A social psychologist explains:
Identity politics, especially what is going on within the academic left, is strange because it is at odds with much of what we know about intergroup relations. Decades ago, psychological scientists established that dividing people into groups and highlighting group differences leads to in-group bias. It also leads to hostility if the groups perceive themselves as fighting over scarce resources. It is human nature to defend one’s in-group and to be suspicious of and hesitant to trust out-groups. Identity politics makes relations between groups worse because it constantly reminds people of their group identity and what distinguishes them from members of other groups. Experimental research also shows that making people feel like victims, which is common in identity politics and on college campuses, increases feelings of entitlement and reduces prosocial behavior.
Feelings of victimhood are also contagious. This is called competitive victimhood. Research shows that when one group is accused of victimizing another group, it causes members of the supposed victimizing group to perceive their own group as victims. Therefore, a lot of identity politics activism is causing harm to intergroup relations. The key to helping members of disadvantaged groups and improving intergroup relations more generally is to focus on what unites people, not what divides them.