Wednesday 27 July 2011

Rationality and economists

Andrew Gelman takes a swipe at economists. I think he's got things wrong. Let's work through it.

First, Gelman argues economists are inconsistent in arguing for consumer rationality while arguing that people need economists to help them overcome their irrationalities, largely about government policies. But these arguments are hardly inconsistent. In environments where individuals face real costs of being wrong or irrational, they consume little irrationality. At the voting booth, their likelihood of decisiveness is sufficiently low that they can indulge biased but comforting beliefs about the true state of the world. That's Caplan's rational irrationality model; I find it rather convincing.

Here's how Gelman thinks we square the circle:
OK, now to return to the puzzle that got us started. How is it that economics-writers such as Levitt are so comfortable flipping back and forth between argument 1 (people are rational) and argument 2 (economists are rational, most people are not)?

The key, I believe, is that “rationality” is a good thing. We all like to associate with good things, right? Argument 1 has a populist feel (people are rational!) and argument 2 has an elitist feel (economists are special!). But both are ways of associating oneself with rationality. It’s almost like the important thing is to be in the same room with rationality; it hardly matters whether you yourself are the exemplar of rationality, or whether you’re celebrating the rationality of others.
I think it's rather that economists recognize that there can be a rather large disconnection between policies that are politically popular and ones that would maximize a reasonable conception of a social welfare function. You can get it through the combination of rational ignorance and logic of collective action or other public choice problems; you can also get it through Caplan's rational irrationality.

Now, I know Gelman rejects that the expected instrumental benefits of voting are low; he says that an altruist weighs the benefits to everybody else of his voting to make things better and consequently voting passes a rational instrumental cost benefit analysis. But surely if your vote is the decisive one making everybody better off as you see it, it's also the one that makes half the voting population worse off as they see it. And so Gelman's argument fails unless the voter can place himself in an epistemically privileged position: he has to know that he's making the voters who disagree with him better off. And I just can't see how that happens. That half the population disagrees with you at the ballot box ought to make you more uncertain about the benefits of your preferred policy unless you truly have expert knowledge.

Fortunately, we economists often do have expert knowledge about economic policy. Well, maybe not about macro beyond a short list of "don't do these twelve things lest you completely ruin everything". But in micro and applied price theory, we're decent.

I rather liked Gelman's PS:
P.S. Statisticians are special because, deep in our bones, we know about uncertainty. Economists know about incentives, physicists know about reality, movers can fit big things in the elevator on the first try, evolutionary psychologists know how to get their names in the newspaper, lawyers know you should never never never talk to the cops, and statisticians know about uncertainty. Of that, I’m sure.


  1. 1) I don't think this statement is anywhere near close to being true all of the time "In environments where individuals face real costs of being wrong or irrational, they consume little irrationality"

    2) If voting makes people happy from doing some public service, and voters know they get a happiness boost, then isn't it rational to go out and vote for people whose known warm fuzzies will exceed their cost of voting irrespective of election knowledge and outcomes?

  2. @Cam: They just need to buy less when the costs are high. Demand curves slope down and all that.

    Sure, voting for the warm fuzzies can be individually rational. But if politicians and policies best able to generate warm fuzzies aren't correlated with policies that would maximize some reasonable social welfare function, then there's a big voter-on-voter externality when folks vote choices are based on the warm fuzzies.