 The open-question argument was extensively discussed in 20th-century metaethics and met with several objections. One said the argument’s persuasiveness depends on the “paradox of analysis”: that any definition of a concept will, if it is successful, appear uninformative. If an analysis does capture all its target concept’s content, the sentence linking the two will be a tautology; but this is hardly a reason to reject all analyses (Langford 1942). Here it can be replied that in other cases accepting a definition leads us to see that the sentence affirming it, while initially seeming informative, in fact is not; thus “a bachelor is an unmarried man” is not informative. This does not happen, however, in the case of “good.” Even if we agree that only pleasure is good, no amount of reflection will make us think “Pleasure is good” is equivalent to “Pleasure is pleasure”; Ross, for one, gave this response (1930: 92–94). Another objection, made from the 1970s on and very influential, says that while the open-question argument may show that the concept “good” is distinct from any non-moral concept, it cannot support a similar conclusion about the property of goodness. (Recall that Moore tended not to distinguish concepts from properties.) Empirical science, the objection runs, uncovers many non-analytic property-identities, for example, that the property of being water is identical to the property of being H2O even though the concepts “water” and “H2O” are distinct. By analogy, the property of goodness could be identical to that of being pleasant even if “good” and “pleasant” have different meanings (e.g. Brink 1989: Ch. 6). Moore’s mistake, then, was to think that what may indeed hold for the concept “good” also holds for the property of goodness. Again, however, it can be replied that natural-kind properties such as being water have special features that allow non-analytic identities but that aren’t had by ethical properties such as goodness, for which such identities are impossible. More specifically, it can be argued, the property of being water is the property of having that underlying structure, whichever it is, the explains the behaviour of the stuff found in lakes, rivers, and streams; when this structure turns out to be H2O, the latter property “fills a gap” in the former and makes the two identical (Parfit 2011, vol. 2: 298–303, 329–38; also Gampel 1996). But this explanation does not extend to the case of goodness, which is not a higher-level property with any gap that needs filling. To be good is not to have whatever other property plays some functional role; it is just to be good. It follows that if goodness is analytically distinct from any natural property, it is metaphysically distinct from it too.