Many Catholics have learned how to refute the idea that there is no absolute truth—what is called global relativism.
It’s pretty straightforward: if global relativism is true, then there is at least one absolute truth, and so global relativism contradicts itself. We simply have to ask, “Is it absolutely true that there is no absolute truth?” and smile.
But there is another form of relativism that’s not self-refuting. Philosophers call it partial relativism, and it says that there are absolute truths in some areas, such as science, but not in all. Many relativists will thus assert that there are no absolute moral truths.
Although the content of moral relativism is not self-refuting, when you think it through you discover that it has several pitfalls.
A moral relativist who wants to be coherent will not simply say that moral relativism is true—he’ll say that we should live in a way consistent with it. (Otherwise, what’s the point?) He’ll say, for instance, that we shouldn’t “impose our morality” on other people, since they might have their own moral truth that’s different from ours but just as valid.
But as soon someone says that we shouldn’t do something (like impose our morality), or that we ought to live in a certain way (a way consistent with moral relativism), then he’s asserting at least one absolute moral truth, isn’t he?
But there can’t be no absolute moral truths and at least one absolute moral truth at the same time!
So, although moral relativism by itself is not self-refuting, saying that we should live in accord with moral relativism is.
There is another problem with moral relativism. This one hits closer to our common human experience.
Consider that to live as if moral relativism were true would involve not making any negative moral judgments about someone’s behavior. For example, if Jack rapes Jill, we would have no grounds within the framework of moral relativism to criticize Jack for his behavior, since he could easily assert that his behavior is morally good for him.
As moral relativists, all we could say is that what Jack did runs counter to our moral belief. But why should Jack care what we like and don’t like? He certainly doesn’t seem to be the type of person who would put other people’s beliefs and feelings before his.
Someone might object that what Jack did is wrong because he harmed Jane or because he coerced her to do something she doesn’t consent to. But this would undermine moral relativism, since it assumes as true the moral principle that we shouldn’t harm someone or do something without consent.
At this point, our friend might resort to a sort of partial-partial relativism and say, “Well, morality is absolute when our actions affect other people (interpersonal morality), but relative when our actions affect only ourselves (personal morality).”
Elsewhere I addressed this idea when it’s applied to sex. But generally speaking, why should we believe that only interpersonal morality is absolute and personal morality is relative? It's a totally arbitrary—and self-serving—principle. A relativist has to defend this idea, not just assert it as though it were self-evident.
Furthermore, am I not a person also? If morality is absolute when it comes to my interaction with other people, why is it not when I’m interacting with myself? If it’s wrong for me to stop other human beings from achieving the ends to which their nature directs them, it should be wrong for me to stop myself from achieving those same ends.
Another problem with this distinction is that it’s hard to think of any action that I might do that in no way affects someone else, at least indirectly.
A man who views pornography, for example, even though he does so all by himself, trains himself to view women merely as objects to be used for his own sexual gratification. Surely, that’s going to affect the way the he relates to other women in reality.
We praise authorities for arresting people who view child pornography, even if they’re doing it in secret, in part because we recognize that this “private” activity has indirect public effects: tacitly supporting an exploitative industry and potentially affecting the way they treat children in reality.
I suppose if someone were the only human being left on Earth, his actions would only affect himself. But that’s a scenario for science fiction, not the real world.
So, if we say that we must live in accord with the truth of moral relativism, we forfeit any grounds on which we can make any negative moral judgments. If we try to split hairs and say that only personal morality is relative, we run into the reality that we are social beings whose moral choices inevitably affect others.
And so, at first glance moral relativism might seem like a safer bet than global relativism. But when you think it through, it becomes clear that moral relativism is not a position that a reasonable human being ought to embrace.