but why does naturalism entail moral relativism?
Naturalism holds that the way to understand the all of nature is through the scientific method.
I’ll answer your question with a question: What scientific method would anyone use to study an objective moral standard and how does a factual situation effect (or affected by) an objective moral standard? Objective moral standards are independent of human subjective beliefs about what is moral/immoral.
Everything in Nature that is objective is subject to the laws of nature and is represented by a theory/theorem. I know of no such theory/theorem for an objective moral standard/quality. Humans might have subjective beliefs, for example, about how the universe came to be but that in no way changes the objective facts about how it did come about. We make scientific progress when our subjective beliefs more closely resemble the objetive truth.
Zoologist observe and study animal behaviorisms. Anthropologists and sociologists study human cultural behaviorisms. The only thing these three disaplines can do is *discribe * these behaviors. In the case of humans the latter two extends to what humans
subjectively believe about their world as to what is right and wrong, good and evil. In discribing different cultures, it is an observed fact that different cultures have different subjective attitudes/beliefs about what is moral or immoral. That is, what’s moral/immoral is
relative to a culture’s intersubjective beliefs. Civil rights, for example, are intersubjective beliefs about what should or should not be a legal right among its citizens. These civil rights are subordinate to cultural beliefs.
What happens if a culture changes its beliefs about what’s moral? Obviously, the moral standard changed…but did the culture’s moral beliefs/understanding progress (as in moral progress) or did the moral beliefs/understanding degress?
There is no way to make that determination unless you can present an objective moral standard by which to
judge a culture’s moral code against. Without an objective standard all you can say is that the culture’s moral code changed and the term “moral progress” would be meaningless. Human rights are believed to be culturally independent. In fact, humanists hold that cultural beliefs about what is moral/immoral are subordinate to human rights. IOW societies are subordinate to human rights philosophy. And as I said in an earlier post, moral progress can only happen when a culture’s moral beliefs more closely resembles that of objective moral standards, to that of a moral Truth
If humans/you hold the belief that human rights are real, not the stuff of myth making (mythology), and that these objective morals don’t conform to the scientific method then we have an interesting situation here. We are saying there is something about the
nature of reality which does not conform to
scientific Naturalism or to the scientific method.
How then do we come about having this knowledge? Is it by intuitionism, a self-evident truth, reasoned faith? Seems to me all three of those have the same meaning.
Atheists who claim to believe in metaphyscial Naturalism (the denial of moral realism) on the one hand and Humanism’s human rights (moral realism) on the other hand are factually being oxymoronic. It makes no sense for anyone to say they are both a moral realist and a moral anti-realist at the same time.