There are more ways for someone to be different from you than to be similar. But psychologically, it works the other way around. We perceive those like us as uniquely distinct and the outgroup as undifferentiated. It’s called the outgroup homogeneity effect.

This effect extends to physical appearance (e.g. faces of other ethnicities looking the same) and mental traits (e.g. people of the other gender all supposedly wanting the same things). Surprisingly, the effect is unrelated to the number of ingroup and outgroup members one knows; it’s not about mere exposure.

I recently wrote about a remarkable case of the outgroup homogeneity effect: Ezra Klein’s strange attempt to make the case that liberaltarian podcaster (and Klein’s co-ethnic) Dave Rubin is a reactionary.

Klein starts by looking at the network graph of podcast appearances which links Rubin to several unsavory reactionaries. But Klein himself is just two podcasts removed from Richard Spencer, so that’s not great. He then defines “reactionaries” narrowly as those who seek “a return to traditional gender and racial norms”. Of course, most of Rubin’s flagship positions (gay marriage, drug legalization, abortion access, prison reform, abolishing the death penalty) have to do with gender and race norms. Specifically: changing them.

I think what happened is that Ezra Klein picked up intuitively on the one important similarity between Rubin and conservative reactionaries: they both strongly dislike him.

People legislate the distinction between pies and tarts and between plums and nectarines, but only geologists care about telling apart inedible rocks. Same with people: it’s important to keep track individually of potential cooperators, reciprocity relationships, etc. But once you model someone as a defector, you don’t need more detail to predict that they’ll defect. The outgroup is good for writing snarky articles about. For this, you don’t have to tell them apart.