First, partisanship undermines clear thinking. Second, it undermines
moral integrity. In both cases, the root cause is the same: the
conflation of friend and foe with right and wrong.
Consider this pair of poll results cited by Andrew Gelman in his wonderful book Red State, Blue State, Rich State, Poor State.
According to a survey conducted in March 2006, nearly 30 percent of
Republicans believed not only that Iraq had possessed weapons of mass
destruction, but that the U.S. military had actually found them.
Meanwhile, in a May 2007 poll, 35 percent of Democrats expressed the
view that President Bush knew about the 9/11 attacks in advance.
It's not just that partisans are vulnerable to believing fatuous
nonsense. It's that their beliefs, whether sensible or otherwise, about
a whole range of empirical questions are determined by their political
identity. There's no epistemologically sound reason why one's opinion
about, say, the effects of gun control should predict one's opinion
about whether humans have contributed to climate change or how well
Mexican immigrants are assimilating -- these things have absolutely
nothing to do with each other. Yet the fact is that views on these and
a host of other matters are indeed highly correlated with each other.
And the reason is that people start with political identities and then
move to opinions about how the world works, not vice versa.
Incidentally, this is why the betting norm is so important. Moving from identity to opinions about how the world works is a lot less tempting once you commit to putting your money where your mouth is.
Consequently, I believe there is an inverse relationship today between
one's commitment to both the truth and the public interest and one's
commitment to partisanship, whether Republican or Democrat. To put it
more bluntly, these days I don't see how you can be both a good citizen
and a zealous partisan. This isn't to say you can't lean one way or the
other. Without a doubt, it's possible to reach a fairly stable
conclusion that one party ID or the other is a relatively better fit.
But it should be an uncomfortable fit. If you can't see that sometimes,
even frequently, your party is dead wrong, and that sometimes the
country would be better off if your party lost, then in my book you've
got a problem. The fact that it's an extremely common problem only
makes it worse.