In both Metaphysics Γ 4 and 5 Aristotle argues that Protagoras is committed to the view that all contradictions are true. Yet Aristotle's arguments are not transparent, and later, in Γ 6, he provides Protagoras with a way to escape contradictions. In this paper I try to understand Aristotle's arguments. After examining a number of possible solutions, I conclude that the best way of explaining them is to (a) recognize that Aristotle is discussing a number of Protagorean opponents, and (b) import another of Protagoras' views, namely the claim that there are always two logoi opposed to one another.

In this essay I argue that the central problem of Aristotle's Metaphysics H (VIII) 6 is the unity of forms and that he solves this problem in just the way he solves the problem of the unity of compositesby hylomorphism. I also discuss the matterform relationship in H 6, arguing that they have a correlative nature as the matter of the form and the form of the matter. IOne recurring theme in the central books of Aristotle's Metaphysics is the unity of substance. This issue is discussed at length in both Z 12 and H 6, and in less detail in several other places (e.g., in Z 17, 1041b11-33 and H 3, 1043b4-14). These two chapters present the scholar with a number of problems: they contain no cross-references and they offer what are apparently differing solutions to the problem of unity. Each chapter also presents its own textual and philosophical problems. On H 6, which will be the focus of this paper, there is virtually no agreement among scholars on any of the major issues that arise. There is, for instance, no agreement on whether the chapter means to address the unity of forms or composites, nor about the nature of Aristotle's solution. But finding answers to these questions is crucial if we are to make sense of the central books of the Metaphysics and their relationship to the rest of the Metaphysics and the corpus. H 6 stands at the end of the two-book work of Z-H, and it addresses issues which have been in play throughoutin particular with the important but difficult issues of the matter-form relationship and the relationship between potentiality and actuality. 1 The latter issue is discus-

This paper discusses two broadly logical issues related to Protagoras’ measure doctrine (M) and the self-refutation argument (SRA). First, I argue that the relevant interpretation of (M) has it that every individual human being determines all her own truths, including the truth of (M) itself. I then turn to what I take to be the most important move in the SRA: that Protagoras recognises not only that his opponents disagree with him about the truth of (M), but also that they hold that (M) is false simpliciter. By recognising that his opponents do not make the relativising concession he makes for them, he is forced to accept that (M) is false. I go on to argue that several other defenders of the SRA end up with a regress which is difficult to end and might not favour anti-Protagoreans. On my reading, by recognising what his opponents believe, Protagoras is barred from adding qualifiers, and the possible regress doesn’t get off the ground. I conclude with brief discussions of how Protagoras might try to avoid the result of the SRA and the argument’s role in this part of the Theaetetus.

Plato's Theaetetus discusses and ultimately rejects Protagoras's famous claim that "man is the measure of all things." The most famous of Plato's arguments is the Self-Refutation Argument. But he offers a number of other arguments as well, including one that I call the 'Future Argument.' This argument, which appears at Theaetetus 178a−179b, is quite different from the earlier Self-Refutation Argument. I argue that it is directed mainly at a part of the Protagorean view not addressed before, namely, that all beliefs concerning one's own future sensible qualities are true. This part of the view is found to be inconsistent with Protagoras's own conception of wisdom as expertise and with his own pretenses at expertise in teaching.