its disciplines, and even authored two works on the subject—Mahakk al-Naẓar (The Touchstone of Reflection) and Miʿyār al-ʿIlm (The Criterion of Knowledge). With time his confidence in this method only grew stronger. More remarkable still, he produced a book entitled al-Qisṭās al-Mustaqīm (The Just Balance), claiming it to be the very teaching of the prophets, whereas he had merely learned it from Ibn Sīnā, who in turn had derived it from the writings of Aristotle. Those who treated definitions after Abū Ḥāmid are precisely those who discussed them in the manner of the Greek logicians.

As for the remaining groups of speculative theologians—Muʿtazilites, Ashʿarites, Karramites, Shiʿites, and others, including authors from the four legal schools and beyond—their view is that the sole function of a definition is to distinguish the defined entity from anything else. Indeed, most of them deem it impermissible to frame a definition that fails to single out the object in question. It is unacceptable, in their eyes, to include within a definition anything shared by the object and by other things, whether one calls that a genus or a general attribute. Rather, they define only by means of what invariably accompanies the object, both positively and negatively, making no real distinction between what is labeled a “differentia,” a “proprium,” or any other term that isolates the object from all else.

This stance is well known in the writings of the rational scholars—too numerous to list in full—among the mutakallimūn, both from those who affirm the divine attributes and others: Abū al-Ḥasan al-Ashʿarī, Qāḍī Abū Bakr Isḥāq, Abū Bakr Ibn Fūrak, Qāḍī Abū Yaʿlā, Ibn ʿAqīl, Abū al-Maʿālī al-Juwaynī, Abū al-Maimūn al-Nasafī the Ḥanafī, and many more. Preceding them were Abū ʿAlī, Abū Hāshim, ʿAbd al-Jabbār and their peers among the Muʿtazilite elders; likewise Ibn al-Nawbakht, al-Mūsā, al-Ṭūsī and other Shiʿite shaykhs; as well as Muḥammad ibn al-Hayṣam and other Karramite authorities. Whenever these scholars speak of definition, they state that the definition—and thus the true reality—of a thing is the distinctive property that sets it apart from everything else.