  A false assumption about negation makes it seem impossible to think or talk about not-being. The inquirers assume that a negation specifies the opposite of the item negated (Sophist 240b, 240d).  Think of opposites as polar incompatibles—a pair of opposed terms that exclude each other. These include polar contraries, such as black and white, or hot and cold, which have some intermediate between them; and contradictories, such as odd and even, large and not-large, or beautiful and not-beautiful, which do not (see Keyt 1973, 300 n. 33). If not-being is the opposite of being, then not-being is nothing at all, and we cannot think about that. A second source of trouble about not-being infects being as well. The speakers mistakenly assume that there is a one-to-one correspondence between a name and a thing: a name picks out something, different names pick out different things, and each thing has one proper name. The Stranger later attributes the idea to some people he derisively calls Late-Learners, who urge that we call a thing only by its own name and not by any other. Thus they allow us to call a man “man” and the good “good,” but they do not allow us to call a man “good” (Sophist 251b–c) (for this interpretation of the Late-Learners, see Moravcsik 1962, 57–59; cf. Bostock 1984, 99–100, Roberts 1986, 230, and Malcolm 2006a, 278).