But don't mistake "The Righteous Mind" for yet another guide to how liberals can revive their rhetoric and electoral appeal. Mr. Haidt is not a partisan with an agenda. He is a social scientist who appreciates America's tribalism, our "groupishness." He worries, though, that our divisions are hardening into mutual incomprehension and dysfunction. His practical aim is modest: not to bridge the divide between left and right, atheist and believer, cosmopolite and patriot, but to make Americans, in all their diversity, more intelligible to one another.
Mr. Haidt describes at length the fascinating research that he and his colleagues have carried out through a website called YourMorals.org. The site asks visitors to state their political and religious preferences and then poses a range of questions meant to elicit a moral response. Participants might be asked, for example, if they agree or disagree with such statements as: "One of the worst things a person can do is to hurt a defenseless animal"; or, "It is more important to be a team player than to express oneself"; or, "In the teenage years, parental advice should be heeded."