 The modal argument does not refute descriptivism applied to every description—after all, Kripke and Putnam do both think that the description “is constituted by H2O” holds necessarily of anything that is water. Rather, the modal argument is intended to exclude as possible descriptions those that could be constitutive of a sense or connotation that is grasped by any competent user of the term. Such a sense, if it exists, would employ descriptions that refer to the observable features of the members of a kind, not those features uncovered by science.