The naturalistic fallacy according to Moore and its relation to Hume will be analyzed for an exposition both clear and updated in contemporary formal logics, which will denounce its limited scope in current metaethics. I’ll identify the origins of the expression naturalistic fallacy in Moore and atempt to refne its meaning and use, contrasting its relationship to the open-question argument and Hume’s Law. Its application is identifed in four aspects: invalidly as the openquestion argument for not establishing a metaphysical connection (...) and providing false cognates, and validly as a categorical error, a misidentifcation error and an inferential error; this last one relatable with Hume’s Law as a procedural argumentation error. Brief applications show the limits of the naturalistic fallacy in that, contradictorily, it isn’t a fallacy but by one of its uses, as well as not rebuting every naturalistic theory (as hedonism and utilitarianism) besides being also an argument in favor of some (non-cognitivists). (shrink)