Disquiet in ethics, or moral philosophy, has its main sources (a) in an irreducibly subjective or personal element contained in moral judgement, (b) in a tension between virtue and happiness, and (c) in the nature of moral disagreement. It will be useful to consider each of these in turn.
(a) It is evident that people worry more often about the objectivity of morals than about the objectivity of fact. A statement about, say, the conditions on a certain planet, even if it cannot be verified, seems to them objective in the issues it raises, because although the human mind is involved in making the statement, it is not involved in what makes it true or false. Thus, what makes it true that there are mountains on the moon would hold even if the human species had never existed. Moreover, the same point applies to factual statements much greater in their complexity. For example, one cannot verify the theory of evolution as one can a simple statement in astronomy; nevertheless, everyone believes that what makes it true or false is independent of human views about it.
The term ‘objective’, no doubt, has many uses; but none is more fundamental than the one discerned above. My view is objectively true, when in holding it I am in contact with reality, when I am forced into believing it by reality itself. So long as I believe that of my view, I shall never be shaken free of it. It is of secondary importance whether I can get others to agree with me or whether I have reasons for my view. For many of my beliefs about the past, for example, I have no evidence at all.