Why buy the cow when you can get the milk for free?

I don’t know why this still surprises me (particularly since expressions like the one in the title to this post have been floating around for several hundred years), but whenever I tell people about my area of interest they seem to understand at an intuitive level what it is we talk about here at Dollars and Sex.

Many of my recent conversations go something like this:

Friendly stranger: “So what are you doing here in France?”
Me (wine glass in hand): “I just finished writing a book.”
F.S. (now intrigued): “Oh, wow. What’s it about?”
Me: “It is about economics.”
F.S. (now peering over my shoulder looking for a way to escape): “Uh huh”
Me: “Well, to be more specific it’s about the economics of sex.”
F.S.: “Seriously? I never really thought those two things went together.”

Here I usually pause to give my companion time to think about this and when I do, every single time, they come back with a comment/question that illustrates that not only do they understand the way that economists think about sex, but they have been thinking the same way for a while.

I had one of these conversations this weekend with an Argentinian who is visiting France for the week. His question was this: “Do you think that it is cheaper for a man to have a girlfriend or is it cheaper for him to be single?”

Just so we are clear, he was talking about the cost of sex. And it’s a great question.

On the one hand having a girlfriend can be expensive for a man, especially if he is the type of man who likes to take care of the woman he is dating – buying her meals, gifts, taking her on trips, et cetera. Those expenses could potentially add up quickly over several months of a relationship.

But being single, or more to the point being a single man who is hoping to have sex, can also be very expensive. Not only is hanging out at nightclubs and bars or going on many first dates pricey, but men who hope to attract female attention also have to shell out for expensive clothes, shoes, grooming services and products and more.

In regard to this last point, modern men are finally starting to understand how expensive it is for women to attract a mate in a world in which many people make these decisions based on personal appearance alone.

I don’t have the answer to this question about which is cheaper, but I think that what it comes down to is frequency of sex. All the data I have seen suggests that the men who have sex the least frequently, after men who have no sex at all, are those who report having more than one sexual partner in the previous three months. The men who have sex the most frequently, for example more than 20 times a month, are almost exclusively men who have only one sexual partner.

So even though it may appear to costs less to head out to the clubs on the weekend than it does to wine and dine a girlfriend, given that the outcome of that outing is uncertain it is probably still the most expensive option.

There are helpful websites that will calculate for men how much they are paying for sex with their girlfriend. Some will even go so far as to compare that cost to having sex with prostitutes over the same period to see if there has been any net savings from having a girlfriend.  But that is a seriously flawed methodology.

From the perspective of an economist, the opportunity cost of having a girlfriend has to take into consideration the cost of that man’s activities had he remained single and, for the vast majority of men, that is not prowling the streets looking for a sex worker.

The “buy the cow” expression is offensive for obvious reasons, but any good economist would tell you that you are never really getting the milk for free. And besides, marriage/cohabitation is economically efficient when it comes to the provision of sexual services and that is one of the reasons so many people think it is worth the initial investment.