Christopher Byrne

Much of the debate about Aristotle’s criticisms of Plato has focused on the separability of the Forms. Here the dispute has to do with the ontological status of the Forms, in particular Plato’s claim for their ontological priority in relation to perceptible objects. Aristotle, however, also disputes the explanatory and causal roles that Plato claims for the Forms. This second criticism is independent of the first; even if the problem of the ontological status of the Forms were resolved to Aristotle’s satisfaction, this second criticism would still stand. The problem here is not that there is no room for Aristotle’s four causes in Plato’s ontology; on the contrary, antecedents for all four can be found in Plato’s works. The problem, instead, is that Plato’s Forms fail to meet the general requirements that Aristotle sets out for the material, efficient, formal, and final causes of perceptible objects. Hence, even if the Forms were immanent in perceptible objects, they would still explain nothing about them.

RÉSUMÉBeaucoup ont soutenu qu'il n'y a pas de place pour des expériences scientifiques dans les sciences naturelles d'Aristote : les expériences interviennent dans la nature, mais Aristote soutient que nous devons simplement observer la nature; si nous intervenions, le résultat serait quelque chose d'artificiel ou contraire à la nature. Contre cela, je soutiens qu'Aristote a non seulement effectué des expériences scientifiques, mais a également maintenu qu'il y a beaucoup de connaissances sur la nature qui peuvent être découvertes expérimentalement.

Although Aristotle's contribution to biology has long been recognized, there are many philosophers and historians of science who still hold that he was the great delayer of natural science, calling him the man who held up the Scientific Revolution by two thousand years. They argue that Aristotle never considered the nature of matter as such or the changes that perceptible objects undergo simply as physical objects; he only thought about the many different, specific natures found in perceptible objects. Against this view, this book argues that Aristotle offers a systematic account of matter, motion, and the basic causal powers found in all physical objects. It argues that Aristotle not only sees all perceptible objects as sharing certain basic physical properties, but he also holds that perceptible objects have these physical properties because they are ultimately made from physical matter of one kind or another. Finally, it argues that for Aristotle the basic properties of matter, including the basic properties of the material elements, cannot be understood teleologically.

Some commentators have argued that there is no room in Aristotle's natural science for simple, or unconditional, physical necessity, for the only necessity that governs all natural substances is hypothetical and teleological. Against this view I argue that, according to Aristotle, there are two types of unconditional physical necessity at work in the material elements, the one teleological, governing their natural motions, and the other non-teleological, governing their physical interaction. I argue as well that these two types of simple necessity also govern everything made out of the elements, that is, all other natural substances and artifacts

In his metaphysics and natural philosophy, Aristotle uses the concept of a material cause,i.e., that from which something can be made or generated. This paper argues that Aristotle also has a concept of matter in the sense of physical stuff. Aristotle develops this concept of matter in the course of investigating the material causes of perceptible substances. Because of the requirements for change, locomotion, and the physical interaction of material objects, Aristotle holds that all perceptible substances must be extended in three dimensions, movable, and corporeal due to their material causes. Thus, perceptible substances are physical substances because they are made out of something physical.

According to a long interpretative tradition, Aristotle holds that the formal cause is the ultimate object of induction when investigating perceptible substances. For, the job of induction is to find the essential nature common to a set of individuals, and that nature is captured solely by their shared formal cause. Against this view, I argue that Aristotle understands perceptible individuals as irreducibly composite objects whose nature is constituted by both their formal and their material cause. As a result, when investigating perceptible objects, the job of induction is to discover their composite, formal and material nature. The process by which universal claims about this composite nature are justified, I argue, is similar to what we now know as mathematical induction. In particular, such claims are grounded in a non-enumerative, but replicable process in which things are resolved into their simplest components. As a result, the observation of past uniformities has, at most, a heuristic function in scientific inquiry.

Aristotle uses two kinds of material cause in his analysis of biological organisms: compositional matter, which persists through their birth and death;and functional matter, which consists of the organs and functional parts out of which biological organisms are made while they are alive. These two kinds of material cause, it has been argued, have quite different explanatory roles: functional matter is required by biological organisms to perform their essential functions,but compositional matter contributes nothing necessary to them and is only responsible for their accidental properties. Against this view, I argue that biological organisms are systematically dependent upon their compositional matter and the latter is responsible for many of their necessary attributes.

Gregory Vlastos has argued that Aristotle and other commentators on the Phaedo have mistakenly interpreted Plato’s Forms to be efficient causes. While Vlastos is correct that the Forms by themselves are not efficient causes, because of his neo-Kantianism he has misunderstood the close connection between the Forms and the explanation of change, including teleological change. This paper explores the connection in Plato’s Phaedo between the Forms, the nature of change, and efficient causality, and argues that Aristotle’s remarks are not as misplaced as Vlastos claims.

In the context of Aristotle's metaphysics and natural philosophy, 'prime matter' refers to that material cause which is both the proximate material cause of the four sublunary elements and the ultimate material cause of all perishable substances. On the traditional view, prime matter is pure potentiality, without any determinate nature of its own. Against this view, I argue that prime matter must be physical, extended, and movable matter if it is to fulfil its role as the substratum persisting through the generation and corruption of these elements and the individuating subject in which their defining properties are found.