Political polarization in the United States

Based on Wikipedia: Political polarization in the United States

Here's a peculiar finding from psychology research: Give people a math problem about skin cream effectiveness, and their performance depends entirely on how good they are at math. Give those same people an identical math problem—same numbers, same format—but frame it as evidence about gun control, and something strange happens. The better they are at math, the worse they perform. Not because they can't do the calculation, but because they're too clever at finding ways to make the numbers say what they already believe.

This single study captures something essential about American political polarization. It's not primarily a story about people disagreeing on policy. It's a story about how our tribal instincts have colonized our capacity to reason.

Two Kinds of Polarization

Political scientists distinguish between two flavors of polarization, and understanding the difference matters enormously.

The first is ideological polarization—the gap between what liberals and conservatives actually believe about policy. Should the government provide healthcare? How much should we regulate carbon emissions? What restrictions on firearms are appropriate? These are substantive disagreements about how society should organize itself.

The second is affective polarization—a fancy term for a simple, ugly phenomenon: how much we dislike and distrust the other side.

Here's the troubling part. Research suggests that affective polarization is growing faster than ideological polarization. Americans might not be as far apart on policy as they think they are—but they increasingly can't stand each other anyway.

Consider: According to the Pew Research Center, the share of Americans who hold unfavorable opinions of the opposing party has doubled since 1994. Those who hold very unfavorable opinions are at record highs. We're not just disagreeing more. We're hating more.

The Evolutionary Trap

Why would our ability to reason collapse when politics enters the equation? The answer may lie in how human cognition evolved.

For most of human history, survival depended on group membership. Getting kicked out of your tribe wasn't a social inconvenience—it was a death sentence. Our ancestors who developed strong instincts for in-group loyalty and out-group suspicion were the ones who lived long enough to have children.

We inherited their brains.

Psychologists have documented that humans display loyalty toward in-groups and hostility toward out-groups almost automatically, regardless of how those groups are defined. The categories can be completely arbitrary—studies have shown that simply dividing people into groups based on coin flips is enough to trigger tribal behavior.

Political parties, with their flags and slogans and clearly defined enemies, activate these ancient tribal circuits with terrifying efficiency.

Some cognitive scientists argue that human reason didn't evolve to find truth at all. Hugo Mercier and Dan Sperber propose that reason evolved for persuasion and social coordination—to win arguments and maintain alliances, not to discover what's actually correct. On this view, the fact that smart people are better at rationalizing false beliefs isn't a bug. It's exactly what the system was designed to do.

A Brief History of American Division

Political polarization isn't new in America. The current moment has historical precedents, though scholars debate how closely they compare.

The most obvious parallel is slavery. Starting in the early 1830s, the country became progressively more divided over whether enslaving human beings was a necessary evil, a positive good, or an abomination. Neither the Missouri Compromise of 1820 nor the Compromise of 1850 resolved the underlying conflict. The Constitution's three-fifths clause gave slaveholding states disproportionate power in Congress. For years, gag rules prevented the issue from even being discussed on the House floor. That particular polarization ended in civil war.

The Gilded Age—roughly 1870 to 1900—was another peak of division. This era featured open political violence and rhetorical combat that makes today's Twitter fights look genteel by comparison. The election of 1896, which pitted William McKinley against the populist William Jennings Bryan, reshaped the political map in ways that entrenched partisan geographic divisions for decades.

Then came a strange interlude. The 1950s and 1960s, despite their obvious tensions over civil rights, were marked by high levels of bipartisanship in Congress. A post-World War II consensus held, and both major parties contained significant ideological diversity. Conservative Democrats and liberal Republicans were common. Legislation regularly passed with support from both sides.

What happened?

The Sorting

The parties sorted themselves.

In 1994, the average Republican was more conservative than 70 percent of Democrats. By 2014, that figure had jumped to 94 percent. The average Democrat went from being more liberal than 64 percent of Republicans to more liberal than 92 percent. The ideological overlap between the parties essentially vanished.

This sorting extended into private life. As of 2018, 80 percent of married couples shared the same party affiliation. Parent-child agreement hit 75 percent. Both represent significant increases from the 1960s. A 2022 study found substantial increases in political polarization among adolescents, driven largely by parental influence. We're not just sorted by party—we're raising the next generation in partisan bubbles.

Many historians trace the acceleration of polarization to specific events and figures. Newt Gingrich's tenure as House Speaker in the 1990s introduced what scholars call "asymmetric constitutional hardball"—an aggressive, take-no-prisoners approach to partisan combat. Pat Buchanan's speech at the 1992 Republican National Convention explicitly declared a "culture war" for the country's future.

In 1994, Democrats lost control of the House of Representatives for the first time in forty years. The narrative of polarization became central to coverage of the 2000 and 2004 elections. After George W. Bush's narrow reelection victory in 2004, historian Simon Schama observed that America hadn't been so divided since the Civil War.

The Asymmetry Question

Here's where things get contentious.

Research on congressional polarization consistently finds an asymmetry: the rightward shift among Republicans has been substantially larger than any leftward shift among Democrats. This isn't a statement about which party is "right" on policy—it's a measurement of how much each party's voting patterns have moved from their historical positions.

Some scholars, like Morris Fiorina, argue that the American public itself isn't as polarized as elites. On this view, politicians and media figures have polarized far more than ordinary citizens, and elite polarization gets wrongly imputed to voters. Most Americans, Fiorina suggests, hold moderate positions and are poorly served by a political class that has sorted itself into warring camps.

Alan Abramowitz offers a contrary view: mass polarization is driving elite polarization through the electoral process. Polarized primary voters select extreme candidates. Those candidates, once in office, behave in polarized ways because that's what their constituents demand.

The truth likely involves bidirectional causation—a feedback loop where elite and mass polarization reinforce each other.

Agreement Hiding in Plain Sight

Despite the acrimony, Americans agree on more than you'd guess from watching cable news.

On healthcare: 79 percent of Americans think insurance should cover pre-existing conditions. Sixty percent believe the government should provide healthcare for citizens. On abortion: 60 percent think it should be broadly legal in the first trimester, though support drops sharply for later procedures. On immigration: 77 percent think legal immigration benefits the country. On guns: 89 percent support increased mental health funding, 83 percent support closing the gun show loophole, 72 percent support red flag laws and permit requirements.

These aren't razor-thin majorities. They're broad consensus positions.

So why do politics feel so polarized? Partly because party leaders and activists hold more extreme positions than their voters. Partly because media coverage focuses on conflict rather than agreement. And partly because of affective polarization—even when we agree on policy, we've learned to despise each other.

The gap between actual agreement and perceived disagreement may be one of the most consequential features of contemporary American politics.

Climate as Case Study

Climate change illustrates how polarization can transform a scientific question into a tribal marker.

In the 1990s, Democrats and Republicans showed similar levels of concern about climate change. Today, only 21 percent of Republicans consider addressing climate change a top policy priority, compared to 78 percent of Democrats. This represents one of the widest partisan gaps on any policy issue.

The science didn't change. The tribal significance of the issue did.

Similar dynamics appear on other environmental questions, gun policy, and military spending. Once an issue becomes coded as belonging to one party's identity, opinions fall into line accordingly. The question stops being "What do I actually think about this?" and becomes "What does someone like me believe?"

The COVID Divide

The coronavirus pandemic provided a natural experiment in polarization.

Research on online conversations during COVID-19 found stark partisan differences. Left-leaning users were more likely to criticize politicians and share disease prevention measures. Right-leaning users were more likely to share content from the White House and, in some cases, spread conspiracy theories about the virus.

Geographic analysis showed that residents of conservative areas were more likely to view COVID-19 as non-threatening and less likely to follow public health guidelines. A disease that could have united the country against a common enemy instead became another front in the culture war.

This pattern—external threats becoming absorbed into existing partisan frameworks rather than transcending them—may be one of the most dangerous features of deep polarization.

The Information Problem

Elites are more polarized than ordinary citizens, but they're also better informed about politics. This creates a paradox: the people who know the most about policy are often the most emotionally invested in their partisan team winning.

In one study, 35 percent of American voters could be classified as "know-nothings" about politics—low-information citizens who hold few strong opinions. These voters are actually less polarized than their better-informed neighbors. They haven't learned which positions their team is supposed to hold.

High-information citizens, by contrast, tend to have strong, consistent opinions that align closely with their party's platform. They've learned the tribal catechism.

This suggests that political polarization isn't simply a matter of ignorance that education could cure. In fact, more information may sometimes increase polarization by teaching people which views they're expected to hold and providing them with ammunition for motivated reasoning.

The Moderate Minority

According to Gallup polling in 2025, the percentage of Americans identifying as politically moderate reached a record low of 34 percent. Among Republicans, 77 percent now call themselves conservative. Among Democrats, 55 percent call themselves liberal.

The center isn't just failing to hold. It's shrinking.

Yet other research, particularly from Stony Brook University political scientists Yanna Krupnikov and John Barry Ryan, suggests that polarization is primarily a phenomenon among the politically obsessed. Americans who don't follow politics closely—who don't watch cable news or argue on social media—are not especially polarized. They're just not paying enough attention to hate the other side properly.

This raises an uncomfortable question: Is political engagement itself making polarization worse?

Compared to What?

A 2020 Brown University study found that the United States was polarizing faster than comparable democracies like Canada, the United Kingdom, Germany, and Australia. This suggests that polarization isn't simply an inevitable feature of modern democracy—something specific to American institutions or culture is amplifying the effect.

Possible culprits include the two-party system, which forces a binary choice; the primary system, which rewards candidates who appeal to their party's most engaged voters; winner-take-all elections, which eliminate incentives for coalition-building; the structure of American media, with its emphasis on conflict and its fragmentation into partisan channels; and the role of money in politics, which amplifies the voices of donors who tend to hold more extreme views.

No single factor explains everything. But the combination has produced a political system that many observers describe as dysfunctional.

Where This Leaves Us

In 2025, The Wall Street Journal described the American political system as experiencing "a total breakdown in trust" between the two parties and among the general public.

Some scholars see this as an existential threat to democratic governance. Democracies require some minimal level of trust to function—trust that the other side will accept election results, trust that political opponents are fellow citizens rather than enemies, trust that institutions will be used for their intended purposes rather than as weapons.

Others argue that we've been here before and survived. The Civil War era, after all, saw polarization escalate to actual armed conflict. The Gilded Age featured assassination, open corruption, and political violence. Compared to those eras, angry tweets seem manageable.

The honest answer is that no one knows how this plays out. We are participants in an experiment whose results haven't come in yet.

What the research does suggest is that the problem isn't primarily one of policy disagreement. Americans agree on more than they realize. The problem is tribal—a fundamental shift in how we perceive fellow citizens who happen to vote differently.

That's both discouraging and, in a strange way, hopeful. Policy disagreements can be intractable when they involve genuine conflicts of interest or values. Affective polarization—the emotional hatred—might be more responsive to intervention, precisely because it's partially divorced from substance.

We might not need to change our minds about policy to change how we feel about each other.

Whether we will is another question entirely.