Qiyās Ghayr Muta？āraf against the Backdrop of Definition of Syllogism: ？Os？mān b. Mu？？afā

al-？arsūsī’s Risāle-i Istidlāliyye Many logicians, starting with Aristotle’s ancient commentators such as Alexander of Aphrodisias, exclude the syllogism of equivalence (qiyās al-musāwāt) and the like from the extension of syllogism and consider them invalid. They claimed that these syllogisms do not produce by themselves as the terms of their premises semantically depend on qualification. One can argue that these logicians reached this conclusion because they limited the extension of syllogism only to Aristotle’s usage of examples of syllogism. However, others, particularly the 18th century Ottoman logicians, argued that these syllogisms produce by themselves and are valid. They contend that if rules of qualification are determined with regard to validity, then the syllogism of equivalence and the like will be valid as well. Ottoman logicians named these syllogisms qiyās ghayr muta？āraf (unfamiliar syllogism), and started treating them in their logic works. Risāla-i Istidlāliyya by ？Os？ mān b. Mu？？afā e？-？arsūsī is a particularly good example of this practice. In this article, first we discuss whether or not the ghayr muta？āraf could be included in the definition of syllogism, and then we append the critical edition of the Arabic text of Risāla-i Istidlaliyya along with its translation into Turkis