An Analysis of Ibn Sina s Reductio ad Absurdum in Demonstrating the Principle of Nothing Proceeds from the One but One

This paper investigates Ibn Sina’s method of demonstrating the principle of “nothing proceeds from the one but one”. He is the first philosopher who has proved it based on logical reasoning. His famous reasoning in this regard in the book al-Isharat is based on reductio ad absurdum; however, Fakhr al-Din Razi and the thinkers after him have attributed another argument to Ibn Sina which is based on the principle of the impossibility of the union of two opposites. This argument has proved to be challenging and has given rise to some extensive discussions; moreover, it has not been explicitly mentioned in Ibn Sina’s works. The writer believes that he has referred to a similar argument in the book al-Mubahithat; however, he has logically based it on reductio ad absurdum. He is also of the idea that Ibn Sina has only resorted to the necessity and contradiction arising from the proposition of the first emanated in the analytic structure of the premises of his own argument.