The purpose of article is to show a new interpretation of Muʿtazila ideas, especially the narration Abd al-Jabbar ibn Ahmad, and an attempt to show the solution of the Muʿtazila to one of the important philosophical challenges, how to understand Rational understanding in the context of language and its communicative constraints. To achieve this goal, the Muʿtazila’s linguistic theory and how they extract the sensible within the limits of language is studied. The main question of this research is to what extent Muʿtazila’s rational approach is capable of resisting the critiques of linguistic turn and postmodern theories. By using of »Inference to the Best Explanation« Method, The results of this study show Muʿtazila present a form of Evidentialism, due to the type of definition of reason (common sense) and its reliance on language and its contractual conventions, potentially and actually have the ability to resolve imported criticisms on the Evidentialism that results from theories of linguistic-cognitive and postmodern rotation. The organization of Argument method in the Muʿtazila can provide a way to defend the rational matter in the postmodern age