No one has launched a nuclear weapon in war since 1945, when U.S. president Harry S. Truman bombed Japan. Support for that decision—the only use of atomic arms in a conflict—has decreased over time. But new research investigating the attitudes of Americans suggests that, in the right scenario, plenty of people would support another atomic assault.
Most U.S. residents have no sway over such a cataclysmic decision. But the psychological factors that tweak our brains are the same ones at play in the minds of presidents and the people who are in charge of those megadeath decisions.
By gaining insight into the minds of the population, these studies illuminate the factors that might affect a leader’s choice to conduct a nuclear strike—and ways to make that choice less likely.
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Decision-Making Science
The lineage of the new work traces back to a study, published in 2017, by Scott Sagan of Stanford University and Benjamin Valentino of Dartmouth College. The researchers presented study participants with hypothetical scenarios: Would they use a nuclear weapon in a war against Iran to save 20,000 American troops, even if doing so killed either 100,000 or two million Iranians?
With smaller casualties, around 56 percent of people would approve an air strike; with larger casualties, around 48 percent would. In both casualty cases, around 59 percent of people would support a president’s decision to strike. When split demographically, Republicans, people older than age 60 and those in favor of the death penalty for murder were significantly more likely to give nuclear launch a go.
Disturbed by the results, scientist Paul Slovic of the firm Decision Research and his colleagues decided to replicate and extend that paper. In an initial study published in the Proceedings of the National Academy of Sciences USA in 2020, they posed the same experimental setup: To save 20,000 American troops, would participants support bombing either 100,000 or two million civilians? But in the answers to that question, they wanted to dig more into the demographics and domestic beliefs of the respondents.
They interpreted the fact that death-penalty proponents were more likely to support nuclear war as potential evidence of a personality trait: punitiveness, or a desire to penalize those who threatened them in some way. In other words, punitiveness equates to “punishing people who you felt deserved it,” Slovic explains.
Slovic and his co-authors wanted to investigate how approval for other punitive domestic policies lined up with nuclear support. Ultimately, they clocked people’s views on abortion, guns, immigration and the death penalty.
They found a linear correlation: the more someone supported policies to restrict abortion, oppose gun control, deport immigrants and employ the death penalty, the more likely they were to support a nuclear strike.
Now, in research by Slovic, Daniel Post—a permanent military professor fellow at the U.S. Naval War College, and a former nuclear strike adviser at the U.S. Strategic Command—, and three other collaborators, the researchers have increased both the number of survey participants and the variables; the study is currently being reviewed at an academic journal. For instance, they altered the number of American troops who would be saved by a nuclear strike to see how low that human quantity could go and still merit nuclear war in the minds of the respondents. Very low numbers of American casualties, it turned out, felt like an existential threat worthy of existential response. “We found that fairly low numbers would still receive fairly high numbers of support for the nuclear option,” Post says.
When the team took American troop numbers out entirely—stating only that a war had been going on for a while and that it had both public opposition and political tensions—some people still supported using a nuclear weapon to end the conflict. Still, as the number of Ajmerican troops spared by a nuclear launch went up, so did support for it.
Approval of punitive domestic policies still correlated linearly with nuclear-strike support. And in every condition, Republicans were again more likely to go nuclear.
That’s relevant to our world because a president’s political party may indicate how likely their authorization of a nuclear attack would be. “I think everybody would agree you want the best decision made possible,” Post says, “not the [one that is] most beneficial to your political party, because that’s not relevant in the nuclear setting. It’s so bad and so big, right? It’s not good for anybody.”
Surprisingly, in a finding that also arose in Sagan and Valentino’s original study, women generally were more likely to approve of nuclear use than men.
In comments taken as part of the survey in Slovic and Post’s new study, women said they felt more protective of the troops—another factor at play beyond desire for violent punishment. “When the troop loss got higher, even low-punishing women went for the nuclear bomb more than low-punishing men,” Slovic says.
But regardless of gender or party or punishing tendency, people’s responses to the new survey changed a lot depending on how the researchers presented the options. In the initial experiment, the choices were to save a given number of American troops by killing either 100,000 or two million Iranians. When the scientists instead gave survey takers three options—don’t strike, use a nuclear weapon to kill 100,000 civilians or use one to kill two million civilians—more people chose the 100,000 option: it looked less bad than the one in the millions.
People who chose not to strike when only given two possibilities often changed their choice, picking the “better bomb” when that was available. “You increase the chances of breaking the nuclear threshold, nuclear use, deterrence failure, etc., just by listing different options,” Post says. “Just by making one look better than another one.”
This result is a well-known phenomenon in psychology called the decoy effect, which is often used in marketing. When you go to the movie theater, a small popcorn may be $4, a medium may cost $7.50, and a large may cost $8. The medium exists mostly to make you think the large is a good deal (it’s not). “In the retail market, the consequences are trivial,” Post says. “It’s which razor people are buying or which TV they bought. But in the nuclear-decision context, the consequences are absolutely not trivial.”
And though presidents occupy a position of authority, they still have the same suggestible human brain as those of us without authority who are buying razors and TVs and popcorn because of subtle manipulation. “There’s a mind involved in this,” Post says.
The No-Go Nuclear Option
Sharon Weiner, a political scientist at American University, has done related mind-reading nuclear research and has collaborated with Slovic on other projects. She is an advocate for taking these particulars of the human brain into account in nuclear decision-making because humans are never more human than when something hard is happening. “You forget all the things you tell yourself you’re going to remember during a crisis,” she says. And a nuclear crisis is, one would imagine, one of the world’s most stressful.
Like Slovic and Post, Weiner has been considering how a president’s nuclear decisions will be influenced by how their advisers present the options. In particular, she wondered whether explicitly telling the president they could choose not to launch might affect the outcome.
The president can always choose the no-go option, but strategic and military advisers might not explicitly point that out. And in the heat of a world-altering moment, the leader might forget, she says. “All the literature about behavioral psychology says they may not think of it,” Weiner says. “And so we thought, Let’s test this. Let’s see: If we give people an option that says, ‘Don’t launch,’ does it change the ratio of people who launch?”
It turns out the answer is yes: in a survey experiment that Weiner presented as part of an event with Slovic and Rose McDermott, who collaborated with Slovic and Post on their new paper, more people choose not to launch when they were directly told that option was available than when they were only given different nuclear death outcomes. “A portion of the people who pick the lowest casualties, they’re the ones who then defect and pick ‘no launch’ when they have that option,” Weiner says. “What this tells me is: If that’s the option they wanted, they didn’t have the presence of mind during the crisis to say, ‘Wait a minute. I’m not taking any of the three things you presented to me. I want a fourth thing.’”
In a real nuclear crisis, Weiner concludes, whatever nuclear options the president’s advisers give at that secret and tense meeting, “there must be an option presented with equal visual and audio support to not launch.”
“There’s no harm in offering that option and requiring that it be there,” she adds.
Together this recent research indicates that what insiders call the “nuclear taboo”—the idea that an international norm exists against using nuclear weapons and that this is why they haven’t blown up in conflict in 80 years—is not as strong as we think. Apparently, many people require little provocation to approve of a hypothetical strike. Given that, just because humans haven’t launched nuclear weapons in 80 years doesn’t mean there’s a magical stigmatic force preventing them from doing so. “If you’re relying on a nuclear taboo to not use nuclear weapons, you need to rethink,” Weiner says.
The decision to break that taboo, the research suggests, is also mercurial—disturbingly like more mundane choices. “One of the takeaways is how unstable the response is and [how it depends on] factors that should not play a role in the decision,” Slovic says. Gender, political party, punitive disposition, the presentation of choices—”All of this bounces people around,” he continues.
And depending on how that bounce lands, it’s something the world might not bounce back from.