The question of free will-occupying a central place in the structure of religious and philosophical anthropology-has preoccupied human thought since antiquity. Within contemporary Islamic principles of jurisprudence (usul al-fiqh), subtle and significant positions have emerged in addressing this problem; yet it has not received sufficient attention from theologians, philosophers, or scholars of anthropology. By "contemporary usuli thought," we refer to the Usul School founded by al-Muhaqqiq al-Khurasani and subsequently developed by his students and followers. In this article, we seek to analyze and assess these views, with particular focus on the thought of Sayyid Muhammad Baqir al-Sadr, who expanded al-Muhaqqiq al-Na'ini's theory, offered a critical evaluation of it, and introduced new conceptual elements. From the results I have reached, it has become clear that al Sayyid al Sadr distinguishes between the theological dimension and the philosophical dimension of the problem of determinism and free will. He does not regard the principle of prior necessity as a demonstrative principle, but rather as an experiential one. He further maintains that it does not encompass voluntary actions, and that we must introduce a new element-namely, the sovereignty of the self-alongside the three philosophical premises. Employing a descriptive-analytical method, the study first presents and evaluates these positions, and thereafter, following critical discussion, delineates the preferred solution to the problem of free will.