Providing an exact explication of rationality in a way that would lead to the explication of the scope of rational discourse is among the most fundamental problems of philosophers. In the current essay the author struggles to reach a comprehensive definition of rationality via an exact description and analysis of ideas of Mulla Sadra (1571-1641) as the most significant philosophical figure in the Islamic world according to which one can present all human achievements in the domain of knowledge and science as manifestations of this rationality. Rationality in Sadra’s intellectual system represents a comprehensive term with an analogically graded meaning that in different levels of certainty guarantees the validity of applied, theoretical and intuitive sciences. This comprehensive perspective of the domain of rational discourse can put an end to many disputes on the exact sense of rationality and in doing so, it can bring about a basis for more interaction and sympathy among scholars in various branches of science and open the path for deeper dialogue.
