According to Mulla Sadra’s theory of necessity, a determined causal law governs the relationship between cause and effect, a relationship that encompasses human behavior. There is no contrast between this determined causal law and free will. This theory will be examined and contrasted with Sayyed Muhammad Baqir al-Sadr’s exposition on free will. Al-Sadr’s theory of al-satfana or mastery suggests that free will is not compatible with the determined casual law. Free action and moral agency is led by the power of mastery. In this study, these two theories will be explained briefly. We shall attempt to evaluate which one of the two is more reasonable and preferable as a theory of human agency.

One of the earliest problems in philosophy that has occupied minds of great philosophers and has been debated in different philosophical ages is the problem of causality and its relation to freedom.

Depth of philosophical problems pertaining to causality and freedom on the one hand and the close relation between these two notions, theoretical and practical systems of man and also many problems in philosophy, theology and humanities such as law, ethics and psychology on the other hand, has made this discussion very important and vital.

In Islamic philosophy, the great Muslim philosopher, Sadrul Muta’llihin, known as Sadra, has made one of the most profound studies of "causality" and its relation to "human freedom".

One of the controversial problems among Muslim philosophers and theologians that led to some of the most heated debates in philosophy and theology is the very problem of "causality" and interpretation of "freedom" on its basis. These debates were marginalized after the decline of traditional theology and its inclusion in philosophy, mostly after the appearance of transcendental philosophy of Sadra. For a short period Sadra’s philosophy managed to be the dominant and governing trend in the history of Islamic thought.

This situation did not last for a long time, because simultaneous to the decline of "theological thought", the science of the principles of jurisprudence tremendously developed in Shi‘a thought and replaced "the theological current" in its intellectual debates with the philosophical thought. In this way, some of the earlier disputes between Muslim theologians and philosophers were revived in another form and a new school with a new way of thinking merged against the philosophical thought, which was embodied in the transcendental philosophy of Sadra. This new school can be called, "The School of Modern Usuliyyun", those who became experts in the principles of jurisprudence.

Among the modern usuliyun, Akhund Mulla Muhammad Kazim Khurasani represents Sadrian Islamic thought. Defending principles of "Sadrian philosophy", Akhund greatly supported the Sadrean view in the interpretation of causality and its relation to freedom.

On the other side, his intelligent and insightful pupil, i.e. Mirza Na‘ini was one of the strong critics of Sadrian view. In a new way and method, he criticized the Sadrian philosophical thought and presented a new viewpoint on the relation between causality and human freedom.
Na‘ini can be considered as the one who started a new way of dealing with the problem of causality and its relation to human freedom. Although his idea was not developed into a complete theory, it opened the way for a new and complete theory that was developed by the great contemporary thinker and philosopher Ayatullah Sayyid Muhammad Baqir al-Sadr. This theory was called the theory of Saltanah, sovereignty.

In this essay, after explaining briefly the philosophical theory of Sadra on the relation between causality and freedom which we shall call later the theory of necessity (wujub) and martyr Sadr’s theory of sovereignty (saltanah), we will compare these two theories with each other. We will also criticize and analyze them.