General question about the possibility of objective moral truth

[Natachan]

Before we talk about the question of making moral judgements of good or bad we need to first establish what morality is. The question takes it for granted that morality is understood by all, and I don't think that's right. So what is morality? It is a determination as to how things fit into certain value sets. Let's say I value human life. As such a moral action would be one that would promote that value of human life. If I don't value human life, then I have no reason not to kill people. As such I would not find it immoral to kill someone. You might disagree with me, and there we have a conflict.

Is either party OBJECTIVELY right? Well, in the sense of "does some external force give a damn" then the answer is no. Neither party has a more valid set of values in this particular situation. However we as humans have evolved as a cooperative social species. Those of us who don't value life don't generally live to tell about it. Those of us that don't value positive social structures generally don't survive to reproduce. As such you could say that we share a similar set of values that lead us to generally similar moral judgements.

I'm not so sure if we can say that people who don't value positive social structures don't survive. Actually my impression is that we have plenty of people of this kind in this world.
At the end my whole question comes up to find an argumentation not for those who keep social rules, but for those who don't. It's very frustrating if you have a real criminal in front of you and you try to explain him that (and why) his behavior is really wrong, while he just denies that there is an objective way to proof that. Of course we can still punish him. But I also want to show him that he himself knows that his behavior is wrong.

As a portion of the population the number is fairly small. Just as the number of people with genetic diseases is small. It is not advantageous, but it does happen.

At the very end you probably CAN'T provide an objective reason to the person who does not value life or positive social consequences.

Then gets to the rather nasty bit, we as a society IMPOSE some of our moral judgements. It is very hard to justify this objectively. Why does the majority get to impose their moral judgements on the minority? This is something I'm still working out on my own. There is some evidence to indicate that these people are sick, and as such it would indicate that their judgements and values might not be completely sound. But again, what is the objective justification? I don't think there is one. I'm not comfortable with that, but that might just be the way it is.