Naturalistic fallacy

In metaethics, the naturalistic fallacy is the claim that it is possible to define good in terms of merely described entities, properties, or processes such as pleasant, desirable, or fitness. The term was introduced by British philosopher G. E. Moore in his 1903 book Principia Ethica. Moore's naturalistic fallacy is closely related to the is–ought problem, which comes from David Hume's Treatise of Human Nature (1738–40); however, unlike Hume's view of the is–ought problem, Moore (and other proponents of ethical non-naturalism) did not consider the naturalistic fallacy to be at odds with moral realism.