Situational ambiguity induces opportunistic rule breaking and erodes social norms

Rules are central to social order, but violations can rapidly spread when compliance is costly to individuals. Here we study rule-following under situational ambiguity, where the applicability of rules is open to interpretation. It is currently unclear how such ambiguity shapes rule compliance and the sway of social influence. We present incentivized experiments (total n = 3226 American Prolific workers) showing that situational ambiguity substantially reduces rule compliance. Observing rule bending or a rule violation reduces compliance, whereas observing compliance does not increase it. The combined effect of situational ambiguity and observing a rule violation is as strong as the effect of either factor on its own, suggesting that many people comply unless an opportunity arises for rule violations that increase their monetary payoffs. Further experiments suggest that these results are partly driven by weakened social norms: situational ambiguity reduces disapproval of rule bending, and observing non-compliance increases expectations that others will violate the rule.