Factionalism is the splintering of a larger group into competing subgroups that prioritize their own interests, identity, or ideology over the whole. It shows up in political parties, religious organizations, workplaces, online communities, and entire nations. While the word often carries a negative charge, the tendency to form factions is deeply wired into human psychology and may trace back millions of years in our evolutionary lineage. What makes factionalism so persistent, and so hard to defuse, is that it feeds on some of the brain’s most basic social machinery.
Evolutionary Roots of Us-Versus-Them
The instinct to split the world into “us” and “them” is not a quirk of modern culture. Researchers have proposed that human tribalism evolved as a response to the threat of group-on-group aggression, particularly among coalitions of males competing for territory and resources. Under this framework, known as the male warrior hypothesis, the tendency to categorize people by group membership and treat insiders favorably while treating outsiders with suspicion was an adaptive strategy for survival.1PubMed Central. Evolution and the psychology of intergroup conflict: the male warrior hypothesis Groups that cooperated internally and competed externally tended to outperform those that did not, and so the psychological hardware for faction-forming got passed along.
This is not uniquely human. A striking 2025 study documented what happened after a community of wild chimpanzees split into two groups. Over the following seven years, members of one group launched two dozen attacks on the other, killing at least seven adult males and seventeen infants. The researchers noted that group identities shifted and escalated into lethal hostility without any of the cultural markers, flags, uniforms, or ideological labels, that people often assume are necessary for organized conflict.2PubMed. Lethal conflict after group fission in wild chimpanzees If our closest living relatives can develop deadly factions purely through social separation, the human version of factionalism sits on a very old biological foundation.
How Fast Factions Form
One of the more unsettling findings in social psychology is just how little it takes to create an in-group and an out-group. In what are called minimal group experiments, researchers assign people to arbitrary teams based on something meaningless, like a preference for one abstract painting over another, and then measure how those people treat members of the other team. Even with these trivial labels, people consistently favor their own group. A study using this design found that participants showed implicit bias and subtly dehumanized the out-group, even when the team assignments cut across a more visually obvious category like race. Participants did not display their usual racial biases; instead, the arbitrary team label hijacked the in-group preference.3PubMed Central. Effects of Minimal Grouping On Implicit Prejudice, Infrahumanization, and Neural Processing Despite Orthogonal Social Categorizations
There are limits, though. A South African study tried to see whether assigning people to mixed-race minimal teams could override racial empathy bias. It could not. While the team labels did generate their own layer of group preference, the deeper racial empathy gap persisted regardless of team assignment.4PLOS ONE. (Not) part of the team: Racial empathy bias in a South African minimal group study The implication is layered: factionalism can spring from almost nothing, but once a deep social division already exists, a superficial new grouping will not erase it. Real-world factions often stack on top of existing identities rather than replacing them.
The Brain’s Empathy Gap
Factionalism does not just shape how you think about others. It changes how your brain responds to their pain. Using EEG recordings, researchers found that when people watched in-group members experiencing sadness, their brain activity mirrored the patterns associated with feeling sad themselves. When they watched out-group members in the same situation, that mirroring largely disappeared. People who scored higher on measures of prejudice showed the weakest empathic brain response to out-group suffering.5PubMed Central. Intergroup differences in the sharing of emotive states: neural evidence of an empathy gap In practical terms, this means factional divides can make it neurologically harder to feel compassion for the other side, not just intellectually harder.
This empathy gap is not the same size everywhere. A cross-cultural neuroimaging study compared Korean and American participants as they observed in-group and out-group members in emotional pain. Korean participants showed a larger gap: stronger empathic brain activation for in-group pain and weaker responses for out-group pain compared to their American counterparts. The difference tracked with cultural attitudes toward social hierarchy. In societies where people have a stronger preference for clear social rankings, the neural machinery for empathy appears to be more selectively tuned toward one’s own group.6PubMed. Cultural influences on neural basis of intergroup empathy Factionalism, in other words, does not just reflect individual psychology; it is amplified or dampened by the cultural environment people grow up in.
How Factionalism Distorts What People Believe
Once someone identifies with a faction, that identity starts filtering what information they accept as true. This goes beyond the common complaint that “people only believe what they want to believe.” Experiments have tested whether partisan bias in accepting misinformation comes from actual differences in knowledge or from something more like identity protection, a motivated desire to defend one’s group. Across two experiments with over 1,400 participants, researchers randomly assigned people to novel identities and then tested whether they were more willing to accept claims that were friendly to their assigned group. They were. People showed lower thresholds for accepting congenial information, even though the group labels were brand new and there were no pre-existing knowledge differences to explain the gap.7PubMed Central. Understanding Partisan Bias in Judgments of Misinformation: Identity Protection Versus Differential Knowledge
This finding has real consequences for how misinformation spreads in factional environments. If the bias were simply about knowledge, you could fix it with better education or fact-checking. But if it is about identity protection, people will resist corrections that threaten their group’s narrative even when they have the cognitive tools to evaluate the evidence. Education helps, but it is not sufficient when the real driver is loyalty.
Factionalism at the Ballot Box
Political factionalism does not just affect what people believe. It changes how they vote. A growing body of evidence points to what researchers call “negative voting,” casting a ballot primarily to oppose the other side rather than to support your own candidate. An analysis of the 2020 U.S. presidential election found that about 59 percent of voters held stronger negative feelings toward the opposing candidate than positive feelings toward their own. For those voters, the probability of casting what amounted to an anti-opponent vote rose sharply. Strong partisan identity and in-group/out-group feelings were among the most important predictors of this behavior.8PubMed Central. The Electoral Consequences of Affective Polarization? Negative Voting in the 2020 US Presidential Election
This dynamic creates a self-reinforcing loop. When politicians realize that voters are motivated more by animosity toward the other side than by enthusiasm for their own platform, campaigns shift toward stoking that animosity. Research on elite polarization finds that as political leaders move further apart ideologically, ordinary partisans report increasingly negative feelings toward both parties, but the opposing party bears the brunt of it.9Electoral Studies. Elite polarization, party extremity, and affective polarization The result is a political ecosystem where faction-driven hostility becomes the dominant currency, crowding out policy debate.
When Factions Feel Threatened
Factionalism intensifies under perceived threat. Studies conducted across four European Union countries examined what happens when national groups feel that their status, resources, or distinctiveness are under attack from an outside group. Both realistic threats (economic competition, physical safety) and symbolic threats (challenges to the group’s values or way of life) predicted a rise in what researchers call collective narcissism: an exaggerated belief in the greatness and entitlement of one’s own group. Collective narcissism, in turn, predicted hostile emotions and aggressive behavioral intentions toward the threatening out-group. Importantly, simply feeling proud of your group, without the grandiose and defensive quality of collective narcissism, did not produce the same hostility.10Group Processes & Intergroup Relations. An intergroup approach to collective narcissism: Intergroup threats and hostility in four European Union countries
The distinction matters because it suggests that healthy group pride and toxic factionalism are not just different points on the same scale. They are qualitatively different psychological states. You can be loyal to your community, party, or nation without developing the brittle, threat-sensitive mindset that leads to factional aggression. But when leaders or media figures frame every disagreement as an existential threat, the collective narcissism switch flips more easily.
Economic Inequality and Zero-Sum Thinking
Material conditions shape how factional people become. When people perceive high economic inequality, they are more likely to adopt zero-sum beliefs: the conviction that one group’s gain necessarily comes at another group’s expense. Across five studies testing this in economic, workplace, and academic settings, researchers found that perceived inequality consistently increased zero-sum thinking, and the mechanism was relative deprivation. When people felt they were getting less than their fair share, they became more likely to see the world as a fixed pie where someone else’s slice was stolen from theirs.11Collabra: Psychology. One’s Loss Is Another’s Gain? Perceived Inequality Amplifies Zero-Sum Beliefs Through Relative Deprivation
Zero-sum thinking is jet fuel for factionalism. If you believe that gains for another group automatically mean losses for yours, cooperation becomes irrational and opposition becomes self-defense. This helps explain why economic downturns and rising inequality often coincide with surges in populist factionalism. The grievance is not imaginary: real disparities exist. But the zero-sum framing transforms complex economic problems, where multiple groups could potentially benefit from the same policy, into tribal standoffs where compromise feels like surrender.
The Amplifying Role of Social Media
Online platforms have not invented factionalism, but they have supercharged it. The architecture of social media, algorithmic recommendation, engagement-based ranking, and network clustering, tends to sort people into ideological silos. Research on the fragmentation of online discourse has found that these structural features restrict cross-group dialogue and erode the kind of collective reasoning that functioning democracies depend on.12arXiv. From Public Square to Echo Chamber: The Fragmentation of Online Discourse You end up in a feedback loop: the platform shows you content that your group already agrees with, content that attacks the other group performs especially well, and you rarely encounter the strongest versions of opposing arguments.
What makes social media distinctive is not just that echo chambers exist. Humans have always sought out like-minded company. The difference is speed, scale, and the absence of social friction. In a face-to-face conversation, social norms and body language moderate how aggressively you attack the other side. Online, those constraints weaken. Outrage travels faster than nuance, and the emotional content that drives engagement is often the most factionally charged. The platforms did not create the underlying tribal psychology, but they have built an environment where it activates constantly and at low cost.
The Founders Saw This Coming (Partly)
Factionalism is not a new concern. When James Madison wrote Federalist No. 10 in 1787, he devoted the entire essay to the problem of factions, which he defined as groups of citizens driven by a shared passion or interest that conflicted with the rights of others or the broader public good. Madison’s proposed solution was scale: a large republic with so many competing factions that no single one could dominate. The idea was that pluralism itself would be the check on any one faction’s power.
How well has that prediction held up? A scholarly re-examination of Federalist No. 10 argues that the founders were overly optimistic. They did not anticipate how effectively factions could capture government through rent-seeking behavior or how deeply institutions could entrench minority rule.13Public Administration Review. Federalist No. 10: Are Factions the Problem in Creating Democratic Accountability in the Public Interest? Madison assumed that geographic distance and the difficulty of coordination would prevent factions from organizing effectively at the national level. Social media and modern communication technology have eliminated both of those barriers. The structural check Madison relied on, the sheer difficulty of organizing a faction across a continent, no longer operates in anything like the way he imagined.
Inoculating Against Factional Manipulation
If factionalism is partly driven by manipulative content that exploits tribal instincts, one promising approach is to teach people to recognize the manipulation before they encounter it. This strategy, borrowed from the logic of vaccination, is called psychological inoculation or “prebunking.” Rather than trying to correct misinformation after people have already believed it, inoculation exposes people to weakened examples of manipulative techniques so they can spot them in the wild.
A series of experiments in the United Kingdom and United States tested whether inoculation could reduce engagement with affectively polarized content on social media. Across three experiments with over 3,200 participants, the inoculation intervention reduced self-reported willingness to engage with hyper-partisan content. The effect was specifically targeted: it reduced engagement with content that attacked the opposing group but did not suppress engagement with issue-based content that simply aligned with the person’s existing views.14PubMed Central. Inoculation reduces social media engagement with affectively polarized content in the UK and US In other words, the intervention dampened the tribal hostility without flattening legitimate political engagement.
Separately, researchers developed and tested inoculation videos designed to prebunk specific manipulation tactics, including techniques used to inflame factional polarization. Results showed that the polarization-focused inoculation video improved people’s ability to distinguish between manipulative and non-manipulative content. Other videos targeting different manipulation tactics increased detection of relevant tricks without making people more suspicious of everything they encountered.15Political Psychology. Tune in to the prebunking network! Development and validation of six inoculation videos that prebunk manipulation tactics and logical fallacies in misinformation The precision matters: a tool that makes people universally cynical is not much help. What these inoculation approaches appear to do is sharpen the ability to tell when someone is deliberately stoking factional anger, without eroding trust in all political communication.
There is a significant caveat, though. The same research that showed inoculation reducing engagement with polarizing content also noted that it may not be sufficient to reduce the generation of that content.16PubMed Central. Inoculation reduces social media engagement with affectively polarized content in the UK and US Inoculation works on the demand side, making audiences less susceptible. But as long as producing factionally inflammatory content remains profitable, whether measured in ad revenue, political donations, or social-media engagement metrics, the supply will keep coming. Reducing factionalism probably requires working on both sides of that equation simultaneously.
When Factionalism Is Not All Bad
It would be easy to walk away from this evidence thinking factionalism is purely destructive, but that framing misses something. The same in-group loyalty that drives factional conflict also drives cooperation, collective action, and solidarity. Labor movements, civil rights campaigns, and pro-democracy coalitions all rely on strong group identification to mobilize people against entrenched power. The difference between a healthy social movement and a destructive faction is not the presence of group loyalty; it is whether the group defines itself primarily by what it is for or by who it is against.
Some political theorists argue that a degree of factionalism is not just tolerable but necessary in a democracy. Competing factions surface genuine disagreements about values, resources, and priorities that would otherwise be papered over by a false consensus. The goal is not to eliminate factions but to keep them from becoming so hostile that compromise becomes impossible. That distinction, between productive pluralism and corrosive tribalism, is where most societies struggle. The psychological research suggests the line is thinner and easier to cross than people generally assume, especially when leaders, media, and platform algorithms all profit from pushing groups further apart.