Four things extremists on both sides have in common
By: Steve Stewart-Williams
Published: Apr 9, 2025
It’s a truth rarely acknowledged that the political spectrum doesn’t always resemble a straight line. Sometimes it curls back in on itself like a horseshoe, with the hard left and hard right ending up closer to each other than to the moderates in their midst.
This idea has always had a whiff of pub logic about it. It turns out, however, that psychological science backs it up.
A recent paper by Jan-Willem van Prooijen and André Krouwel explores the psychology of political extremists on both ends of the spectrum. It identifies four key traits that both tend to have in common, and which distinguish them from moderates:
Psychological distress
Cognitive simplicity
Overconfidence
Intolerance
So while the radical left and radical right might disagree on just about everything - immigration, inequality, pineapple on pizza - they still resemble each other in some deep and rather unflattering ways.
Let’s take a tour.
1. Psychological Distress
First up: psychological distress - a gnawing sense of meaninglessness born of anxious uncertainty.
The idea here is that when people feel lost, small, or insignificant, they often go searching for something that will make them feel found, big, and important. Enter ideology - and the more extreme, the better. Extremist ideologies turn a complicated, chaotic world into a battle between good and evil, right and wrong, us and them.
Recent research supports this proposal: People experiencing psychological distress are more likely to gravitate toward radical ideologies, whether on the left or on the right. This clashes with traditional thinking in social psychology, according to which distress, uncertainty, and threat tend only to push people rightward. Apparently, any port will do in a psychological storm, as long as it offers a sense of purpose and clarity.
2. Cognitive Simplicity
Next, we have cognitive simplicity: the tendency to view the world in stark black-and-white terms.
Life is complex. Immigration policy is complex. Climate change is complex. Even choosing what to watch on Netflix is complex if you think too hard about it. If you’re feeling overwhelmed, nuance starts to feel less like insight and more like a burden. That’s where extremist ideologies come in. They offer a comforting alternative: simple answers to the complex questions of life.
In one study, both far-left and far-right respondents believed that the EU refugee crisis had a simple solution - they just disagreed on what it was. Moderates, in contrast, were more likely to recognize that the issue was, in fact, horrendously complicated.
The quest for cognitive simplicity can also be seen in conspiracy thinking. Whether it’s chemtrails or the Koch brothers, the far-left and far-right are both prone to conspiracy theories. The theories each side holds differ wildly, but the appeal is the same: a straightforward (if sinister) explanation for a messy world.
3. Overconfidence
This one follows logically from the last: If you see the world in simple terms, you're more likely to think that you’re right about it. This opens the door to an unwelcome guest: overconfidence.
Political extremists - whether waving red flags or wearing red caps - tend to think their views are not just correct, but obviously correct. They’re also more prone to “belief superiority”: the conviction that their views aren’t just true, but also morally and intellectually superior to everyone else’s.
Unfortunately for the extremists, belief superiority isn’t a great predictor of actual knowledge. In fact, one study spanning 45 nations and more than 63,000 participants, found that political extremists are less knowledgeable than moderates - particularly the slightly left and slightly right. In short, those who shout the loudest may understand the least.
4. Intolerance
Finally, we come to intolerance - perhaps the most obvious and most worrying of all four traits.
Extremists on both sides tend to view people with opposing views not just as wrong, but as morally deficient. And when you believe you’re defending the one true path to salvation - whether that’s socialism or nationalism - it becomes easier to justify shutting out, shouting down, or even punishing those who disagree.
Traditionally, intolerance was seen as a uniquely right-wing pathology. And true enough, conservatives are more likely to be biased against certain groups. But leftists aren’t immune to bias. They have their own collection of prejudices, often aimed at groups they associate with right-wing thinking - Christians, businesspeople, and the like.
The main takeaway? Political orientation is a fuzzy predictor of intolerance. Political extremism, on the other hand, is a much stronger one.
Final Thoughts: Horseshoe Theory, Revisited
What does it all mean?
It means that although left-wing and right-wing extremists might seem like polar opposites, they’re more like estranged siblings. They’re shaped by similar psychological forces, just channeled in different ideological directions.
None of this is to say that all radicals are bad, or all moderates wise. History is full of moderate cowards and radical heroes. But if you’re ever tempted to paint your political opponents as uniquely irrational, intolerant, or deluded… well, take a look in the horseshoe-shaped mirror first.
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Abstract
In this article, we examine psychological features of extreme political ideologies. In what ways are political left- and right-wing extremists similar to one another and different from moderates? We propose and review four interrelated propositions that explain adherence to extreme political ideologies from a psychological perspective. We argue that (a) psychological distress stimulates adopting an extreme ideological outlook; (b) extreme ideologies are characterized by a relatively simplistic, black-and-white perception of the social world; (c) because of such mental simplicity, political extremists are overconfident in their judgments; and (d) political extremists are less tolerant of different groups and opinions than political moderates. In closing, we discuss how these psychological features of political extremists increase the likelihood of conflict among groups in society.
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Discussion
The four psychological features discussed here suggest that political extremism is fueled by feelings of distress and is reflected in cognitive simplicity, overconfidence, and intolerance. These insights are important to understanding how political polarization increases political instability and the likelihood of conflict between groups in society. Excessive confidence in the moral superiority of one’s own ideological beliefs impedes meaningful interaction and cooperation with different ideological groups and structures political decision making as a zero-sum game with winners and losers. Strong moral convictions consistently decrease people’s ability to compromise and even increase a willingness to use violence to reach ideological goals (Skitka, 2010). These processes are exacerbated by people’s tendency to selectively expose themselves to people and ideas that validate their own convictions. For instance, both information and misinformation selectively spread in online echo chambers of like-minded people (Del Vicario et al., 2016).
This article extends current insights in at least three ways. First, the features proposed here help to explain why throughout the past century not only extreme-right but also extreme-left movements (e.g., socialism, communism) have thrived in times of crisis (Midlarsky, 2011). Second, understanding the mind-set of extremists in all corners of the political spectrum is important in times of polarization and populist rhetoric. The current propositions provide insights into why traditionally moderate parties in the EU have suffered substantial electoral losses. In particular, the support for well-established parties on the moderate left (e.g., social democrats) and moderate right (e.g., Christian democrats) has dropped in recent years, whereas the support for left- and right-wing populist parties has increased (Krouwel, 2012). Third, the present arguments are based on evidence from multiple countries with different political systems (van Prooijen & Krouwel, 2017), which suggests that they apply to both two-party systems (e.g., the United States) and multiparty systems (e.g., many European countries).
Of importance, the features presented here can have both negative and positive societal implications. Many movements that were once considered radical have been responsible for important social change (e.g., human-rights movements). For instance, in the study by Tetlock and colleagues (1994), not only extreme slavery advocates but also extreme abolitionists showed decreased integrative complexity compared with people considered moderate at the time; however, few people nowadays would dispute that the abolitionists were morally right (it indeed requires little cognitive complexity to conclude that slavery is wrong). People can endorse both harmful oversimplifications and simple moral truths with high confidence; moreover, intolerance of hate-driven ideological movements (e.g., White supremacism) can be compatible with moral progress.
To conclude, although there are important psychological differences between people with left-wing and people with right-wing ideologies, there are also substantial similarities between left- and right-wing extremists that differentiate them from political moderates. The features presented here provide a psychological perspective on political extremism and contribute to a more complete understanding of how political ideology predicts human cognition, emotion, and behavior.
