A quotation of an anonymous 'logician' in Avicenna's categories

This paper provides an analysis of chapter I, 3 of the Maqūlāt ('Categories') of Avicenna's Kitāb al-Šifā' (Book of the Cure), devoted to the Aristotelian distinction between 'being in a subject' and 'said of a subject' (as traced in the second chapter of the Categories). The enquiry will focus on a literal quotation of an anonymous commentator, given by Avicenna in this chapter, which will be discussed extensively, in order to give plausible hypotheses concerning its source and authorship. Before coming to the text, a brief account of the Greek and Arabic background of the issues at stake will be given; after discussing the quotation, the analysis will concentrate on Avicenna's refutation of the commentator, which ultimately gives more than one clue to assess his identity. It will be argued that the quoted text is a translation or a paraphrase of a passage of Porphyry's In Aristotelis Categorias expositio per interrogationem et responsionem, and the mentioned 'logician' is either Porphyry himself, or a later Arabic commentator rephrasing Porphyry's text. An English translation of the second part of Maqūlāt I, 3 is given in the Appendix.