You often hear about “ideology” these days.

Even if that word isn’t mentioned, it’s very much what’s being discussed. When President Donald Trump denounces the left, he’s talking about gender ideology or critical race theory or DEI. When the left denounces Trump, they talk about fascism. Wherever you look, ideology is being used to explain or dismiss or justify policies.

Buried in much of this discourse is an unstated assumption that the real ideologues are on the other side. Often, to call someone “ideological” is to imply that they’re fanatical or dogmatic. But is that the best way to think about ideology? Do we really know what we’re talking about when we use the term? And is it possible that we’re all ideological, whether we know it or not?

Leor Zmigrod is a cognitive neuroscientist and the author of The Ideological Brain. Her book makes the case that our political beliefs aren’t just beliefs. They’re also neurological signatures, written into our neurons and reflexes, and over time those signatures change our brains. Zmigrod’s point isn’t that “brain is destiny,” but she is saying that our biology and our beliefs are interconnected in important ways.

I invited Zmigrod onto The Gray Area to talk about the biological roots of belief and whether something as complicated as ideology is reducible to the brain in this way. As always, there’s much more in the full podcast, so listen and follow The Gray Area on Apple Podcasts, Spotify, Pandora, or wherever you find podcasts. New episodes drop every Monday.

This interview has been edited for length and clarity.

What is ideology? How are you defining it?

I think ideology has two components. One is a very fixed doctrine, a set of descriptions about the world that’s very absolutist, that’s very black and white, and that is very resistant to evidence. An ideology will always have a certain kind of causal narrative about the world that describes what the world is like and also how we should act within that world. It gives prescriptions for how we should act, how we should think, how we should interact with other people. But that’s not the end of the story.

To think ideologically is both to have this fixed doctrine and also to have a very fixed identity that influences how you judge everyone. And that fixed identity stems from the fact that every ideology, every doctrine, will have believers and nonbelievers. So when you think ideologically, you’re really embracing those rigid identity categories and deciding to exclusively affiliate with people who believe in your ideology and reject anyone who doesn’t. The........

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