Does Stagnant Male Income Explain Falling Fertility and Marriage?

Mostly Agreeing With Lyman Stone's hypothesis

Sociologist and demographer Lyman Stone has a recent post out on How to Raise Fertility. The post begins with a graph from John Burn-Murdoch’s recent FT piece showing that there is a global trend in falling marriage rates in sync with falling fertility.

Source

Lyman then makes two claims:

1. The biggest reason marriage is falling is male economic underperformance.

2. While we try to find solutions for that issue, in the meantime, marriage subsidies work very well.

Lyman proposes a theory that connects male economic performance and marriage rates through male income acting as an insurance policy for their partner. This is different than being providers of income: women today have high incomes on their own. But they also know that if they have a child, they will certainly face a short term shock to their income and possibly a much longer term one. A high earning partner can smooth out consumption during these periods like an insurance policy would. This is a believable theory for why male income might be important for marriage rates and especially important for follow-on fertility.

Next, Lyman shows some correlations between male’s income changes and female’s fertility changes or marriage rates in the US. For example, he shows that the male age groups with the weakest income growth are young men and, correspondingly, that the female age groups with the fastest fertility decline are young women. Then, he shows that states with higher young male income growth had larger increases (or smaller decreases) in marriage rate.

There are two issues I have with this analysis. First and foremost is a lack of global data. Fertility and marriage decline are global trends, so that's the first place one should look to disprove a theory. Lyman acknowledges this problem but doesn’t rectify it. It is hard to believe that young male income is falling in all of the countries where John Burn-Murdoch documents marriage decline. Take Turkey for example, whose marriage rate declined by nearly 30 percent since 2000. I couldn’t find income by age group data, but over this period Turkey’s GDP per capita increased by 330% all while female labor force participation was below 35%. It doesn’t pass the sniff test that young male income would be falling under these conditions and yet Turkey’s marriage rate is falling.

The second problem is that falling young male income is a relatively recent phenomenon but falling fertility is not. All of the countries plotted below had rising young male incomes for most of the graphed period, but fertility rates declined nonetheless.

Indeed, this is something John Burn-Murdoch points out in his piece. Most of the fertility decline in the past is explained by married couples having fewer children, and only recently it has started to be caused mostly by fewer marriages. This is actually a piece of evidence in favor of Lyman’s first claim that stagnant male incomes explain the more recent decline in marriage, but it cuts against the claim in his title that this is “How to Raise Fertility.” If most of the fertility decline in the past wasn’t caused by low male incomes or falling marriage rates, then we won’t fix most of the fertility decline by reversing these trends.

I don’t have any problems with the arguments Lyman makes for his second claim, that marriage rates can be boosted by subsidies. He links to compelling evidence from lottery winners showing that a wealth increase leads to higher marriage rates and fertility rates for men. The fact that a completely untargeted wealth subsidy can significantly increase marriage rates is strong evidence that a more targeted marriage subsidy would have even larger effects.

So I basically come away agreeing that subsidizing marriage is a promising and high leverage first step to at least stave off further decline in fertility at least in the US and other western nations. It probably isn’t enough to recover to early 20th century TFRs since earlier fertility decline wasn’t due to falling marriage rates, but maybe getting our heads above water at a TFR of 2 is what’s most important anyways. There is also a chance that more married couples cause downstream cultural changes that can raise fertility beyond the static effect that one would predict from more marriage.