Recent research published in quarterly public opinion suggest that highly publicized and morally framed acts of violence can influence public attitudes toward political aggression. This study provides evidence that the arrest of Luigi Mangione following the assassination of UnitedHealthcare CEO led to increased support for partisan violence within the Democratic Party.
The study was carried out by Chiara Varziu, assistant professor of political communication at Vrije Universiteit Amsterdam, and Alessandro Nye, associate professor of political communication and journalism at the University of Amsterdam. Vargiu and Nai are also co-authors of the 2026 book The psychology of aggressive politics: Perceptions, evaluations, and implications.. Their research regularly examines political hostility and how it changes public opinion.
“In our research, my co-authors and I investigated various forms of aggressive political rhetoric, focusing specifically on when and why citizens come to consider it acceptable,” Vargiu said. “But over the past few years, we have witnessed numerous episodes of not just aggressive rhetoric, but actual political violence.”
“In polarized settings like the United States, political opponents are increasingly seen as enemies or threats (due in part to the same aggressive rhetoric we have been studying), which raises questions about how people respond to such violence,” Vargiu explained. The U.S. political landscape is increasingly polarized, with occasional acts of politically motivated aggression. In this environment, scholars want to understand what motivates ordinary citizens to justify violence against political opponents.
“There is a long-standing theory in social psychology that suggests that intragroup violence provokes hostile reactions against the group seen as responsible, sometimes encouraging aggression in return,” Vargiu said. “However, the actual research on this is a bit mixed, with recent studies finding no evidence of such retaliatory responses in the context of partisan violence.”
Previous research on attacks on politicians has shown that such incidents do not usually increase public appetite for violence among the victims’ supporters. Supporters of affected politicians tend to refrain from supporting aggressive tactics. The assassination of UnitedHealthcare CEO Brian Thompson in December 2024 presented an entirely different scenario. The gunman, Luigi Mangione, targeted business executives rather than politicians or elected officials.
The health insurance industry is highly unpopular among many Americans, who consider it a broken and exploitative system. A public narrative quickly emerged online that cast the gunman as a vigilante fighting systemic corruption. The researchers had a unique opportunity to test how this particular narrative affected partisan hostility. “When the assassination of the CEO of UnitedHealthcare occurred, we happened to be on the scene conducting an investigation, so we were able to investigate this question firsthand,” Varguiu said.
To explore this dynamic, scientists used data from a two-wave survey of American adults. The first wave occurred from September 4 to November 5, 2024, and 3,100 people responded. The second wave lasted from November 6 to December 17, 2024, with 2,479 participants retained. The researchers worked with the polling company YouGov to recruit a sample that reflected the country’s demographics based on factors such as age, gender, and education.
The study utilized a rolling cross-sectional design. This means that a small random subset of participants was invited to take part in the survey every other day over a period of time. This method is very useful for studying unexpected events. This avoids the problem of people choosing to respond to a survey just because important news has been reported. This allows researchers to compare the attitudes of people who responded to a survey immediately before a particular event with those who responded immediately after the event.
The assassination occurred on December 4, during the second wave of data collection. A few days later, on December 9, authorities arrested Mangione and publicly identified him. The researchers used these two dates as concrete boundaries to measure changes in public opinion.
During the study, participants read fictitious newspaper articles to measure their tolerance for political violence. The text described a man violently attacking a political opponent with a baseball bat after an ideological argument. Respondents then answered five questions on a scale of 0 to 100 to indicate their level of support for the hypothetical attacker. They assessed whether they could support the act, whether the violence was justified, and whether they believed the attacker was likely provoked.
Participants also evaluated whether such things always happen in the United States and whether the perpetrators should face criminal charges. Scientists combined these responses to create an overall measure of support for partisan violence. Looking at the group of respondents as a whole, there was no significant change in overall support for political violence. However, when we split the data by political party, a different pattern emerged.
“Firstly, violence itself did not immediately lead to increased support for violence,” Virgiu told Cypost. “In fact, in the immediate aftermath of the killing, Democrats decreased their support for partisan violence slightly, not more.”
“This change only happened after Luigi Mangione was arrested and identified, and the public began to reconstruct him as a ‘folk hero,’” Valgiu pointed out. “This suggests that what mattered most was not the act of violence itself, but the story that followed.”
Reactions to the murder of a corporate executive extended into the political realm. “Second, and perhaps more disturbing, is that even though this killing was not explicitly connected to partisan politics (the victim was not a politician, the shooter was not a representative of either political party), people were still filtering it through a partisan lens,” Vargiu explained.
“Democrats became more supportive of violence against Republicans in particular, rather than violence in general. This shows that in a country as polarized as the United States, formally partisan acts of violence can still provoke partisan reactions.”
“Thirdly, the direction of the change itself is clear,” Vargiu said. “One might have expected that Republicans with stronger ties to victims would be more supportive of retaliatory violence[to protect their side]but that hasn’t been the case.”
“Instead, it was Democrats whose views were more aligned with the perpetrators’ claims that became more supportive of violence,” Vargiu explained. “This suggests that public acceptance of political aggression may have more to do with hostility toward the other side than with in-group defense. People support violence not because their own side has been attacked, but because they already feel enough hostility toward the other side that violence against them appears justified.”
To analyze the data over time, the scientists also used interrupted time series analysis. This statistical method examines data collected at multiple time points before and after a specific intervention to detect changes in underlying trends. This analysis confirms that over time, Democrats have become more likely to claim that the hypothetical attackers were provoked, especially after Mangione’s arrest.
To ensure the findings were accurate, the scientists tested additional psychological and personal factors. They investigated whether a general desire for social disorder, feelings of relative deprivation, or a person’s physical health influenced answers. The concept of “Need for Chaos” describes a desire to destroy or overturn established social hierarchies.
People high in the desire for chaos were more likely to justify hypothetical violence and less likely to want criminal prosecution of hypothetical attackers. Participants who reported feeling unwell also expressed support for fictitious violence, likely reflecting negative personal experiences with the health care system. Even after accounting for these variables, partisan differences remained a consistent finding across analyses.
The researchers note that this data needs proper context to avoid misunderstandings. “We want to be clear that our results should not be interpreted as saying that Democrats are more violent or that liberals are more prone to political violence,” Vargiu warned. “That would be a misinterpretation of both our data and the broader research on this topic.”
“In fact, previous research (including some of the research discussed in the paper) suggests that people on the left tend to be less dispositionally aggressive, on average, thanks to traits such as compassion and openness to experience, which are often found in people on the left.”
“What our findings actually show is different, and in some ways more worrying, that a compelling narrative around violence can be powerful enough to change attitudes even among groups that are unlikely to support violence in the first place,” Vargiu said. “The real point is that moral stories about violence can sway public opinion no matter where people start, not that one side is inherently more violent than the other.”
The limitations of this natural experiment must be considered. The study measured stated attitudes toward hypothetical scenarios rather than actual acts of violence in the real world. Expressing sympathy for an attacker in an anonymous survey does not necessarily mean that person will behave aggressively in real life.
The specific details of the Mangione case are also very unique and may not apply to other situations. The perpetrator’s viral allegations, the health insurance industry’s intense unpopularity, and America’s uniquely polarized climate all contributed to the public reaction. Similar acts of violence committed in different cultural contexts do not necessarily produce the same changes in public opinion.
The researchers also noted that they could not directly track which study participants actually saw viral online stories that portrayed the shooter as a hero. They can only observe that the timing of arrests coincides with changes in attitudes. Future research should aim to test the precise psychological mechanisms that are actually at work. Scientists need to investigate how people process moral frames in media and how these stories directly interact with personal grievances.
The study, “Partisan Differences in Support for Political Violence: Results from a Natural Experiment in the United States,” was authored by Chiara Vargiu and Alessandro Nye.
