Jonathan Haidt's theory is really interesting; it answers a lot of questions I've had in the past few years about "conservative vs liberal". Though I'd say I'm a liberal (by temperament more than by ideological loyalty), I've outgrown the idea that my political opponents disagree with me simply because they are ill-informed or stubborn.
There are a great many decent, intelligent folks who can't in good conscience support my views, and, I hasten to add, there are a sizable number of people who agree with my politics, but who are jerks and blowhards.
I just wish good people of all stripes could learn to find middle ground, but group allegiance and knee-jerk opinions (whose proponents imagine are simply expressions of common sense) sometimes prove too tenacious.