No doubt psychological theories may be put forward as to the origin of ethical from non-ethical ideas, such as the fear of punishment, but even if they originated historically from non-ethical ideas this would not prove that they now contained nothing beyond these ideas. With all new kinds of ideas there must have been a time at which they originated in the race as a whole or in any individual of it from psychological antecedents which did not contain the ideas. Besides, the moral facts of which we are aware when we see that certain actions are right or wrong and certain qualities good or bad are much more certain than could be any psychological theory which claimed to explain them away. Such a theory would rest on the psychology of children and savages, in whom the ideas originated, and the impossibility of obtaining reliable introspective evidence from such subjects makes it of itself highly speculative. The same remarks apply to any theory of ethics based on a study of the way in which children learn the use of ethical terms. In any case if the psychological theory merely tells us what experiences preceded the formation of the ethical ideas it is innocuous, while if it claims to analyze them in terms of these non-ethical experiences it is open to the objections already brought against naturalistic theories of ethics.
(A. C. Ewing, "Subjectivism and Naturalism in Ethics," Mind, n.s., 53 [April 1944]: 120-41, at 135-6)
Keith Burgess-Jackson, J.D., Ph.D. 