This argument asserts that there is no such thing as objective good or evil, thus allowing for a “different strokes” approach to what most people would consider moral atrocities. According to a moral relativist, we should do nothing to address the blatant fascism in North Korea or child sex trafficking in Thailand, simply because their culture’s version of morality is different than ours.
Likewise, we cannot condemn the horrors of the past such as slavery. By claiming every society’s assessment of morality is equally acceptable, we not only allow but perpetuate cycles of injustice, and immorality. Furthermore, the assertion that no moral rules can be fairly applied to the whole of humanity is, in itself, a moral rule being applied to the whole of humanity.