The main theme of this article is the statement of the proof of the Sincere by Ibn Sina. In order to determine his crucial part one should raise such questions as: what is the origin of the demonstration and who for the first time offered it? What is the nature of this proof formulation by Ibn Sina as one, or rather, the most prominent among Islamic philosophers and what is the distinctive feature of his statement of this demonstration? What objections are so far raised or can be made to this argument? Can these objections and doubts be removed and so his statement of it be tenable? In answering these questions we come to the conclusion that Al-Farabi is the first philosopher to have presented the Proof of the Sincere in his fusus al-Hikam (Bezels of Wisdom) and that Avicina was the first who developed a statement of it on the basis of the Sincere's method in five of his works. It is worth noting that none of the objections raised could undermine Ibn Sina's statement of this proof.
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