unity of instance

Investigating the essence and the attributes of the Necessary Being is among the main discussions of the ‘metaphysics in its particular sense’. Especially, in the Islamic world, due to the explicit statements in the religious texts as well as the dominant culture, the philosophers made the greatest effort to resolve the issues pertaining to this topic. The mode of relationship of the attributes with the essence and with one another is, as far as the concept and the instance are concerned, one of those issues. Avicenna, as one of the pillars of the Islamic philosophy, has put forward a theory on the discussion of the conceptual unity of the attributes of the Necessary Being with one another, which has not been accepted by other philosophers. After him, Mulla Sadra has attempted to deface Avicenna’s theory, and others, following him, have criticized Avicenna. In this article, we have tried to delineate Avicenna’s theory so that it is clarified whether Mulla Sadra’s critique on this theory is right or not.