The article gives a brief description of the work on logic “Isaguji” by Athir ad-din al-Abhari, which has become widespread in the Muslim East, in general, and in the Tatar public education system, in particular, which would make a certain contribution to the study of the content of the educational process in Tatar confessional schools of the indicated period. The paper provides some brief information on the history of the emergence of Logic as a science, as well as it mentions the contribution of Muslim scientists to its development. Al-Abhari's work is a propaedeutic to Logic and in terms of content, it can be divided into the following main sections: about words, about definitions, about types of judgments and inferences. The study of such a subject as Logic in Tatar madrasahs to a certain extent contributed, along with other disciplines, to the development of students’ mental activity and expanded their understanding of the surrounding reality.