We consider two-stage collective decision problems where some agents have private information about alternatives and others don’t. In the first stage informed agents (experts) may or may not disclose their private information, thus eventually influencing the preferences of those initially uninformed. In the second stage the resulting preferences of all agents after disclosure are aggregated by a social choice function. We provide general conditions on social choice functions guaranteeing that the collective outcome will be the same that would obtain if all agents shared all the information available in society. Experts should be granted a coalitional veto power: changes in the social outcome that are due to changes in the preferences of other agents after information disclosure should not harm all the experts at the same time. We then specialize our general results. When the set of experts is a priori determined, we characterize those strategy-proof rules defined on single-peaked or separable preference domains that ensure that desired level of information disclosure. We also prove that, when the set of experts is unknown, no voting rule can fully achieve this goal, but majority voting provides a unique second best solution when preference profiles are single-peaked.

我们考虑两阶段集体决策问题，其中一些代理拥有有关替代方案的私人信息，而另一些则没有。在第一阶段，知情代理人（专家）可能会也可能不会透露他们的私人信息，从而最终影响那些最初不知情的人的偏好。在第二阶段，披露后所有代理人的最终偏好由社会选择函数聚合。我们提供了关于社会选择函数的一般条件，保证集体结果将与如果所有代理共享社会中所有可用信息时获得的结果相同。专家应被授予联合否决权：信息公开后其他代理人的偏好变化引起的社会结果的变化不应同时损害所有专家。然后我们专门研究我们的一般结果。当专家组是先验确定的时，我们描述了在单峰或可分离偏好域上定义的那些策略证明规则，以确保所需的信息披露水平。我们还证明，当专家组未知时，没有投票规则可以完全实现这一目标，但当偏好配置文件为单峰时，多数投票提供了一个独特的次优解决方案。