Why some people resort to vigilantism—to the admiration of many

The murder of UnitedHealthcare CEO Brian Thompson riveted the nation, leading to public support in some circles for the alleged killer, Luigi Mangione, and intense anger toward the health insurance industry. The tragedy has laid bare questions about the psychological and societal factors that shape our views on vigilantism.

As the Mangione case was breaking, another vigilante—Daniel Penny—was on trial for allegedly killing Jordan Neely, a homeless, mentally ill Black man who was threatening riders on the New York subway. Like Mangione, Penny was praised in some quarters as a hero, while others saw him as a racist zealot.

Why do individuals take the law into their own hands? What drives public support for such actions? How is a lack of trust in institutions linked to vigilantism and other extreme behaviors? The psychology behind vigilantism is complex, involving individual traits, societal influences, and the interplay between emotion and reasoning.

There are both individual and contextual reasons for why people become vigilantes, according to Fan X. Chen, PhD, a senior researcher at the Talbert House Center for Health and Human Services Research.

Vigilantes may be driven by a mix of prosocial and antisocial traits, such as criminal narcissism and sadism, while perceiving themselves as kind, heroic, and morally superior. Chen and colleagues found that people with a sense of victimhood may develop a vigilante identity focused on punishing perceived wrongdoers (Chen, F. X., et al., Personality and Individual Differences, Vol. 197, 2022opens in new window).

At the contextual level, their research shows vigilantes often see their environments as filled with violations of norms and rules, and they lack faith in authorities to address these issues effectively. This perception motivates them to seek out and punish “perpetrators” outside of the formal justice system. “Vigilantes are not purely motivated by sadism,” Chen said. “To their perception, they are doing this for public good or to help other people.”

Supporters of vigilantes share the belief that the justice system fails to punish perceived wrongdoing. Isabel Pinto, PhD, director of the Social Psychology Lab at the University of Porto, conducted research showing that when people perceive formal institutions of social control, such as the justice system, as ineffective, they are more likely to support harsh and informal measures to punish those they see as offenders (Pinto, I., et al., Peace and Conflict: Journal of Peace Psychology, Vol. 30, No. 3, 2024opens in new window).

People are more likely to support vigilantes who are seen as defending core societal values or those who are part of their in-group, according to Pinto’s research. This is because the mismatch between the expected behavior of institutions and their actual behavior is seen as more threatening to one's in-group, and individuals support informal punishment to perceived wrongdoers. The danger is that vigilantism can result from the demonization of groups that are perceived as threats to individuals’ social identity, as is the case with marginalized groups, such as the unhoused or immigrants.

“Demonization is the perception that the ‘other’ has bad intentions against us. So, violence is legitimized as a defense that the in-group needs,” Pinto said. This demonization may increase support for vigilantes who are seen as defending the in-group against perceived threats—whether or not those threats are real.

Media, particularly social media, can amplify or reinforce narratives glorifying vigilantism, allowing people to find justifications that align with their feelings and biases. Misinformation on these platforms impacts moral judgments about vigilantism and other extreme behaviors.

“When people seek out information that confirms their existing beliefs on social media, that is a very dangerous cycle,” said Clifford Workman, PhD, a visiting assistant professor in the Department of Psychological and Brain Sciences at the University of Delaware. Our ability to reason is just as susceptible to misinformation as our emotions and may reinforce biases and extremist views, he said.

Workman’s research shows that people’s social values can influence their endorsement of violence (Workman, C. I., et al., AJOB Neuroscience, Vol. 11, No. 4, 2020opens in new window). Scientists asked study participants about their views on various sociopolitical issues. They then conducted functional MRIs of the subjects’ brains while they judged the appropriateness of violent protests that aligned with or deviated from their views. They found that certain brain areas were more active when people thought violence was appropriate, especially if it aligned with their beliefs. This suggests that strong moral convictions can make people more likely to support violence.

Dehumanizing language is often used to justify violence against certain groups, Workman added. “Talking about people in that way makes it a lot easier to view them as disposable in service of some moral greater good,” he said.

Vigilantism is a complex issue rooted in the erosion of trust in society and institutions. Psychological research has shown contributing factors include pervasive economic disparities, inequities in the criminal justice system, and the perception that some corporations put profit over public welfare.

Researchers who examined how to reduce vigilante violence in India and Pakistan found such violence was often fueled by false rumors and targeted minoritized groups. They found disseminating credible information to correct misinformation, even in polarized settings, can decrease support for vigilante actions and increase the desire to hold vigilantes accountable (Badrinathan, S., et al., American Political Science Review, 2024opens in new window).

Most people see their moral values as fixed. Yet research has found that moral judgments are flexible and shift based on factors such as personal relationships, emotional biases, and the ability to generate “post-hoc rationalizations” for behavior, according to Liane Young, PhD, a professor of psychology and neuroscience at Boston College who studies moral psychology.

If someone knows a person well, they might assume there’s a plausible explanation for their questionable actions, while they would judge a stranger more harshly.

“If you see somebody [you know] taking money out of a tip jar, you might think they’re making change for the meter because you believe this person wouldn’t do something shady or unethical,” said Young. “But if you don’t know who that person is, then you might come to a different conclusion.”

Our brains are wired to interpret evidence in a biased way to maintain a positive view of someone they respect or are close to, ignoring inconsistent information. Similarly, a person’s background or experiences can shape how they view ethical dilemmas. For instance, some might see a violent act as justified if they believe the victim represents something negative, like corporate greed.

Experts in psychology said addressing these societal concerns will require a long-term and comprehensive approach. Immediate steps that have been shown to work include investing in media literacy education from an early age to stimulate critical thinking and questioning of facile arguments that justify vigilantism. Diversifying one’s media diet with nuanced explorations of complicated issues can lessen confirmation of existing biases. Finally, limiting time on social media can reduce exposure to inflammatory rhetoric that rationalizes extreme behavior.