Batman has the Joker. Superman has Lex Luthor. Pre-1990s America had the Soviet Union.

Whether we like it or not, our own identity as "us" depends on having an "other." Every time we define an in-group of "our people," we unavoidably define an out-group of "their people." We define ourselves not only by what we are, but also by what we are not.

And it's not just humans who do it. Lower primates such as apes, and other animals all the way down to insects divide into groups. They support members of their own group and fight or oppose members of other groups.

America in 2024 is in some ways an example of what happens when a group loses its "other." Until the fall of the Soviet Union in 1991, Americans had a big, scary "other" that threatened the existence of our national group. At best, it united us; at worst, it dampened our internal quarrels.

But when the external threat disappeared, our unity started to disintegrate and we turned on each other. Urban Americans started to view "fly-over country" as a hellscape of unwashed, illiterate hicks; Americans outside the big cities started to view their urban cousins as a group of undeserving elitists who enriched themselves by offshoring American jobs.

In other words, if we don't have in-groups and out-groups, we'll create them. And we'll tend to view out-group members with suspicion and hostility.

We can't change the reality of in-groups and out-groups. But if we're aware of what's driving their existence, we can at least reduce the harm they cause to us and our country.