  To complete our account of Protagoras’ views on language and reality we need to mention the thesis that it is impossible to say what is false, which occurs in three Platonic passages, Euthydemus 284a–c, Theaetetus 188d–189a and Sophist 236e–237e. According to this argument falsehood is impossible, since to say what is false is to say what is not (legein to mē on), whereas anyone who speaks has to say something that is (on ti); hence saying what is not is saying what is not anything, i.e., not saying anything. Hence, since of contradictory statements one must be false, it is not possible to contradict (ouk estin antilegein  (Euthydemus 286b)). This argument has its origin in Parmenides’ claim (DK 28B2) that ‘You could not know what is not … nor could you say it’, and its application to falsehood and the impossibility of contradiction is ascribed to various fifth-century figures, including ‘Protagoras and his associates and even earlier people’ (hoi amphi Prōtagoran … kai hoi eti palaioteroi (Euthydemus 286c2–3)), Prodicus (in another fragment of Didymus, published in 1966), Cratylus (Cratylus 429d) and Antisthenes (Aristotle Metaphysics 1024b32–4). In the case of the latter two the thesis connects with other more general theses about language which they are reported to have held. Thus Cratylus has attributed to him by Plato the thesis that each thing has its own proper name, which expresses, through its etymology, the nature of the things it names, and which has significance only when correctly applied, but is otherwise a mere empty sound. Hence there can no such thing as the misapplication of a name (since a misapplied name is not a name, but a mere sound), and hence no such thing as a false statement, since (it is assumed) every false statement involves the misapplication of some name. Similarly Antisthenes held that each thing has its own proper definition or description, which cannot be applied to anything else, from which again the impossibility of falsehood follows. In the case of Protagoras it is hard to find any such connection. On the most plausible construal of subjectivism no one’s belief can contradict anyone else’s belief, but that does not appear to rule out an individual’s having inconsistent beliefs. Further, subjectivism does not rule out false statements; I can falsely assert ‘The wind is cold for me’ when in fact it is not cold for me. Though Protagoras seems to have had a fairly high tolerance threshold for inconsistency, it is hard to see how one and the same person could assert both that it is impossible to contradict and that on every matter there are two opposed logoi. The wording of the attribution to Protagoras in the Euthydemus is suspiciously vague, suggesting that Plato is attributing to Socrates a vague memory of Protagorean subjectivism, rather than precise recall of any particular doctrine.