Led Guardian wrote:
Ah, but while the Mayans had their own way of making the sacrifices justifiable, that is not a justification in all cultures. In the US, while the right to practice one's religion is far-reaching, human sacrifice is not allowed. Even if the people committing the sacrifice believe it will achieve some beneficial effect, the US and its citizens have deemed that this is murder, and is wrong. That there makes that moral relative to the culture. What is justifiable in one culture is not necessarily considered justifiable in another.
A slight mix-up: killing group members is the action, sacrifice to the sun is the justification. Other groups have the death penalty, a self defense clause, abortion rights (group membership debatable), assisted suicide, widow burning,....
Often, too, the moral justification for a killing or mass killing comes after the fact, and is created by the perpetrator of the killing. The Inquisition for instance. The church killed Jews and pagans to solidify their power base, not something generally considered to be a moral justification. However, when presented to the public, they were killing evil heretics who were trying to destroy and corrupt God's Children. Granted, some of the people who were in charge may have genuinely believed this reason, but I think it is overly optimistic to believe they all did.
The moral justification of an action does not have to be its actual cause or reason. If you save a child from a burning building in order to be treated as a famous hero, you still do a morally good thing (assuming saving children from fiery death is a morally good thing). That of course doesn't mean that motivation does not play a role, if you do the right thing for the right reason we might find it especially recommendable.
Furthermore, I do indeed believe that many people in their everyday life try to act according to morals even explicitly. "You just don't do that" and so on. And another caveat: of course if someone is motivated by a moral believe does not make that moral believe true.
Also, you're argument that certain universal morals are independent of particular groups of moral-makers assumes that just because a majority (even a vast one) believes something, then it is truth.
Not at all. The very point is to transcend the category of belief. Believing something to be true, no matter how many people do so, does not make it true in any way. If anything it will tilt your judgment on whether it's true or not, but like anyone, you may be wrong.
My argument aims to show that all human beings, simply by virtue of being social animals (We live with others), moral makers (rational agents, engaged in practices of justifying their actions to one another) and cognitive predictors (we think about the future) find themselves in a situation where a rule regulating (forbidding it, requiring justifications for exceptions and creating a sense of what counts as a justification) the killing of members of one's own in-group (the people you live with, your society) will be set up. The reason is two fold: for one, as I mentioned, we need a sense of security and certainty in order to actively be engaged in our world and will, if healthy, do whatever it takes to create that sense. For another, cooperation requires living people to cooperate with no. No group can survive the continuous killing of it's own members.
A similar, but weaker argument can be made concerning the regulation of sexuality, but that argument hinges of reproduction being linked closely to sex, a connection that modern technology (contraceptives) has basically severed in the western countries.
As you see, the argument does not argue from what people believe, but from a reason why any survivable society at all, simply by what the human condition (or human nature, if you will) entails, will come to accept certain morals. Note that none of the reasons I gave for adopting those morals are moral reasons and also note that in some sense, it is a very abstract argument, it is concerned with the necessary requirements for the possibility of sociality at all, not with any sociality in particular.