Every given branch of knowledge could be studied with a first-order or second-order approach; a second-order approach means the own branch of knowledge would be the issue of the study. Having more than two thousand years history, philosophy has potentiality to be studied from different points of view. A historical study of Islamic philosophy could take topic-based, philosopher-based, school-based, period-based, or problem-based approaches. Problem-based approach in study of Islamic philosophy, is an approach that has ability to build a reliable basis for discussing previous philosophers’ questions and mental atmosphere for either deep understanding or pedagogical aims. Although, originality of existence issue, as a philosophical issue, well justified scientifically in Mulla Sadra’s time, but regarding problem-based approach, it is concluded that it did not appear as an issue suddenly and out of blue, rather it had its own scholar roots in history of philosophy; assessing these roots provide a clear image of transcendental philosophy.