Theoretical Superstructures of Theological Rule "God's actions are caused by motives" or God does not do anything devoid of wisdom

Many disciplines owe their credit and validity to other sciences. Ilm al-Usul is a discipline of Islamic studies which owes its credit and validity partially to theology and its principles. A lot of theological rules have been used in various issues of legal and jurisprudential principles. The principle "God's actions are caused by motives" is a rational principle per se and it has been affirmed by verses 28 and 39 of Chapter al-Dukhan where the Quran says, "And We did not create the heavens and the earth and what is between them in sport. We did not create them both but with the truth, but most of them do not know." This study seeks to mention the opinions of theologians about the rule as well as those of the exegetes about the verses. Thereupon, the effect of those principles and verses on legal studies have been clearly mentioned and it becomes clear as to how far they have influenced the verbal discussions, rational concomitance, validity (authoritativeness) and practical laws in a way that it can be considered as one of the presuppositions of the affirmative foundations of the issues of Ilm al-Usul.