Wilde heuristics and Rum Tum Tuggers: preference indeterminacy and instability

Abstract

Models in decision theory and game theory assume that preferences are determinate: for any pair of possible outcomes, a and b, an agent either prefers a to b, prefers b to a, or is indifferent as between a and b. Preferences are also assumed to be stable: provided the agent is fully informed, trivial situational influences will not shift the order of her preferences. Research by behavioral economists suggests, however, that economic and hedonic preferences are to some degree indeterminate and unstable, which in turn suggests that other sorts of preferences may suffer the same problem. Even fully informed agents do not always determinately prefer a to b, prefer b to a, or feel indifferent as between a and b. Seemingly trivial situational influences rearrange the order of their preferences. One could respond that decision theory and game theory are not meant to describe actual behavior, and that they instead adumbrate an ideal of rationality from which human action diverges in various ways. When the divergences are small and systematic, they help us identify the heuristics that conspire to help people approximate rationality. One such heuristic, dubbed the Wilde heuristic, is explored. However, the divergences documented by behavioral economists threaten to be too large to handle through idealization. The Rum Tum Tugger Model, in which indifference is intransitive, is spelled out as one promising way for decision and game theory to retrench. Preferences may be locally unstable and indeterminate, but when the differences between options are sufficiently large, they approximate stability and determinacy.