One of the things I love about Bryan Caplan is his intellectual fearlessness. It was clearly on display in his series of posts about single mothers.

It says something about both Bryan and myself that I have had many replies to him but none of them were published until Bryan offered me a smoother handle.

He says

b. Sex with birth control, unlike abstinence, does not lead to chronic burning lust.

c. Potentially poor women who delay child-bearing have a high chance of finding a reliable man before becoming infertile.

Both of these statements are wrong.

Baby lust is quite real, almost certainly genetically determined and probably explains a fair fraction of the differences in outcome among women. I don’t simply mean in income but in how one’s life turns out overall.

Second, it almost certainly not the case that potentially poor women have a high chance of finding a reliable man before becoming infertile. In a polygamous society or one that imposed an effective cartel on sex this might be true but this is not even going to come close to being true in modern America. This is because there is a serious dearth of reliable men.

That marriage market naturally clears with a fair number of women unable to find suitable life-long partners is the main driver of social-sexual institutions, customs and taboos.

I should add that Bryan’s prescription of promiscuous birth-controlled sex lowers a women’s rank in the marriage market, meaning that both baby lust and lust lust are going to make things harder for you. This is worsened by the fact that both are likely driven by sensitivity to oxytocin.

On a more general note, I think one of the core differences between Bryan and myself on this issue is my natural assumption that poor single mothers are engaging in utility maximizing behavior.

This implies that the alternatives to being a poor single mother are worse and that people accept this fate because they have low endowments in the marriage market.

For example, Bridget Moynihan commented on the – to her – shocking number of proposals she got when she was left single and pregnant. My response was that she was simply encountering men who were trying to buy an asset they mistakenly thought was available at fire sale prices.

That marriage to Moynihan was not available at fire sale prices tells you a lot about the lack of arbitrage possibilities in the marriage market. People who end up on the outs probably have little chance of ending up anywhere else.