Monday, September 20, 2010

why "scientific consensus" fails to persuade

NSF | Individuals with competing cultural values disagree about what most scientists believe. Whether a scientist is seen as knowledgeable and trustworthy depends on a person's cultural values. Suppose a close friend who is trying to figure out the facts about climate change asks whether you think a scientist who has written a book on the topic is a knowledgeable and trustworthy expert. You see from the dust jacket that the author received a Ph.D. in a pertinent field from a major university, is on the faculty at another one, and is a member of the National Academy of Sciences. Would you advise your friend that the scientist seems like an "expert"?

If you are like most people, the answer is likely to be, "it depends." What it depends on, a recent study found, is not whether the position that scientist takes is consistent with the one endorsed by a National Academy. Instead, it is likely to depend on whether the position the scientist takes is consistent with the one believed by most people who share your cultural values.

This was the finding of a recent study conducted by Yale University law professor Dan Kahan, University of Oklahoma political science professor Hank Jenkins-Smith and George Washington University law professor Donald Braman that sought to understand why members of the public are sharply and persistently divided on matters on which expert scientists largely agree.

"We know from previous research," said Dan Kahan, "that people with individualistic values, who have a strong attachment to commerce and industry, tend to be skeptical of claimed environmental risks, while people with egalitarian values, who resent economic inequality, tend to believe that commerce and industry harms the environment."

In the study, subjects with individualistic values were over 70 percentage points less likely than ones with egalitarian values to identify the scientist as an expert if he was depicted as describing climate change as an established risk. Likewise, egalitarian subjects were over 50 percentage points less likely than individualistic ones to see the scientist as an expert if he was described as believing evidence on climate change is unsettled. Fist tap Dale.