According to Henri Tajfel’s social identity theory, when we incorporate a group into our identity, we derive our sense of self-worth from being a member of that group. We therefore become heavily invested in seeing “us” positively and “them” negatively. It’s our investment in social identities that underlies group discrimination and racism. The reason I want to see your gender-ethnic-racial-political-national group as inferior is because it validates the preeminence of my own group, thereby giving me a sense of pride and righteous superiority.