The fact that many people take it upon themselves to impose costly punishment on free riders helps to explain why collective action sometimes succeeds despite the prediction of received theory. But while individually imposed sanctions lead to higher contributions in public goods experiments, there is usually little or no net efficiency gain from them, because punishment is costly and at times m...

Conflicts of interest arise between a decision maker and agents who have information pertinent to the problem because of differences in their preferences over outcomes. We investigate how the decision maker can extract the information by distorting the decisions that will be taken. We show that only slight distortions will be necessary when agents’ signals are sufficiently accurate or when the ...

This paper introduces a new class of judgment aggregation rules, to be called ‘scoring rules’ after their famous counterparts in preference aggregation theory. A scoring rule generates the collective judgment set which reaches the highest total ‘score’across the individuals, subject to the judgment set having to be rational. Depending on how we de…ne ‘scores’, we obtain several (old and new) so...

In a framework allowing infinitely many individuals, I prove that coalitionally strategyproof social choice functions satisfy “tops only.” That is, they depend only on which alternative each individual prefers the most, not on which alternative she prefers the second most, the third, . . . , or the least. The functions are defined on the domain of profiles measurable with respect to a Boolean a...

We apply the idea of partial honesty, first introduced by Dutta and Sen [Nash Implementation with Partially Honest Individuals, Game Econ. Behav. 74 (2012) 154-169.] in a complete information setting, to environments with incomplete information. We show that with private values and at least three individuals, incentive compatibility and no veto power are together sufficient for full implementat...

This paper provides a brief introduction to the use and usefulness of Suzumura consistency, a coherence requirement for binary relations that weakens transitivity. The property is introduced by Suzumura (1976b) in the context of collective choice but, as demonstrated in some recent contributions, its applicability reaches beyond the boundaries of social-choice theory. In addition to a summary o...

Contrary to communitarian market criticism institutions relying on money and bidding can strengthen faculties of ‘self-governance’. Securing procedurally egalitarian bidding on the basis of declared monetary evaluations guarantees that all realized changes of a status quo are in an ‘objective’ (pecuniary) sense equally advantageous for all members of the community. We show how to use this idea ...

We consider estate division problems and show that for any claim game based on a (estate division) rule satisfying efficiency, equal treatment of equals, and order preservation of awards, all (pure strategy) Nash equilibria induce equal division. Next, we consider (estate division) rules satisfying efficiency, equal treatment of equals, and claims monotonicity. Then, for claim games with at mos...

We study the possibilities of constructing strategy-proof rules that choose sets of alternatives as a function of agents' preferences over such sets. We consider two restrictions on the domain of individual preferences over sets. Assuming that all singletons are in the range of the rule, we show that only dictatorial rules can be strategy-proof on the larger domain. The smaller domain also allo...

This introduces the symposium on judgment aggregation. The theory of judgment aggregation asks how several individuals’ judgments on some logically connected propositions can be aggregated into consistent collective judgments. The aim of this introduction is to show how ideas from the familiar theory of preference aggregation can be extended to this more general case. We first translate a proof...