[PHI 2200] The Slippery Slope of Moral Relativism

Metaethical Moral Relativism (MMR) is the thesis that "the truth or falsity of moral judgments, or their justification, is not absolute or universal, but is relative to the traditions, convictions, or practices of a group of persons." By "group of persons," it is usually meant a culture or society. For example, the moral judgment "Female Genital Mutilation (FGM) is morally wrong" is true relative to a Western culture, such as the society of the United States, but false relative to a non-Western culture, such as the society of Somalia.

Now, is there a principled reason for thinking that the unit of relative truth must be a culture or society? If there isn't, then one could argue that MMR collapses to the thesis that "the truth or falsity of moral judgments, or their justification, is not absolute or universal, but is relative to the convictions and practices of an individual person." After all, even within a culture or society, different individuals have different beliefs, convictions, and practices. If so, then one could argue as follows:

1. There is a continuum between the moral convictions and practices of a culture or society and the moral convictions and practices of an individual person.
2. In terms of that continuum, the moral convictions and practices of a culture or society and the moral convictions and practices of an individual person differ only in degree.
3. Therefore, no principled distinction can be drawn between the moral convictions and practices of a culture or society and the moral convictions and practices of an individual person.

If (3) is true, then there is no principled reason for thinking that the unit of relative truth must be a culture or society rather than an individual person. Is this a compelling argument? What do you think?