A week and a half before the midterm elections, a man broke into Speaker Nancy Pelosi’s house, screaming “Where’s Nancy?” and attacked her husband with a hammer. David DePape, charged in the attack, had posted a slew of rants that included references to a sprawling conspiracy theory known as QAnon, which claims that Democratic, Satan-worshipping pedophiles are trying to control the world’s politics and media.

Several hours before, Fox News’s Tucker Carlson interviewed right-wing activist Christopher Rufo, who claimed drag queens participating in book readings were trying to “sexualize children.” The people who support these events, he said, want to create “a sexual connection between adult and child, which has of course long been the kind of final taboo of the sexual revolution.”

With the support of former President Donald Trump, the pedophile conspiracy theory has contributed to a widening spiral of threats and violence, including the deadly January 6 Capitol insurrection. A revival of the “groomer” smear against the LGBTQ community (a reference to a pedophile) has ramped up the aggression. Right-wing media personalities and activists have created or amplified conspiracy theories about Pelosi, Hillary Clinton, Bill Gates and others.

Dehumanizing and vilifying a person or group of people can provoke what scholars and law enforcement officials call stochastic terrorism, in which ideologically driven hate speech increases the likelihood that people will violently and unpredictably attack the targets of vicious claims.

At its core, stochastic terrorism exploits one of our strongest and most complicated emotions: disgust.

In my new book Flush, I describe how psychologists have come to view disgust as a kind of behavioral immune system that helps us avoid harm. Whether in response to feces or rats, disgust triggers an aversion to things that can make us physically sick. The emotion has a darker side, however: in excess, it can be weaponized against people.

Propagandists have fomented disgust to dehumanize Jewish people as vermin; Black people as subhuman apes; Indigenous people as “savages”; immigrants as “animals” unworthy of protection; and members of the LGBTQ community as sexual deviants and “predators” who prey upon children.

That horrifying history is now repeating itself, as political extremists create dangerous new strains of contempt and hatred. During the COVID pandemic, there has been a surge of racism and xenophobia, as well as violence against foreigners who are baselessly blamed for importing disease and crime.  

Even when disgust doesn’t incite outright violence, it can still cause harm. Clinical psychologist Steven Taylor, author of The Psychology of Pandemics, told me that the ongoing monkeypox outbreak has further amplified bigotry. The disease’s mode of transmission through close physical contact and its symptoms of pus-filled sores, he says, make it a perfect vehicle for eliciting disgust. Its name and origins in Africa have stoked racist misinformation about how it spreads, and its link to men who have sex with men has fueled stigma and homophobia as well

People who are trying to outlaw gender-affirming care for transgender kids and purge pro-gay books from library shelves have stirred up disgust by invoking the specter of sexual “grooming”; others have made the same accusations against those speaking out against such legislative efforts, and some have used the idea to fuel disinformation about the cause of scattered pediatric monkeypox cases. The manufactured grooming mythology has spurred another round of moral disgust and outrage.

In response to Rufo’s diatribe, Carlson—who has an average of over three million viewers—explicitly linked drag queens to pedophiles: “Why would any parent allow their child to be sexualized by an adult man with a fetish for kids?” Rufo then suggested that parents should push back and “arm themselves with the literature” supposedly laying out the child sexualization agenda. Carlson replied, “Yeah, people should definitely arm themselves.”

Some people have. Researchers have estimated that transgender people are more than fourfold more likely to be the victims of violent crime than their cisgender counterparts, and while not a direct link to violence, other scientists have linked disgust sensitivity and authoritarianism to a higher opposition to transgender rights. Over the past few months, assailants repeating the groomer slur have threatened to kill drag queens and LGBTQ people, as well as educators, school officials, librarians, parents and lawmakers who have come to their defense.

In the lead-up to the midterm elections, a blitz of far-right radio ads targeting Black and Hispanic stations in swing states has repeated falsehoods about transgender people and a QAnon warning that the Biden administration will make it easier for children “to remove breasts and genitals”—an attempt to evoke disgust. Other ads aimed at white audiences claim minorities are the true aggressors and destroyers of social norms. One decries “anti-white bigotry.” Another warns ominously, “Stop the woke war on our children.”

The cynical appeal to protecting children by attacking minorities has exposed a bitter irony: disgust is an emotion that evolved to keep us out of danger, but people have long misused it to inflict cruelty and catastrophic harm.

No single intervention is likely to reduce the boil of this toxic stew. But a better understanding of how disgust works and how we can be manipulated by our sense of revulsion may help us turn down the heat. Just as we can overcome our fears, Taylor said, we can break free of disgust. Desensitization and habituation can lessen its potency. Other research suggests that interventions based on compassion, empathy and trust-building can help weaken its contribution to prejudice. Awareness and education can uncover unconscious biases and expose the tactics of those who weaponize it, like those inciting the current wave of ugly antisemitism.

A day after the attack on Paul Pelosi, Hillary Clinton reacted to the suspect’s apparent far-right influences by tweeting, “The Republican Party and its mouthpieces now regularly spread hate and deranged conspiracy theories. It is shocking, but not surprising, that violence is the result. As citizens, we must hold them accountable for their words and the actions that follow.” In response, new Twitter owner Elon Musk tweeted a hateful conspiracy theory by a notoriously misleading news site that blamed Pelosi’s attack on the LGBTQ community; Musk later deleted the tweet, but then joked about it.

What can stop stochastic terrorism and break the cycle of disgust-fueled vilification, threats and violence? Turning off the source of fuel is a start. Programs to counter violent extremism, particularly those that emphasize early intervention and deradicalization, have yielded some successes in at-risk communities. Other programs disrupt the ideological ecosystem that creates radical conspiracies through counseling, education and other community interventions. Beyond understanding how our emotions can be exploited to demonize others, we can refuse to buy into “both-sides” false equivalence and the normalization of dangerous rhetoric and extremism. We can do better at enforcing laws against hate speech and incitement to violence. And ultimately, we can disengage with media platforms that make money by keeping us disgusted, fearful and forgetful of our own decency—and shared humanity.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.

A version of this article with the title “Weaponization of Disgust” was adapted for inclusion in the May 2023 issue of Scientific American.