Anglo-American moral philosophers in our period were well aware of issues about the objectivity and justification of ethical claims. These issues were central to the whole project of metaethics. Challenges to these claims went by the names of relativism, skepticism, and subjectivism. So far as I can tell, there was no general agreement about how these challenges should be met.
Frankena's distinction of three kinds of relativism is perspicuous. The first of these is descriptive relativism, of which the best-known form is cultural relativism. This is the claim, in effect a thesis in sociology or anthropology, that different groups of people, different cultures, have substantively different ethics, i.e., they recognize different things as good or bad, different things as obligatory or forbidden. At a certain level this is clearly true. What is disputed is how fundamental these differences are and what they do or do not entail for normative ethics.
The second type of relativism is normative relativism. Normative relativism asserts that different cultures should act on their different ethical beliefs or principles. Where descriptive relativism says that people in culture X and people in culture Y have and act on different ethical principles, normative relativism says that it is right for people in culture X to act on their ethical principles and right for people in culture Y to act on their different ethical principles. The Romans are right to do as the Romans do. If, for example, a certain culture regards the claims of honesty as taking precedence over the claims of family loyalty, then people in that culture ought to give precedence to the claims of honesty. But if a certain other culture regards family loyalty as taking precedence over honesty, then people in that culture ought to give precedence to the claims of family loyalty.
The third type of relativism is metaethical relativism. This is the view that there is no objective rational way of justifying ethical claims, and so, that different, even contradictory, ethical claims are equally justified, or rather equally unjustified. This would seem to be close to, if not identical with, ethical skepticism, which we will take up in a moment.
Some people have blurred the lines between descriptive or cultural relativism on the one hand and normative and metaethical relativism on the other, or even appealed to cultural relativism in support of normative or metaethical relativism. Moral philosophers in our period tend to criticize those appeals as fallacious. The differences between cultures, even if they go very deep, are not sufficient to establish that either normative or metaethical relativism is true.
Introductions to ethics in our period did not agree about how to describe the challenges of relativism and skepticism, much less about how to meet them. Ewing discusses skepticism on pp. 26-27, 98, and 110-11 of his Ethics and then gives pp. 111-15 to cultural relativism. He also discusses what he calls the subjective view of ethics on pp. 26-27 and 156-57. Harman, whose index includes only proper names, has no discussion of skepticism or relativism, but his chapter 3 is entitled "Emotivism as Moderate Nihilism." Raphael has no index entries for skepticism or for relativism but does have a couple of entries for subjectivism. Rachels has no entries for skepticism or for relativism, but his second chapter is concerned with cultural relativism and his third chapter with subjectivism. Frankena does not discuss skepticism as such, presumably because he thinks his discussion of metaethical relativism says what needs to be said about it. Readers who look up "Ethical Skepticism" in Paul Edwards's Encyclopedia of Philosophy will be referred to "Emotive Theory of Ethics," "Ethical Relativism," and "Ethical Subjectivism."
Philosophers in our period apparently recognized that issues about the objectivity and justification of ethical claims were too complex and difficult to be treated, on anything beyond the simplest level, in introductions to ethics. On a higher or more technical level there was no general agreement about how these issues should best be treated. In this situation I would suggest that we draw a rough and ready distinction between two different contexts in which problems of objectivity, justification, relativism, skepticism, and subjectivism come up for discussion. The first context is theoretical: the continuing effort to come to terms with the legacies of Moore, Prichard, Ross, Ayer, Stevenson, Hare, and the heirs to their arguments. The second context is more obviously practical, not to say existential: addressing requests to justify particular claims about duties and obligations, or trying to answer the general question "Why should I be moral?"
(excerpted from chapter 1)