 Locke’s pragmatic account of language and the distinction between nominal and real essences constitute an anti-essentialist alternative to this Aristotelian essentialism and its correlative account of the classification of natural kinds. He claims that there are no fixed boundaries in nature to be discovered—that is there are no clear demarcation points between species. There are always borderline cases. There is debate over whether Locke’s view is that this lack of fixed boundaries is true on both the level of appearances and nominal essences, and atomic constitutions and real essences, or on the level of nominal essences alone. The first view is that Locke holds that there are no Aristotelian natural kinds on either the level of appearance or atomic reality. The second view holds that Locke thinks there are Aristotelian natural kinds on the atomic level, it is simply that we cannot get at them or know what they are. On either of these interpretations, the real essence cannot provide the meaning to names of substances. A.O. Lovejoy in the Great Chain of Being, and David Wiggins are proponents of the second interpretation while Michael Ayers and William Uzgalis argue for the first (Uzgalis 1988; Ayers 1991: II. 70).