Evan Keeling

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.

Aristotle's theory of perception is complicated by the fact that he recognizes three kinds of perceptible object: special, common, and incidental, all of which have different levels of reliability. Focusing on De Anima 3.3, 428b17–25, this paper discusses why these three sorts of perception are true and false. It argues that perceptions of special objects can be false because of the blind-spot phenomenon and that common objects are typically perceived as predicated of an incidental object. This helps explain why perceptions of common objects are the most error prone. The paper ends with a suggestion about the importance of predicational perception for Aristotle's epistemology.

This volume consists of fourteen essays in honor of Daniel Devereux on the themes of love, friendship, and wisdom in Plato, Aristotle, and the Epicureans. Philia (friendship) and eros (love) are topics of major philosophical interest in ancient Greek philosophy. They are also topics of growing interest and importance in contemporary philosophy, much of which is inspired by ancient discussions. Philosophy is itself, of course, a special sort of love, viz. the love of wisdom. Loving in the right way is very closely connected to doing philosophy, cultivating wisdom, and living well. The first nine essays run the gamut of Plato's philosophical career. They include discussions of Plato's Alcibiades, Euthydemus, Gorgias, Phaedo, Phaedrus, and Symposium; and Aristotle's Nicomachean Ethics, Politics, Protrepticus and Magna Moralia. It ends with a discussion of Epicurean friendship.

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.

This paper is a test case for the claim, made famous by Myles Burnyeat, that the ancient Greeks did not recognize subjective truth or knowledge. After a brief discussion of the issue in Sextus Empiricus, I then turn to Plato's discussion of Protagorean views in the Theaetetus. In at least two passages, it seems that Plato attributes to Protagoras the view that our subjective experiences constitute truth and knowledge, without reference to any outside world of objects. I argue that these passages have been misunderstood and that on the correct reading, they do not say anything about subjective knowledge. I then try out what I take to be the correct reading of the passages. The paper concludes with a brief discussion of the importance of causes in Greek epistemology.

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.