  Negative predication has received considerable attention in the scholarly literature on the Sophist (for helpful accounts of the various interpretations, and their advantages and disadvantages, see Keyt 1973 and Crivelli 2012). Some scholars think that Plato needs a second notion of negation in addition to difference (understood as distinctness or non-identity), such as incompatibility, to accommodate negative predication. On this view, flying is incompatible with one of Theaetetus’ properties (namely sitting). The incompatibility interpretation requires Plato to change the meaning of heteron from “different” to “incompatible,” and there is no evidence in the text that he does. The Oxford interpretation (mentioned above § 6.1) has the advantage of keeping a single meaning for heteron but calls for universal quantification over properties: to analyze the statement “Theaetetus is not flying,” one must show that flying is different from everything that Theaetetus is—a man, snub-nosed, sitting, and so on. The Sophist does not provide evidence of such an approach (see Wiggins 1971; Bostock 1984, 113; White 1993, §§ 10, 11).