Over at Econlog Bryan Caplan bets that India’s fertility will be sup-replacement within 20 years. My first inclination was to think that this was a totally easy call for Caplan to make. After all, much of southern India, and the northwest, is already sup-replacement. And then I realized that heterogeneity is a major issue. This is a big problem I see with political and social analysis. Large nations are social aggregations that are not always comparable to smaller nations (e.g., “Sweden has such incredible social metrics compared to the United States”; the appropriate analogy is the European Union as a whole).
So, for example, India obviously went ahead with its demographic transition earlier than Pakistan. But what this masks is that the two largest states in terms of population in India, in the far north, actually resemble Pakistan in demographics, not the rest of India. Uttar Pradesh, with a population 20 million larger than Pakistan, has similar fertility rate as India’s western neighbor. Bihar currently has a slightly higher fertility rate than Pakistan when you look at online sources (though the proportion under 25 is a little lower, indicating that its fertility 10-15 years ago was lower than Pakistan’s, it is simply that Pakistan is now transitioning toward replacement faster than Bihar).
The key for Caplan’s bet is that over time Uttar Pradesh and Bihar will become a larger and larger proportion of India’s population. Though they’ll probably drop in fertility, for the purposes of Caplan’s bet perhaps the better question is whether Uttar Pradesh and Bihar will attain sub-replacement fertility in 2032, not India. That’s a much different question than India as a whole. I think Caplan has an even chance of winning, but it’s not guaranteed.