Photograph by Liv Oeian / Shutterstock

Last month, Greta Thunberg, the Swedish teenage activist, excoriated world leaders for their ongoing failure to address the climate crisis. “You have stolen my dreams and my childhood with your empty words,” she said at one point during her speech at the United Nations. Thunberg has been galvanizing public support for climate action since rising to prominence with her school strike about a year ago, and her latest remarks are no exception. They’ve attracted millions of views all around the internet—and nearly as many strong opinions. The praise and scorn she received in the aftermath of her address spotlights not only the power and intricacy of moral language, but also its ability, when articulated in a sound argument, to change public opinion on contentious moral and political issues.

Seeing the reactions to Thunberg’s speech, Frederic Hopp, a graduate student in the Media Neuroscience Lab at the University of California, Santa Barbara, decided, with the lab’s director, René Weber, to give it a close read using a tool the lab developed that combines algorithms, text-mining, and human evaluations. “All humans possess inborn moral intuitions that can be categorized along five broad categories,” Weber has said. “The environment and cultural context influence how these capacities become relevant.” The five categories, or moral foundations, are care/harm (feeling compassion for the suffering and vulnerable), fairness/cheating (making sure people are getting what they deserve), loyalty/betrayal (keeping track of who is “us” and who is “them”), authority/subversion (valuing order, tradition, and hierarchy), and sanctity/degradation (believing certain things are elevated and pure and shouldn’t be tarnished). Hopp told me, “There’s good empirical evidence that you are more or less successful in persuading people not just for climate change but other issues, too, depending on how you frame these arguments in moral terms and which foundations you stress.”

It seems Thunberg struck the right chord.

Many studies have shown that people who prioritize issues of care/harm and fairness/cheating tend to be politically liberal. On the other hand, people who value all five foundations similarly tend to be politically conservative. These trends, far from being fodder for philosophical conjecture, translate to real-world behavior. One study found that the composition of people’s moral intuitions could predict which candidate they supported in the 2016 presidential primaries. Another showed that it’s possible to make liberals more supportive of conservative positions, like increasing military spending, and conservatives more supportive of liberal positions, like legalizing same-sex marriage, by changing the moral language used to support each position. Perhaps unsurprisingly, given that environmentalists tend to be liberal, Hopp and Weber found Thunberg’s speech loaded with language related to care/harm (like “growth,” “future,” and “suffering”) and fairness/cheating (like “right,” “solutions,” and “consequences”).



It seems Thunberg struck the right chord. Though they’re more prominent for liberals, those two moral foundations appeal strongly to people on both sides of the aisle. This means moral arguments that tap into them are, according to Irina Vartanova, a researcher at the Institute for Futures Studies, “the universal arguments, the arguments that are accepted by everyone.”

In a recent paper, Vartanova and her colleagues showed just how powerful universal arguments can be. Using data from a survey that tracked public opinion in the United States on 74 different moral issues from 1972 to 2016, they created a measure of how strongly common arguments (such as, “We should limit carbon emissions because people are suffering”) connect to the care and fairness foundations compared to opposing arguments (such as, ”We shouldn’t limit carbon emissions because it would impede economic growth”). If a given argument is rooted more deeply in care and fairness than its counterargument, it has what the researchers call a “harm-fairness connection advantage.”

A model of public opinion change they developed not only reaffirmed that public opinion is becoming more liberal on many issues, but also showed that the rate of this change depends largely on the strength of the harm-fairness connection advantage: the bigger the advantage for a given argument, the faster the leftward shift among liberals and conservatives alike. The model offers, as the researchers wrote, “an explanation for why gay rights, gender equality, and racial equality are gaining support faster than opinions in favor of abortion rights, affirmative action, and suicide, for which harm-and-fairness considerations are much less clear-cut.” Vartanova and her colleagues seem to have shown how exposure to the right arguments can predictably change not just individual opinions, but the belief system of an entire society: As they put it, “Our model illustrates that psychology can create culture.”

Of course, this assumes that people can freely exchange ideas. For the harm-fairness connection advantage to move public opinion, “you need to deploy effective arguments, and you also need to make sure that the questions are being discussed,” said Pontus Strimling, a professor of economics at the Institute for Futures Studies and lead author of the study. “Another part of this whole movement is because we’re talking about these issues. This process can’t work unless people are actually discussing it.” So, in countries like China and Russia—and even in ostensible bastions of free speech like the United States—strong moral arguments don’t always win out.

Still, this research goes to show that social change doesn’t just materialize on its own. The widespread belief that, as Martin Luther King put it, “the arc of the moral universe is long, but it bends toward justice” has attracted criticism from those who believe that it mistakenly treats change as an inevitability. “Nothing bends toward justice without us bending it,” wrote political commentator Chris Hayes. At least for those who lean liberal, it seems moral arguments are a crucial part of that bending.

So who actually gets to do the bending? The importance of moral arguments means the greatest catalysts of—or obstacles to—social change may be those who decide which arguments are disseminated. “We can’t get around the role of moral foundations in society,” said Matt Miles, a professor of political science at Brigham Young University—Idaho. “The question is who is it that’s going to connect the dots between the moral foundations and the policy. Those people end up being the powerful people in society.”

Thunberg has a large platform, and her attempts to connect the dots do appear capable of swaying opinions. But it remains to be seen whether harm- and fairness-based language is the most effective way to motivate climate policy. The optimal set of moral arguments for environmentalism may not happen to be the two that reliably drive change on other issues. “The positions really have their own logic as to what fits them,” said Strimling. “You can stretch it a bit but not that much. You’re kind of stuck with the arguments that fit your position.” For example, some research suggests that environmentalists may benefit from using arguments based on the foundation of sanctity/degradation.

One way or another, the needle is moving. An increasing percentage of Americans—44 percent, according to Pew, up from 34 percent in 2015—believe addressing the climate should be among their government’s top priorities. And Thunberg has certainly done more than her fair share of the work. But as the dangers of the climate crisis become less and less hypothetical, activists may want to use all the rhetorical tools they can get. Thunberg, for her part, may have weighted her remarks toward care and fairness, but she didn’t omit loyalty. “You are failing us,” she said. “But the young people are starting to understand your betrayal.”

Scott Koenig is a doctoral student in neuroscience at CUNY, where he studies morality, emotion, and psychopathy. Follow him on Twitter @scotttkoenig.

