A reader points to a fascinating column by Megan McArdle, based on the work of social psychologist Jonathan Haidt, of whom she and I are both fans. The headline on the column is, “Why Liberals Can’t Admit to Thinking Like Conservatives.” Haidt, who is a secular liberal, has argued that one reason liberals and conservatives talk past each other is that liberals reason from a more limited set of moral foundations than do conservatives.

In Haidt’s theory, liberals make their moral and political decisions by drawing on two foundations: “Care/Harm” and “Fairness/Cheating.” Conservatives use these two foundations as well, but add three more: “Loyalty/Betrayal,” “Authority/Subversion,” and “Sanctity/Degradation.” In Haidt’s view, conservatives often understand liberals more than liberals understand conservatives, because conservatives get the Harm and Fairness foundations, but liberals don’t intuit the other three.

So that’s Haidt’s theory, which I find to be a very useful prism through which to understand our disputes. Like me, McArdle is a Haidt fan, but she says that she has long had a couple of skeptical questions about his theory. For one, even though liberals and libertarians might say, as a matter of principle, that they wouldn’t find anything morally wrong with incest between two consenting adults, provided that there were no chance of pregnancy, in practice very many of them would not want to be friends with people engaged in such a relationship. In other words, people don’t always think and behave in ways that their principles obligate them to.

For another, says McArdle, “liberals may indeed resort to reasoning from sanctity, group loyalty, and authority — but the questions Haidt has asked simply may not capture that tendency.” More:

This problem occurred to Jeremy Frimer, who did a paper on how conservative and liberal attitudes towards authority shift when you shift who the authority is. “Together with my collaborators Dr. Danielle Gaucher and Nicola Schaefer, we asked both red and blue Americans to share their views about obeying liberal authorities (e.g., “obey an environmentalist”). In an article that we recently published in Personality and Social Psychology Bulletin, we found that liberals were now the ones calling for obedience. And when the authorities were viewed as ideologically neutral (e.g., office manager), liberals and conservatives agreed. Only when people perceived the authority to be conservative (e.g., religious authority) did conservatives show a positive bias.”

Now Frimer has a new paper, co-authored with Haidt, on sanctity. And again they find liberals arguing from a broader range of moral foundations than Haidt’s work initially suggested. When it comes to desecrating the purity of a mountain, instead of, say, the American flag, it turns out that liberal mountain climbers care a lot, even though no sentient being is harmed by the action.

Read McArdle’s entire article. Her point is that liberals may well make decisions based on Loyalty, Authority, and Sanctity, but they apply those feelings and intuitions to different sources.

I get this. How else could you explain the Social Justice Warrior passion on campus that censures speech thought to offend or oppress victims classes if not with reference to Sanctity? If LGBTs (for example) are the Chosen People, then one may not utter blasphemy against them. And so forth. And notice too how so many on the cultural left defended Planned Parenthood against the undercover sting by taking refuge in the Authority of the law. I would bet money that every liberal who complained publicly about what the undercover investigators did are people who believe that the lawbreaking Edward Snowden was a hero. (And hey, he might have been; I think most of us, liberal and conservative both, can agree that there are times when an unjust law ought to be broken.)

Plus, I have a couple of old-left friends who still insist that Alger Hiss was innocent. There is, I am certain, no evidence at all that would convince them otherwise. They believe in being Loyal to the cause. One of them even told me that if McCarthy were right, and all the people he accused were Soviet spies, then Whittaker Chambers was a rat bastard because he was disloyal.

The point is, it’s not that liberals are anti-authority, or against the concept of sanctity; or unfamiliar with loyalty. It may be that they apply them very differently. McArdle’s dour conclusion is that with “sanctity” a category that is by its very nature impervious to reason, we may be facing a culture war that no one can win.