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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...

(This entire section contains 4512 words.)

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often was convinced that his arguments demonstrated where these predecessors made their mistakes in such a way that all rational people would agree. Aristotle’sOrganon (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 matter. In the above sentence, “this tree” refers to some matter that one can see, touch, and perhaps even smell, and “is tall” refers to the shape or form of the matter. Pure matter, however, is inconceivable. No matter what one tries to picture, it always has some shape or form. Therefore, considered by itself, matter is mere potentiality as opposed to actuality.

Can one, then, conceive of pure form? That is difficult, though nonetheless possible according to Aristotle. It is possible, for example, to conceive of a particular song’s melody without actually hearing the song. In fact, Ludwig van Beethoven conceived and composed his ninth symphony after he became totally deaf. In Aristotelian terms, he knew its form without ever experiencing its matter. Though Beethoven’s is a special sort of case, it does help Aristotle make sense of God as pure form. In the vast majority of cases, though, Aristotle maintains that the matter and form of a thing always constitute a real unity and that they can only be separated conceptually.

People’s ability to conceptually separate a thing’s matter and form explains a second basic fact about language. A capacity with which all normal human beings are born is the ability to observe an incredible array of different sized, shaped, and colored objects and realize that they are all trees. Of course, the capacity to know that something is a tree presupposes much experience and instruction, but the fact remains—normal human beings are able to learn what makes an object a tree. Aristotle draws two conclusions from this fact. First, normal human beings are endowed with a capacity (nous) that enables them to abstract forms from matter. Second, nature is divided into natural kinds that humans discover and name when they abstract a thing’s substantial form.

This last point leads to one final distinction—the difference between a thing’s substantial form and what Aristotle calls its accidental form. A substantial form is that which makes a thing what it is. Change a thing’s substantial form, and the thing becomes something else. Cut down an actual tree, and the mass of matter is no longer a tree but is potentially a house, firewood, or compost, which will eventually turn to dirt. Yet a tree can undergo many changes and still remain a tree. Prune a limb from a tree or pick its fruit and the accidental form of the tree changes. Yet the tree remains a tree.

With these distinctions, Aristotle believes that he is able to justify commonsense beliefs about the world in the face of Heraclitus’s arguments. While it is true that the five senses reveal that the accidental forms of things are continually changing, it is not true that a thing’s substantial form is always changing. Thus, while there is a sense in which Heraclitus is correct, his failure to distinguish between matter and form, actuality and potentiality, and substantial forms and accidental forms invalidates his radical conclusion that everything is in a continual state of flux.

Having demonstrated that some things can remain the same, it remains for Aristotle to answer Parmenides and demonstrate how things can change. Aristotle begins by distinguishing two quite different uses of the verb “to be.” To say, “The table is” (that is, “the table exists”) says something quite different from saying, “The table is white.” The former “is” asserts the existence of a thing; the latter “is” does not. “Whiteness” does not name a substantial form that itself exists; it only names an accidental form that cannot exist apart from actual things. While a table is actually white, it is also potentially red. Furthermore, if someone paints the table, and it becomes actually red, the table itself does not cease to exist while another table suddenly begins to exist. Parmenides’ failure to distinguish between actuality and potentiality leads to his radical conclusion that nothing changes.

Aristotle is now in a position to analyze the commonsense notion of change by elucidating four ways that people use the word “cause.” Consider, for a moment, a bronze statue. There are four different replies to the question of what makes that thing a statue: because it is made of bronze (material cause); because it is in the shape of a man (formal cause); because an artist shaped the matter the way that he did (efficient cause); or because an artist wanted to make a beautiful object (final cause). All four statements are true, yet no single one gives a complete explanation of the statue. According to Aristotle, any complete explanation of what a thing is, or why a thing changes, must mention all four kinds of causes.

The need for a final cause in all complete explanations has been the topic for much controversy, though there is no controversy that final causes play a central role in all Aristotle’s thought. His ideas about causation are discussed in book 12 of the Metaphysics. Here, Aristotle repeatedly says that an infinite series of causes is impossible, but his words are somewhat misleading. He does not mean to assert that there is no infinite series of causes and effects. In fact, he believes that the universe itself must be infinite. What Aristotle means by his claim is that if such an infinite series of causes exists without a first cause, then the series as a whole is itself unintelligible. In any series of causes, until the stopping point can be ascertained, one cannot really determine who or what is responsible for any member of the series. Yet since Aristotle believes that the universe always existed in some form, its first cause cannot exist at some point of time prior to all others. Instead, the first cause must be conceptually first.

Not all answers to the question, Who or what is responsible for the some particular thing or movement?, refer to something that exists temporarily prior to the thing or movement being explained. A large bowl of food will cause a hungry dog to run toward it. In such a case, it is sufficient, says Aristotle, that the cause (the bowl of food) and the effect (the dog’s running) exist simultaneously; the cause does not have to exist before the effect. Similarly, Aristotle argues that God’s existence as the most perfect of beings is the final cause or end of all motion, even though both God and the universe have always existed.

Furthermore, the fact that God moves the universe as a final cause, rather than as an efficient cause, explains why God Himself does not require a cause. In Aristotle’s metaphysics, God is an unmoved mover. He is thus ultimately responsible for all movement and change in the universe without Himself moving. It makes no more sense to ask, “What moves God?” than it does to ask, “Why is a vacuum empty?”

Nicomachean Ethics

First published: Ethika Nikomacheia, 335-323 b.c.e. (English translation, 1797)

Type of work: Philosophy

Aristotle argues that happiness is the result of distinctly human activities performed well.

Aristotle believed that ethics was more a matter of character than of following rules. He was more concerned with what a person was than what he did. He realized that to a large extent a person’s character is created by his actions. Yet making one’s actions conform to rules was not the goal of morality. A person can obey all the rules of chess without being a very good chess player. So too, a person can follow all the rules of morality—never lie, steal, murder, or commit adultery—without being an especially good person.

The goal of morality, according to Aristotle, is human happiness. One of the questions that has received much attention from modern moral philosophers—Why be moral?—never arose for Aristotle because he simply assumed that achieving a stable and lasting happiness was everyone’s goal.

Of course, Aristotle understood that there is a wide divergence of opinion among people as to what constitutes happiness—some say it is wealth, others say it is power or honor, still others say it is pleasure. People will only know which of these, or which mix of these, really leads to a life well lived, says Aristotle, by first determining the proper work or function of a person qua person.

The function of a carpenter is to build houses, and the function of an author is to write books. Given these distinct functions, it is not unreasonable to assume that a carpenter would feel frustrated if forced to write a book, and conversely, that an author would feel frustrated if forced to build a house. Each of these would rather be doing that which he or she is uniquely suited to do. Aristotle takes this argument one step further and argues that human beings are happiest when they are acting in accordance with their essential nature.

The essential nature of anything is the thing’s work or function, that is, that which it does better than anything else. Observation reveals that humans are superior to all other animals in two areas, reasoning and social organization. Aristotle does not say that only humans are capable of reasoning. A dog can infer from his master’s facial expression that he is about to be punished. Yet dogs cannot discover, or understand, what is common to all punishments because they cannot know (nous) the essence of punishment. Dogs may be able to communicate with a series of growls and barks, but they are not able to create a language that defines and categorizes things according to their essential natures.

Similarly, while dogs live in packs and exhibit a rudimentary social nature, that social structure is determined by instinct. This tendency is evident by the invariant nature of that organization within a single species. Human social organizations are voluntary, and thus, they exhibit a wide variety of political structures ranging from the monarchical to the democratic.

Aristotle now becomes more specific as to exactly how human beings flourish. Since they are by nature rational, humans have a need and desire for knowledge. Only when this natural desire is fulfilled can humans be truly happy. Second, the nature of a person as a social animal means that men and women have a natural need and desire for friends. The Nicomachean Ethics devotes a fifth of its chapters to the nature and value of friendship.

In Aristotle’s philosophy, a human being’s rational and social nature feed and nourish each other. Their rational capacities, for example, must be developed by good parents and teachers, and good parents and teachers are only found in well-ordered societies. Conversely, well-ordered societies presuppose knowledgeable citizens. Thus, knowledge and virtue go hand in hand.

Aristotle defines virtue as “the mean relative to us, a mean which is defined by a rational principle, such as a man of practical wisdom would use to determine it.” He explains himself with an example. Consider, he says, the different caloric needs of a heavyweight boxer in training and of a teacher during spring break. What may be too few calories for the boxer may very well be too many for the teacher. There is no set number of calories that all people ought to ingest. Similarly, consider the virtue of liberality. What may be a stingy contribution to charity by a rich man may be an overly generous contribution by a person of moderate means with a family to support.

Yet Aristotle is not a moral relativist. He is not saying that, since people in different cultures have different beliefs about what is right or wrong, there are therefore no moral absolutes. There is nothing in Aristotle’s ethic that makes mere difference of belief a morally relevant factor in the determination of the mean. A society that believes that wealth is largely the result of individual initiative might believe that contributing 2 percent of one’s income to charity is a worthy goal. A different society that believes that wealth is largely a gift of nature might believe that giving only 2 percent of one’s income to the less fortunate would be unthinkably tight. Though these two cultures have different beliefs, that in itself, Aristotle would say, is morally irrelevant in determining the morally proper mean.

While the caloric needs of different people vary, what those needs are is not determined by majority opinion, but by the nutritional expert. So too, the mean in moral matters is not determined by popular opinion. Rather, it is determined by a rational principle, and that rational principle is in turn determined by the man or woman of practical wisdom.

The healthy individual has a desire for exercise and proper food. Regardless of what others say, his judgment in these matters is correct because of the obvious effect of his wholesome practices on his own life. According to Aristotle, one ought to reason similarly in ethical matters. Just as people know a physically healthy person when they see one, they also know a happy person when they see one. Of course, when Aristotle says a person is happy, he is not referring to an emotional state of someone who wins the state lottery. Such a condition is the result of external conditions and not the result of voluntary action. Rather, when he speaks of the happy woman, he is speaking of the woman who is happy largely as a result of what she has herself done. Her happiness is stable because it “feeds on itself” in the same way that a winning college basketball team continues winning year after year because it is able to recruit the best high school players. Similarly, a happy person is one who succeeds in the worthy things that she sets out to do. When she does, she receives satisfaction, and this in turn encourages her to set out to accomplish other worthwhile goals. That causes the cycle to repeat. It is this sort of person that Aristotle says determines the “rational principle” in moral matters.


First published: Peri potiks, c. 334-323 b.c.e. (English translation, 1705)

Type of work: Literary criticism

This is a work of theoretical and practical literary criticism, especially with regard to tragic drama.

Aristotle’s Poetics, though short, has been widely influential outside philosophical circles. Yet it is doubtful that it can be fully appreciated outside Aristotle’s philosophical system as a whole.

Central to all Aristotle’s philosophy is the claim that nothing can be understood apart from its end or purpose (telos). Not surprisingly, the Poetics seeks to discover the end or purpose of all the poetic arts, and especially of tragic drama. Understood generally, the goal of poetry is to provide pleasure of a particular kind. The Metaphysics begins, “All men desire to know by nature,” and the Nicomachean Ethics repeatedly says that the satisfaction of natural desires is the greatest source of lasting pleasure. The Poetics combines these two with the idea of imitation. All people by nature enjoy a good imitation (that is, a picture or drama) because they enjoy learning, and imitations help them to learn.

Of particular interest to Aristotle is the pleasure derived from tragic drama, namely, the kind of pleasure that comes from the purging or cleansing (catharsis) of the emotions of fear and pity. Though the emotions of fear and pity are not to be completely eliminated, excessive amounts of these emotions are not characteristic of a flourishing individual. Vicariously experiencing fear and pity in a good tragedy cleanses the soul of ill humors.

Though there are many elements of a good tragedy, the most important, according to Aristotle, is the plot. The centrality of plot once again follows from central doctrines of the Metaphysics and the Nichomachean Ethics. In the former, Aristotle argues that all knowledge is knowledge of universals; in the latter, he states that it is through their own proper activity that humans discover fulfillment.

For a plot to work, it must be both complete and coherent. That means that it must constitute a whole with a beginning, middle, and end, and that the sequence of events must exhibit some sort of necessity. A good dramatic plot is unlike history. History has no beginning, middle, and end, and thus it lacks completeness. Furthermore, it lacks coherence because many events in history happen by accident. In a good dramatic plot, however, everything happens for a reason. This difference makes tragedy philosophically more interesting than history. Tragedy focuses on universal causes and effects and thus provides a kind of knowledge that history, which largely comprises accidental happenings, cannot.