Metaphysical Investigations

It seems that Muslim philosophers, for salving some philosophical problems have claimed that some promises or concepts are self- evident. Of such problems is question of external actualization of existence or quiddity of things that some of thinkers argued that their views are self- evident. In this case, Sadrian philosophers under influence of Mulla Sadra, maintain that his view of the rule of principality of existence and credibility of Quiddity is self-evident. So far as in Mulla Sadra's works, however, there are three meanings for principality of existence and credibility of quiddity, some of contemporary philosophers believe that only a special interpretation of that rule makes possible to be self -evident. In this paper, it is tried to show that most of believers in principality of existence have tried to consider own view as self-evident which sometimes is different from Mulla Sadra's view and included of external composition of existence and quiddity. There are, also, other philosophers that their points of view concerning self-evidence of principality of existence is not acceptance of quiddities as external existents but they think quiddities are manifestations of ontological participations while their view can't be accepted as self-evidence theory.