An Overview of Logic in Avicenna
Authors: Coşkun Abdulkadir 
Published: June 2022

Avicenna, who defines logic as a method of reaching non-actual information based on actual information, or a method that protects people from mistakes while thinking, basically aims to reach information in the art of logic. In this respect, logic is a tool that leads to knowledge. Although Ibn Sînâ included the logic in all his works, he dealt with logic in more detail in his works called Kitâb Al-Shifâ and Remark and Admonitions. Besides, in Kitâb Al-Shifâ, written by Ibn Sînâ in accordance with the Peripatetic tradition, all the logic topics that Aristotle examined were the subject of research in the order put forward by Aristotle after Isagoci, while the Ishârât did not include categories and five arts were also included. very little has been mentioned. Avicenna's corpus of logic is more voluminous than Aristotle's texts. In this, besides Avicenna's making the subjects of logic a subject of wider examination, it was effective that he also made the comments after Aristotle the subject of examination. After him, the approach in Ishârât was more effective than the approach in Kitâb Al-Shifâ in terms of the handling of logic issues in the Islamic world. Concentrating on thought rather than the relationship between language and thought, Ibn Sînâ determines the subject of logic as second intelligibles based on the first intelligibles in terms of reaching the unknowns from the known. The unknown is basically reached through the mind. However, intuition (hads) is one of the ways to reach knowledge. Avicenna bases his understanding of logic on the following three basic principles: the distinction between language and thought, the distinction between matter (content) and form, and the distinction between essence and existence. The distinction between existence and essence is one of the most fundamental distinctions in the mind's perception of essences and the separation of logic into tasawwur and tasdîq. Although the concepts of tasawwur and tasdîq are taken as far as Aristotle and the Stoics, Avicenna interpreted these two concepts as the basic concepts that make up the logical system. The part of the logic up to the propositions, which we can describe as conceptual logic, constitutes imagination, and after propositions, affirmation. Introduction to Logic (Îsâgûcî/Al-Madhal) is a preparation for Categories, and Categories is an introduction to Peri Hermeneias. While the Prior Analytics is the book in which the theory of syllogism is revealed, the five arts consisting of Burhân (demonstration), Jadal (topics), Safsata (fallacies), Khatâba (rhetoric) and Shi’r (poetry) constitute the content of logic and are the application area of syllogism. Conceptual (imaginative) knowledge is an act of visualizing the existence by abstracting it and does not contain judgment. However, since the judgment is made with at least two concepts, there is no judgment without the concept. “What is it” and “which/which one” are the basic questions in reaching the concept obtained with the definition indicating the nature of something. In the proposition, which is the basis of confirmation and divided into simple and compound, the basic questions are "is there" and "why" questions. The one that leads to tasdîq, which means making a positive or negative judgment by establishing a connection between the two concepts, is hujjah/ihtijâj, that is, proof, reasoning, and the most basic reasoning method is syllogism. In classical logic, the main purpose is to reach syllogism, and in syllogism, the aim is to reach the demonstration that allows precise knowledge. According to Avicenna, who successfully adapted the concept of matter-form to logic, it is possible to talk about the form and substance of the proposition, which is the simplest form of tasdîq, as well as the substance and form, that is, the content and form, of the competent form of qiyâs. While the form of the proposition is shaped according to its quantity, quality and modality, its content is classified based on truth and falsity. Qiyâs is also divided into two according to its form and content. According to its form, syllogism is basically called iqtirânî and exceptional qiyâs, while according to its matter, it consists of propositional classes and five arts based on it in terms of truth value.