When people use the term tribalism, they are usually aiming to capture a toxic dynamic in collective life, such as the one that characterizes much of contemporary American politics. But what happens between groups is often both a symptom and a reinforcer of unhealthy patterns within individual groups as well. Such patterns include the suppression of dissenting voices and a cult mentality in which members seek only to affirm one another’s worldview.

These characteristics describe how people can behave in groups, but they do not always apply. Indeed, in most cases, they do not. If you think about the many groups in your life, such as your workplace or your daughter’s soccer team, how many of them are at war with a sinister outgroup and try to suppress intergroup contact or internal dissent? Neither of us belongs to many, if any, groups that fit this description.

When humans identify with a group, we are motivated to pursue the group’s interests and goals. But while that feeling provides the fuel for collective action, group norms set the direction, determining what forms those actions take. In some experiments, psychology researchers have sought to manipulate whether people believe that their own group tries to treat outsiders fairly. Participants who are led to believe that their group normalizes fairness engage in less in-group favoritism than do people who think that their group has a discriminatory norm.