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Steven Landsburg is a great economics writer, with a monthly Slate column and many popular economics books. But he is also a sharp theorist, and his October 2007 Journal of Public Economic Theory paper is in fact the best theory paper I’ve read in several years, as it helps to resolve fundamental issues in moral philosophy.
Now unfortunately Landsburg’s paper is too philosophical to get the attention it deserves from economists, and too mathematical to get the attention it deserves from philosophers. But one might hope that at least he would be calling as much attention as possible to his paper. Alas, it seems not. I doubt he will mention it in his column or popular books. And though he is speaking at our department in a few weeks, he has so far rejected my suggestion to talk on this paper; he’d rather talk about his third paper so far on quantum game theory.
So I am left to wonder: does he know something I do not about the value of this paper? In any case, here is the idea:
When we make "social choices," i.e., when we choose outcomes that affect many people, we want to consider how those outcomes affect these people. And we want to consider not so much direct physical affects, but rather how outcomes affect preferences. That is, we want outcomes that give people more of what they want, and less of what they don’t want.
When making such a choice we must ask: who counts for how much? For example, does a little more benefit count about the same for each of us, or do we emphasize helping those who are the worse off? Answers to such questions can be encoded in a "social justice function," which says how to best achieve social justice when there are conflicts between our differing desires.
Now we may each care not only about ordinary wants, but also about social justice. That is, we may each care directly about who counts how much in our social choices, and thus in effect care about which social justice function governs social choices. Thus our social choices will have two effects: they will satisfy more or less of our ordinary wants, and they will also give us more or less of the kind of social justice we desire.
When we can each desire different sorts of social justice, Landsburg shows that most social justice functions are not "self-justifying" in the sense of doing as well as possible on both these affects. i.e., best satisfying both ordinary wants and our thirst for social justice. In fact, he offers some plausible conditions under which there is only one self-justifying social justice function!
This suggests a fascinating resolution of basic questions in moral and political philosophy, such as "how much equality should we have?" Landsburg’s answer: just as much equality as we collectively want to have.
What Evidence Reluctant Authors?
“I'm not sure why you say that Landsburg has only shown things about "current" preferences; the math seems more general than that.” That was sloppy language on my part. What I meant was that from an evolutionary perspective moral preferences evolved to help us obtain resources; they are means to the end of increased resources. If that is true, why should we want the social planner to allocate resources to include moral preferences in the objective function? It’s almost like observing that someone works 80 hours a week, and so including a preference for work along with a preference for money in inferring their utility function. (The difference is that a person can tell you that they don’t like work, and they really just want the money. But economists don’t like to take what people say at face value anyway.) Ultimately this line of thought leads us to ask why we should want a social planner to maximize preferences anyway. One answer is that this is what utilitarian philosophy tells us. But once Landsburg starts to question the bases of the tradition, he invites more fundamental questioning. I think this is was a couple of earlier commentators were getting at in suggesting that he had too narrow a view of morality.
"I expect the conditions can be considerably weakened, but that it will take a lot more math work to prove that fact." Maybe, but Landsburg says "It is clear that something like Hypothesis 2 is necessary to generate a uniqueness theorem," and the intuition behind the accompanying example (Remark 1, p.8) seems quite general. I suspect the same is true of hypothesis 1. If hypothesis 1 is not true, the topography of the objective function changes as the allocation of goods changes and in general uniqueness fails because the maximum shifts as the topography changes. I suppose it might be possible to find some condition that ensures that the maximum is stationary even though the topography otherwise changes, but I'd surprised if such a condition weren't restrictive.
I should emphasize that I find hypothesis 1 & 2 normatively very attractive. Hypothesis 1 says in effect that your view as to the just distribution of goods should not change as the actual distribution of goods changes, and I think Landsburg is right in saying that this formalizes this requirement "that preferences have genuine ethical content." Hypothesis 2 says that your ethics have to be more than pure self-interest. (Hypothesis 2 does not say that your philosophical preferences must oppose your self-interest. Landsburg's point is that at the allocation that maximizes the objective function, you will believe that you are getting more than you think you deserve, not that you must believe that you don't deserve anything.)
I think it is an attractive normative position to say that if your preferences don't satisfy hypotheses 1 & 2 then we are justified in refusing to consider them in constructing the social planner’s objective function. If we were normatively willing to impose that restriction then it would seem to follow from Landsburg's paper that there would be a unique self-justifying welfare function. Landsburg hints that hypothesis 2 formalizes the basic notion behind Kantian moral philosophy. I don’t know enough about Kantian moral philosophy to know whether he is right about this, but if he is, his paper might amount to a reconciliation of the utilitarian and Kantian traditions. If that is so, it would be a major philosophical contribution.
My concern is that Landsburg’s opening claim is that he will show that the objective function arises endogenously, without the introduction of values from outside the economic model. For this claim to be supported his hypotheses 1 & 2 would have to be descriptively true. No doubt that is why he calls them hypotheses, rather than conditions. But if they are interpreted as conditions imposed for normative reasons, those reasons come from outside of economics. His paper may well be a major contribution to moral philosophy, but I don’t think it succeeds in divorcing economics from moral philosophy.