  The problem becomes clear if one thinks of, for instance, the claim that water is H2O. That water is H2O cannot be discovered simply by appreciating the meanings of the terms involved, so if a person were to wonder of some water whether it is really H2O he would not thereby be revealing some incompetence with the terms in question. His question would be, in the relevant way, an Open Question, even if, in fact, water is H2O. Similarly, some moral realists argue that value might, in fact, be properly identified with, say, what satisfies desires we desire to have (to take one proposal Moore considered) even though this cannot be discovered simply by appreciating the meanings of the terms involved. As a result, a person might intelligibly wonder whether something that satisfied a desire she desired to have was actually good. The question might be, in the relevant way, an Open Question, even if, in fact, value is whatever satisfies a desire we desire to have. Of course the point here is not that one or another such proposal is true, but that the openness of the Open Question is not good grounds for supposing such proposals could not be true.