Promises, Expectations & Causation

Promises often foster trust and cooperation. A recent literature explores why. Two explanations have been proposed, and experimental tests provided some support and some controversy: - Charness & Dufwenberg (2006) (C&D) propose an expectation-based explanation (EBE). People are guilt averse (GA): person i feels bad if he hurts j relative to j’s expectations. A promise from i to j, then, changes j’s expectation and i does not renege because he would feel guilty if he did. - Vanberg (2008) proposes a commitment-based explanation (CBE) whereby “people have a preference for promise keeping per se” (p. 1468). EBE thus combines GA with the idea (not implied by GA) that promises shape beliefs. CBE instead posits that promises have a direct causal effect on promise keeping because people have an intrinsic motivation to keep their word. The empirical implications of these two theories are substantially different.