We prove a general possibility result for collective decision problems where individual allocations are one-dimensional, preferences are single-peaked (strictly convex), and feasible allocation profiles cover a closed convex set. Special cases include the celebrated median voter theorem (Black...

Approval voting allows voters to support as many candidates as they wish. One advantage of the method is that voters have weak or no incentives to vote insincerely. However, the exact meaning of this statement depends on how the voters' preferences over candidates are extended to sets. We show...

This paper analyzes strategy-proof collective choice rules when individuals have single-crossing preferences on a finite and ordered set of social alternatives. It shows that a social choice rule is anonymous, unanimous, and strategy-proof on a maximal single-crossing domain if and only if it is...

Can mechanism design save democracy? We propose a simple design that offers a chance: individuals pay for as many votes as they wish using a number of "voice credits" quadratic in the votes they buy. Only quadratic cost induces marginal costs linear in votes purchased and thus welfare optimality...

We extend approval voting so as to elect multiple candidates, who may be either individuals or members of a political party, in rough proportion to their approval in the electorate. We analyze two divisor methods of apportionment, first proposed by Jefferson and Webster, that iteratively...

We study the possibilities for agenda manipulation under strategic voting for two prominent sequential voting procedures, the amendment and the successive procedure. We show that a well-known result for tournaments, namely that the successive procedure is (weakly) more manipulable than the...

This paper considers the problem of allocating an amount of a perfectly divisible resource among agents. We are interested in rules eliminating the possibility that an agent can compensate another to misrepresent her preferences, making both agents strictly better off. Such rules are said to be...

This paper discusses the implications of strategic voting for institutional design in environments where the only role of elections is to aggregate information. We adopt a mechanism design perspective, which assumes that prior to a standard voting game, a fictitious designer has to select the...

A committee chooses whether to approve a proposal that some members may consider ethical. Members who vote for the proposal receive expressive utility, and all pay a cost if the proposal is accepted. Committee members have different depths of reasoning. The model predicts that features that...

Sen's classic social choice result supposedly demonstrates a conflict between Pareto and even minimal forms of liberalism. By providing the first direct mathematical proof of this seminal result, we underscore a significantly different interpretation: rather than conflicts among rights, Sen's...