What separates conservatives from liberals? In the past decade, the most illuminating answers to this question have come from Jonathan Haidt, a New York University psychologist whose research bears directly on the emerging 2016 presidential campaign — even if his answers might not be quite right.
Haidt’s basic finding is simple. Throughout history, human beings have operated under five sets of moral commitments: avoidance of harm, fairness, loyalty, authority and sanctity. Conservatives recognize all five, but liberals recognize only the first two.
Conservatives and liberals agree on the importance of avoiding harm. If someone assaults someone else, people of every political stripe object. The two sides also agree on the importance of fairness. People who cheat one another, or break promises, meet with bipartisan disapproval — even if people often disagree over what fairness requires.
According to Haidt’s research, what separates conservatives from liberals is that they also care a great deal about loyalty, authority and sanctity. Suppose that people have betrayed their family, or that they have acted disrespectfully toward their parents or their bosses, or that they have engaged in a disgusting act. Conservatives are far more likely than liberals to feel moral outrage.
To test this claim, Haidt asked people in the U.S. and Britain this question: “When you decide whether something is right or wrong, to what extent are the following considerations relevant to your thinking?” Both liberals and conservatives emphasized “whether someone was harmed” and “whether someone acted unfairly.” But conservatives were much more inclined to think that it was also relevant whether people betrayed their group or did something disgusting — and whether the people involved were of the same rank.
More dramatically, Haidt also asked thousands of people how much money they would have to be paid to engage in certain actions, such as kicking a dog in the head or shooting an animal (harm), cheating in a game of cards or throwing out a box of ballots to help their favorite candidate (unfairness), burning their country’s flag or breaking off relations with their family (disloyalty), cursing their parents to their face or making a disrespectful hand gesture to their boss or teacher (abuse of authority), and getting a blood transfusion from a disease-free child molester (violation of sanctity). People’s answers could range from $0 (“I’d do it for free”) up to a million dollars or “never for any amount of money.”
On the harm and fairness questions, liberals and conservatives did not require substantially different amounts. But for questions that involved loyalty, authority and sanctity, conservatives required a lot more money — strongly suggesting that for them, those values loomed especially large.
The difference even maps onto preferences for dog breeds. Conservatives are especially likely to want dogs that are loyal and obedient. (Everyone wants dogs that are clean.)
In his later work, Haidt has rightly emphasized a sixth moral foundation, one that conservatives and liberals both respect, but that they understand differently: liberty. He finds that conservatives are more likely to emphasize the right to be let alone, while liberals emphasize the rights of vulnerable groups, such as racial minorities, whose freedom requires (in their view) government support. Nonetheless, the biggest and most consistent partisan differences involve loyalty, authority and sanctity.
Haidt’s central claim is that across partisan lines, people often fail to understand one another, because a moral concern that strongly motivates one group may be obscure or unintelligible to another. Democrats are wrong to be puzzled when rural and working-class Americans turn out to favor Republicans. There is no puzzle here, because Republicans are more likely to speak to their deepest moral commitments.
These claims are arresting, but it’s not clear that they are entirely right. Insofar as liberals focus on the environment, they are often motivated by ideas about the sanctity of nature. More than conservatives, liberals appear disgusted by cigarette smoking. Nor are they indifferent to loyalty: If a civil rights leader publicly opposed affirmative action, or if a prominent Democrat broke with the party on health care or climate change, many liberals would feel a sense of betrayal. Conservatives may be more likely to emphasize loyalty in the abstract, but in concrete cases, everyone cares about that virtue.
That said, Haidt has compiled a mountain of evidence to support his general conclusions. There’s a big lesson here for those who aspire to public office, including the White House: If they neglect the values of loyalty, authority and sanctity, they’re not going to speak to the moral commitments of a large segment of the American electorate.
Cass R. Sunstein is director of the Harvard Law School’s program on behavioral economics and public policy and is a columnist for Bloomberg View.