Philosophers put forward moral theories in order to provide clear, coherent, and comprehensive descriptions of morality and its justification. No philosopher would accept the view that his theory provides incorrect answers to some moral questions, even if it is granted that it provides correct answers to most others. Almost all moral theories, on the standard interpretations, provide correct answers to most noncontroversial moral questions. However, if a moral theory gives an incorrect answer to any noncontroversial moral question, it cannot be trusted to give a correct answer to any controversial moral question. To claim that a moral theory gives an incorrect answer to any moral problem [sic; should be "question"] is to reject that theory or, at least, to require that it be revised.
(Bernard Gert, Common Morality: Deciding What to Do [New York: Oxford University Press, 2004], viii)
Note from KBJ: I have a different conception of moral theory, or what I call normative ethical theory. The point of a normative ethical theory, such as theological voluntarism, natural law, or act-utilitarianism, is to systematize one's beliefs. A normative ethical theory states a necessary and sufficient condition for moral rightness (understood as permissibility). To a theological voluntarist, for example, an act is right if and only if it conforms to God's will. To an act-utilitarian, an act is right if and only if it maximizes happiness. In propounding a theory, I express my own commitment to the theory and submit it to others for their consideration. I suppose someone could interpret this process as getting the truth about moral rightness, but it's not necessary to view it that way. (I'm a subjectivist about value.) If someone points out that my theory has an unacceptable implication, I have three options: (1) I can abandon the theory (not likely!); (2) I can deny that my theory has the stated implication (this is known as grasping the bull by the horn); and (3) I can admit that my theory has the stated implication but accept it (this is known as biting the bullet). This process of theorizing, objecting, and replying, which can be carried out at a high level, helps to sharpen the theory, which in turn helps people understand precisely what it is that they are accepting when they accept it.
