Uniform Random Dictatorship: A characterization without strategy-proofness

Although they exclude any possibility of a compromise ex-post, uniform random dictatorship methods provide a solution to conflicts of interest that guarantees an ex-ante fairness. Axiomatic characterizations of random dictatorships in the classical literature of social choice theory use strategy-proofness. In a probabilistic framework that embeds tops-onlyness and anonymity, for three or more alternatives, we provide a characterization that uses an independence condition instead: uniform random dictatorship is the only social choice rule that is efficient and independent. This characterization also establishes that under efficiency and anonymity, independence and strategy-proofness are equivalent. In the particular case of two alternatives, independence becomes vacuous and we propose a characterization without independence.