Keith Stanovich is author of The Rationality Quotient and emeritus professor of applied psychology and human development at the University of Toronto. He writes:

As a political strategy, this “party of science” labelling might be effective, but epistemic superiority cannot simply be declared on the basis of a few examples. A cognitive scientist is forced to be pedantic here and rain on the progressive parade. In fact, any trained social scientist would be quick to point out the obvious selection effects that are operating. The issues in question (climate science and creationism/evolution) are cherry-picked for reasons of politics and media interest. In order to correctly call one party the party of science and the other the party of science deniers, one would of course have to have a representative sampling of scientific issues to see whether members of one party are more likely to accept scientific consensus.

In fact, it is not difficult at all to find scientific issues on which it is liberal Democrats who fail to accept the scientific consensus. Leftists become the “science deniers” in these cases. In fact, and ironically, there are enough examples to produce a book parallel to the Mooney volume cited above titled Science Left Behind: Feel-Good Fallacies and the Rise of the Anti-Scientific Left (2012). To mention an example from my own field, psychology: liberals tend to deny the overwhelming consensus in psychological science that intelligence is moderately heritable.

This isn’t the only instance of left-wing science denial, though. In the area of economics, progressives are very reluctant to accept the consensus view that when proper controls for occupational choice and work history are made, women do not make more than 20 per cent less than men for doing the same work.

Progressives tend to deny or obfuscate (just as conservatives obfuscate the research on global warming) the data indicating that single-parent households lead to more behavioral problems among children. Overwhelmingly progressive university schools of education deny the strong scientific consensus that phonics-based reading instruction facilitates most readers, especially those struggling the most. Many progressives find it hard to believe that there is no bias at all in the initial hiring of women for tenure-track university positions in STEM disciplines. Progressives tend to deny the consensus view that genetically modified organisms are safe to consume. Gender feminists routinely deny biological facts about sex differences. Largely Democratic cities and university towns are at the forefront of the anti-vaccine movement which denies a scientific consensus. In the same cities and towns, people find it hard to believe that there is a strong consensus among economists that rent control causes housing shortages and a diminution in the quality of housing. [Research citations for all the above are available from the author here.]

I will stop here because the point is made. There is plenty of science denial on the Democratic side to balance the anti-scientific attitudes of Republicans toward climate change and evolutionary theory. Neither political party is the party of science, and neither party exclusively contains the science deniers. Each side of the ideological divide accepts or denies scientific consensus depending upon the issue in question. Each side finds it hard to accept scientific evidence that undermines its own ideological beliefs and policies.

Bias is difficult to see. That’s one of the reasons that toleration and a healthy pluralism so important.