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. (shrink)

This article aims at reconstructing the logic and assessing the force of Socrates' argument against Protagoras' 'Measure Doctrine' at Theaetetus 171a–c. I examine and criticise some influential interpretations of the passage, according to which, e.g., Socrates is guilty of ignoratio elenchi by dropping the essential Protagorean qualifiers or successfully proves that md is self-refuting provided the missing qualifiers are restored by the attentive reader. Having clarified the meaning of MD, I analyse in detail the broader section 170a–171d and argue, against (...) an extensive scholarly consensus, that it contains two slightly different formulations of the same argument, and not two distinct arguments, that Socrates does not highlight his own strategy at 171a–c as especially clever, and that his argument successfully shows that md turns out to be untenable for Protagoras himself when submitted to scrutiny in dialectical contexts, without aiming at proving its absolute falsehood. Finally, I clarify the philosophical import of the final image of Protagoras' momentary return from the underworld. (shrink)

In this paper I discuss the dialogues between 'Protagoras', Theodorus and Socrates in "Theaetetus" 161-171 and emphasise the importance for this passage of a dilemma which refutation is shown to pose for relativism at 161e-162a. I argue that the two speeches delivered on Protagoras' behalf contain material that is deeply Socratic and suggest that this feature of the speeches should be interpreted as part of Plato's philosophical case against relativism, reflecting the relativist's own inability to defend his theory from attempts (...) to refute it. I then discuss Theodorus' role in the refutation of Protagoras and argue that his voice is needed to get relativism disproved in the self-refutation argument of 171a-c. I conclude with a brief discussion of the image of Protagoras at 171d. (shrink)