In honor of Mark Sanford and that other guy from Nevada, the fun-loving crowd over at Planet Money has been talking about the economics of adultery, and even got Simon to comment for them. I’m all in favor of a cute model, but I think this is as much a sign of the over-expansion of economic reason as anything else.

Chana Joffe-Walt’s post asks this question of the typical cheating politician: “Didn’t he know he’ll get caught, put his family through hell, exhaust all of us with the details and jeopardize his career? The costs are so great, how could the affair possibly be worth it?”

Well, that assumes that he was going to get caught, and the odds of being caught in an affair are one of those things that are inherently very difficult to measure (and that cheaters are likely to underestimate, because of selection bias). We can see the numerator, but we can’t see the denominator. It also assumes that trading your political career for a steamy affair is a bad outcome. On some level, don’t you suspect that a lot of male politicians do it because they want to impress women, and that affairs are part of the payoff of politics? And what sane person would really want to be in electoral politics anyway?

More generally, the motivations that drive people to want to have sex with people they are not married to, or otherwise live secret lives other than the one they are supposed to live, seem to me not only too complex for a Chicago-school rational-actor model, but even perhaps too complex for a behavioral model. That is, I suspect that this type of behavior involves multiple actors inside the same person: one person who combines the ambitious, values-touting politician; the typical middle-aged man going through a midlife crisis and hoping for someone to validate his self-image; and, of course, the lout who thinks with something other than his brain. I think combining those sides of the psyche into a single utility model and maximizing it subject to a budget constraint (be it money or time) is basically a fantasy. But economists these days wil stop at nothing.

By James Kwak