Full Idea
Good does not, by definition, mean anything that is natural; and it is therefore always an open question whether anything that is natural is good.
Gist of Idea
It is always an open question whether anything that is natural is good
Source
G.E. Moore (Principia Ethica [1903], §027)
Book Reference
Moore,G.E.: 'Principia Ethica' [CUP 1980], p.44
A Reaction
This is the best known modern argument for Platonist idealised ethics. But maybe there is no end to questioning anywhere, so each theory invites a further question, and nothing is ever fully explained? Next stop - pragmatism.
Related Ideas
Idea 3894 We may define 'good' correctly, but then ask whether the application of the definition is good [Scruton]
Idea 22754 Saying the good is useful or choiceworth or happiness-creating is not the good, but a feature of it [Sext.Empiricus]