Do Americans understand the scientific consensus about issues like climate change and evolution?
At least for a substantial portion of the public, it seems as if the answer is no. The Pew Research Center, for instance, found that 33 percent of the public believes that "humans and other living things have existed in their present form since the beginning of time" and 26 percent think that there is not "solid evidence that the average temperature on Earth has been getting warmer over the past few decades."
Unsurprisingly, beliefs on both topics are divided along religious and partisan lines. For instance, 46 percent of Republicans said there is not solid evidence of global warming, compared with 11 percent of Democrats.
As a result of surveys like these, scientists and advocates have concluded that many people are not aware of the evidence on these issues and need to be provided with correct information. That's the impulse behind efforts like the campaign to publicize the fact that 97 percent of climate scientists believe human activities are causing global warming.
In a new study, a Yale Law School professor, Dan Kahan, finds that the divide over belief in evolution between more and less religious people is wider among people who otherwise show familiarity with math and science, which suggests that the problem isn't a lack of information. When he instead tested whether respondents knew the theory of evolution, omitting mention of belief, there was virtually no difference between more and less religious people with high scientific familiarity. In other words, they knew the science; they just weren't willing to say that they believed in it.
Kahan's study suggests that more people know what scientists think about high-profile scientific controversies than polls suggest; they just aren't willing to endorse the consensus when it contradicts their political or religious views. This supports what my colleagues and I have found: Factual and scientific evidence is often ineffective at reducing misperceptions and can even backfire on issues like weapons of mass destruction, health care reform and vaccines. With science, as with politics, identity often trumps the facts.
So what should we do? One implication of Kahan's study and other research in this field is that we need to try to break the association between identity and factual beliefs on high-profile issues — for instance, by making clear that you can believe in human-induced climate change and still be a conservative Republican like former Rep. Bob Inglis or an evangelical Christian like the climate scientist Katharine Hayhoe.
But we also need to reduce the incentives for opinion leaders to spread misinformation to their followers in the first place, as with the "birther" myth about President Barack Obama. Once people's cultural and political views get tied up in their factual beliefs, it's very difficult to undo regardless of the messaging that is used.
It may be possible for institutions to help people set aside their political identities and engage with science more dispassionately under certain circumstances, especially at the local level. Kahan points, for instance, to the relatively inclusive and constructive deliberations that were conducted among citizens in southeast Florida about responding to climate change. However, this experience may be hard to replicate — on the Outer Banks of North Carolina, another threatened coastal area, the debate over projected sea level rises has already become highly polarized.
The deeper problem is that citizens participate in public life precisely because they believe the issues at stake relate to their values and ideals, especially when political parties and other identity-based groups get involved — an outcome that is inevitable on high-profile issues. Those groups can help to mobilize the public and represent their interests, but they also help to produce the factual divisions that are one of the most toxic byproducts of our polarized era. Unfortunately, knowing what scientists think is ultimately no substitute for actually believing it.
Brendan Nyhan is an assistant professor of government at Dartmouth College. © 2014 New York Times