Some new impossibility theorems

Mas-Colell and Sonnenschein [1972] have proved a well-known impossibility theorem for acyclic social preference. They showed that if social preference is acyclic for each configuration of individual preferences, and if the mapping between individual and social preferences satisfies the Pareto axiom, the independence of irrelevant alternatives, and May's positive responsiveness axiom, then there must be an individual i such that for any x and y, xP_iy ⇒ xRy. This individual might be considered a "vetoer."