Explain Holmes' statement: "Diversity seems to be more widespread in specific application than in principle."
Holmes means that specific moral systems, while varying across cultures, still are informed by broader concerns. As he argues in Ethics: Approaching Moral Decisions:
...how societies define property rights and how they punish wrongdoers can vary greatly, but they still may be equally concerned about both conserving property and punishing wrongdoers, and equally concerned about an ordered society.
This is written in the context of a critique of relativism, which focuses on the specific circumstances that give rise to moral beliefs. Relativists argue that moral beliefs are contingent on social realities, and thus vary so much from society to society that it makes little sense to try to posit a universal morality. Indeed, to do so, relativists argue, is usually to attempt to impose one's own moral code on other cultures. Holmes is a Christian ethicist, and believes that there are, within reasonable constraints, moral concerns that transcend cultural contexts, and that certain cultural practices should not be tolerated.