In a book written early in this century, Principia Ethica, G. E. Moore put forward the view that naturalism (which see) in any of its forms commits the naturalistic fallacy. Moore thought that "good" names a "non-natural" "simple" quality and is never equivalent in meaning to any combination of natural qualities. This was revealed, Moore thought, by the fact that, after listing any "natural" quality of something (pleasurable, for example), we can always raise the question "but is it good?" See Prescriptivism.