The study investigates whether polarization over scientific and
risk policy issues arises because people are (1) misled by an
over-reliance on rules of thumb, (2) subject to distorting
cognitive dispositions such as dogmatism, aversion to complexity,
and need for closure, or (3) seeking to bolster and protect their
sense of social identity. Kahan categorizes the relevant social
psychological research theories into (1) the public irrationality
thesis; (2) the Republican Brain hypothesis; and (3) the expressive
rationality thesis.
One theory of how this polarization arises is what Kahan calls
the public irrationality thesis. Nobel-winning economist Daniel
Kahnemann argues that humans employ two different cognitive systems
to evaluate new information. The first uses fast cognitive efforts
such as rules of thumb while the second relies on slower, more
effortful systematic reasoning. People adopt many of their
cognitive rules of thumb, heuristics that are triggered by
emotional reactions to new situations, from groups with whom they
share cultural or ideological commitments. This theory implies that
when challenged with new information or arguments, it’s just easier
for most people to believe what their peers believe. The downside
of this knee-jerkism is that there is no tendency for public
deliberation to converge on effective public policies to deal with
societal risks