As their greek predecessors, mathematicians and arab-speaking philosophers raised several important epistemological questions. One of those questions concerns the concept of equality and the concept of congruence of geometric magnitudes. What was the meaning of such concepts? How were they related to the idea of movement? Answers to these questions were often combining metric elements and other, philosophical (topological) elements, and I chose to study those of a mathematician, of a philosopher, and of a mathematician-philosopher.

This paper shows for the first time that Maimonides significantly relied on Avicenna's “Refutation of astrology” (Al-Išāra ilā fasād ῾ilm aḥkām al-nujūm) when composing his own refutation, the “Epistle on astrology” (῾Al Gezērat ha-kōkhabīm). Maimonides consulted a copy of Avicenna's Refutation, partially using its structure as a model for his Epistle, and adapting some of its arguments. Therefore, it may be said with certainty that Maimonides carefully read at least one of Avicenna's works, and that his Epistle is not based solely on his own previous works, the “Commentary on the Mishnah”, the “Code of Jewish law”, and the “Guide of the perplexed”.

In this article, I examine key passages from the Aš῾arite theologian Faḫr al- Dīn al-Rāzī’s (d. 606/1210) final work, Al-Maṭālib al-῾āliya (“ The lofty inquiries ”), in order to theorize Rāzī’s cosmology and angelology. In his attempt to prove the existence of these beings, Rāzī divides reality into material and intelligible realms. Angels, which signify the celestial intellects and spheres, exist as non-space-occupying beings and represent an aspect of the intelligible world. Of these, some are associated with celestial bodies, and others are entirely unassociated with materiality. I then present evidence for the possibility that Rāzī believed that these celestial spiritual beings are pre-eternal with God. These positions indicate a certain degree of conceptual continuity with the falsafa tradition, and reflect al-Ġazālī’s (d. 505/1111) previous integration of the philosophical structure of reality into some of his texts. Additionally, one may look to other philosophical currents that developed in the Islamic world beyond the falāsifa, and connect Rāzī’s cosmology to both the Hermetic tradition and the Epistles of the Iḫwān al-Ṣafā᾿.

This paper argues that Ibn Ṭufayl (d. 1185) in his Ḥayy ibn Yaqẓān offers a surprisingly intellectual reading of the term fiṭra (pl. fiṭar) and one that has significant consequences for our understanding of the story. We will see that at crucial junctures in the text, fiṭra emerges solely in an intellectual context, implying a gulf amongst humanity that defies common understandings of the term as egalitarian. This gulf, I argue, illuminates the political implications of the tale. For while he emphasizes the broad compatibility of the more established, revealed and the philosophical path recently arrived in Andalusia, Ibn Ṭufayl, with the help of fiṭra, shows that the philosophical life is one for the very few. Attention to Ibn Ṭufayl's use of fiṭra might thus explain one of his reasons for writing this tale for the court. Its overall message heightens the role of religion and tempers the political significance of philosophy in two ways: by arguing that only select individuals have the capacity to access truth independently from revelation; and by denying these exceptionally gifted the ability to communicate their findings to the masses.

Ibn Raḥīq is an 11th century scholar who compiled a book on popular astronomy. This work included a section in which he summarizes basic knowledge of the Milky Way as it was wide spread in the first centuries after the hejira. Ibn Raḥīq gives a comprehensive overview of the perception of the Milky Way that reaches from its use as a test for knowledge of the religious tradition and for agricultural purposes on the one hand to an exact astronomical description of its shape in the sky during the year and to theories of its nature and composition on the other hand. We use a comparison of his text to those of Ibn al-Haytham and others to investigate the role the Milky Way played in early Islamic civilization from its beginning until the 15th century.

Before Ṯābit b. Qurra's translation, there was a first Arabic version of Nicomachus’ Introduction to arithmetic. Full of mistakes, it was revised by an anonymous student of al-Kindī. Thanks to the part that Freudenthal and Levy have edited and translated, we are now able to identify this reviser as Aḥmad b. al-Ṭayyib al-Saraḫsī, who we also identified as the author of the Rasā᾿il Iḫwān al-Ṣafā᾿. The comparison of the gloss written by this reviser with a new fragment of Saraḫsī on one part, and with the “ Epistles of the Brethren in Purity ” on the other, corroborate Saraḫsī’s authorship of the epistles. Furthermore, studying the misunderstandings on Nicomachus’ text in this kindianised version gives a new light on al-Kindī’s attempt to unify philosophy and on the specific ontology of the Brethren in Purity.