This study focuses on Fakhr al-Dīn al-Rāzī’s thesis of the impossibility of giving a complete definition (al-ḥadd al-tāmm) and discusses its impact, the parties to the debate, and especially the positive argument contra al-Rāzī by the Ottoman savant Ṭāşköprīzāde. The negative argument of al-Rāzī postulates that the complete definition is strictly circular, for the totality of parts that makes up the defined object are included in the definition, and the object is identical to the sum of its parts. Therefore, complete definition strictly commits the fallacy of definining a thing by itself. Ṭāşköprīzāde argues against this view by defending the possibility of complete definition. According to him, although in complete definition the defined object and the defining features include the same set of things, the modes of their presentation to the mind are different. Thus, a complete definition becomes circular only if both the content of the defined object and its mode of presentation to the mind are the same. If it can be shown that the contents of the definiendum and definiens have distinct modes of presentation, then the charge of circularity is discarded. In this article, I illustrate the two opposing approaches by distinguishing between form and content, or sense and reference. Both parties take for granted that the contents of the definiens and the definiendum are the same when it comes to the complete definition. The main point of contention lies in the modes of apprehending the contents. This article analyzes the arguments of two opposing semantic theories particular to the completedefinition and shows that the question emerges as a result of the theories of constant form and variable form concerning meaning. In the period between al-Rāzī and Ṭāşköprīzāde, Ṭūsī bolstered the complete definition whereas al-Ījī refuted it. Both Ṭūsī’s and al-Ījī’s arguments will be discussed.

This research focuses on the previously unpublished treatise by Sayyid Sharīf al-Jurjānī, Risāla fī taqsīm al-‘ilm. The research is based on comparative evaluation of available manuscipts and is composed of a critical edition of the treatise and its analysis. The treatise is about the division (taqsīm) of ta~awwur (conception) and tadīq (assent) as divisions of knowledge. Al-Jurjānī presents views from different schools of logic. In the analysis section, I discuss the treatise’s philosophical background and show that the aforementioned division is the first step of a chain of propositions on what the goal and methods of logic are focusing on the possibility of learning. Remaining sections focus on the references in the treatise to various views and summarise them. Finally al-Jurjānī’s position in this scene is made explicit through his critical analysis of competing views advocated by these different schools. For al-Jurjānī, division of knowledge can be analysed formally and informally. Formally, the division should be restrictive and informally, it should emphasize methods of logic, that are proof (hujja) and definition (ta‘rīf). The article shows that the goal of al-Jurjānī’s discussion on the division of knowledge as conception and assent is basically to take the discussion out the context of traditional discussions on quiddity but rather build it on the division formally and the goals of the division informally.