What public choice and philosophy should not learn from one another

American Journal of Economics and Sociology, The,  Jan, 2004  by Robert Sugden

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Reading Loren Lomasky's sketch of the 1982 Center for the Study of Public Choice induced a strong sense of nostalgia. Although Lomasky's and my paths did not cross, I spent two summers at the Center around that time. As an economist, I did not experience quite the same sense of culture shock that Lomasky reports; but I found the academic environment just as stimulating as he describes it. But there will be enough nostalgia in this symposium without my adding any more. Nor, since Lomasky seems to endorse the contact sport model of scholarly debate, shall I waste time on those parts of his argument with which I agree. I shall focus on an issue on which we may disagree.

Lomasky offers accounts of public choice and of political philosophy in which these disciplines have complementary strengths and weaknesses. In particular, he sees complementarities between their theories of motivation and suggests that each discipline can learn something from the other. I shall argue that the theories of motivation used by public choice theorists and philosophers, however different in substance, share a common weakness: an a priori, non-empirical mode of analysis. This common feature facilitates the transfer of ideas between the two disciplines, but it limits the usefulness of both of them.

Lomasky criticizes political philosophers for modeling human beings as rational moral agents, receptive to arguments grounded on good reasons. Thus, philosophers' prescriptions for human society tend to be unconstrained (or inadequately constrained) by considerations of what is and is not feasible, given human nature as it really is. For example, John Rawls's (1971) theory of justice presupposes that individuals have a sense of justice (although it does take seriously the idea that there may be "strains of commitment" in living up to particularly demanding moral theories). Lomasky sees this approach as having the same weakness that Adam Smith (in a passage much loved by historically minded public choice theorists) attributed to the "man of system," who "seems to imagine that he can arrange the different members of a great society with as much ease as the hand arranges the different pieces upon a chess-board" and who fails to appreciate that "in the great chess-board of human society, every single piece has a principle of motion of its own, altogether different from that which the legislature might chuse to impress upon it" (1976[1759]: 233-34). Lomasky thinks it is more useful to understand individual motivation as it in fact is, and to design social and political institutions so that they produce good results when operated by people who are so motivated. This, of course, aligns him with the constitutional approach to public choice that James Buchanan has advocated for so long.

However, Lomasky is dissatisfied with the model of human motivation that is generally used in public choice theory. This model treats individuals as self-interested; it does not admit the possibility that an individual might act on moral of ethical principles, even when the costs of doing so are low. As Lomasky has pointed out before, the opportunity cost of acting on principle is often much less in voting than in markets, for the simple reason that in a large electorate, each individual's vote has a negligible chance of affecting any outcome (Brennan and Lomasky 1985). Thus, a unified theory of motivation that takes proper account of opportunity cost might predict that principle has a greater role (and self-interest a lesser role) in voting than in markets. Public choice theory needs a realistic theory of motivation, but a theory of pure self-interest is too simplistic.

So far, I agree with Lomasky. But I am not wholly convinced by what I take to be his conclusion, that what is needed is a combination of the approaches of public choice theory and of political philosophy. Notice that neither approach is grounded in empirical hypotheses about human psychology or human nature. Political philosophy, at least as represented by Lomasky, is concerned with good reasons: the question of how, as a matter of psychological fact, good reasons motivate people to act is left unanswered. But public choice theory--like the economic theory from which it is an offshoot--does not concern itself with the psychology of motivation either. It simply asserts the apriori postulate that, for each individual, there is a well-defined set of self-interested preferences, on which that individual invariably acts. When pressed, economists usually defend this assumption on the grounds that it corresponds with the requirements of rational behavior. In other words, they appeal to a notion of good (prudential) reasons and do not concern themselves with the question of how such reasons motivate.

So, I suggest, there is a sense in which political philosophers and public choice theorists are partners in guilt. Both disciplines hold out to the scholar the tempting prospect of being able to say something significant about the world without having to investigate actual facts. (In his contribution to this volume, Richard Wagner describes exactly this temptation when he explains how he had been attracted to public choice theory as a way of avoiding what he saw as the investigative grind of traditional political science. I must confess that at a similar age, I was attracted to economics in preference to history for rather similar reasons.) However, an empirical social science has to rest on empirical foundations.