David Autor and Melanie Wasserman summarize trends in education and labor market outcomes by gender. Timothy Taylor locates their explanation for the relative decline among males.

the earnings power of non-college males combined with gains in the economic self-sufficiency of women—rising educational attainment, a falling gender gap, and greater female control over fertility choices—have reduced the economic value of marriage for women. This has catalyzed a sharp decline in the marriage rates of non-college U.S. adults—both in absolute terms and relative to college-educated adults—a steep rise in the fraction of U.S. children born out of wedlock, and a commensurate growth in the fraction of children reared in households characterized by absent fathers.

The second part of the hypothesis posits that the increased prevalence of single-headed households and the diminished child-rearing role played by stable male parents may serve to reinforce the emerging gender gaps in education and labor force participation by negatively affecting male children in particular. Specifically, we review evidence that suggests that male children raised in single-parent households tend to fare particularly poorly, with effects apparent in almost all academic and economic outcomes. One reason why single-headedness may affect male children more and differently than female children is that the vast majority of single-headed households are female-headed households. Thus, boys raised in these households are less likely to have a positive or stable same-sex role model present.

As I interpret it, their story is one of mutually reinforcing economic and social trends. The economic trend is that the comparative advantage of non-college-educated males in the work force has declined, as innovation and globalization have increased productivity in manufacturing. This reinforces a social trend in which those males are not attractive marriage partners, so that women who formerly would have married them are instead having children out of wedlock. This social trend then reinforces the economic trend, because men born out of wedlock are disadvantage when it comes to being able to remain in school.

I would say that the trends are real, but the narrative is controversial. I think this is a situation where you pick your narrative to fit your policy recommendation. Are you Bryan Caplan, and do you recommend promoting marriage? Then your narrative has to be that marriage plays a causal role in improving men’s earnings. Are you Barack Obama, and do you recommend expanding pre-school and access to college? Then your narrative is that the the main causal factor is education. Are you Charles Murray and do you recommend promoting Victorian virtues? Then your narrative is that this is a civilization-barbarism problem, and we have to reverse the slide into barbarism.

My preferred narrative is that Neal Stephenson predicted this in The Diamond Age. The Vickies and the Thetes have divergent lifestyles, and I suspect that the attempt by the Vickies to impose their lifestyle on the Thetes is doomed to fail.

On the topic of marriage trends, Reihan Salam writes,

instead of serving as a foundation of a successful adult life (a “cornerstone”), it is seen as a culmination of a successful young adulthood (a “capstone”), according to the authors of the Knot Yet report on delayed marriage.

Pointing out the likely correlation between a decline in marriage and an increase in government dependency, Salam writes,

My suspicion is that it will be very difficult to construct such a post-marital libertarian agenda, but that’s not to suggest it’s a futile effort.

He then writes,

What I find interesting is the emerging tension between two tendencies on the center-left: (1) the civil libertarian desire to protect the autonomy of families, particularly families rooted in minority cultural traditions, as a post-marital culture yields ever more children raised in the context highly fragile, unstable family relationships; and (2) the egalitarian imperative to do more to build the human capital of children raised in the poorest households, an effort that may well require increasingly intrusive, heavy-handed, paternalistic interventions.

At the risk of being uncharitable, I do not think that (1) is a factor. Using the three-axes model, the single mom is in the oppressed class and her disadvantaged offspring are in the oppressed class, end of story.

In the talk that I gave in Phoenix, I compared universal pre-school to eugenics. Both appeal to the same desire to improve the human race based on “scientific evidence” of the unfitness of some parents.