This article analyses Avicenna's Ḥayawān III, 1, which deals with the well-known disagreement between physicians and philosophers on the origination of blood vessels (arteries and veins) and nerves. However, the proposed analysis is not limited to this chapter and its main topic. The more general purpose of this article is to reconstruct the psycho-medical context in which Avicenna's exposition lies, that is, the soul's oneness and the consequent conditions for body ensoulment (i. e. the soul's need for a primary, unitary attachment to the body through the heart and the cardiac pneuma). The article then outlines the strategy through which Avicenna presents medical positions (heart, brain, and liver are all on an equal footing) that challenge his (and Aristotle's) anatomical model, which is coherent with his theory of the soul. In this connection, firstly, the article shows how Avicenna takes physicians’ arguments apart in a philosophical context (he usually points at their logical shortcomings). Then, it clarifies the contribution of anatomy to determine the conditions of body ensoulment and, ultimately, how to reconcile medical practice with philosophical truths, if need be.

Parmi les écrits consacrés à la réflexion des rayons « visuels» et solaires sur les différents miroirs, il en existe deux, qui ont précédé bien d'autres, et qui occupent une position centrale dans l'histoire de la catoptrique : l'un est attribué à Euclide, l'autre à Ptolémée. À ces deux noms, on en ajoute un troisième jusqu'ici inconnu, Thiasos. Dans cet article, nous reprenons l'histoire textuelle et conceptuelle de cette tradition de recherche catoptrique.

I argue that Avicenna allows for at least one case where we can intellectually grasp a particular individual as such: Each human intellect can intellect itself as numerically this one intellect without relying on any general notion or concept. This is because humans can retain their individuality when separated from their bodies. I discuss passages in which Avicenna appears to affirm and deny that humans can intellect themselves. I conclude that in contrast to the self-awareness that Avicenna showcases in his “floating human” thought experiment, human self-intellection is a rare achievement, and I explain how it differs from the more perfect self-intellection of the divine intellect.

In his analysis of the hypothetical (šarṭīyya) connected (muttaṣila) and disjunctive (munfaṣila) propositions (Al-qiyās, section V), Ibn Sīnā suggests that they can be quantified and presents in section VI a hypothetical system containing the conditional ones, which is exactly parallel to categorical syllogistic and makes use of the same conversion rules and the same proofs. In section VII, he provides four lists of hypothetical quantified propositions whose clauses are themselves quantified and says that the relations of the Aristotelian square of opposition hold for them. In addition, he says that some conditional universal affirmative propositions are equivalent to some universal negative ones with opposed consequents, and to some quantified disjunctive ones. The problem is that these claims are incompatible with each other, since they require two different readings of the universal affirmative conditional proposition, which Ibn Sīnā does not distinguish clearly. In this paper we solve the problem by distinguishing explicitly between these two readings and showing that the first one satisfies the conversion rule of the universal affirmative and the relations of the logical square, and validates all the admitted moods, while the second one satisfies the contraposition rule and the equivalences stated by Ibn Sīnā. This accounts for all Ibn Sīnā’s claims and makes the system coherent.

The polymath Ibn al-Ṣalāḥ (d. 1154 CE) is known for a number of comparatively small treatises on specific aspects of ancient Greek mathematical and philosophical works. He devotes many of his works to greater or smaller errors that he found in the works by Euclid, Ptolemy, and Aristotle. The aim of the present paper, which focuses on three treatises on Ptolemy and Aristotle, is to describe Ibn al-Ṣalāḥ’s method and aim in these works. I argue that his treatises on the Almagest, On the Heavens, and Posterior Analytics follow a similar structure and that there is much value for modern research resulting from the bibliographical details provided by Ibn al-Ṣalāḥ. To give but just one example, Ibn al-Ṣalāḥ attests to the existence of a so far unknown Arabic translation of Aristotle's Posterior Analytics. In this way, this paper is the first to establish Ibn al-Ṣalāḥ’s research profile: his works tell us which sources were available to scholars active in Baghdad and Damascus in the 12th century CE and how he tried to resolve contradictions from the different versions of authoritative texts. Thus, this paper enhances our knowledge of the Graeco-Arabic transmission of scientific and philosophical texts.

In the fresh reading proposed here of the still not satisfactorily interpreted passages in Metaphysics Ε2-3, Aristotle emerges as making a case against determinism based on a robust notion of the accident. Accidental beings are uncaused causes and have their rightful place in Aristotle's ontology. The resulting physical indeterminism is here used as a litmus test for the exegetical practice of the great Commentator, Averroes, whose self-proclaimed, and later proverbial, loyalty to Aristotle's text will be shown to give way to idiosyncratic interpretations at times. His explanations of Metaphysics Ε2-3 are sparse and no less obscure than Aristotle's text. It is only when read together with his commentaries on the Physics, to which he explicitly refers twice in his Long commentary on Metaphysics Ε2-3, that a surprising picture emerges. Averroes recycles the notion of the accident, now reconceptualised in cosmological terms, and – putting it to the opposite use of Aristotle's – weaves it into an original theory of motion that integrates both supra- and sublunar realms into a deterministic framework of uninterrupted causal chains, thus safeguarding the principle of Divine providence.