This dissertation is a study of the intellectual history of Ṣadr al-Dīn Dashtakī (d. 903/1498) and Ghiyāath al-Dīn Dashtakī (d. 949/1542), two important Shirazi philosophers and Shi'i thinkers who lived in the late Timurid and early Safavid period. It argues that Avicennan philosophy was revived and provided with a new impetus at a time when it was under attack by Ash'ari thinkers belonging to the later tradition. Paradoxically, many of the later Ash'ri thinkers saw it fit to engage in metaphysical speculations that took the Avicennan tradition as its basis. Yet, these same thinkers accused Avicenna and his followers of advancing specious arguments and for making incoherent statements about God, the cosmos, religious matters, and the general nature of things. So overarching was this later Ash'ari tradition, that it became the intellectual tradition par excellence in the centuries leading up to the Safavid period. In many of their major philosophical writings, the Dashtakīs sought to decouple Avicennan philosophy from Ash'ari kalām, and, at the same time, to attack the foundations of the Ash'ari tradition. In doing so, the Dashtakīs proposed a particular reading of Avicenna that was purified of Ash'ari influences and closer to philosophical Shi'ism.