One of the chief objections to attacks on moral relativism (often held by philosophical naturalists) is that morality is defined by culturally accepted norms. Thus, they argue, that there is an absolute in the sense that society holds some actions to be right and others wrong, but that morality is not an absolute in the sense that the standard of moral conduct never changes.
I want to first note that there is a big difference between “moral norm” based on statistical averages found in any given society and “moral absolutes” which are independent of public opinion, thus transcendent. While the former does change based on the cultural milieu, the latter is the only one capable of enacting and sustaining moral change in culture. In other words, without the objective moral view found exclusively in Christianity that all humans are created equal, and that that equality rests on a non-physical component of what makes us up (soul), there would be no real reason to oppose racism, racial slavery, or any other form of systematic oppression of others.
One must also define the “norm” being referred to. Norm is a statistical term which relies on a sample set of data. Depending on the sample size, and the constitution of the same, the calculated norm can vary widely. Statistics are also effected by other factors as well. So when we talk about “moral norms” it is far from clear what is actually being referred to. What region are we talking about? What people in that region are we referring to? What questions are we asking and what metrics are we measuring? All of these effect the outcome of what we deem the “moral norm”.
So while “norms” may change, that is not what constitutes morality. Simply put, if a relativist were to reduce morality down to statistical averages then all they are left with the ability to merely describe a moral behavior and not the ability to prescribe it. In the end, all they could say is that someone’s behavior falls outside of a statistical average at any given point in time. Relativists would not have a valid basis for calling any action objectively wrong in any capacity, just merely a deviation from a particular standard.
What is interesting is that even using statistical averages relativists still manage to smuggle in a moral absolute in the form of “everyone ought to conform to the statistical averages”. Where does this absolute come from, or does it ultimately succumb to being relegated to realm of subjective personal preference?
When it comes to morality, either there are absolutes or there are no absolutes. However to say that there are no absolutes is to claim an absolute which means that no matter how you slice it, everyone believes in moral absolutes. The only question is where we get those absolutes and why we think they are binding on everyone else.