Rationality and Social Choice

Are there “consistent” procedures for aggregating individuals’ preferences into collective judgments? This question was first posed formally more than thirty years ago by the economist Kenneth J. Arrow, now of Stanford University. After listing intuitively appealing properties that any preference aggregation procedure should satisfy, Arrow proved that these properties were incompatible: no procedure satisfying all of Arrow’s axioms can be found, not for lack of ingenuity, but because none exists. Consistency is impossible.1