On Tuesday night, Eric Trump told Sean Hannity how he really feels about Democrats and his father’s political opponents: “I’ve never seen hatred like this. To me, they’re not even people.”

The statement is of the hyperbolic sort that commonly plays on Fox News’s opinion programming. But this is considerably more troubling. The language is plainly dehumanizing, and such language — historically and psychologically — is dangerous.

Now, Eric Trump’s phrasing is unlikely to incite anything horrible. It was a flip remark that he probably put little thought into.

But let’s take this as an opportunity to remember that the language we use to talk about people we disagree with matters deeply. Dehumanization is already disturbingly prevalent in America. We don’t need influential people stoking it further.

Dehumanization is a mental loophole that allows us to dismiss other people’s feelings and experience

Look back at some of the most tragic episodes in human history and you will find words and images that stripped people of their basic human traits. In the Nazi era, the film The Eternal Jew depicted Jews as rats. During the Rwandan genocide, Hutu officials called Tutsis “cockroaches” that needed to be cleared out.

In the wake of World War II, psychologists wanted to understand how the genocide had happened. And we got Stanley Milgram’s infamous electroshock experiment, which showed how quickly people cave to authority. There was also Philip Zimbardo’s “prison experiment,” which showed how easily people in positions of power can abuse others. At Stanford, Albert Bandura showed that when participants overhear an experimenter call another study subject “an animal,” they’re more likely to give that subject a painful shock. If you think of murder and torture as universally taboo, then dehumanization of the “other” is a psychological loophole that can justify those acts.

From these experiments and those that followed, it became clear that “it’s extremely easy to turn down someone’s ability to see someone else in their full humanity,” Adam Waytz, a psychologist at Northwestern University, told me earlier this year. Studies find even children as young as 5 years old see the world in terms of us versus them.

In the months since Donald Trump’s election, it’s become shockingly commonplace for Americans to blatantly dehumanize Muslims and Mexican immigrants — and then use violence against them. Hate crimes against Muslims in the US are at their highest levels since 2001. And there’s plenty of anecdotal evidence (and some empirical research too) that America is becoming a coarser, meaner place.

Eric is not the only Trump to use dehumanizing language. You may recall that Donald Trump Jr. compared Syrian refugees to a bowl of Skittles. And one of the president’s favorite vocal tics is say people who fail at things are “like dogs.”

Dehumanizing beliefs are linked to aggression

In the 1970s, Bandura predicted that dehumanization would lead to increased aggression. Today, there’s something similar: Willingness to dehumanize others predicts aggressive attitudes — and perhaps actions — towards those people. Dehumanization makes you less likely to believe a person is capable of having agency (i.e. an independent mind) and experience (i.e. the ability to feel complicated emotions). You can start to see a person as more animal than human.

Dehumanization likens our opponents “to disease, disease carriers, or … a faceless horde,” Nick Haslam, one of the world’s leading experts in dehumanization psychology, told me early this year. “That helps you have less compassion for them; that allows you to see them as morally unequal and not deserving.”

Simply put: Dehumanization is a mental loophole that lets us harm other people.

We can’t kid ourselves. Inside us all is the same mental machinery that fueled the atrocities of the past century. “We think others to death and then invent the battle-axe or the ballistic missiles with which to actually kill them,” writes the philosopher Sam Keen. Turning on dehumanization won’t immediately lead to massacre, but it does make it easier to make life marginally worse for the marginalized. And yes: dehumanization exists in America today, particularly towards Muslims and immigrant groups. It’s self-sustaining: Believing you have been dehumanized is correlated with willingness to dehumanize and act violently against others.

It matters that Eric Trump said this. We often look to the powerful and influential for cues on how to behave. If it’s okay for the rich and successful Eric Trump to believe his father’s opponents are less than human, then others may too.