A pair of truly enterprising social scientists, Jussim and Crawford, have been investigating bias against science among conservatives and liberals. Jussim reports the results of their study published in a peer-reviewed journal that showed in this sample, liberals are “far more biased” than conservatives:

Liberals viewed the articles reporting ‘liberal’ results (affirmative action and same sex relationships are good) as truer and reflecting less author bias than the articles reporting ‘conservative’ results.  Conservatives, in contrast, viewed the truthfulness and bias in the articles as nearly identical, regardless of their results.

That is not the most interesting part however.  When they tried to publish their findings that in this one study at least biases were larger for liberals, “We could not get this published.  It was rejected at two separate journals.”

So they rewrote it keeping the data in the tables, but never mentioning in the text the major new finding that liberals’ bias was greater in this sample:

This time, it was accepted.  Now, even though the text does not mention finding that liberals were more biased than conservatives, the pattern is right there, in the data reported in tables and figures, for anyone to see.  The paper shows that liberals are more biased than conservatives, at least when and how we studied it.  Neither I nor Jarret would or did claim that such a pattern is always necessarily true.  But it was true in our data.  We were just not permitted to say so.

Social science is extremely vulnerable to liberal groupthink. But I suspect the biggest reason liberals are more biased is that they seldom meet people who disagree with them.