Inside the Political Brain

How we're built for bias in public life -- and why that makes it so hard to fix our irrational political structures.

[optional image description]The brain defends existing beliefs as if repelling an attack. / Shutterstock

Why is the American political system so irrational? Why is it that, even though a lot less partisanship and a lot more compromise would be good for the country, nobody can seem to get us there?

The good news is that science is starting to figure this out. The bad news is that it seems to be fundamentally rooted in who we are -- creatures who can detect bad and emotional reasoning when others are guilty of doing it, but not so much when we're doing it ourselves.

Of late, researchers in political science and psychology have been talking a great deal about an idea called "motivated reasoning" -- thought and argument that seems rational and dispassionate, but really isn't anything of the sort. Motivated reasoning is becoming a buzzword, but few have sketched out why it is such a powerful idea: Because it fits so nicely with everything we now know about evolution and the human brain.

Evolution built the human brain -- but not all at once. The brain has been described as a "confederation of systems" with different evolutionary ages and purposes. As a result of this tinkering on a geologic timescale, we find ourselves with an evolutionarily older brain lying beneath and enveloped by a newer brain, both bound together and acting in coordination.

The older parts -- the subcortex, the limbic regions -- tend to be involved in emotional or automatic responses. These are stark and binary reactions -- not discerning or discriminating. And they occur extremely rapidly, much more so than our conscious thoughts. The newer parts of the brain, such as the prefrontal cortex, empower abstract reasoning, language, and more conscious and goal-directed behavior. In general, these operations are slower and only able to focus on a few things or ideas at once. Their bandwidth is limited.

Thus, while the newer parts of the brain may be responsible for our species' greatest innovations and insights, it isn't like they always get to run the show. "There are certain important circumstances where natural selection basically didn't trust us to make the right choice," explains Aaron Sell, an evolutionary psychologist at Griffith University in Australia. "We have a highly experimental frontal lobe that plays around with ideas, but there are circumstances, like danger, where we're not allowed to do that." Instead, the rapid-fire emotions take control and run an automatic response program -- e.g., fight or flight.

How does this set the stage for motivated or emotional reasoning?


Mirroring this evolutionary account, psychologists have been talking about the "primacy of affect" -- emotions preceding, and often trumping, our conscious thoughts -- for three decades. Today they broadly break the brain's actions into the operations of "system 1" and "system 2," which are roughly analogous to the emotional and the reasoning brain. System 1, the older system, governs our rapid fire emotions; System 2 refers to our slower moving, thoughtful, and conscious processing of information. Its operations, however, aren't necessarily free of emotion or bias. Quite the contrary: System 1 can drive system 2. Before you're even aware you're reasoning, your emotions may have set you on a course of thinking that's highly skewed, especially on topics you care a great deal about. (Freud called this the subconscious.)

How do system 1's biases infiltrate system 2? The mechanism is thought to be memory retrieval -- in other words, the thoughts, images, and arguments called into one's conscious mind following a rapid emotional reaction. Memory, as embodied in the brain, is conceived of as a network, made up of nodes and linkages between them -- and what occurs after an emotional reaction is called spreading activation. As you begin to call a subject to mind (like Sarah Palin) from your long-term memory, nodes associated with that subject ("woman," "Republican," "Bristol," "death panels," "Paul Revere") are activated in a fanlike pattern -- like a fire that races across a landscape but only burns a small fraction of the trees. And subconscious and automatic emotion starts the burn. It therefore determines what the conscious mind has available to work with -- to argue with.

And then when we proceed to argue, and we use emotions to reinforce our beliefs -- making us even more ready to argue to defend our beliefs the next time around. Our reasoning skills are not objective, but driven by motivations and recollections we can barely discern consciously.

Since it is fundamentally rooted in our brains, it should come as no surprise that this kind motivated reasoning emerges when we're quite young. As children develop into adolescents, motivated reasoning also develops. In fact, one of the experiments showing this is memorable enough that it is worth describing in some detail.

Psychologist Paul Klaczynski of the University of Northern Colorado wanted to learn how well adolescents are capable of reasoning on topics they care deeply about. So he decided to see how they evaluated arguments about whether a kind of music they liked (either heavy metal or country) led people to engage in harmful or antisocial behavior (drug abuse, suicide, etc.). You might call it the Tipper Gore versus Frank Zappa experiment, recalling the 1980s debate over whether rock lyrics were corrupting kids and whether some albums needed to have parental labels on them.

Presented by

Chris Mooney is a science and political journalist, podcaster, and the host of Climate Desk Live. He is the author of four books, including the New York Times bestselling The Republican War on Science

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