Abstract

Debreu (American Economic Review 50:186–188, 1960) famously criticized Luce (Individual choice behavior, Wiley, New York, 1959) choice model with what became known as the red-bus blue-bus example: if a choice set contains two distinct alternatives C (car) and B (blue bus) then adding a third alternative A (red bus) that is essentially identical to B does not affect the choice probability of C but reduces the choice probability of B by half. Debreu’s critique highlights the existence of substitution effects violating the principle of independence from irrelevant alternatives—the cornerstone of Luce (Individual choice behavior, Wiley, New York, 1959) choice model. This paper weakens this principle to construct a model of probabilistic choice satisfying Debreu’s critique.