I first encountered my friend Dr. Gary Slutkin’s work nearly two decades ago, and it changed the way I see the world. Not in the incremental way that most good ideas adjust your thinking—a new variable here, a refined model there—but in the way that a truly Copernican-scale idea does: by rotating the entire frame, so that what had seemed fixed suddenly moves, and what had seemed chaotic suddenly coheres.
The idea is this: violence is not a moral failing, a political problem, or an inescapable feature of human nature. It is a contagious disease. Not metaphorically — epidemiologically. Like its viral and bacterially-based cousins, violence spreads by exposure, progresses through susceptibility, and transmits from person to person following the same mathematical logic as cholera, tuberculosis, or COVID-19. Exposure to violence predicts future violence the way exposure to a pathogen predicts infection. The intergenerational transmission of abuse, the copycat logic of mass shootings, the way war abroad comes home as domestic violence—these are not coincidences or metaphors. They are the characteristic signatures of a contagion.
In his extraordinary new book, The End of Violence: Eliminating the World’s Most Dangerous Epidemic, Slutkin—an infectious disease physician and epidemiologist who spent years fighting TB, cholera, and AIDS for the World Health Organization—marshals decades of evidence for this reframing. He draws on over a hundred studies showing that violence follows the same epidemiological rules as other communicable diseases. And he demonstrates that the same epidemic-control playbook that has rid the planet of smallpox and turned the corner on AIDS can be, and indeed is being, applied to violence in all its forms—from gang shootings in Chicago to civil wars in the Middle East, from domestic abuse to authoritarianism.
What makes this more than an intellectual exercise is that it works. Through Cure Violence Global, the organization Slutkin founded, communities in over ninety cities and multiple countries have seen reductions in violence of 40 to 70 percent—and in some places, its near-wholesale elimination for years at a stretch. Over twenty five communities in over fifteen cities have gone to zero for up to three years. Over a dozen cities in the U.S. have gone to 50-60 year lows, some to all-time record lows. The most violent city in the world dropped to forty-third. 70-90% drops have been seen in communities in Mexico, Colombia and Honduras. Those are not aspirational projections, but documented results, achieved by treating violence the way we treat any other epidemic: by interrupting transmission, reducing exposure, and changing behavioral norms.
The implications ripple outward in every direction. If violence is a disease and not a destiny, then it is not a permanent feature of who we are. It is something that happens to us, through exposure and susceptibility, and it is something we can stop. That idea—that an end of violence is not a utopian fantasy but a practical public health objective, achievable with tools we already possess—is among the most consequential claims I have encountered in a quarter century of work at the intersection of science, innovation, and social change. It is discomfiting, as many of the best ideas are, precisely because it challenges our fundamental notions of who and what we are.
Gary and I sat together recently to discuss the ideas at the heart of his book and their implications for the world we are living in now. I’ve edited our conversation for clarity and flow.
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ZOLLI: Gary, I’m in my mid-fifties, and I’ve lived my whole life in what feels like a kind of political Holocene—a relatively stable period where it was possible to grow up believing that the moral arc of the universe was long, but that it naturally, eventually bent toward justice. With one civil rights victory after another, it was possible to believe that, after some necessary generational shuffling, we would, inevitably, tackle humanity’s great remaining challenges on our way to building a more tolerant, progressive, stable world.
What we’ve been living through recently seems like a great repudiation of all that. We’re seeing a mass rejection of compassion, an embrace of authoritarianism, a return of zero-sum thinking, and an increase in violence at every level, from schoolyard bullying to the hyperviolence of war. Do you agree, and if so, why do you think it’s arrived?
SLUTKIN: Let me give you the frame through which I think about this. As you know, my lens on violence is one of health. Violence is a disorder—an illness— that causes characteristic signs and symptoms, morbidity, and mortality. So it meets the definition of disease. And this particular disorder has many forms—about a dozen—from bullying to mass shootings, community violence to suicide, authoritarianism to war. They all cause each other. War causes domestic violence. Child abuse causes many of the others. So even though it looks like many different phenomena, it’s actually one disease with many different symptom complexes.
The time period you’ve described—that you’ve been blessed to live in—is one in which this illness has been in remission. Just as cholera wasn’t in Somalia for twenty years and then reappeared.
After World War II, there was an extensive study of what had led to the rupture and global mass violence. A great deal of contemporary social science developed exploring the question: how did this happen? And much of this research focused on leaders—what we’d call index cases or super-spreaders. But what became more interesting was the study of followers: those who obeyed and went along, and how they were manipulated. What made them susceptible — because, as with every infectious disease, you have to consider both exposure and susceptibility.
With COVID, some people get very sick, and some don’t, for a mix of biological and behavioral reasons. With violence, susceptibility stems from grievance and prior humiliation, both of which operate in pain centers of the brain. It’s the carrying of this pain, combined with upbringing, that was found to make so many of the followers susceptible. We need to understand how that susceptibility is manifested now.
ZOLLI: You employ a very expansive definition of violence—one that extends from bullying and psychological dominance, through intimate acts of violence, to systemic tyranny. And I think we often see the trees and not the forest. We don’t see the connectivity between these domains, how violence cascades from one context to another, and from one generation to another.
For example, it strikes me that in many ways we’re not just living in Donald Trump’s world but in Fred Trump’s world—a man who, by all accounts, was incredibly abusive, who wanted to make his child comfortable with the psychology of intimidation and violence. In some ways, we’re living in the long shadow of that relationship.
SLUTKIN: I should clarify—the definition I use for violence is not mine, it’s the World Health Organization’s: the intentional use of threat, force, or power, with outcomes including physical injury, death, psychological harm, and even deprivation.
Within that definition, it turns out these different types of violence are all in the same category. They’re also the same disease because they cause each other. Exposure to war makes you more likely to do violence against your wife. Your wife isn’t the enemy—so how do you explain it? A person abused as a child is more likely to abuse their own child. Logically, a previously abused parent should be the least likely to abuse a child, because they, of all people, know how terrible it is to be abused. So how does any of that make sense other than as violence reproducing more of itself, from person to person, and generation to generation?
ZOLLI: You spoke a few minutes ago about susceptibility – let’s turn to exposure. You’ve said the brain operates on proximity—but not just physical proximity. Relational proximity.
SLUTKIN: Right. The brain part that operates proximity isn’t just about physical proximity, but also relational. If there’s a leader you feel very close to, even though they’re far away—through social media, through television—if you feel close, you’re close as a contact. You’re more likely to pick it up. And those centers of the brain—pain centers, reward centers—they don’t know anything. What I mean is they don’t know right from wrong, good from bad, dangerous from safe. They’re semi-mechanical. So the brain gets hijacked, just like your intestines get hijacked with cholera. When you start to see cruelty and destruction from a country’s leader, it’s automatic. It’s not anything about the person. It’s the way the disease works.
And we know how to manage contagious diseases.
ZOLLI: So, with these forms of susceptibility and transmission in mind, how do we actually interrupt and stem the transmission of violence? What does it mean, practically speaking, to manage violence as a contagious disease?
SLUTKIN: It’s the same basic playbook we use for any epidemic. There are three elements that work together.
The first is public education. You have to help people understand what they’re dealing with. When I was fighting TB in refugee camps in Somalia, patients wouldn’t stay on their medications. I sat down with fifteen village elders and spent four hours explaining how the bug worked — invisible, traveling through the air, multiplying in the next person. When I finished, there was this long silence, and the great sheikh said softly, “Why didn’t anyone ever tell us this?” Within weeks, treatment completion jumped from 50 to 85 percent — nearly the threshold where transmission stops. The sheiks and the elders and the community did that. We just helped them understand the disease.
With violence, it’s the same. When people can now understand that it’s contagious — that exposure changes your brain, that it spreads through proximity — their behavior changes. They can start to reject it.
The second is interruption. You find the people most likely to transmit violence next, and you reach them before they do. That’s what violence interrupters are — community health workers for this epidemic. They come from the same communities, they have credibility and trust, and they’ve often been through it themselves. They detect conflicts that are about to turn lethal and intervene in-person, often in the middle of the night. They cool things down, they help people find off-ramps, and then they follow up — the same way you’d follow up with a TB patient to make sure they’re staying on their meds.
The third is changing norms. After every shooting, we mobilize — marches, vigils, public gatherings — not to blame anyone but to make the statement that this is not normal and not acceptable. When we started in West Garfield Park in Chicago, which we were told was the worst police district in the country, we had a ninety-day stretch with zero shootings within months. By year’s end, shootings were down 67 percent. And that was before we even had interrupters — it was all public education and community responses.
Now, all of this has to be held together by a system — training, coordination, data, paid workers. The places that have built those systems are seeing 40 to 70 percent reductions. Some have gone to zero for years. The system is what holds the gains. This is what every city and every community and every country needs to have.
ZOLLI: I think about all the contemporary technologies of connection we’ve built. I imagine that, in one sense, social media must make dealing with violence harder, because they create tighter connections, in time and space — more psychological closeness regardless of physical distance. But it also occurs to me that if we use these tools effectively, they could helpful in suppressing violence.
SLUTKIN: Exactly. The purpose of understanding the way COVID is transmitted is to reduce your exposure. If it’s in the air, being outside dilutes it. If someone’s coughing, I’m backing off, I’m wearing a mask. If you begin to see violence in this way—operating through eye and brain—you say, I don’t want that exposure. I’m not going to look at that. I’m not going to be around that. Parents know this.
ZOLLI: That reminds me of a small moment from my own life. I was sitting in this very chair a couple of years ago, and my phone buzzed with an “urgent breaking news” alert. I picked it up, and the alert was about Larry Nassar, the doctor who abused young female gymnasts. New, salacious details had been revealed, and the “alert” promised to reveal them.
And my thumb swipe was so routinized — almost autonomic — that I hadn’t even processed the substance before my thumb was hovering over the text. I sort of caught myself mid-gesture, and thought: do I want this in my brain? Do I need this? Will I take action on it? Or is this just intended to shock?
It strikes me that we live in a world where violence is not just transmitted but merchandised—commercialized, monetized – through exactly those kinds of systems. And it puts young people on one side of a device and the world’s best attention engineers on the other. It’s a very unfair fight.
SLUTKIN: This is because of the way the brain is structured from evolution. Violence is salient—your ancestors had to pay attention to it on the savannah. Sexual content is salient. Rapidly changing images grab your attention. TV people and movie people know these things very well. These systems evolved to protect us, like our immune system. But they can go too far – as they do in autoimmune diseases, or hypercoagulation. Violence is a state where what were protective systems goes too far. And that’s why you start to see people doing violence and having a good time. Not just being cruel, but enjoying cruelty. The system has gone awry.
ZOLLI: Let’s talk about what it might take to respond at scale to the spreading epidemic of violence. Again, here the link to infectious diseases is instructive: the fights against TB, HIV, and many other diseases feature well-funded constituencies, advocacy groups, billionaire philanthropists, and departments of public health empowered to go after them. Where, analogously, do things stand with efforts to combat violence?
SLUTKIN: For community violence, it’s well off the runway. There are probably a hundred cities in the U.S. that have offices of violence prevention in the mayor’s office, the health department, or both. The first of these were Baltimore and NYC. This is developing in Latin America—Colombia, Mexico, Honduras—and about five other countries at an earlier stage. It’s the system in communities in Colombia, Mexico, Honduras that have driven violence down 70 to 90 percent. And that has driven communities in the U.S. and Latin America e to zero for up to three years. It’s because they have a system.
When we’re talking about authoritarianism and war, we need to mimic the campaigns that eliminated smallpox and turned the corner on AIDS and polio—global initiatives. The UN has helped stop many conflicts, but it’s been ad hoc. It’s still too much about who to blame and condemn. What’s needed is a system that full time prevents and stops the problem in the earliest stages possible, the assigning of blame does not help.
ZOLLI: If we put a tenth of the ambition into solving violence that we put into the next version of AI chatbots, we’d be living in a very different world.
SLUTKIN: But here’s the thing people don’t realize: people don’t want to do violence.
ZOLLI: Say more about that.
SLUTKIN: I’ve had many personal conversations with gang leaders and others. Without their peer group in the room – they don’t want to do violence. It’s a hundred-and-eighty degrees different from trying to change sexual behavior—people don’t want to wear condoms. Smoking behavior is hard to change. But violent behavior—people do not want it. We had a major cartel leader give a speech saying, “I never thought I’d be able to get out of this. And I never thought my son would have to live a different way. Now I can see that he won’t have to.” They want help getting out. People doing violence are “in a fix”.
These leaders—whether in Russia or Israel or Iran—they’re in a fear space. They want help figuring out how to get out safely. Two-thirds of people in their situation end up in prison, exile, or assassinated. The lucky ones die in office. What they need is physical safety, social safety, and some kind of legal and financial safety. That’s the off-ramp. It can always be figured out with the right messengers, workers, or ambassadors, and the right intensity and continuity of effort.
ZOLLI: You know, the idea that violence is not a human universal—that it’s not a default condition of human beings—would be news to people who live within a hundred meters of my house. It’s revolutionary. Yet you’ve shown that we know more about violence now than we knew about AIDS at a comparable point in that epidemic’s story.
Yet, in contrast to AIDS, what also seems to be in short supply right now is the confidence and optimism that comes from saying, “We can do a big thing”. The money exists, the resources exist, the evidence exists. What we need is to remind people of what we are collectively capable of.
SLUTKIN: It’s kind of obvious, isn’t it? We urgently need to remind people that we can do big things and that we can solve problems. And it doesn’t take a complete consensus. We didn’t have that many funders for the global AIDS program—three or four that were big. It took two or three people who said, “Oh, this makes sense.”
ZOLLI: I wonder about the other tools we can bring to bear as well, beyond money. Right now, literally trillions of dollars are pouring into the development of AI, trained on the corpus of human stories and knowledge… all those books, tweets, papers, and the common wisdom they encode. I wonder a lot about the default understanding of human nature we’re encoding in AI, and what we can expect AI to do based on that image.
On the one hand, I worry that we’re about to encode a category error into these systems — that we’re intrinsically violent. On the other, I wonder about how we might use these tools like AI to nudge humanity past these assumptions that have been our default for so long. What would it mean to foster AI that assumes the malleability of human nature, our ability to respond to new norms, let go of old ones, and build new self-concepts for humanity. That’s a lesson to teach our kids and our algorithms.
SLUTKIN: You know, that’s a really important point, and it connects to something I think about a lot. We’ve had violence in the category of “we can’t do anything about it” for a very long time. Or in the category of “that’s just who we are.” And if that’s what you feed into these systems — that violence is human nature, that it’s inevitable — then that’s what they’ll reflect back to us. And it will reinforce the very thing we need to move past.
But here’s what I’d want any system to know, whether it’s a person or a machine: violence is not a human universal. There are entirely nonviolent societies. There are places that were extraordinarily violent that aren’t anymore. Tibet went from a warrior culture to a model of compassion. Europe went from the most violent continent on earth to a continent of safety and stability for decades. And even in some of the most violent communities we work in have gone to zero. So the data says something very different from the assumption.
And if you could encode that — that this is a contagious process, not an identity; that it responds to intervention; that people don’t actually want to do it and are looking for help getting out — well, that changes everything. That’s not optimism. That’s epidemiology. That’s our future. Violence can be put into the past, as we have put so many other diseases – that we don’t even think about anymore.
Image: Detail from Unitled, Jennifer Ząbek
