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. Moreover, rules are often ambiguous and open to interpretation, creating “wiggle room" to bend rules in self-serving ways. It is currently unknown how ambiguity shapes rule compliance and the sway of social influence. Here we present incentivized experiments (total n=3,226 American Prolific workers) showing that ambiguity substantially reduces rule compliance. Observing rule bending or a rule violation reduces compliance, but observing compliance does not increase it. The combined effect of ambiguity and bad examples is as strong as the effect of either factor on its own, indicating that many people comply unless an opportunity arises for self-serving rule violation. Further experiments suggest that these results are due to weakened social norms: ambiguity reduces disapproval of rule bending, and people expect violations to increase after observing non-compliance.