Libertarians are often cast as amoral calculating rationalists with an unseemly hedonistic bent. Now new social science research upends that caricature. Libertarians are quite moral, the researchers argue—just not in the same way that conservatives and liberals are.

The University of Virginia social psychologist Jonathan Haidt has done a lot of work in the past probing the different moral attitudes of American liberals and conservatives. With time he realized that a significant proportion of Americans did not fit the simplistic left/right ideological dichotomy that dominates our social discourse. Instead of ignoring the outliers, Haidt and his colleagues chose to dig deeper.

The result: a fascinating new study, "Understanding Libertarian Morality: The Psychological Roots of an Individualist Ideology," that is currently under review at the Journal of Personality and Social Psychology. In probing libertarians' moral thinking, Haidt and his colleagues—Ravi Iyer and Jesse Graham at the University of Southern California and Spassena Koleva and Peter Ditto at the University of California at Irvine—used the "largest dataset of psychological measures ever compiled on libertarians": surveys of more than 10,000 self-identified libertarians gathered online at the website yourmorals.org.

In his earlier work, Haidt surveyed the attitudes of conservatives and liberals using what he calls the Moral Foundations Questionnaire, which measures how much a person relies on each of five different moral foundations: harm/care, fairness/reciprocity, ingroup/loyalty, authority/respect, and purity/sanctity. Typically, conservatives scored lower than liberals on the harm and fairness scales—that is, they gave those issues less weight when making moral judgments—and scored much higher on ingroup, authority, and purity.

In the new study, Haidt and his colleagues note that libertarians score low on all five of these moral dimensions. "Libertarians share with liberals a distaste for the morality of Ingroup, Authority, and Purity characteristic of social conservatives, particularly those on the religious right," Haidt et al. write. Libertarians scored slightly below conservatives on harm and slightly above on fairness. These results suggest that libertarians are "likely to be less responsive than liberals to moral appeals from groups who claim to be victimized, oppressed, or treated unfairly."

Another survey, the Schwartz Value Scale, measures the degree to which participants regard 10 values as guiding principles for their lives. Libertarians put higher value on hedonism, self-direction, and stimulation than either liberals or conservatives, and they put less value than either on benevolence, conformity, security, and tradition. Like liberals, libertarians put less value on power, but like conservatives they have less esteem for universalism. Taking these results into account, Haidt concludes that "libertarians appear to live in a world where traditional moral concerns (e.g., respect for authority, personal sanctity) are not assigned much importance."

Haidt and his colleagues eventually recognized that their Moral Foundations Questionnaire was blinkered by liberal academic bias, failing to include a sixth moral foundation, liberty. They developed a liberty scale to probe this moral dimension. Unsurprisingly, the researchers found that libertarians dramatically outscored liberals and conservatives when it came to putting a high value on both economic and lifestyle liberty. Haidt and his colleagues conclude, "Libertarians may fear that the moral concerns typically endorsed by liberals or conservatives are claims that can be used to trample upon individual rights—libertarians' sacred value."

Next the researchers wondered, "Might libertarians generally be dispositionally more rational and less emotional?" On the standard inventory of personality, libertarians scored lower than conservatives and liberals on agreeableness, conscientiousness, and extraversion. Low scores on agreeableness indicate a lack of compassion and a proud, competitive, and skeptical nature. Like conservatives, libertarians are not generally neurotic, tending to be emotionally hardy. And like liberals, libertarians scored high on openness to new experiences, indicating that they have broad interests.

Libertarians scored lower than both liberals and (especially) conservatives on sensitivity to disgust. The authors suggest this tendency "could help explain why they disagree with conservatives on so many social issues, particularly those related to sexuality. Libertarians may not experience the flash of revulsion that drives moral condemnation in many cases of victimless offenses."

Some of the more intriguing results involve the empathizer/systemizer scale. Empathizers identify with another person's emotions, whereas systemizers are driven to understand the underlying rules that govern behavior in nature and society. Libertarians, unlike both liberals and conservatives, scored very high on systemizing. The authors note, "We might say that liberals have the most 'feminine' cognitive style, and libertarians the most 'masculine.'?"

The researchers also found that libertarians tend to be less flummoxed by various moral dilemmas, such as the famous "trolley problem." In the trolley problem, five workmen will be killed by a runaway trolley unless you move a track switch which will divert the train but kill one workman—or, in another version, push a fat man off a bridge stopping the trolley. Typically, most people will choose to move the switch, but refuse to push the fat man. Why the difference? The utilitarian moral calculus is the same—save five by killing one. According to the researchers, libertarians are more likely to resolve moral dilemmas by applying this utilitarian calculus.

Taking various measures into account, the researchers report that libertarians "score high on individualism, low on collectivism, and low on all other traits that involved bonding with, loving, or feeling a sense of common identity with others." Haidt and his fellow researchers suggest that people who are dispositionally low on disgust sensitivity and high on openness to experience will be drawn to classically liberal philosophers who argue for the superordinate value of individual liberty. But also being highly individualistic and low on empathy, they feel little attraction to modern liberals' emphasis on altruism and coercive social welfare policies. Haidt and his colleagues then speculate that an intellectual feedback loop develops in which such people will find more and more of the libertarian narrative agreeable and begin identifying themselves as libertarian. From Haidt's social intuitionist perspective, "this process is no different from the psychological comfort that liberals attain in moralizing their empathic responses or that social conservatives attain in moralizing their connection to their groups."

I find Haidt's account of the birth of libertarian morality fairly convincing. But as a social psychologist, Haidt fails to discuss what is probably the most important and intriguing fact about libertarian morality: It changed history by enabling at least a portion of humanity to escape our natural state of abject poverty. Libertarian morality, by rising above and rejecting primitive moralities embodied in the universalist collectivism of left-liberals and the tribalist collectivism of conservatives, made the rule of law, freedom of speech, religious tolerance, and modern prosperity possible. Liberals and conservatives may love people more than do libertarians, but love of liberty is what leads to true moral and economic progress.

Ronald Bailey is reason's science correspondent.