  Moore’s “Open Question Argument” for the conclusion that goodness is a non-natural property is closely related to his worries about the naturalistic fallacy. Consider any proposed naturalistic analysis N of a moral predicate M. The Open Question Argument maintains that it will always be possible for someone competent with moral discourse without conceptual confusion to grant that something is N but still wonder whether it is really M. Whether goodness is co-instantiated with any natural property or set of natural properties is in this sense always a conceptually open question. If, however, N really was an accurate analysis of M then the question, “I know it is N but is it M?” would not be open in this way for a conceptually competent judge any more than the question, “I know he is a bachelor but is he unmarried?” can be an open one. Moore himself used the Open Question Argument to defend a non-naturalist account of goodness but held that rightness was reducible to goodness. Moore held that it was true by definition that right actions maximize goodness, though he later came to the conclusion that this definition of rightness was also vulnerable to an Open Question Argument. A very similar argument was used by Sidgwick to establish that certain moral notions are irreducible (see Sidgwick 1907: Book I, Chapter 3) and Moore credits Sidgwick with the idea (Moore 1903: 17). More recently, some philosophers have argued that naturalism cannot capture the normativity of moral properties, and these arguments also seem to be very similar to the Open Question Argument. The idea seems to be that for any naturalistic reduction one offers of some seemingly normative notion one can, without betraying any conceptual incompetence, admit that something has the property specified by the reductive account but hold that this lacks normativity—does not provide any reasons for action (see Dancy 1996: 180–183). 