Haidt’s research leads him to posit five psychological foundations of human moral sentiment, each with a distinct evolutionary history and function, which he labels harm, reciprocity, ingroup, hierarchy, and purity. While the five foundations are universal, cultures build upon each to varying degrees. Imagine five adjustable slides on a stereo equalizer that can be turned up or down to produce different balances of sound...If you’re a sharia devotee ready to stone adulterers and slaughter infidels, you have purity and ingroup pushed up to eleven. PETA members, who vibrate to the pain of other species, have turned ingroup way down and harm way up.
...Democrat-leaning liberals draw almost exclusively from harm and reciprocity, Republican-leaning conservatives draw more from the whole range of moral emotion.
On the last point, color me skeptical.
Liberals less concerned with in-group solidarity? True, they might not have an American flag on their lawn. It would leave less room for the "impeach them both" sign.
The liberals on the County Council that is considering a ban on trans fats would never be accused of appealing to the primitive emotions of purity/disgust.
And if research shows that liberals are relatively indifferent to hierarchy and authority, who am I to question that? After all, this is only a blog post, not a peer-reviewed journal. And I don't have tenure.