Irrational Random Utility Models

We show that the set of aggregate choices of a population of rational decision-makers - random utility models (RUMs) - can be represented by a population of irrational ones if, and only if, their preferences are sufficiently uncorrelated. We call this representation: Irrational RUM. We then show that almost all RUMs can be represented by a population in which at least some decision-makers are irrational and that under specific conditions their irrational behavior is unconstrained.