Sexual economics, a theory in need of reworking

Recently, my attention was caught by the idea of the "sexual marketplace".  Specifically, there's a theory of sexual economics created by Baumeister and Vohs.  If you'd rather not read the paper, the Austin Institute* made a fancy video about it:



*Apparently, it's a think tank run by Mark Regnerus.  Yes, that Mark Regnerus.

Note that the video makes a bunch of claims about how people should behave, rather than just how they do behave.  I'll get to that part later. 

Basic Sexonomics

Baumeister and Vohs (B&V) model sex as an exchange that takes place within a marketplace.  We're ignoring everything except straight sex because, sure, that's ~90% of the sex.  So far, fine with me.  Since I'm a physicist I think you can make a simple model of anything.

But B&V add one extra component to the theory.  Men like sex more than women.  Therefore, sex is "sold" by women, and "bought" by men.  Men don't typically pay in money, but instead may offer

a fancy dinner, or a long series of compliments, or a month of respectful attention, or a lifetime promise to share all his wealth and earnings with her exclusively.

I'll just grant, for the sake of argument, that men really do want sex more than women, and I won't discuss whether that's cultural or biological.  The idea that women are "sellers" doesn't follow.

In general, sex is an exchange where both parties benefit, regardless of whether anything is bartered for it.  There are people who don't like sex, but they're not really participating in the market.  You'd think people would just have sex all the time, but I suppose you need time for other stuff and there's probably diminishing returns.  I also suppose there's also some opportunity cost associated with having sex with this person rather than that one.

Anyway, you can imagine supply and demand curves, where the demand curve is the marginal value to men, and the supply curve is the marginal "cost" to women.  Since sex is valuable to both parties, the "cost" is actually negative, but whatever.  The efficient market price is at the intersection of the supply and demand curves.  Since men want more sex than women, the efficient market price is positive (from men's perspective).

I worked really hard on this graph so you know it's right. 

However, it is not clear to me that the pricing will be the same across the board.  That may be true in the case of interchangeable products like bread, but is clearly not the case for people.  It may be the case that on the margins, paying women for sex can be the only way to make mutually beneficial agreements, but it's not obvious that this applies to the market as a whole.  For people who positively value sex, a large range of prices are possible (anywhere between the supply and demand curve shown above).

It is not merely that each person has a different valuation of sex.  It's that the value of sex is a function of both who you are and who you're having sex with.  I don't know how you get from this two-variable function to the supply and demand curves. I don't know if it's even sensible to speak of supply and demand curves.  You can't just assume that all human variation automagically averages out.

B&V also repeatedly emphasize that men are paying by giving the women committed relationships.  So the sexual market, where women sell sex, is coupled to a relationship market, where men sell relationships.  The thing is, like sex, relationships also benefit both parties, and again they ignore that aspect.

This all makes me wonder, where are B&V getting this from?

Although not many others have explicitly discussed sex as a female resource, we believe that that view is implicit, though often unstated, in many writings.  For example, Wilson (2001) recently published a widely influential sociological analysis of the decline of marriage in Western cultures, in the course of which he found it necessary to invoke unsupported assumptions such as [...]

Translation: "We may not have much evidence for our theory, but other researchers don't have evidence for our theory either, so nyah!"

In fairness, they offer a bunch of other evidence, such as prostitution, and societal attitudes towards infidelity in men and women.  And certainly, you can fit some facts about our culture into the theory.

However, at times it just seems like B&V are really fishing for the "that totally confirms my pre-existing prejudices" response:

Advanced Sexonomics

Typically, a group of men brought back meat for the group and all the meat was shared.  Miller et al. argued that this arrangement obscured individual hunting ability, and therefore women could not easily use gifts of material resources as a sign of long-term mate potential.

Here's the obligatory evopsych just-so story.

A low price of sex favors men, whereas a high price favors women.  Therefore, men will tend to support initiatives that lower the price of sex, whereas women will generally try to support a higher price.

And that's why feminists are in favor of slut-shaming.

Why should a woman care whether men in her community purchase pornographic materials and masturbate? But if pornography satisfies some of the male demand for sex, then it may reduce the total demand for her own sexual favors, and as a result the price she can obtain will be lower.

I guess that is one explanation.

Sexual decision making is likely to be more complex for the woman than the man.  Faced with a suitor desiring sex, she may feel pulled in conflicting directions.

Is there some economic principle that I'm unaware of that says "sellers" are more emotionally conflicted than "buyers"?  (It should be noted that B&V are not economists.)

As social exchange theorists emphasize, the value of any commodity rises and falls with scarcity. [...] By analogy, sex would have high value if the woman has had few lovers or is known to be reluctant to grant sexual favors, whereas the same activity might have less value if the woman is reputed to be loose or to have had many lovers.

In my understanding of economics, the value of a commodity rises and falls with global scarcity.  If one person can sell more of a commodity, they simply earn more profits.  So maybe there are some people who prefer sex with sexually inexperienced people, but that's just an ad hoc preference, not a rational response to the market.

Both men and women said they would be more upset if their partner had sex with a man than a woman.  This fits the view that, in sex, women give and men take.

Again, B&V make it out like this is a rational response to the market, rather than an expression of ad hoc preferences.  I really don't see how this could be.  Most sex benefits both parties, and it only "costs" women in that there is an opportunity cost.

[cw: rape] A milder version [of this theory] thus holds simply that female coercion of male victims lacks an important dimension, namely theft of the resource, and so the trauma and victimization are less severe.

I really don't think the theft of resources is the most important factor for trauma!  It's not like hiring a prostitute and having your check bounce.  Alright, I'm done with this paper!

Normative Sexonomics

Even aside from the merits of sexual economic theory, the video at the top is awful.  It argues that sex has become cheap (because birth control), and therefore men are less likely to pay women with marriage.  The video argues that this is bad.  Therefore, women should collude to make sex more expensive again.

Within their own stupid theory, if there's more sex and less marriage, this satisfies men's preferences.  Why is it bad for men to get what they supposedly want?

Message: Men's desires are destructive to society.

Collusion is kind of a ridiculous idea.  In theory, if enough women collude, this could give them an advantage in a market.  However, the women who are not part of the collusion reap even more benefits, so there's not much incentive to collude.  The only way collusion is possible here is if it's coerced.  For example, by public shaming of women who have sex too freely.

Message: We need more slut-shaming.

Saying "sex is cheap" sure makes it sound bad.  However, within the theory, the more expensive sex is, the less equitable the market is, so cheaper sex means more equality.  Note also that as sex becomes cheaper, sexual economic theory becomes less valid.

Message: Men and women have become more equal, and it's making our theory break down, so we need to stop it!