This is all very basic socialization and training.
The examples you linked pointed to correlations but they didn't control for genetics. They didn't compare the correlations between biological children and adopted children, so the strength of the socialization effect is unknown.
Whether its unPC to say so. Kids have to be raised a bit like dogs using pavlovian techniques of punishment and reward. They will modify their behavior and beliefs accordingly until they grow enough of a frontal lobe to question it. By then a lot of behaviors can be set in.
Here's the thing. I'm not being contradictory when I agree with your point. Yes, this works and there are two factors in play. There is the gene-environment interaction effect. The kid's behavior can be modified because your socialization is leading him towards a behavior that he finds rewarding in some sense that he would have trouble developing or discovering at his own at that stage of his life. This is less successful when socialization efforts battle against natural inclinations. The second point is that the heritability of behavior increases in effect as we mature, so the lessons you teach when they are young and which run against the child's inclinations will gradually be thrown off as the child begins to control more of his environment. The lesson doesn't stick and the only reason it did stick for a while is because of the parent's total control over the child's environment.
It would not be neurochemicals, it would be synapses, but just the same I get what you are getting at. I understand Haidt's argument I am just saying that stating group loyalty is a moral is subjective.
The feeling of correctness would have a neurochemical basis, the process of developing a logical understanding would involve the firing of synapses.
As for group loyalty being subjective, yeah, that's Haidt's point. A liberal who doesn't see it doesn't recognize the moral basis but a conservative who does see it does recognize the moral basis. That chasm make the issue subjective.
Your argument is similar to a blind man telling a sighted man that a rainbow is subjective. A rainbow is not subjective to a sighted man, it's as real as a tree, house, car, person. A blind man can say that a dog is objective because he can be aware of it through senses other than sight but a rainbow, even if he understands the physics of it, is beyond his senses - it's not as real as a dog.
Take that to the extreme and you have nationalism, hardly a moral virtue.
What are you talking about? Nationalism is as much a moral virtue as caring about equality and fairness.
We lead with our hearts and we hate to see suffering, but we also tend to ignore other realities. Society has become much more humane as a result, but it also became much more expensive because liberals tend not to know how to strike a balance.
This is only true to a point. Liberals do lead with their hearts and are more feeling creatures than conservatives. They do hate to see suffering. The solutions that liberals proposed though don't paint them in the same light. Stealing from other people in order to provide aid to third parties doesn't indicate caring nor self-sacrifice. I can match the most heartfelt liberal in a caring content if I can make all of my donations to aid needy people on your credit card. I'd be lying to myself though if I convinced myself that all of my agitation, effort and spending proved to me that I was a caring person.
Interestingly enough, when the definition of caring is changed from "spending other people's money on a problem" to "sacrificing one's own well being to remedy a problem" then we see that it is conservatives who top the scale.
So there is this fine distinction in play here - liberals are certainly hyper
aware of inequality and suffering, much more so than conservatives, but they don't follow through as well in terms of sacrificing their own well-being to remedy those problems.
As for society becoming more humane, there are always two sides to a coin, so looking only at the benefits which flow from a social welfare transfer scheme while ignoring the harms which were created on the other side of the coin, leads to a misleading conclusion. For Who, From Whom?
Really, neither group is complete or good in their moral perspective
This is tricky because the conclusion really depend on how YOU define complete. Conservatives completely overlap liberals on ALL moral categories. We understand WHY liberals feel as they do. If completeness depends on understanding, then conservatives are complete. However, if completeness depends on matching the scale of liberal intensity in their moral categories, then no, conservatives can't compete and hence do not meet the condition of completeness. Of course, liberals not understanding two important moral values held by conservatives makes them incomplete by any definition and this is probably why so many liberals can't really get their heads around what the hell conservatives are thinking and feeling, why it looks so damn alien and evil to them.
There really is no one size fits all solution here.
This only holds true if society benefits from the intensity of liberal moral values. Conservatives are bothered by lack of fairness and by inequality but liberals are bothered much more. So any policy solutions which develop from the increased intensity are really what we're looking at.