Zeno of Sidon vindicatus: a mereological analysis of the bisection of the circle

  1. Maffezioli, Paolo
Journal:
Logic and Logical Philosophy

ISSN: 2300-9802 1425-3305

Year of publication: 2022

Pages: 1-20

Type: Article

DOI: 10.12775/LLP.2022.032 GOOGLE SCHOLAR lock_openOpen access editor

More publications in: Logic and Logical Philosophy

Abstract

I provide a mereological analysis of Zeno of Sidon’s objection that in Euclid’s Elements we need to supplement the principle that there are no common segments of straight lines and circumferences. The objection is based on the claim that such a principle is presupposed in the proof that the diameter cuts the circle in half. Against Zeno, Posidonius attempts to prove the bisection of the circle without resorting to Zeno’s principle. I show that Posidonius’ proof is flawed as it fails to account for the case in which one of the two circumferences cut by the diameter is a proper part of the other. When such a case is considered, then either the bisection of the circle is false or it presupposes Zeno’s principle, as claimed by Zeno.