Abstract

The point of departure in my story is the contrast between two models of democratic voting process: popular democracy and what might be called committee democracy. On one interpretation, voting in popular democracy is a procedure whose function is to aggregate the individuals’ preferences to something like a collective preference, while in committee democracy what is being aggregated are committee members’ judgments. The relevant judgments on the agenda often address an evaluative question. It is such value judgments that this paper focuses on. The question is how their aggregation differs from aggregation of preferences. I focus on the case in which the two aggregation scenarios exhibit a far-reaching structural similarity: more precisely, the case in which, in the judgment aggregation scenario, the individual inputs are value rankings. This means that, formally, the individual judgments in this case have the same structure as preference rankings over a given set of alternatives, but while in a preference ranking the alternatives are ordered in accordance with one’s preferences, a value ranking expresses one’s comparative evaluation of the alternatives: say, this alternative is best, those two alternatives are second-best, that alternative is third-best, etc. I suggest that this difference in the nature of individual inputs in two aggregation scenarios has important implications for the task of aggregation. In particular, distance-based methods that look fine for the aggregation of judgments turn out to be inappropriate for the aggregation of preferences: Minimization of distance from individual inputs violates the Pareto condition. When applied to judgment aggregation, distance-based methods can also be approached from the epistemic standpoint: the questions canl be posed concerning their advantages as a truth-tracker. In this context, what matters is not only the probability of the outcome of the aggregation procedure being true, but also the expected verisimilitude of the outcome: its expected distance from truth.