(Masterpieces of World Literature, Critical Edition)

At the very heart of Aristotle’s philosophy is the conviction that all things are teleologically ordered. There are two fundamentally different ways in which people explain events or things (understood in their broadest sense). Something is explained teleologically when its purpose or intention is made known. For example, a chair can be explained as an object made for sitting and a person’s raised hand as an attempt to attract the teacher’s attention. Alternately, something is explained causally when its physical antecedents are made known. For example, the crack in the brick wall can be explained as the result of a prior earthquake.

During the seventeenth and eighteenth centuries, there was a strong reaction against teleological explanations because it was believed that all real knowledge gives power and control over nature. Since teleological explanations of nature do not typically help to prevent or predict natural phenomena, they were deemed to be sterile, as was Aristotle’s philosophy as a whole. This period’s rejection of Aristotle, however, was based largely on a misreading of his works. Aristotle did not ignore physical causes. The majority of Aristotle’s work deals with topics and issues that today are considered scientific. Moreover, Aristotle’s scientific investigations reveal a great care and concern for thorough observations and the collection of empirical evidence before reaching any conclusions.

Though Aristotle himself never ignored or belittled the investigation of physical causes, his view of nature and the modern scientific view of nature are quite different. The tendency today is to follow the seventeenth century’s view of science as primarily an attempt to control nature. Aristotle, instead, emphasized science’s attempt to understand nature, and that, he steadfastly insisted, would include both kinds of explanations. In his work De anima (335-323 b.c.e.; On the Soul, 1812), Aristotle notes that some of his predecessors have tried to explain anger in terms of physical causes, while others have tried to explain it in terms of a person’s intentions to seek retaliation. When asked whose explanation was better, Aristotle responded, “Is it not rather the one who combines both?”

According to Aristotle, an explanation is complete only if it has a place in a systematic and unified explanation of the whole of reality. The incredible range of topics on which Aristotle wrote is not simply the result of his wide interests. Rather, it is also the result of his conviction that all complete explanations must have their place in a systematic whole.

The goal of the special sciences—biology, physics, or astronomy, for example—for both Aristotle and modern scientists is to deduce an explanation of as many observations as possible from the fewest number of principles and causes as possible. Yet Aristotle would add that the scientist’s work is not complete until those principles and causes are themselves explained. If the “first principles” of a discipline are simply assumed to be true, then the whole discipline is left hanging in midair.

Aristotle’s method of justifying first principles begins with the notion of dialectic. Aristotle’s principal works start with a discussion of what his predecessors have said on the topic being studied. While such a review would always include conflicting opinions, Aristotle believed that if conflicting opinions are forced to defend themselves against their opponent’s objections, the result is typically a distinction that allows the two partial truths to be unified into a larger and more complete truth.

Though Aristotle was always seeking to find some truth in conflicting opinions, he was neither a skeptic nor a relativist with regard to scientific or moral knowledge. He was never reticent to point out his predecessors’ mistakes, and he often was convinced that his arguments demonstrated where these predecessors made their mistakes in such a way that all rational people would agree. Aristotle’s Organon (335-323 b.c.e.; English translation, 1812) contains the tools of such demonstrations and, as such, is the first systematic formulation of the principles of deductive and inductive logic. While contemporary logicians have increased the power and versatility of Aristotle’s logic, his analysis of fallacious reasoning has never been shown to be in error.


First published: Ta meta ta physika, 335-323 b.c.e. (English translation, 1801)

Type of work: Philosophy

This work is an analysis of what it means to exist and a determination of the kinds of things that actually exist.

Twentieth century philosophers have distinguished between descriptive metaphysics and revisionist metaphysics. Aristotle’s metaphysics is clearly an attempt to describe, analyze, and justify the common beliefs about humanity and the world, not an attempt to persuade people to revise their prephilosophical views of the world in some radical fashion. Unless the revisionist metaphysics of Aristotle’s contemporaries is understood, however, it is impossible to understand Aristotle’s own accomplishment.

Previous philosophers, such as Heraclitus, argued that the only source of knowledge is that which is observed through one of the five senses, and since the testimony of the five senses reveals a continually changing world, it follows that absolutely nothing remains the same. A rock or a mountain may at first seem fairly stable, but close examination reveals that they, too, are continually being diminished by the winds and the rains. As Heraclitus said, it is impossible to step into the same river twice. Rocks and mountains may not change as quickly, but they change no less surely.

To be told that rivers, rocks, and mountains are continually changing appears to be relatively innocuous. Yet the logic of Heraclitus’s argument makes it impossible to stop there. If the only source of knowledge is through the senses, then absolutely everything must be in a continual state of flux. A person who robs a bank, for example, can never be caught because whoever is charged with the crime is necessarily a different person than the one who actually committed it. Heraclitus’s philosophical conclusions are clearly in radical opposition to the commonsense view of the world.

Other philosophers, such as Parmenides, argued for the exact opposite conclusion, namely, that all change is illusory. While Heraclitus appealed to empirical data, Parmenides appealed to reason. Consider everything that really exists in the entire universe precisely as it is at this particular instance, he believed. Whatever that “everything” is, it is by definition the Real, and anything else must therefore be unreal. Now if the Real were to change, it would become something that it is not, that is, it would become unreal. Yet the unreal does not exist. Thus, for anything to change is for it to become nonexistent. All change must therefore be unreal.

The radical opposition of Parmenides’ philosophical conclusions are obvious from the start. What is not so obvious is exactly where his reasoning is mistaken. While the common people will be able to continue their daily tasks without ever addressing either Heraclitus or Parmenides’ arguments, it would be inconsistent for Aristotle to insist that first principles must be dialectically justified and then simply ignore these revisionist arguments. Commonsense assumptions must be justified.

The three assumptions that Aristotle seeks to justify are, first, that things exist; second, that some things move and change; and finally, that the things in this universe that exist, move, and change are not totally unintelligible. The common element of all three beliefs is the notion of a “thing.” What is a thing? Aristotle says that things have being (existence) and that a metaphysician’s task is to make clear exactly what being is. In fact, he often defines the subject matter of metaphysics as the study of all things insofar as they exist.

Compare this definition with the definition of other disciplines. The subject matter of physics, says Aristotle, is things insofar as they are moving or changing objects. The subject matter of biology is things insofar as they are alive. The subject matter of ethics is things insofar as they are able to make rational choices between competing goods. One notices how the various subject matters of different disciplines constitute a hierarchical series from the particular to the general. Thus, a single person can be studied on at least three different levels. First, her or she can be studied by the moral philosopher as a “thing” capable of making rational choices. At a more general level, he or she can be studied by the biologist as a “thing” that is alive. At an even more general level, her or she can be studied by the physicist as a “thing” that moves.

The crucial metaphysical question for Aristotle thus becomes the following: Is there any more general level at which one can study things than at the level of the physicist? Aristotle thinks that there is, namely, at the level at which things are studied simply insofar as they exist. This way of defining the different disciplines ensures that no important questions are begged. In particular, it leaves open the question of whether anything exists apart from space and time. One of the important conclusions in the Metaphysics is that such a being, the unmoved mover or God, does exist. Yet before addressing such interesting and difficult theological questions, Aristotle wisely directs his attention to the more mundane, but almost as difficult, question, What is a thing?

Aristotle begins by cataloging the ordinary sorts of things that exist in this universe. There is this particular rock, that particular tree, and his friend Theaetetus. The point of any catalog is to organize different things into classes where all members of a class share something in common. People do this sort of thing all the time. The very act of speaking constitutes a kind of ordering of objects into classes. To say, “Theaetetus is snub-nosed,” is to place a particular individual into one class of things as opposed to a different class. This ability to speak, and hence, classify, is grounded in two basic facts.

First, there are two fundamentally different sorts of words—substantives and words that describe substantives. In Aristotle’s terms, there are subjects and predicates. Certain words or phrases are always subjects, and others are always predicates. For example, it makes sense to say, “This tree is tall,” but it makes no sense to say, “Tall is this tree” (unless this statement is understood simply as a poetic way of saying, “This tree is tall”). This fundamental fact of language leads to Aristotle’s distinction between form and...

(The entire section is 4512 words.)