LIKE SOCIALISM, RELATIVISM HAS ALSO BEEN AROUND FOR A LONG TIME

Perhaps the clearest early expression of relativism is found in Aristotle's Nicomachean Ethics (350 BC), Book V, chapter 10:

It is the opinion of some people that all the rules of justice are conventional, because that which is natural is immutable and has the same authority everywhere, as fire burns equally here and in Persia, but they see the rule of justice continually altering.

But this is not altogether true, though it is true to come extent. Among the gods indeed it is probably not true at all; but in this world, although there is such a thing as natural justice, still all justice is variable.