 In another classic challenge to SEU, Ellsberg (1961) asked subjects to consider a setup in which an urn contains 30 red balls and 60 black or yellow balls in unknown relative proportions and report their preferences between various bets on the colour of a ball drawn at random from the urn. The preferences elicited were the ones holding between\(f_1\) and \(g_1\) below, on the one hand, and \(f_2\) and \(g_2\), on the other: