The Islamic philosopher Avicenna reported that he had read Aristotle’s Metaphysics forty times and still had not understood it. Such a comment is illuminating both for metaphysics as a subject matter and for Aristotle’s treatise. Both are difficult to understand, but Aristotle’s work, baffling as it is, remains one of the best sources on metaphysics. Its structure is somewhat puzzling, probably because Artistotle’s students, not the philosopher himself, assembled the work from their notes. Therefore, Aristotle did not name the treatise. It was placed in the collection of his writings after the treatise Physica (second Athenian period, 335-323 b.c.e.; Physics, 1812) and so earned the name of meta-(after the) physics.

Accidental as this title seems, it still describes the content of the treatise fairly accurately. In modern times, much of the Physics (the discussion of the infinite) might be classed as metaphysics, and some of the topics of the Physics (change and movement) are repeated in the Metaphysics; however, the Metaphysics does go beyond the Physics. First principles, not the principles of natural movement alone, are the subject. The Metaphysics takes up questions beyond those of physical nature as such and moves on not only to first principles but also to an Unmoved Mover. It is true that Metaphysics stands somewhat alone in Aristotle’s writings. Much of the general interpretation of Aristotle’s other works will vary according to the way in which the Metaphysics is either bypassed or interpreted. That is, this treatise rightly occupies a metaphysical (basic) position within Aristotle’s vast writings.

Causes and Substance

Book Alpha, which begins with the famous sentence, “All men by nature desire to know,” is sometimes called the first history of philosophy. In it, Aristotle reviews the theories of the pre-Socratics and of Plato, and much of the information available about the pre-Socratics comes from Aristotle’s accounts. Aristotle works out his own theories through a critical appraisal of other doctrines, indicating the strong and the weak points of each theory and incorporating the strong points in his own view.

Aristotle first gives a brief epistemology, describing the modes for gaining knowledge and, finally, for the achievement of wisdom. Such true knowledge can only be a knowledge of causes, particularly of ultimate causes. It is this that leads Aristotle to consider previous theories and types of cause, ending in the famous doctrine of the four kinds of cause: the formal cause (the plan); the final cause (the purpose); the material cause (that which is used); and the efficient cause (that which initiates change).

Such a theory of causation is crucial to metaphysics, because what one wants is knowledge of truth, and one cannot know truth without its cause. In order to demonstrate that this can be done, Aristotle must affirm the existence of a first principle and the impossibility of either an infinite series or infinitely various kinds of causes. If it were otherwise, knowledge could not be obtained....

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Definition of Metaphysics

In book Gamma, Aristotle begins with the definition of metaphysics as the science that investigates “being as being.” Other branches of philosophy treat various particular kinds of things, but metaphysics considers the one starting point of all things, the first principles and highest causes. Because being falls immediately into genera, the various sciences correspond to these genera. Yet certain properties are peculiar to being as such, and the philosopher seeks to discover the truth about these.

To complete such basic inquiry, the philosopher must first find principles that are certain, and Aristotle provides a statement of the principle of noncontradiction as an example. Few principles can have the certainty that such a principle has, and one cannot demand demonstration of all things. Basic axioms cannot be proved, although they can be established indirectly by intuition or by the impossibility of their opposite being true. The starting point of demonstration cannot be demonstration but something accepted as true in itself. What metaphysicians must develop is a grasp of the basic principles that lie behind all demonstration, and then they ought to demand demonstration only of matters in which such proof is possible. They must grasp the principles of being itself.

Philosopher’s Lexicon

At first glance, book Delta seems puzzling. Sometimes called the philosopher’s lexicon, it appears to be (and is) simply an extended series of definitions of crucial terms. On closer inspection, these terms prove to be the basic metaphysical vocabulary (made up of such terms as “beginning” and “cause”). Metaphysics has always proceeded by spending time on the definition of a few key words. However, instead of attempting to give a single definition for each of these thirty or so terms, what Aristotle does is to list several common or possible meanings that may be given to each term. He does point up the more important meanings and focuses on any of metaphysical significance, but on the whole, the book is a straightforward analysis of various common meanings given to these philosophically important terms.

The four causes are listed again in this book (they are not always defined in the same terms). The term “necessity” is of some special interest, since Aristotle uses it in the positive sense (“cannot be otherwise”), very much as Plato uses “eternal,” whereas “necessity” for Plato in the Timaeos (last period dialogue, 360-347 b.c.e.; Timaeus, 1793) is a symbol of nonrationality and chaos. Aristotle denies unity as an overreaching concept and makes it merely an attribute of things. The philosopher also defines “substance” as the individual thing that is the bearer of...

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Next Aristotle returns to the crucial question of substance, which he calls “first in every sense.” The essence or the universal, the genus, and the substratum (that which underlies a thing) are all called substance. In deciding which of these meanings of substance is primary, Aristotle is never completely clear. As far as knowledge is concerned, essence is prior. However, Aristotle does not consider Plato’s forms to be self-subsistent substances; forms, or universals, exist only in things. At the other extreme, matter as pure potentiality is unknowable in itself, and there is no definition for the individual as such.

The causes of substances are the objects of Aristotle’s search, but sensible substances all have matter and are thus subject to potentiality. Essence certainly attaches to the form and to actuality, and in that sense, the form of the thing has a prior claim to be called substance. Substance is the primary category, and all other categories depend on it. In virtue of the concept of substance, all other beings also are said to be. It is clear that actuality is prior to potency. “Potency” is every principle of movement or rest, whereas substance or form is actuality.

Prime Mover

Arguing that eternal things are prior in substance to perishable things, Aristotle begins his argument for the existence of an eternal Prime Mover. No eternal things exist potentially (and on these grounds, he excludes the existence of an actual infinite). Nothing that is necessary can exist potentially. Yet such eternal and necessary substances must exist, for if these did not exist, nothing would exist. In things that are from the beginning, in eternal things, there is nothing bad, nothing defective, nothing perverted. How is there to be order unless there is something eternal and independent and permanent? In pursuing the truth, one must start from the things that are always in the same state and permit no change.

The process of change cannot go on to infinity. It is necessary that there should be an eternal unmovable substance. It is impossible that movement should either have come into being or cease to be. Movement also is continuous in the sense that time is. There must, then, be a principle whose very essence is actuality. There is something that moves without being moved, being eternal substance and actuality. The object of a desire moves in this way; it moves without being moved. The final cause, then, produces motion as being loved or desired, but all other things move by being moved.

Such a First Mover exists of necessity, and its mode of being is good. The heavens and the world of nature depend on such a principle. This substance...

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Additional Reading

Ackrill, J. L. Essays on Plato and Aristotle. New York: Oxford University Press, 1997. This work contains important and insightful reflections on two of the most influential thinkers in Western philosophy.

Adler, Mortimer J. Aristotle for Everybody: Difficult Thought Made Easy. New York: Scribner’s 1997. A reliable interpreter provides an account that introduces Aristotle’s thought in accessible fashion.

Bar On, Bat-Ami, ed. Engendering Origins: Critical Feminist Readings in Plato and Aristotle. Albany: State University of New York Press, 1994. Feminist...

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