The evolution of proof of the truthful from Naṣīr al-Dīn al-Ṭūsī to Naṣīr al-Dīn kāshī

The proof of the truthful (Burhān-i ṣiddīqīn) is one of the valid and most prominent arguments to demonstrate the existence of God in the Islamic philosophy and theology. It was invented first by Avicenna (Ibn Sīnā) and developed via later philosophers and theologians. The proof due to its own credibility received a noticeable reception of the post-Avicennian Imāmī theologians, who tended to the philosophical views of Avicenna, in medieval period. Naṣīr al-Dīn al-Ṭūsī and al-ʿAllāma al- Ḥillī, among them, set forth various version of it in their works. Naṣīr al-Dīn kāshī tried to invent a new and unique version of the proof of the truthful (Burhān-i ṣiddīqīn) as well. Kāshī’s argument has not been received much attention so far, although it deserve it. In this article, we try to show the evolution of proof of the truthful (Burhān-i ṣiddīqīn) in the Shiʿite Philosophical theology, from Naṣīr al-Dīn al-Ṭūsī to Naṣīr al-Dīn kāshī. This survey shows that the post-Avicennian Imāmī theologians like Naṣīr al-Dīn al-Ṭūsī and al-ʿAllāma al-Hillī have followed an Avicennian method for proving the existence of God and that they tried to benefit from Philosophical teachings of Avicenna for demonstrating the existence of God. This new approach in Shiite theology led to the revolution of arguments for proving God in Imāmī Shiʿite theology in the medieval period.