Frans De Haas

Jaap Mansfeld and Frans de Haas bring together in this volume a distinguished international team of ancient philosophers, presenting a systematic, chapter-by-chapter study of one of the key texts in Aristotle's science and metaphysics: the first book of On Generation and Corruption.In GC I Aristotle provides a general outline of physical processes such as generation and corruption, alteration, and growth, and inquires into their differences. He also discusses physical notions such as contact, action and passion, and mixture. These notions are fundamental to Aristotle's physics and cosmology, and more specifically to his theory of the four elements and their transformations. Moreover, references to GC elsewhere in the Aristotelian corpus show that in GC I Aristotle is doing heavy conceptual groundwork for more refined applications of these notions in, for example, the psychology of perception and thought, and the study of animal generation and corruption. Ultimately, biology is the goal of the series of enquiries in which GC I demands a position of its own immediately after the Physics.The contributors deal with questions of structure and text constitution and provide thought-provoking discussions of each chapter of GC I. New approaches to the issues of how to understand first matter, and how to evaluate Aristotle's notion of mixture are given ample space. Throughout, Aristotle's views of the theories of the Presocratics and Plato are shown to be crucial in understanding his argument.

The distinction between potentiality and actualityActuality in Aristotle has its origin in Platonic ethicsEthics. In his psychological and ethical works Aristotle’s notion of potentiality is embedded in a causal framework that is characteristic of life in general. A key theme is the distinction of various meanings of ‘to know’. In his early work the possession of knowledgeKnowledge is distinguished from its use. In De anima Aristotle adds the potentiality for acquiring knowledge as characteristic of the genus human being. He argues that the stages of actualization of knowledge are instances of a more comprehensive biological and ethical development. Life is the fulfillment of soulSoul as formal, efficient and final causeCause, with the potentiality of body as material cause. The unity of body and soul is derived from the causal nexus of potentiality and actuality, like a power and the instrument in which it resides. In such cases potentiality is complex and depends on numerous conditions. Failure of full realization may occur when any of the necessary conditions of the development and realization of the fulfillment of human life are lacking, whether in the environment (e.g. climate), the body (illness, drunkenness), or the soulSoul (natural virtue, firm character, attention).

This volume sheds new light on Alexander of Aphrodisias' On Mixture and Growth as an intelligent and carefully crafted rebuttal of Stoic blending, which Alexander regarded as the closest rival of his own brand of hylomorphism. The authors explore Alexander's dialectical method and determine the precise character of the Stoic theory he attacks. The problematic notions of mutual co-extension and infinite division appear in their proper context, while the successive stages of the process of blending are carefully distinguished from the resulting state of the blend. In this perspective the discussion of growth that closes Alexander's work finds its natural place.

This paper argues that the changes in the interpretation of Aristotle’s De anima that Alexander is famous for were spawned by ethical concerns (among others). Alexander works hard to create the largest possible distance between the chains of antecedent causes that define Stoic determinism on the one hand, and Aristotle’s causal chain of animal locomotion in De anima and De motu animalium on the other—despite (or because of?) the possible historical relations between Aristotle and Stoic determinism. Alexander denies Aristotle’s chain every necessity, and tries to remove any impression that each of the links is itself a motion or a moved mover. As perfections or activities (ἐντελεχεῖαι) they are exempt from motion. Only in this way, Alexander must have thought, could Aristotle’s moral psychology be a worthy adversary of 2nd century Stoicism.

In this paper I explore the ways in which Alexander of Aphrodisias employs and develops so-called ‘common notions’ as reliable starting points of deductive arguments. He combines contemporary developments in the Stoic and Epicurean use of common notions with Aristotelian dialectic, and axioms. This more comprehensive concept of common notions can be extracted from Alexander’s commentary on Metaphysics A 1–2. Alexander puts Aristotle’s claim that ‘all human beings by nature desire to know’ in a larger deductive framework, and adds weight to Aristotle’s use of the common understanding of the notion of ‘wisdom’. Finally I will indicate how these upgraded common notions are meant to play an important role in the general framework of metaphysics as a science.

In this paper I propose a reading of Plotinus Enneads VI.1-3 [41-43] On the genera of being which regards this treatise as a coherent whole in which Aristotle's Categories is explored in a way that turns it into a decisive contribution to Plotinus' Platonic ontology. In addition, I claim that Porphyry's Isagoge and commentaries on the Categories start by adopting Plotinus' point of view, including his notion of genus, and proceed by explaining its consequences for a more detailed reading of the Categories. After Plotinus' integration of the Categories into the Platonic frame of thought Porphyry saw the possibilities of exploiting the Peripatetic tradition both as a means to support the Platonic interpretation of the Categories and as a source for solutions to traditional questions. His allegiance to a division of being into ten, and his emphasis on semantics rather than ontology can be explained from this orientation. In the light of our investigation the alleged disagreement between Plotinus and Porphyry on the Categories changes its appearance completely. There are differences, but these can be best explained as confirmation and extension of Plotinus' perspective on the Categories and its role in Platonism.

Philoponus’ commentary on the Posterior Analytics isPosterior Analytics littered with mathematical terminology and elaborate discussions of mathematical proofs which go far beyond Aristotle’s own references to mathematics in this work. Why? In this paper I argue that Philoponus’ commentary displays the ongoing programme of mathematically enlightened readings of philosophical texts which lamblichus inaugurated. I reconstruct this framework of interpretation, which affects the understanding of both logic and psychology, from lamblichus’ De communi mathematica scientia, and confirm the allegiance of Ammonius and his school to a closely similar framework. I show that against this background we can better understand at least three features of Philoponus' work: (1) the development of tekmeriodic proof as the necessary counterpart to demonstration ; (2) the conviction that all sciences, including mathematics, give access to Platonic metaphysics, or dialectic, by following the chain of demonstration upwards, and (3) the interpretation of Aristotle’s conversion of syllogisms as mathematical conversion, with as its favourite example Plato’s proof for the immortality of the soul in the Phaedrus.