Abstract. Argumentation through reductio ad absurdum is very commonplace in the sciences and even in the dialogues of natural language. Nevertheless, problems arise when logicians tend to look for a structural analysis of reductio ad absurdum. Aristotle (d. 322 BC) was the first to find a solution, and formalized reductio ad absurdum within his theory of syllogism. Ibn Sina (d. 1037), afterwards, believed that reductio ad absurdum is a compound syllogism, and decomposed it to one conditional conjunctive syllogism and one repetitive syllogism. Ibn Sina’s analysis of reductio ad absurdum was prevalent among the logicians of the Islamic era. Mulla Sadra (d. 1640), within this framework, presented further logical and philosophical analyses on reductio ad absurdum. One of the main sections of his logical work, al-Tanqih, is devoted to reductio ad absurdum. Moreover, in his glosses on The Commentary of Hikmat al-Ishraq, Mulla Sadra has written a detailed comment on reductio ad absurdum and its differences with direct syllogism. In his magnum opus, al-Asfar, Mulla Sadra has also considered reductio ad absurdum and its basics, contents, and the process of its yielding a conclusion, at two different places of the work. In the present paper, Mulla Sadra’s account of reductio ad absurdum in each of the three aforementioned works is presented and discussed, and his novelties are examined. As such, Mulla Sadra would show us his other face as a competent logician, and some open problems that could be pursued in the footsteps of the present research would also emerge.