Donald Trump tells lies.

His deceptions and misleading statements are easy to unmask. In one example—among hundreds of well-documented lies—FBI director James Comey told Congress in March that there is “no information that supports” Trump’s claim that President Barack Obama tapped his phone.

But Trump’s political path presents a paradox. Far from slowing his momentum, his deceit seemed only to strengthen his support through the primary and the national election. Now every time a lie is exposed, his support among Republicans does not seem to waver very much. In the wake of the Comey revelations, his average approval rating mainly held at around 40 percent.

This has led many people to ask themselves: How does the former reality-TV star get away with it? How can he tell so many lies and still win support from many Americans?

Journalists and researchers have suggested many answers, from a hyperbiased, segmented media to simple ignorance on the part of GOP voters. But there is another explanation that no one seems to have entertained. It is that Trump is telling “blue lies”—a psychologist’s term for falsehoods, told on behalf of a group, that can actually strengthen bonds among the members of that group.

Children start to tell selfish lies at about age three, when they discover adults cannot read their minds: I didn’t steal that toy. Daddy said I could. He hit me first. At around age seven, they begin to tell white lies motivated by feelings of empathy and compassion: That’s a good drawing. I love socks for Christmas. You’re funny.

Blue lies are a different category altogether, simultaneously selfish and beneficial to others—but only to those who belong to your group. As University of Toronto psychologist Kang Lee explains, blue lies fall in between generous white lies and selfish “black” ones. “You can tell a blue lie against another group,” he says, which makes it simultaneously selfless and self-serving. “For example, you can lie about your team’s cheating in a game, which is antisocial but helps your team.”

In a 2008 study of seven, nine and 11-year-old children, Lee and his colleagues found that children become more likely to endorse and tell blue lies as they grow older. For example, given an opportunity to lie to an interviewer about rule breaking in the selection process of a school chess team, many were quite willing to do so, older kids more than younger ones. The children telling this lie did not stand to selfishly benefit; they were doing it on behalf of their school. This line of research finds that black lies drive people apart, white lies draw them together and blue lies pull some people together while driving others away.

Around the world, children grow up hearing stories of heroes who engage in deception and violence on behalf of their in-groups. In Star Wars, for example, Princess Leia lies about the location of the Rebels’ “secret base.” In the Harry Potter novels (spoiler alert!), the entire life of double agent Severus Snape is a lie, albeit a blue one, in the service of something bigger than himself.

That explains why most Americans seem to accept that our intelligence agencies lie in the interests of national security, and we laud our spies as heroes. From this perspective, blue lies are weapons in intergroup conflict. As philosopher Sissela Bok once said, “Deceit and violence—these are the two forms of deliberate assault on human beings.” Lying and bloodshed are often framed as crimes when committed inside a group—but as virtues in a state of war.

This research—and these stories—highlights a difficult truth about our species: we are intensely social creatures, but we are prone to divide ourselves into competitive groups, largely for the purpose of allocating resources. People can be prosocial—compassionate, empathetic, generous, honest—in their group and aggressively antisocial toward out-groups. When we divide people into groups, we open the door to competition, dehumanization, violence—and socially sanctioned deceit.

“People condone lying against enemy nations, and since many people now see those on the other side of American politics as enemies, they may feel that lies, when they recognize them, are appropriate means of warfare,” says George Edwards, a political scientist at Texas A&M University and one of the country’s leading scholars of the presidency.

If we see Trump’s lies not as failures of character but rather as weapons of war, then we can come to see why his supporters might view him as an effective leader. From this perspective, lying is a feature, not a bug, of Trump’s campaign and presidency.

Research by Alexander George Theodoridis of the University of California, Merced, Arlie R. Hochschild of the University of California, Berkeley, Katherine J. Cramer of the University of Wisconsin–Madison, Maurice Schweitzer of the University of Pennsylvania and others have found that this kind of lying seems to thrive in an atmosphere of anger, resentment and hyperpolarization. Party identification is so strong that criticism of the party feels like a threat to the self, which triggers a host of defensive psychological mechanisms.

For millions and millions of Americans, climate change is a hoax, Hillary Clinton ran a child sex ring out of a pizza parlor and immigrants cause crime. Whether they truly believe those falsehoods or not is debatable—and possibly irrelevant. The research to date suggests that they see those lies as useful weapons in a tribal us-against-them competition that pits the “real America” against those who would destroy it.

It is in blue lies that the best and worst in humanity can come together. They reveal our loyalty, our ability to cooperate, and our capacity to care about the people around us and to trust them. At the same time, blue lies display our predisposition to hate and dehumanize outsiders and our tendency to delude ourselves.

This hints at the solution, which starts with the idea that we must appeal to the best in one another. While that may sound awfully idealistic, the applications of that insight are very concrete. In a new paper in the journal Advances in Political Psychology, D. J. Flynn and Brendan Nyhan, both at Dartmouth College, along with Jason Reifler of the University of Exeter in England, summarize everything science knows about “false and unsupported beliefs about politics.”

They recommend a cluster of prosaic techniques, such as presenting information as imagery or graphics instead of text. The best combination appears to be graphics with stories. But this approach runs up against another scientific insight, one that will be frustrating to those who would oppose Trump’s lies: who tells the story matters. Study after study shows that people are much more likely to be convinced of a fact when it “originates from ideologically sympathetic sources,” as the paper says—and it helps a lot if those sources look and sound like them.

In short, it is white conservatives who must call out Trump’s lies if they are to be stopped.

What can the rest of us do in the meantime? We must make accuracy a goal, even when the facts do not fit our emotional reality. We start by verifying information, seeking out different and competing sources, cultivating a diverse social network, sharing information with integrity—and admitting when we fail. That is easy. But the most important and difficult thing we can do right now, this line of research suggests, is to put some critical distance between us and our groups—and so lessen the pressure to go along with the herd.

Donald Trump lies, yes, but that does not mean the rest of us, his supporters included, need to follow his example.