Social Choice Theory and Deliberative Democracy : A Reconciliation

The two most influential traditions of contemporary theorizing about democracy, social choice theory and deliberative democracy, are generally thought to be at loggerheads, in that the former demonstrates the impossibility, instability or meaninglessness of the rational collective outcomes sought by the latter. We argue that the two traditions can be reconciled. After expounding the central Arrow and Gibbard-Satterthwaite impossibility results, we reassess their implications, identifying the conditions under which meaningful democratic decision making is possible. We argue that deliberation can promote these conditions, and hence that social choice theory suggests not that democratic decision making is impossible, but rather that democracy must have a deliberative aspect. 1. Two Traditions of Democratic Theory In the past decade the theory of democracy has been dominated by two very different approaches. Within democratic theory as conventionally defined the strongest current is now deliberative. For deliberative democrats, the essence of democratic legitimacy is the capacity of those affected by a collective decision to deliberate in the production of that decision. Deliberation involves discussion in which individuals are amenable to scrutinizing and changing their preferences in light of persuasion (but not manipulation, deception, or coercion) from other participants. Claims for and against courses of action must be justified to others in terms they can accept. Jürgen Habermas and John Rawls, respectively the most influential continental and Anglo-American political philosophers of the late 20 century, have both identified themselves as deliberative democrats. Deliberative democrats are uniformly optimistic that deliberation yields rational collective outcomes. The main competing tradition is social choice theory, whose proponents generally deduce far less optimistic results. To social choice theorists, the democratic problem involves aggregation of views, interests, or preferences across individuals, not deliberation over their content. From the seminal work of Kenneth Arrow on, it has been argued that such aggregation is bedeviled by impossibility, instability and arbitrariness. Arrow proved the non-existence of any aggregation mechanism satisfying a set of seemingly innocuous conditions. This critique of democracy was radicalized by William Riker, who argued that any notion of a popular will independent of the mechanism used to aggregate preferences was untenable. Given that there is no good reason to choose any particular mechanism over any other, supposedly democratic collective choices are arbitrary, and democracy is emptied of meaning. As Hardin puts it, social choice theory has exposed “flaws – grievous foundational flaws – in democratic thought and practice.” Riker's radicalization of the social-choice-theoretic critique created a chasm between the two traditions that might seem impossible to bridge. We argue that the two traditions can in fact be reconciled. Though social choice practitioners may be unaware of it, some even arguing the opposite, we argue that their theory points to the functions deliberation can perform in making collective decisions both tractable and meaningful, thus providing a crucial service to deliberative democracy. The structure of this paper follows the results of social choice theory, for it is these that both pose the challenges to democracy and pinpoint the locations at which deliberative responses must be sought. Methodologically, our arguments consist of a logical component, a normative component and an empirical-hypothetical component. The logical component takes an “if-then”-form: If condition X obtains, then, by the logic of social choice theory, meaningful collective decisions are possible. The normative component defends the claim that the constraints required for bringing about condition X are inherent in or consistent with core elements of deliberative democracy. The empirical-hypothetical component, finally, seeks to render plausible the empirical hypothesis that deliberation facilitates the