Abstract

In Islamic philosophy, although “ontology” has a very high position and a large part of discussions and issues are allocated to it, "epistemology" is not that much detailed for different reasons. One of the few issues discussed in detail in the Islamic philosophy under "ontology" is the issue of "mental existence". Among the historians of philosophy it is known that the discussion was proposed by Fakhar al-Din al-Razi, then through Khaje Nasir al-Tusi it reached the philosophers of the school of Shiraz where it was expanded, and eventually it was Molla Sadra who brought the final solution to the issue. In this paper, that author has shown that despite this claim, the issues of mental existence including the proof of mental existence, its nature, suspicions about it, and the answers to them were discussed by the great Muslim philosopher, Avicenna, who has thought enough about them as a philosopher and all subsequent philosophers are influenced by him in this matter.