Conformity, reciprocity and the sense of justice. How social contract-based preferences and beliefs explain norm compliance: the experimental evidence

Compliance with a social norm is a matter of self-enforceability and endogenous motivation to conform which is relevant not just to social norms but also to a wide array of institutions. Here we consider endogenous mechanisms that become effective once the game description has been enriched with pre-play communication allowing impartial agreements on a norm (even if they remain not binding in any sense). Behavioral models understand conformity as the maximization of some “enlarged” utility function properly defined to make room for the individual’s “desire” to comply with a norm reciprocally adhered to by other participants—whose conformity in turn depends on the expectation that the norm will be in fact reciprocally adhered to. In particular this paper presents an experimental study on the “conformity-with-the-ideal preference theory” (Grimalda and Sacconi in Const Polit Econ 16(3):249–276, 2005 ), based on a simple experimental three person game called the “exclusion game”. If the players participate in a “constitutional stage” (under a veil of ignorance) in which they decide the rule of division unanimously, the experimental data show a dramatic change in the participants’ behavior pattern. Most of them conform to the fair rule of division to which they have agreed in a pre-play communication stage, whereas in the absence of this agreement they behave more egoistically. The paper also argues that this behavior is largely consistent with what Rawls (A theory of justice, Oxford University Press, Oxford, 1971) called the “sense of justice”, a theory of norm compliance unfortunately overlooked by economists and which should be reconsidered after the behaviorist turn in economics.