A couple of years back, I wrote up a column, "The Science of Libertarian Morality," based on a preliminary research paper by social psychologists Ravi Iyer, Jesse Graham, Spassena Koleva, Peter Ditto and Jonathan Haidt. That updated study has now been officially published in the journal PLoS One as, "Understanding Libertarian Morality: The Psychological Dispositions of Self-Identified Libertarians."

There is a nice summary of the study's findings over at Haidt's The Righteous Mind web site:

1) On moral values: Libertarians match liberals in placing a relatively low value on the moral foundations of loyalty, authority, and sanctity (e.g., they're not so concerned about sexual issues and flag burning), but they join conservatives in scoring lower than liberals on the care and fairness foundations (where fairness is mostly equality, not proportionality; e.g., they don't want a welfare state and heavy handed measures to enforce equality). This is why libertarians can't be placed on the spectrum from left to right: they have a unique pattern that is in no sense just somewhere in the middle. They really do put liberty above all other values. 2) On reasoning and emotions: Libertarians have the most "masculine" style, liberals the most "feminine." We used Simon Baron-Cohen's measures of "empathizing" (on which women tend to score higher) and "systemizing", which refers to "the drive to analyze the variables in a system, and to derive the underlying rules that govern the behavior of the system." Men tend to score higher on this variable. Libertarians score the lowest of the three groups on empathizing, and highest of the three groups on systemizing. (Note that we did this and all other analyses for males and females separately.) On this and other measures, libertarians consistently come out as the most cerebral, most rational, and least emotional. On a very crude problem solving measure related to IQ, they score the highest. Libertarians, more than liberals or conservatives, have the capacity to reason their way to their ideology. 3) On relationships: Libertarians are the most individualistic; they report the weakest ties to other people. They score lowest of the three groups on many traits related to sociability, including extroversion, agreeableness, and conscientiousness. They have a morality that matches their sociability – one that emphasizes independence, rather than altruism or patriotism.

The press release for the study also notes:

Convergent with previous research showing the ties between emotion and moral judgment, libertarians displayed a more rational cognitive style, according to a variety of measures. Asked directly, using a series of standard psychological measures available at YourMorals.org, they reported being less neurotic, less disgusted, and less empathic, compared to liberals and conservatives, while also reporting a greater need for cognition and systematic understanding of the world. When given moral dilemmas – e.g. being asked whether it is ok to sacrifice five people to save one – they reported fewer qualms than other groups, a pattern of responding that is consistent with a rational/utilitarian style. Libertarians tended to do better on logic problems that included answers designed to fool more intuitive thinkers.

I concluded my earlier column by observing that I find the research results fairly convincing, but noted that the most important fact about libertarian morality is that …