Who taught there was no absolute right or wrong?

The belief that there is no absolute moral orientation, and no absolute right or wrong, is called Moral Relativism. Among the most prominent contemporary philosophical defenders of moral relativism are Gilbert Harmann and David B. Wong. Notable historical philosophers and those of similar profession that proposed and described forms of moral relativism include the Greek historian Herodotus and sophist Protagoras, and the Chinese Daoist philosopher Zhuangzhi.