A social choice rule aggregates the preferences of a group of individuals over a set of alternatives into a collective choice. The literature admits several social choice rules whose recommendations are supposed to reflect a compromise among individuals. We observe that all these compromise rules can be better described as procedural compromises, i.e., they impose over individuals a willingness to compromise but they do not ensure an outcome where everyone has effectively compromised. We revisit the concept of a compromise in a collective choice environment with at least three individuals having strict preferences over a finite set of alternatives. Referring to a large class of spread measures, we view the concept of compromise from an equal loss perspective, favoring an outcome where every voter concedes as equally as possible. As such, being a compromise may fail Pareto efficiency, which we ensure by asking voters to concede as equally as possible among the Pareto efficient alternatives. We show that Condorcet consistent rules, scoring rules (except antiplurality) and Brams-Kilgour compromises (except fallback bargaining) all fail to ascertain an outcome which is a compromise. A slight restriction on acceptable spread measures suffices to extend the negative result to antiplurality and fallback bargaining. This failure also prevails for social choice problems with two individuals: all well-known two-person social choice rules of the literature, namely, fallback bargaining, Pareto and veto rules, short listing and veto rank, fail to pick ex-post compromises. We conclude that there is a need to propose and study rules that satisfy this equal loss, or outcome oriented, notion of a compromise.

社会选择规则将一组个人对一组备选方案的偏好聚合成一个集体选择。文献承认了一些社会选择规则，其建议应该反映个人之间的妥协。我们观察到，所有这些妥协规则可以更好地描述为程序妥协，即它们强加给个人妥协的意愿，但它们并不能确保每个人都有效妥协的结果。我们重新审视了集体选择环境中的妥协概念，其中至少三个人对有限的选择集有严格的偏好。参考一大类传播度量，我们从等损失来看妥协的概念观点，赞成每个选民尽可能平等地承认的结果。因此，妥协可能会降低帕累托效率，我们通过要求选民在帕累托有效替代方案中尽可能平等地承认这一点来确保这一点。我们表明，Condorcet 一致规则、评分规则（除了反复数）和 Brams-Kilgour 妥协（除了后备谈判）都无法确定妥协的结果。对可接受的利差措施的轻微限制足以将负面结果扩展到反多元化和后备谈判。这种失败也适用于两个人的社会选择问题：文献中所有著名的两人社会选择规则，即后备谈判、帕累托和否决规则、短名单和否决等级，都没有选择事后妥协。