 Ibn Sīnā [hereafter: Avicenna] (980–1037 CE) is—directly or indirectly—the most influential logician in the Arabic tradition. His work is central in the re-definition of a family of problems and doctrines inherited from ancient and late ancient logic, especially Aristotle and the Peripatetic tradition. While, in general terms, Avicenna squarely falls into a logical tradition that it is reasonable to characterize as Aristotelian, the trove of innovations he introduces establishes him as a genuinely new canonical figure. Every later logician in this tradition confronts him, either as a critic or as a follower, to the extent that, with few exceptions, Aristotle and the Peripatetic tradition almost entirely disappear from the scene. Arabic logic accordingly divides into two areas and periods: pre-Avicennan and post-Avicennan (Street 2004).[1]