How cultural commitments damage your ability to reason

start counting. Source: unlistedsightings/flickr

When people don’t accept the scientific evidence, it may be useless to present them with yet more evidence. They are not stupid. They are simply protecting their cultural identity.

Here’s the journalism:

Science confirms: politics wrecks your ability to do math

And here’s the original study, Motivated Numeracy and Enlightened Self-Government

Kahan, Dan M., Peters, Ellen, Dawson, Erica Cantrell and Slovic, Paul, Motivated Numeracy and Enlightened Self-Government (September 3, 2013). Available at SSRN: http://ssrn.com/abstract=

Abstract: 
Why does public conflict over societal risks persist in the face of compelling and widely accessible scientific evidence? We conducted an experiment to probe two alternative answers: the “Science Comprehension Thesis” (SCT), which identifies defects in the public’s knowledge and reasoning capacities as the source of such controversies; and the “Identity-protective Cognition Thesis” (ICT) which treats cultural conflict as disabling the faculties that members of the public use to make sense of decision-relevant science. In our experiment, we presented subjects with a difficult problem that turned on their ability to draw valid causal inferences from empirical data. As expected, subjects highest in Numeracy—a measure of the ability and disposition to make use of quantitative information—did substantially better than less numerate ones when the data were presented as results from a study of a new skin-rash treatment. Also as expected, subjects’ responses became politically polarized—and even less accurate—when the same data were presented as results from the study of a gun-control ban. But contrary to the prediction of SCT, such polarization did not abate among subjects highest in Numeracy; instead, it increased. This outcome supported ICT, which predicted that more Numerate subjects would use their quantitative-reasoning capacity selectively to conform their interpretation of the data to the result most consistent with their political outlooks. We discuss the theoretical and practical significance of these findings.