Since the cultural turn of the 1970s, liberals have focused on cultural change as a way of achieving justice. They assumed that people conform to dominant social norms which they learn about through the media and through others in society. So the operating hypothesis is that, if you create the impression that (for example) racial equality is the dominant social norm through consistent and uniform expression of those views and the suppression of racist norms, then racism will disappear as people start to conform to those new values. (This is in contrast to the prior Marxist-influenced social science which assumed that culture mainly reflects economic realities, and you can't make racism just disappear while keeping the same economic conditions.)

Jonathan Haidt is a social psychologist and one of the co-authors of the paper. His work theorizes five foundations of morality—basically, ways of assessing the moral value of an act: harm, fairness, respect for authority, loyalty to one's group and purity/sanctity. The impact of the cultural turn shows up in his research. He found that conservatives tend to use all five foundations, while liberals only use the first two. Obviously for liberals, the remaining three are associated with patriarchal authority, nationalism and religious oppression.

So, he's not just demanding equal representation of political ideologies. It seems that Haidt believes that the dominance of liberalism among social psychologists is harmful to the field because it is associated with a strategy of cultural change which obliges liberals to avoid lines of research into these other foundations of morality.

The group that you call "liberals" is spread out across the political spectrum, from the center to the far left. Some are authoritarian, others are libertarian and even anarchist. They do not present any unified front; in fact, there's so much disagreement among "liberals" that they would never consider themselves to be a single group unless forced to choose among a very small set of labels.

I agree with the authors that homogeneity can be bad for a field, but I don't think this can be fixed by increasing the mindshare of conservatism. There are plenty of people who would pick "liberal" on a "liberal or conservative?" questionnair and still devote their lives to researching, for example, people's relationship with authority. Not personally believing it to be a matter of morality might even help the researcher become more objective.

But liberals' political views aren't relevant here. What matters for Haidt is that irrespective of their true politics, people who identify as liberal tend to be hostile to 3 of the moral foundations.

I'm not saying his approach is right, just that his ultimate goal is not political diversity as such. I agree that there are other approaches to correcting bias, and the fact that he doesn't even consider those makes me think something else is going on. Liberals tend to believe that morality is a product of reason. Haidt thinks it comes from innate dispositions or intuitions, which I think is closer to a conservative viewpoint.

> But liberals' political views aren't relevant here.

How does one justify a sweeping generalization about some group of people while totally ignoring diversity within that group? "I don't care what they truly believe, but methinks they believe that three of my six (not five) moral foundations are unimportant." doesn't sound particularly convincing.

> I'm not saying his approach is right, just that his ultimate goal is not political diversity as such.

That's exactly what I was trying to point out in the GGGP comment. This is little more than a conservative political agenda wrapped in the language of diversity. Yes, some people emphasize some of the "foundations" more than others. But unless Haidt can convince us that we ought to take all of them seriously, his views are utterly uninteresting in the context of ethics.

When religious people demand that creationism be taught at school "for balance", most HNers can easily see through their thinly veiled political agenda. But when a conservative and/or libertarian guy makes an argument that has an identical logical structure, anyone who dares to disagree gets downvoted into oblivion. Funny, but I guess that's exactly how political biases work IRL.