Mr. Haidt’s hypothesis is that there are five dimensions of morality: harm (don’t harm others), fairness, loyalty to one’s group, respect for authority, and purity. Furthermore, his theory is that liberals only understand harm and fairness, while conservatives value all dimensions of morality. You can read a more detailed academic article if you are curious.
Do liberals have loyalty?
I remembered this story about a significant bisexual subculture at Stuyvesant High School:
Alair is headed for the section of the second-floor hallway where her friends gather every day during their free tenth period for the “cuddle puddle,” as she calls it. There are girls petting girls and girls petting guys and guys petting guys. She dives into the undulating heap of backpacks and blue jeans and emerges between her two best friends, Jane and Elle, whose names have been changed at their request. They are all 16, juniors at Stuyvesant. Alair slips into Jane’s lap, and Elle reclines next to them, watching, cat-eyed. All three have hooked up with each other. All three have hooked up with boys—sometimes the same boys.
Good grief: high school! I mean, can't we keep this kind of thing on premium cable where it belongs?
To these kids, homophobia is as socially shunned as racism was to the generation before them. They say it’s practically the one thing that’s not tolerated at their school. One boy who made disparaging remarks about gay people has been ridiculed and taunted, his belongings hidden around the school. “We’re a creative bunch when we hate someone,” says Nathan.
So it seems liberals have no shortage of ingroup loyalty, even at the expense of the official liberal virtues of care and reciprocity (not to mention authority). Although, I suppose it could be argued that this particular display of solidarity has nothing to do with morality. Indeed, the "cuddle puddle" seems to share the motivation of little boys that pull the legs off spiders: it's fun to torment those that can't fight back.
Do liberals have purity?
Again in reference to the story above: if we take at face value the outrage -- outrage! -- expressed at intolerance, we see a concern for purity: we mustn't sully our society with intollerant thoughtcrime such as this.
The modern environmental movement has a whiff of purity about it, eg. we mustn't sully ANWR with oil exploration, for instance; more generally, nature must remain "pristine"; ie. uncontaminated by human activity. Michael Crichton has written about this.
Do liberals have authority?
Tough call. Liberals love authority in Castro's Cuba and Kim's North Korea, but they have little appetite to actually live there themselves. They might profess deference to the authority of SCOTUS, for instance, or "science", but this is transparently offered in bad faith. Sure, when James Watson says that mankind evolved from common stock with apes, liberals are all about the authority of science. But when Watson says that we evolved differently than Africans, authority quickly loses out to purity -- thoughtcrime! -- in the condemnations that follow. Liberals tell us that we must defer to the scientific community about global warming, but not about the Yucca nuclear waste depository.
No, liberals aren't really interested in authority.