Recognizing the importance of our social environment in generating customs and beliefs, many people suppose that ethical relativism is the correct metaethical theory. Furthermore, they are drawn to it for its liberal philosophical stance. It seems to be an enlightened response to the sin of ethnocentricity, and it seems to entail or strongly imply an attitude of tolerance toward other cultures.
Tolerance is certainly a virtue, but is this a good argument for it? I think not. If morality is relative to each culture, then if the culture in question does not have a principle of tolerance, its members have no obligation to be tolerant.
Not only do relativists fail to offer a basis for criticizing those who are intolerant, they cannot rationally criticize anyone who espouses what they might regard as a heinous principle. Relativists cannot morally criticize anyone outside their own culture. Adolf Hitler’s genocidal actions, as long as they are culturally accepted, are as morally legitimate as Mother Teresa’s work of mercy.
There are other disturbing consequences of ethical relativism. It seems to entail that reformers are always (morally) wrong since they go against the tide of cultural standards. William Wilberforce was wrong in the eighteenth Century to oppose slavery, the British were immoral in opposing the burning of widows in India.
There is an even more basic problem with the notion that morality is dependent on cultural acceptance for its validity. The problem is that of culture or society is notoriously difficult to define. This is especially true in a pluralistic society like our own where the notion seems to be vague with unclear boundaries.
One person may belong to several societies (subcultures).. if Mary is a US citizen and a member of the Roman Catholic church, she is wrong if she chooses to have an abortion and not-wrong if she acts against the teaching of the church on abortion.
This moral Babel.. has lost its action-guiding function.
Louis Pojman
Ethical Theory