What was G.E. Moore’s naturalistic fallacy?
Moore (1873–1958) contended that goodness cannot be analyzed in terms of any other property. In his Principia Ethica (1903) he wrote:
It may be true that all things which are good are also something else, just as it is true that all things which are yellow produce a certain kind of vibration in the light. And it is a fact, that Ethics aims at discovering what are those other properties belonging to all things which are good. But far too many philosophers have thought that when they named those other properties they were actually defining good.
Moore thought that we know what is good directly, just as we know the color yellow when we see it. Thus, “We can only point to an action or a thing and say ‘That is good.’ We cannot describe to a blind man exactly what yellow is. We can only show a sighted man a piece of yellow paper or a yellow scrap of cloth and say ‘That is yellow.’“ The same is true of what is good. Whenever what is good is defined in terms of some “natural” property, such as “resulting in the good for the greatest number,” the naturalistic fallacy has been committed because it is always possible to ask of something that has the natural property, “Yes, but is it good?”
Moore’s notion of the non-reducible nature of goodness became for a while a concept and standard for other ethicists to both refute and match in rigor.