We analyze the aggregation problem without the assumption that individuals and society have fully determined and observable preferences. More precisely, we endow individuals and society with sets of possible von Neumann-Morgenstern utility functions over lotteries. We generalize the classical neutrality assumption to this setting and characterize the class of neutral social welfare function. Th...

Cooperating agents need to reach group decisions on several logically related issues. These decision-making problems are studied in social choice theory by the discipline of judgment aggregation. Judgment aggregation produces group decisions by aggregating individual answers to binary questions, however existing aggregation rules are defined for a very restricted setting, insufficient for aggre...

Different social planners may have different opinions on the wellbeing of individuals under different social options (Roberts, 1980). If utilities are translationor ratio-scale measurable, or if the social ranking might be incomplete, or if interplanner comparability is allowed; then there exists non-dictatorial aggregation rules. We propose extensions, intersections, and mixtures of the Pareto...

We define a family of rules for dividing m indivisible goods among agents, parameterized by a scoring vector and a social welfare aggregation function. We assume that agents’ preferences over sets of goods are additive, but that the input is ordinal: each agent simply ranks single goods. Similarly to (positional) scoring rules in voting, a scoring vector s = (s1, . . . ,sm) consists of m noninc...

We define a family of rules for dividing m indivisible goods among agents, parameterized by a scoring vector and a social welfare aggregation function. We assume that agents’ preferences over sets of goods are additive, but that the input is ordinal: each agent simply ranks single goods. Similarly to (positional) scoring rules in voting, a scoring vector s= (s1, . . . ,sm) consists of m nonincr...

We define a family of rules for dividing m indivisible goods among agents, parameterized by a scoring vector and a social welfare aggregation function. We assume that agents’ preferences over sets of goods are additive, but that the input is ordinal: each agent simply ranks single goods. Similarly to (positional) scoring rules in voting, a scoring vector s= (s1, . . . ,sm) consists of m nonincr...

We provide a generalization of Harsanyi (1955)’s aggregation theorem to the case of incomplete preferences at the individual and social level. Individuals and society have possibly incomplete expected utility preferences that are represented by sets of expected utility functions. Under Pareto indifference, social preferences are represented through a set of aggregation rules that are utilitaria...

In voting theory the well-known Gibbard-Satterthwaite theorem is about the manipulability of aggregators which consists of the aggregation of individual preferences expressed as a complete ordering over the set of alternatives. This paper deals with the generalization of such a theorem in a context where each individual expresses a fuzzy preference (weak) ordering. This extension is called H-ma...

This paper studies the behavioral foundations of non-Bayesian models of learning over social networks and develops a taxonomy of conditions for information aggregation in a general framework. As our main behavioral assumption, we postulate that agents follow social learning rules that satisfy “imperfect recall,” according to which they treat the current beliefs of their neighbors as sufficient ...

In social choice theory, preference aggregation refers to computing an aggregate preference over a set of alternatives given individual preferences of all the agents. In real-world scenarios, it may not be feasible to gather preferences from all the agents. Moreover, determining the aggregate preference is computationally intensive. In this paper, we show that the aggregate preference of the ag...