First, a bit of autobiography. I grew up in a Republican family. My father was originally from Bayonne, N.J., and it was the corruption of the Democratic political machine there that made him a Republican. As a child, I heard stories about how his friends had bought government jobs by making the appropriate âdonationsâ to city bosses. When he left Bayonne to raise his family in a more bucolic and less graft-prone Jersey suburb, he took with him a firm conviction about who the good guys were.  Years later, when I left home for college and began the study of economics, I read great works on both sides of the political divide. I devoured âThe Affluent Society,â by John Kenneth Galbraith, and âCapitalism and Freedom,â by Milton Friedman. I appreciated both as compellingly written books by brilliant minds, but I had little doubt that Friedmanâs case for limited government was the more persuasive.  To be sure, that judgment reflects some confirmation bias â the tendency of people to interpret evidence in a way that is consistent with their previous beliefs. No one can escape his or her own history. For better or worse, my father and Milton Friedman bear joint responsibility for why, when I have occasionally entered the political arena, it has been on the side of the Republicans.  Yet I have lived most of my adult life in Massachusetts, as a professor at Harvard, where Democrats far outnumber Republicans. Republicans are rare enough among my Harvard colleagues that I am often considered something of an oddity.  In 1993, for instance, when Bill Clinton was moving into the White House, I was approached by a Harvard dean. âGreg,â he said, âI asked one of your colleagues whether you might be among the faculty taking leave to join the new administration. He told me that you were a Republican. Is that possibly true?â I told him it was. The dean would have been less surprised if I had told him that I was born on Jupiter.  This personal history makes me a bit of an outsider wherever I am. Among most of my friends and colleagues here in Massachusetts, I am that oddball conservative. Among most of my family and political allies, I am that oddball from liberal Harvard. Yet hanging out with both Democrats and Republicans has some benefits. One is that I avoid the disdain that each group often feels for the other.  A classic result in social psychology, called the Robberâs Cave experiment, sheds light on the current dysfunctional political dynamic. It was conducted in 1954 by the psychologist Muzafer Sherif.  Mr. Sherif took a group of 22 boys, 12 years old, to a summer camp in Robberâs Cave State Park in Oklahoma. The boys did not know one another but came from similar backgrounds. They were all being raised in white, middle-class, Protestant, two-parent families. The boys were randomly split into two groups.  During the first week of camp, the groups were separated. The boys within each group participated in various activities together, like hiking and swimming. They bonded with one another, and each group developed its own norms of behavior. The two groups named themselves the Eagles and the Rattlers.  In the second week of camp, the Eagles and the Rattlers were brought together for competitive team activities like baseball and tug-of-war. Even though the boys had similar backgrounds, the competition was far from friendly. Taunting, name-calling and vandalizing the other teamâs property were common. The teams were so aggressive that the researchers sometimes had to physically separate them. When the boys were later asked about the experience, they described their own team as virtuous and the opposing team in much more negative terms.  In short, group identity and competition led to irrational and self-righteous hostility. Doesnât that sound like the political rhetoric we hear on the daily news?  Now imagine that Mr. Sherif had added a wrinkle to his experiment. Suppose that one of the boys had been required to switch teams every day. It seems likely that this boy would have developed friendships in both groups and, at the same time, would have been viewed by both with suspicion. He probably would have said: âHey, guys, the other team really isnât so bad. Theyâre a lot like us.â But his words would most likely have been ignored.  That is how I feel every day. While among Republicans, I want to say President Obamaâs goal of universal health insurance has a noble motivation, and it is impossible to achieve without a significant expansion in the role of government. While among Democrats, I want to say President Obama has vastly oversold the Affordable Care Act. The law is unlikely to reduce the cost of health care as promised, will shrink the economy by increasing implicit marginal tax rates and will, by virtue of its scope and complexity, lead to numerous other unintended consequences.  Mr. Sherif did not try my hypothetical wrinkle to his experiment, but he did manage to return some harmony to the Eagles and the Rattlers. After the period of zero-sum competition was over, the boys faced a series of âsuperordinateâ goals that transcended group concerns. For example, the boys had to deal with an interruption in their water supply, a problem that could be solved only if the two groups worked cooperatively. After several joint activities, the animosity lessened. When the camp was over, the boys agreed to return home on a single bus, and they happily socialized with members of the other group.  HOW to apply this lesson to national politics is far from clear. Perhaps it suggests that the best policies are those that transcend traditional partisan divides. Ronald Reaganâs 1986 tax reform and Bill Clintonâs 1996 welfare reform were major legislative achievements that garnered support from both sides of aisle. By contrast, the vote on President Obamaâs 2010 health care reform was entirely one-sided, so it is no surprise that the law is still the source of much rancor.  Comity is hard to achieve. From a lifetime of experience, I know that most people donât view Democrats and Republicans symmetrically. In their view, truth and virtue lie entirely with the group to which they happen to belong. If that describes you, just remember that the Eagles and the Rattlers once thought the same thing.  N. Gregory Mankiw is a professor of economics at Harvard. He was an adviser to President George W. Bush.
A psychologistâs long-ago experiment shows how two groups of 12-year-olds rose above taunting and name-calling: by facing goals that transcended group concerns. Government leaders might learn from it.