Arnold Kling thinks about human nature:
I believe that humans in large societies have two natural desires that frustrate libertarians.
1. A desire for religion, defined as a set of rituals, norms, and affirmations that are shared by a group and which the group believes it is wrong not to share. Thus, rooting for your local sports team is not a religion, because you realize that it is not wrong for someone else not to root for your local sports team. But if you are against GMO foods, then you believe that those who disagree with you are wrong.
2. A desire for war. I think that it is in human nature to fantasize about battles against tribal enemies. War arises when those fantasies are strong enough to drive behavior.
Though he mentioned tribalism, I think tribalism needs to be pulled up to the top as one of the main two tendencies. I commented:
I would have recast your second bullet point into a predilection for tribalism rather than a fondness for war. I think it is more all-encompassing. It is tribalism that leads to war, but it also leads to any number of other dysfunctional practices, like protectionism, immigration restrictions, etc.
In addition, tribalism is making it more and more difficult for basic politics to work, particularly for libertarians. As a libertarian, I used to make common cause with the Left on things like gay marriage and the Right on things like regulatory reform. This is increasingly hard to do -- if one does not hold all the group's other beliefs, they don't want to work with you on a narrow issue. Several years ago I was uninvited from co-chairing an effort on gay marriage because others in the group did not like my stances on unrelated issues like education choice.
A few weeks ago there was a bizarre spectacle of a woman who supports the imposition of Sharia law in the US helping to lead the women's march. What the hell? Countries with Sharia law often look like apartheid but for women rather than blacks. Why is is a leading women's advocate supporting such a thing?
This seeming contradiction makes sense, though, in the context of tribalism. The "other" tribe (the Right) opposes sharia law and is skeptical of fundamental Islam so our side must fully embrace it. There is no longer the possibility of any subtlety, like "I don't traffic in gross generalizations about Muslims and welcome them to this country but Sharia law (at least as practiced in some countries, I don't have the religious history chops to know if it is being interpreted correctly) has many things in it that are an abomination to individual rights and Muslims coming to this country are going to have to leave parts of that behind."
This is one of my emerging rules of politics: if one political group holds a position that does not seem consistent or logical in the context of their other positions, assume they are holding this position because their rival political group has already staked out the opposite side.
Update: In retrospect, most of what I am calling tribalism he is calling religion, so I think we are saying the same thing with different words.