The Economics of Sex

Sexual freedom and economic theory. What does it mean for men and women?

How Not to Apply Game Theory to Marriage

Why marriage is not competition...

OK, in my last post, I promised to reserve judgment on the new book Spousonomics: Using Economics to Master Love, Marriage, and Dirty Dishes by journalists Paula Szuchman and Jenny Anderson, which applies basic principles of economics to marital situations. But Ms. Szuchman contributed a post to The Wall Street Journal's "Ideas Market" blog today, outlining several recommendations drawn from the book, which gave me a chance to preview it before my copy arrives in the mail.

The economics is solid—the authors know their stuff and they apply it well. Too well, actually, because they succumb to one of the worst flaws of economists (and social scientists in general): favoring a convenient model when it contradicts the real world. No model can capture the myriad intricacies of real world behavior, and by necessity they have to leave less important things out to focus on the more important things. But when important things are left out because they don't fit into a preferred modeling framework, the model is driving the study, not the other way around (as it should be). And if the model isn't appropriate for the study at hand, the results are going to be skewed.

Case in point—the final paragraph in Ms. Szuchman's post, under the title "Scheme":

Thinking ahead, learning from past experience, putting yourself in your spouse's shoes-these are all strategies straight from the game-theory playbook (game theory being the study of behavior in strategic situations). In fact, if you think like a game theorist, you'll find that marriage is really just a two-person repeated game. In the game, each person is trying to achieve the best results possible, given the limitations that there's another person involved. Think of that other person and you're being strategic. You're also being pretty romantic.

No, by definition you're being self-centered, which is neither romantic nor the path to a successful marriage. Game theory of the type the author refer to is called (not surprisingly) noncooperative game theory, which studies the way self-interested decision-makers interact in strategic situations. In my last post, for instance, I used noncooperative game theory to look at the behavior of competitors (business, political, and mating), which is a seminal application of this type of game theory. Competitors don't care about each other, but spouses or partners do (or should), especially if they want a successful relationship.

People in committed relationships don't treat each other as just another factor to account for in their strategic planning; they actively consider each other's interests as well. It is for this reason that we don't expect people who truly care about each other to fall into the prisoners' dilemma traps discussed in my last post; they're not constantly on the lookout for chances to exploit the other person, or on guard against being taking advantage of, and therefore they're more likely to cooperate.

Noncooperate game theory simply doesn't apply to people who care about each other; we have cooperative game theory for that, though it's less well-known and not nearly as popular. Sure, it's edgy to apply noncooperative game theory to marriage, especially in our Freakonomic age, but that doesn't make it right (in the sense of "correct"). (And don't get me started on a quote from earlier in her post: "what's marriage, if not a union between two trading partners?" Same idea, broader context—markets are great, but behavior that's successful in the marketplace will not necessarily be successful elsewhere.)

----------

You can follow me on Twitter and also at the Economics and Ethics blog and The Comics Professor blog.

The Economics of Sex