Edited by Daisy Yuhas

Disagreement has incapacitated our politics and our collective ability to get things done. But where do these conflicts come from? A split between liberals and conservatives, many might say. But underlying that division is an even more fundamental fissure in the way people view the world.

In politics, researchers usually define “conservativism” as a general tendency to resist change and tolerate social inequality. “Liberalism” means a tendency to embrace change and reject inequality. Political parties evolve with time—Democrats were the conservative party 150 years ago—but the liberal-conservative split is typically recognizable in a country's politics. It's the fault line on which political cooperation most often breaks down.

Psychologists have long suspected that a few fundamental differences in worldviews might underlie the conservative-liberal rift. Forty years of research has shown that, on average, conservatives see the world as a more dangerous place than liberals do. This one belief seemed to help explain many American conservative stances in policy disagreements, such as support of gun ownership, border enforcement, and increased spending on police and the military—all of which, one can argue, are meant to protect people from a threatening world.

But new research by psychologist Nick Kerry and me at the University of Pennsylvania contradicts that long-standing theory. We find instead that the main difference between the left and the right is whether people believe the world is inherently hierarchical. Conservatives, our work shows, tend to believe more strongly than liberals in a hierarchical world, which is essentially the view that the universe is a place where the lines between categories or concepts matter. A clearer understanding of that difference could help society better bridge political divides.

We discovered this by accident. My team was undertaking an ambitious effort to map all the most basic beliefs that people hold about the world we share. We call these tenets “primal world beliefs,” or “primals” for short. Primals reflect what individuals think is typical about the world—for instance, that most things are beautiful or that life is usually full of pain and suffering. We suspect these beliefs hold important implications for people's mental health and well-being.

Our effort began with 10 projects to identify possible primals. As part of our work, we gathered data from more than 80,000 tweets and 385 influential written works, including the Bible and the Bhagavad Gita. From that information and several rounds of statistical analysis using data from more than 2,000 people, we identified 26 primals and found that most beliefs clustered into three categories of assumptions about the world: that it is generally dangerous or safe, dull or enticing, and alive or mechanistic. We have created a free, scientifically validated online survey if you wish to learn how your own primals compare with the average (search for “discover your primals”).

In most of our studies, we also asked people to share their political party preference and to rate how liberal or conservative they consider themselves. In an early study focused on well-being, I noticed a surprising relation between people's beliefs and how they answered these two questions. Belief that the world was dangerous was not as linked to party or ideology as past research—including some of our own—said it should be.

We conducted nine more studies with nearly 5,000 participants, mostly Americans, to make sure we had it right. These studies pointed away from the “dangerous world” belief as the core difference between liberals and conservatives and toward a different primal called hierarchical world belief. That primal, we found, was 20 times more strongly related to political ideology than dangerous world belief.

People who score high in hierarchical world belief see the world as full of differences that matter because they usually reflect something real, inherent and significant. Such individuals often separate things of greater value from things of lesser value. You might imagine that to them the world looks full of big, bold black lines. In the opposite view—held by people with lower scores for this belief—differences tend to be seen as superficial and even silly. For those with this perspective, the world is mostly dotted lines or shades of gray. (To reiterate, primals concern tendencies only. Even people with a strong hierarchical world belief see some lines as arbitrary.) In our work, this primal was high in conservatives and low in liberals.

Most types of hierarchical thinking that have been studied, such as social dominance orientation, concern preferences about how humans should be organized. But hierarchical world belief relates to how people think the world actually is—regardless of what they'd like to see. In addition, this primal applies not only to human groups but to everything, including plants, other animals and inanimate objects. For people high in this belief, the universe is the kind of place where lines matter.

One reason our discovery is exciting is that it hints at ways to work through specific political deadlocks. For example, consider debates around LGBTQ+ topics. Conservatives may feel that the line separating men and women is natural and innate—a big, bold line—whereas liberals may see that distinction as more superficial and culturally based. Welfare payments and policies, too, might be seen through a hierarchical lens, with some assuming that lines between rich and poor often reflect meaningful differences in people's work ethic, talent, morality or value to society.

The line relevant to the abortion debate is perhaps conception. Conservatives believe this line marks the beginning of human life and thus matters a great deal. A nonhierarchical perspective would be that life emerges incrementally across many thresholds.

Immigration debates often involve literal lines, such as the border between the U.S. and Mexico. If nonhierarchical world belief shapes liberal thinking, then no one should be surprised that liberals deprioritize enforcing those boundaries.

Knowing about the left-right split on hierarchical world belief could have practical value. In 1905 English author G. K. Chesterton wrote, “The most practical and important thing about a man is still his view of the universe.” Although I might not go that far, Chesterton has a point. Whether you want to empathize with people on the other side, beat them in elections or convince them of a policy's merits, understanding others' primals can be useful. Again, primal world beliefs are about the world's tendencies—but people also expect some exceptions. That nuance creates an opening for productive debate.

For instance, imagine a liberal trying to convince a conservative to adopt a more inclusive policy on transgender issues. If they assume that conservative beliefs are informed by fear of danger, they might note that transgender people are much more likely to be assaulted than most other people are. But another tactic would be blurring lines—perhaps noting that a small but consistent number of babies are born with atypical genitalia and arbitrarily assigned a sex at birth, which suggests the line between male and female is not always perfectly clear. If hierarchical world belief is more at play than dangerous world belief, assuaging fears may be less effective than describing why a specific line is a bit arbitrary.

To reach a point of cooperation—even amid intense disagreement—people often need to grasp other perspectives. Our work shows that conservatives and liberals disagree more about the meaning of differences than about the prevalence of danger. That insight may seem modest, but it's a big step in the right direction.

Are you a scientist who specializes in neuroscience, cognitive science or psychology? And have you read a recent peer-reviewed paper that you would like to write about for Mind Matters? Please send suggestions to Scientific American’s Mind Matters editor Daisy Yuhas at pitchmindmatters@gmail.com.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.