Investigating the Functional Distinction Between Harm and Purity Norms

Abstract

Many debates in moral psychology have revolved around the function of harm norms (e.g., against causing pain to others) and purity norms (e.g., against sexual deviance or consuming taboo foods). Two key pieces of this debate are 1) whether purity norms constitute a separate moral domain than harm norms, each with distinct evolved functions, and 2) if so, whether the function of purity norms is to guard people from disgusting behavior that may signal the threat of disease-causing pathogens. Paper 1 addresses the first point by examining how increasing attention to a violator’s mental states (e.g., whether they acted intentionally or accidentally) changes the way people process harm and purity violations. Using behavioral and neuroimaging techniques, it supports a growing literature demonstrating that judgments of purity violations are influenced less by information about the violator’s intent than judgments of harm violations and suggests distinct functions for harm and purity norms. Paper 2 addresses both points by examining how the relational-context of a violation (e.g., whether an action is directed at oneself or another person) impacts judgments of harm and purity violations. Three studies demonstrate that unlike moral judgments of harm violations, moral judgments of purity violations are more tied to the negative impact a violator has on themselves as opposed to others. Moreover, when a participant was the target of another person’s impure actions, their moral judgments of the action were predicted more by perceptions of harm than purity, suggesting that purity norms do not necessarily track concerns about pathogen exposure. Finally, given the evidence in Papers 1 and 2, Paper 3 tests a novel functional distinction between harm and purity norms whereby harm norms regulate the negative impact people have on each other while purity norms function to define group boundaries by setting expectations about how people conduct themselves. Together, these papers challenge current accounts of the evolutionary origins of harm and purity norms and suggest important new avenues for fully characterizing the function of distinct moral norms.