It seems that the divide between conservatives and liberals grows sharper every day, especially during election season.  But what is the source of this bitter partisanship?
Research by Jonathan Haidt and Jesse Graham may begin to provide an answer.  Their research suggests that people of different political affiliations are not merely divided over the specific values they hold, but are divided on the very foundations of their values.  Using evolutionary theory and anthropological evidence as a guide, these researchers split moral values, or norms, into five basic “foundations”: harm/care, justice/reciprocity, in-group loyalty, respect/authority, and purity. [1]  For example, though someone might believe that murder, progressive taxation, and sexual promiscuity are all morally wrong, they are clearly wrong in different ways. The moral foundations view captures this intuition by creating clear divisions between them: the first is concerned with harm, the second with justice, and the third with purity.

Further research has demonstrated that people with different political affiliations place a different degree of emphasis on these five foundations[2]. Graham and Haidt found that while both liberals and conservatives value harm/care and justice/reciprocity, liberals tended to weight these norms as more important than conservatives.  Meanwhile, conservatives were much more likely than liberals to emphasize the importance of loyalty, respect, and purity norms.

This can be illustrated with an example.  Many liberals point out that comprehensive sex education would reduce rates of teen pregnancy and STD transmission.  Here, liberals are chiefly concerned with avoiding harm and caring for others.  On the other hand, conservatives who favor abstinence-only education may do so because they are somewhat less concerned with harm, but greatly value purity.

This research highlights the difficulty of discussing these polarizing issues.  Liberals are left wondering why conservatives are so concerned with less important norms like purity, and conservatives are left wondering why liberals can be so blasé about something as important as purity.  Though common ground is sometimes difficult to find, there is some evidence that people are sensitive to different value systems, and may be able to consider another’s values when making their moral judgments.[3]  Hopefully, future research in moral psychology will improve the appreciation of different moral viewpoints.