With the possible exception of Poland, there is no advanced industrial country as deeply polarized as America is today. Gridlock in Washington is a failure of American politics, and the solution--if there is one--can only come from the resources of America's political tradition.
Haidt's typology may fit the United States, but it has less application for European countries (including Britain) where political consensus is stronger and religion much weaker.
Pointer from Arts and Letters Daily, a venerable, outstanding blog that has surprised me by surviving the death several years ago of its founder, Denis Dutton.
Perhaps the essence of Gray's critique is this:
Human beings are not amoebae that have somehow managed to turn themselves into clever primates. They are animals with a history, part of which consists of creating cultures that are widely divergent. Using evolutionary psychology to explain current political conflicts represents local and ephemeral differences as perennial divisions in the human mind. It is hard to think of a more stultifying exercise in intellectual parochialism.
Gray makes some useful points. However, I think that his strongest criticisms are of positions that Haidt did not take, so that Gray is knocking down straw men.
For example, I do not see Haidt as universalizing the political culture of the United States. Instead, I think he would universalize the tendency for group conflict in politics and religion. Haidt would universalize the inability of groups to resolve their religious and moral disagreements through reasoned argument. On the contrary, reasoned argument can often cause opposing groups to dig in harder. That is my main take-away from The Righteous Mind, and I thought it deserved an extended essay.