In this paper I focus on Proclus’ concept of the instrumental cause in his commentary on the Timaeus (In Tim.). Unlike earlier Neoplatonists who do not make much use of this type of causality, Proclus relates the instrumental cause to the hypostasis of nature (φύσις). The Demiurge uses nature as an instrument in his ordering and creation of the cosmos. How does Proclus arrive at this understanding of nature? I argue that the definition of nature as an instrumental cause is (...) in part based on his critical reception of Aristotle who identifies nature with the formal, efficient, and/or final cause. That is, Proclus did not develop his views on the causality of nature only by looking at the Timaeus (and other Platonic sources), but also by engaging with Aristotle’s rich – and, to a certain extent, authoritative – reflections on this issue. (shrink)

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)