The Numbers Say The Numbers Aren't Good Enough

[Editor's note: I wrote this article in 2014 so the numbers may not be quite up to date.]

There are few activities more counterproductive than trying to convince people to change their minds about their most deeply held beliefs. It’s hard enough trying to convince a Beatles fan that the Rolling Stones are the better band, never mind getting a liberal to support the death penalty or a conservative to expand welfare. This makes sense when the subject in question is a matter of opinion. But it also happens in science even when the evidence is clear, such as in the case of climate change.

The problem lies in the way that people make decisions. People don’t actually care all that much about the evidence. You show them a bunch of numbers and they can twist them to suit their purposes. Stories are much more effective in getting people to change their minds. So if scientists want to convince the public of the truth on such matters as climate change, they need to change the way they communicate. More stories, less numbers.

A study conducted last September by Yale law professor Dan Kahan and other researchers from around the country has demonstrated that people hold onto their beliefs even when presented with evidence that contradicts their opinions[1]. Over a thousand Americans took a test to determine their mathematical skill and a survey to determine their political leanings. They were then given a math problem. They were presented evidence that showed whether a skin cream was effective in curing rashes, or whether gun control laws were effective in curbing violence. When asked if the skin cream was effective, 75 percent of those who scored high on the math test got the correct answer regardless of their political leanings. However, in the group that scored high on the initial math test, liberals were 45 percentage points more likely than conservatives to answer that gun control laws reduced crime even when the evidence presented showed that the opposite was true.

It would be easy to look at studies like this one and assume that there’s no point in trying to convince anyone of anything. But the study, and many of those commenting on it, ignore or neglect to mention one important fact. The conclusions only apply to the people who have identified themselves as liberal Democrats or conservative Republicans. That leaves about 30% of people unaccounted for, political moderates[1]. The study can’t say whether moderates are as fixed in their beliefs as those at the ends of the political spectrum, or if they might actually be open-minded people willing to weigh evidence before making their minds up about an issue.

But at least some of those people must be open-minded. People do change their minds. According to Pew Research polls, in 2003, 33 percent of Americans favored gay marriage and a decade later 49 percent favored it[3]. Even if I didn’t have the numbers to confirm this, I still have my own experiences. Through my high school years I would describe myself as socially conservative. In line with my Catholic upbringing, I was pro-life and uncomfortable with homosexuality. But as I went to college and later joined the work force, my views gradually changed. I got to know people who were different from me and learned that they really weren’t that different. Today it would be fair to call me a liberal. I am pro-choice and I have a diverse cast of friends.

But people are actually more likely to change their minds about societal issues than scientific ones. From 2006 to 2013, Pew Research polls indicate that the number of Americans who believe humans cause global warming has actually dropped[4]. But in 2013, a study of thousands of scientific papers published in peer reviewed journals from 1991-2011 showed that of those papers that took a position on global warming, 97 percent agreed that human beings cause global warming[2].

When talking about science, the numbers usually start flying, but it turns out that people don’t find numbers all that convincing. If they already agree with the argument, they say the numbers never lie. But if they don’t, then it’s just lies, damned lies, and statistics.

Timothy Wilson, a psychology professor at the University of Virginia, says that stories are more effective than data in getting people to change their minds[5]. This agrees with my own experiences. When I arrived at MIT, my roommates ended up being a Muslim Tanzanian-American from Queens and a Dominican from the Bronx who occasionally put on a purple dress and red high heels. At first I had reservations, but they turned out to be huge hockey fans. How bad could it be? Sure they were New York Rangers fans, but nobody’s perfect. Interacting with people of different backgrounds showed me that I had more in common with them than I first thought.

That’s the difficulty in convincing people to change their minds on scientific matters. The numbers don’t have faces or stories for people to relate to. Scientists do. Many scientists would like to think that the numbers and evidence should be enough, but the numbers and evidence of studies like Kahan’s show that they’re not. If they want people to trust and believe them, they need to get their faces out there and tell their stories.

End Notes

1.     Kahan, Dan M. and Peters, Ellen and Dawson, Erica Cantrell and Slovic, Paul, Motivated Numeracy and Enlightened Self-Government (September 3, 2013). Yale Law School, Public Law Working Paper No. 307. Available at SSRN: http://ssrn.com/abstract=2319992 or http://dx.doi.org/10.2139/ssrn.2319992

2.     John Cook et al. Quantifying the consensus on anthropogenic global warming in the scientific literature, 2013 Environmental Research Letters 8 024024. Available at IOP: http://iopscience.iop.org/1748-9326/8/2/024024/article

3.     Pew Research. Growing Support for Gay Marriage: Changed Minds and Changing Demographics (March 20, 2013). http://www.people-press.org/2013/03/20/growing-support-for-gay-marriage-changed-minds-and-changing-demographics/

4.     Pew Research. Keystone XL Pipeline Draws Broad Support (April 2, 2013). http://www.people-press.org/2013/04/02/keystone-xl-pipeline-draws-broad-support/

5.     Wilson, Timothy (2011). Redirect: The Surprising New Science of Psychological Change. Little, Brown and Company. ISBN 0-316-05188-8.