An Analysis and Investigation of Thomas Aquina's Approach to Ibn- Sina's Demonstration of Seddiqin'

We will try to solve the following problem in this article: although Thomas Aquinas has accepted many of Ibn-Sina's metaphysical bases in his philosophy, why he has not presented a demonstration similar to the 'Seddiqin demonstration'? To solve this problem, I have first investigated Ibn-Sina's metaphysical bases of the 'Seddiqin demonstration' such as the distinction between existence and essence, occurrence of being on essence, analogical gradation of the concept of existence, the meaning of necessity and possibility and also causality; then the different accounts of this demonstration in his different writings is analyzed. In the second part of this article, the metaphysical bases needed to propose a demonstration such as the 'Seddiqin demonstration' in the philosophy of Thomas, are investigated; such as the following bases: the distinction between existence and essence, occurrence of being on essence, similarity of the concept of existence, the meaning of necessity and possibility and also causality. Then I have investigated the different analysis of the researchers who study Thomas from the third method and have also studied the accounts close to the third method in his writings. Finally it is proved that Thoma's third method is not the 'Seddiqin demonstration'; and analyzing the theory of similarity, I will show that based on some analyzers of Thoma's theory of similarity and also based on his denial of the general resemblance of the cause and the caused between God and the creatures, it is not possible to pose the 'Seddiqin demonstration' in the philosophy of Thomas; although some other analysis of analyzers of Thoma's theory show the possibility of posing such a demonstration in his philosophy.