Abstract

Thabit ibn Qurra (836-901) was an influential figure in the Kindi Circle, a group of scholars who popularized the classical, scientific, and philosophical texts in Muslim society under the reign of the early ‘Abbasid dynasty. He is primarily known for his translations, commentaries, and expositions in astronomy and the exact mathematical disciplines, but he figures also in the Neoplatonic interpretation of Aristotelian philosophy.

Thabit ibn Qurra (836-901), astronomer, mathematician, and philosopher, worked at the Islamic ‘Abbasid court during the classical stage in medieval Muslim intellectual history. He was a major figure in the so-called Kindi Circle and so participated in the project in which the philosopher al-Kindl (d. after 870) sought to popularize the philosophical and scientific works which the Muslim world inherited from the Greeks as part of the Graeco-Arabic translation movement. Of Sabian origin and thus of this partially pagan but certainly scholarly community of Harran, Thabit was well-prepared to start his career with knowledge of the important languages (Greek, Syriac, and Arabic) that were the main tools of the translation movement and of the scholarly discussions that took as fundamental, philosophical and scientific principles, those of the preIslamic Aristotelian and the subsequent Neoplatonic commentary tradition (of both pagan and Christian Greek Near Eastern communities).

In the field of philosophy, Thabit’s familiarity with the Aristotelian corpus is evident from his compendia and abridgments of parts of the Aristotelian logical Organon (Categoriae, De interpretatione, Analytica priora). Indicative of his philosophical studies is an acute presentation of Aristotle’s Metaphysics and his translation (or reportedly ‘‘correction’’) of Themistius’ paraphrase of Aristotle’s work. One work, his Concise Exposition of Aristotle’s Metaphysics, gives us indication of Thabit’s intellectual allegiances and achievements. In this work, the concentration of attention is directed toward the ‘‘theological’’ core (the metaphysica specialis) of Chaps. 6-9 in the book Lambda and the content concerned with a type of reconciliation of its doctrines and Islamic (or at least monotheistic) tenets. Examples of this effort is to be seen in his attribution of will to the vague and pagan articulated ‘‘First Principle’’ and his Islamic-inspired choice of the term tawJild to describe its ‘‘unicity.’’ As a result of these pieces of evidence, we can conclude that Thabit ascribed to the “theologizing” interpretation that was very important to the success of the Kindi cycle of works in medieval Islamic intellectual circles. The overall content of this most important philosophical work ascribed to Thabit displays an original and percipient understanding of Aristotelian doctrine. While clarifying Aristotle’s position on the two subjects of the First Mover being the cause of corporeal substance’s existence and the First Principle being cause of the universe’s existence from eternity, Thabit is quite skilled at introducing and providing solutions for the logical consequences of Aristotle’s arguments. The structure of the work also evinces Thabit’s expert knowledge of Neoplatonic commentaries; this is especially evident in his prolegomenon’s inclusion of the points of information expected in the earlier works.

While Thabit displays an appreciation for the ancient philosophical tradition as well as acumen applied to its problems, he was and is best-known for his work in astronomy (and its attendant fields of astrology and mathematics). In astronomy he not only clarified many aspects of the heritage of Ptolemy, but also contributed original thought that would lead eventually to the common perception of astronomy as an exact science. These contributions included a new empiricist approach to astronomical data and at the same time a ‘‘mathematizing’’ trend in astronomical research by the use of geometrical models. His thought in the field of mathematics is displayed in a textual dialogue with his contemporary 'Isa b. Usayyid. Three issues were addressed. In one, Thabit propounded the Neoplatonic doctrine that numbers have an existence separable from numbered things. In another, he defended the view that infinite numbers actually exist. This research into finitude and infinitude were to be of some importance to the Muslim philosophical tradition, particularly when applied to the question of divine knowledge of universals (the topic of the third question) as well as discussions on the postmortem existence of particularized or individuated human souls. This correspondence is to be included in the vast mathematical corpus composed by ThaIbit which includes treatises on geometry (planes and their terminations; the study of planes in relation to discrete substances; the magnitudes of pure figure) as well as mathematics proper (treatises on discrete numeration, etc.).

ThaIbit’s intellectual heritage was of profound importance to developments in the medieval Arabic fields of philosophy and the exact sciences. His penchant for the Platonic tradition was perhaps the most influential trend in determining what of the Platonic corpus would be translated and how its implications for the relevant fields of research would be addressed. His approach to those fields would have major implications for the development of philosophy and the exact sciences at least until the later medieval age.

See also: > al-Kindl, Abu Yusuf Ya'qub ibn Isljaq > Mathematics and Philosophy in the Arab World