true as economies shift toward services, where women’s comparative advantages are better rewarded (Ngai and Petrongolo, 2017). The mismatch operates at both the extensive and the 18 intensive margins: more women remain childless, and mothers have fewer children on average.
> This argument is attractive because it explains why East Asia and now Latin America have such low TFRs. These are the societies where the gender mismatch is largest.19 It also suggests an intriguing possibility: societies with highly unbalanced gender norms start with very high TFRs, as men impose their preferences (Ashraf et al., 2014), and end with very low ones, as women resist (Doepke and Kindermann, 2019, Doepke and Tertilt, 2018). A paradoxical reversal of demographic fortunes.
...
> In short, modernity in its current form seems largely incompatible with replacement-level fertility.
Last week I posted a new paper with Patrick Norrick: “Terra Incognita: The Economics of a Shrinking World.”
We chose the title deliberately. No society in history has experienced the fertility levels now seen in South Korea, China, Thailand, Colombia, Chile, and many other countries. Our knowledge of the causes (and of the economic consequences) remains far more limited than most public discussion acknowledges. Much of what we write is, at best, educated conjecture.
The paper also struggles against a space limit. We wrote 20,000 words, far from the 250,000 or so we would need to address some issues in more detail (if I had the time and resources to hide away for a year, I could do that, but not now). That means some ideas are only sketched.
Nonetheless, we emphasize several important points.
First, fertility has fallen very fast everywhere: rich and poor countries, east and west, north and south, conservative and liberal societies, religious and non-religious societies (with the exception of the Jewish population of Israel; fertility has also collapsed among the Muslim population within the pre-1967 borders), you name it. Even in sub-Saharan Africa we see fast and unprecedented drops in fertility (alas, from a high initial level).
Second, and this is really interesting, the fertility collapse has been concentrated in poor and lower-middle-income countries much more than in rich countries. By now, income per capita and fertility are positively correlated within OECD countries. We conjecture this will hold globally in a few decades.
Third, and related to the second point, the fertility collapse has been concentrated among poor and lower-middle-income women within countries. In countries such as the U.S., the rich and highly educated now have more children than the poor and less educated.
Fourth, we document why we do not understand the data from the U.N. World Population Prospects. See, for example, Tables A.1 and A.2.
Fifth, we explain why some proposed mechanisms struggle when confronted with the data.
A more subtle point is at work here. Many commentators do not seem to understand the difference between proximate causes and ultimate causes. Yes, births might have gone down because fewer women are in long-run relationships. That is the proximate cause. But you need to explain why fewer women are in long-run relationships (the ultimate cause), and saying that they spend more years in school, to take one example, does not get us very far. Why do they spend more years in school? Once you start down the whole chain of reasoning, things become much harder than they seem.
The paper can be found here:
sas.upenn.edu/~jesusfv/Demog…
Comments always welcome!