 At the time Feyerabend was developing these views, he was working very closely with Karl Popper. There has been much controversy concerning Feyerabend’s evolving relationship to Popper, especially given its tumultuous trajectory, the revisions Feyerabend made concerning his debts to Popper in the reprints of his original papers (see Preston 1997), informal accusations of plagiarism by Popperians (see Collodel 2016), and Feyerabend’s subsequent increasingly vocal denials of his debts to Popper (Oberheim 2006, Ch. 3.4). It has however always been clear that Feyerabend developed his views on incommensurability while working as a vocal proponent of Karl Popper’s critical rationalist philosophy (Preston 1997, Oberheim 2006, Collodel 2016), and that there are many different interpretations of the relationships between their ideas. Bschir (2015) recently emphasizes just how Popperian Feyerabend’s philosophy was at that time, and casts Feyerabend’s idea of incommensurability as a positive extension of many of Popper’s views. Oberheim (2006) argues that incommensurability is exactly the point at which Feyerabend breaks the Popperian framework. Many (including Popper) seem to interpret Feyerabend’s conception of incommensurability as a rather misguided development (or even misunderstanding) of Karl Popper’s views (see Bschir 2015, Collodel 2016), which Feyerabend often repeated, sometimes seemingly as if they were his own. In any case, incommensurability marks the point after which Feyerabend and Popper’s philosophies dramatically part ways, as they lead to very different conceptions of progress (see Tambolo 2017). 