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Constructing Epistemic Authority in Porphyry's "Commentary on Ptolemy's Harmonics"

Matteo Milesi

University of Michigan

In this paper I argue that the Neoplatonist philosopher Porphyry establishes his own epistemic authority in the Commentary on Ptolemy’s Harmonics by conducting an unconventional polemic against the source-text that he is commenting on.

 Ancient commentaries are battlefields for an intellectual war fought on two fronts: on the one hand, commentators need to justify their hermeneutic endeavor by presenting their source-text as authoritative; on the other hand, they need to find a way to carve out a position for their own intellectual independence. A balance between these two opposing needs is usually found in the way commentators dialectally engage with previous interpreters, who become the targets of harsh criticisms (Sluiter 2000 and 2013). But how is this tension played out in a commentary that stands at the beginning of an exegetical tradition, when there are no previous competitors to attack? Porphyry’s Commentary on Ptolemy’s Harmonicsprovides an ideal case-study to answer this question, since the author explicitly claims to be the first person to have ever commented on Ptolemy’s work. I show how Porphyry recognizes Ptolemy’s authority in the field of harmonic theory while at the same time depicting Ptolemy as an exegete engaging in an activity that is very similar to that performed by Porphyry himself. In this way, Porphyry transforms his source-text into a direct competitor, and by attacking it he is able to reaffirm his own authority as a commentator.

My claim may appear controversial, since recent scholarship on the Commentary has noticed a general doctrinal agreement between Porphyry and Ptolemy, who is openly criticized only once (Barker 2016; Raffa 2016). However, my approach differs from that of Barker and Raffa since this paper does not focus on the doctrines articulated in the bulk of the commentary, but on how, in the preface, Porphyry presents his source-text and constructs and justifies his own role as an interpreter. Hence, my analysis is primarily concerned with the rhetorical dimension of the Commentary, not with its scientific content.

In the preface, Porphyry claims that Ptolemy has brought the science of harmonics to perfection, thus justifying his own interest in commenting on Ptolemy’s text; however, he also adds that Ptolemy did not add any new insights, but he merely assessed the theories of his predecessors (κρίσις τῶν παρ’αὐτοῖς θεωρημάτων). The judgment of a text (κρίσις) is the culmination of the exegesis of a text according to ancient grammatical theorists (e.g. Dion. Thrax Ars 1). Hence, by describing Ptolemy’s text as a sort of commentary on previous doctrines, Porphyry is implicitly reshaping the figure of Ptolemy in his own image. In this way, Porphyry now has a direct competitor against which he can vindicate his own epistemic superiority. More specifically, Ptolemy qua commentator is criticized for his lack of clarity and “academic integrity”. Porphyry promises to amend these flaws in his own Commentary by simplifying the complex mathematical theories exposed by Ptolemy and by shedding light on the actual origins of the ideas that Ptolemy plagiarizes as his own.

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Philosophical Thought and Language

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