Life. Aristotle was born in 384 BCE. at Stagirus, a Greek colony and seaport on the coast of Thrace. His father Nichomachus was court physician to King Amyntas of Macedonia, and from this began Aristotle's long association with the Macedonian Court, which considerably influenced his life. While he was still a boy his father died. At age 17 his guardian, Proxenus, sent him to Athens, the intellectual center of the world, to complete his education. He joined the Academy and studied under Plato, attending his lectures for a period of twenty years. In the later years of his association with Plato and the Academy he began to lecture on his own account, especially on the subject of rhetoric. At the death of Plato in 347, the pre-eminent ability of Aristotle would seem to have designated him to succeed to the leadership of the Academy. But his divergence from Plato's teaching was too great to make this possible, and Plato's nephew Speusippus was chosen instead. At the invitation of his friend Hermeas, ruler of Atarneus and Assos in Mysia, Aristotle left for his court. He stayed three year and, while there, married Pythias, the niece of the King. In later life he was married a second time to a woman named Herpyllis, who bore him a son, Nichomachus. At the end of three years Hermeas was overtaken by the Persians, and Aristotle went to Mytilene. At the invitation of Philip of Macedonia he became the tutor of his 13 year old son Alexander (later world conqueror); he did this for the next five years. Both Philip and Alexander appear to have paid Aristotle high honor, and there were stories that Aristotle was supplied by the Macedonian court, not only with funds for teaching, but also with thousands of slaves to collect specimens for his studies in natural science. These stories are probably false and certainly exaggerated.

Upon the death of Philip, Alexander succeeded to the kingship and prepared for his subsequent conquests. Aristotle's work being finished, he returned to Athens, which he had not visited since the death of Plato. He found the Platonic school flourishing under Xenocrates, and Platonism the dominant philosophy of Athens. He thus set up his own school at a place called the Lyceum. When teaching at the Lyceum, Aristotle had a habit of walking about as he discoursed. It was in connection with this that his followers became known in later years as the peripatetics, meaning "to walk about." For the next thirteen years he devoted his energies to his teaching and composing his philosophical treatises. He is said to have given two kinds of lectures: the more detailed discussions in the morning for an inner circle of advanced students, and the popular discourses in the evening for the general body of lovers of knowledge. At the sudden death of Alexander in 323 BCE., the pro-Macedonian government in Athens was overthrown, and a general reaction occurred against anything Macedonian. A charge of impiety was trumped up against him. To escape prosecution he fled to Chalcis in Euboea so that (Aristotle says) "The Athenians might not have another opportunity of sinning against philosophy as they had already done in the person of Socrates." In the first year of his residence at Chalcis he complained of a stomach illness and died in 322 BCE.

Writings. It is reported that Aristotle's writings were held by his student Theophrastus, who had succeeded Aristotle in leadership of the Peripatetic School. Theophrastus's library passed to his pupil Neleus. To protect the books from theft, Neleus's heirs concealed them in a vault, where they were damaged somewhat by dampness, moths and worms. In this hiding place they were discovered about 100 BCE by Apellicon, a rich book lover, and brought to Athens. They were later taken to Rome after the capture of Athens by Sulla in 86 BCE. In Rome they soon attracted the attention of scholars, and the new edition of them gave fresh impetus to the study of Aristotle and of philosophy in general. This collection is the basis of the works of Aristotle that we have today. Strangely, the list of Aristotle's works given by Diogenes Laertius does not contain any of these treatises. It is possible that Diogenes' list is that of forgeries compiled at a time when the real works were lost to sight.

The works of Aristotle fall under three headings: (1) dialogues and other works of a popular character; (2) collections of facts and material from scientific treatment; and (3) systematic works. Among his writings of a popular nature the only one which we possess of any consequence is the interesting tract On the Polity of the Athenians. The works on the second group include 200 titles, most in fragments, collected by Aristotle's school and used as research. Some may have been done at the time of Aristotle's successor Theophrastus. Included in this group are constitutions of 158 Greek states. The systematic treatises of the third group are marked by a plainness of style, with none of the golden flow of language which the ancients praised in Aristotle. This may be due to the fact that these works were not, in most cases, published by Aristotle himself or during his lifetime, but were edited after his death from unfinished manuscripts. Until Werner Jaeger (1912) it was assumed that Aristotle's writings presented a systematic account of his views. Jaeger argues for an early, middle and late period (genetic approach), where the early period follows Plato's theory of forms and soul, the middle rejects Plato, and the later period (which includes most of his treatises) is more empirically oriented. Aristotle's systematic treatises may be grouped in several division:

Logic
1. Categories (10 classifications of terms)
2. On Interpretation (propositions, truth, modality)
3. Prior Analytics (syllogistic logic)
4. Posterior Analytics (scientific method and syllogism)
5. Topics (rules for effective arguments and debate)
6. On Sophistical Refutations (informal fallacies)

Physical works
1. Physics (explains change, motion, void, time)
2. On the Heavens (structure of heaven, earth, elements)
3. On Generation (through combining material constituents)
4. Meteorologics (origin of comets, weather, disasters)

Psychological works
1. On the Soul (explains faculties, senses, mind, imagination)
2. On Memory, Reminiscence, Dreams, and Prophesying

Works on natural history
1. History of Animals (physical/mental qualities, habits)
2. On the parts of Animals
3. On the Movement of Animals
4. On the Progression of Animals
5. On the Generation of Animals
6. Minor treatises
7. Problems

Philosophical works
1. Metaphysics (substance, cause, form, potentiality)
2. Nicomachean Ethics (soul, happiness, virtue, friendship)
3. Eudemain Ethics
4. Magna Moralia
5. Politics (best states, utopias, constitutions, revolutions)
6. Rhetoric (elements of forensic and political debate)
7. Poetics (tragedy, epic poetry)

Logic. Aristotle's writings on the general subject of logic were grouped by the later Peripatetics under the name Organon, or instrument. From their perspective, logic and reasoning was the chief preparatory instrument of scientific investigation. Aristotle himself, however, uses the term "logic" as equivalent to verbal reasoning. The Categories of Aristotle are classifications of individual words (as opposed to propositions), and include the following ten: substance, quantity, quality, relation, place, time, situation, condition, action, passion. They seem to be arranged according to the order of the questions we would ask in gaining knowledge of an object. For example, we ask, first, what a thing is, then how great it is, next of what kind it is. Substance is always regarded as the most important of these. Substances are further divided into first and second: first substances are individual objects; second substances are the species in which first substances or individuals inhere.

Notions when isolated do not in themselves express either truth or falsehood: it is only with the combination of ideas in a proposition that truth and falsity are possible. The elements of such a proposition are the noun substantive and the verb. The combination of words gives rise to rational speech and thought, conveys a meaning both in its parts and as a whole. Such thought may take many forms, but logic considers only demonstrative forms which express truth and falsehood. The truth or falsity of propositions is determined by their agreement or disagreement with the facts they represent. Thus propositions are either affirmative or negative, each of which again may be either universal or particular or undesignated. A definition, for Aristotle is a statement of the essential character of a subject, and involves both the genus and the difference. To get at a true definition we must find out those qualities within the genus which taken separately are wider than the subject to be defined, but taken together are precisely equal to it. For example, "prime" "odd" and "number" are each wider than "triplet" (i.e., a collection of any three items, such as three rocks); but taken together they are just equal to it. The genus definition must be formed so that no species is left out. Having determined the genus and species, we must next find the points of similarity in the species separately and then consider the common characteristics of different species. Definitions may be imperfect by (1) being obscure, (2) by being too wide, or (3) by not stating the essential and fundamental attributes. Obscurity may arise from the use of equivocal expressions, of metaphorical phrases, or of eccentric words. The heart of Aristotle's logic is the syllogism, the classic example of which is as follows: All men are mortal; Socrates is a man; therefore, Socrates is mortal. The syllogistic form of logical argumentation dominated logic for 2,000 years.

Metaphysics. Aristotle's editors gave the name "Metaphysics" to his works on first philosophy, either because they went beyond or followed after his physical investigations. Aristotle begins by sketching the history of philosophy. For Aristotle, philosophy arose historically after basic necessities were secured. It grew out of a feeling of curiosity and wonder, to which religious myth gave only provisional satisfaction. The earliest speculators (i.e. Thales, Anaximenes, Anaximander) were philosophers of nature. The Pythagoreans succeeded these with mathematical abstractions. The level of pure thought was reached partly in the Eleatic philosophers (such as Parmenides) and Anaxagoras, but more completely in the work of Socrates. Socrates' contribution was the expression of general conceptions in the form of definitions, which he arrived at by induction and analogy. For Aristotle, the subject of metaphysics deals with the first principles of scientific knowledge and the ultimate conditions of all existence. More specifically, it deals with existence in its most fundamental state (i.e. being as being), and the essential attributes of existence. This can be contrasted with mathematics which deals with existence in terms of lines or angles, and not existence as it is in itself. In its universal character, metaphysics superficially resembles dialectics and sophistry. However, it differs from dialectics which is tentative, and it differs from sophistry which is a pretence of knowledge without the reality.

The axioms of science fall under the consideration of the metaphysician insofar as they are properties of all existence. Aristotle argues that there are a handful of universal truths. Against the followers of Heraclitus and Protagoras, Aristotle defends both the laws of contradiction, and that of excluded middle. He does this by showing that their denial is suicidal. Carried out to its logical consequences, the denial of these laws would lead to the sameness of all facts and all assertions. It would also result in an indifference in conduct. As the science of being as being, the leading question of Aristotle's metaphysics is, What is meant by the real or true substance? Plato tried to solve the same question by positing a universal and invariable element of knowledge and existence -- the forms -- as the only real permanent besides the changing phenomena of the senses. Aristotle attacks Plato's theory of the forms on three different grounds.

First, Aristotle argues, forms are powerless to explain changes of things and a thing's ultimate extinction. Forms are not causes of movement and alteration in the physical objects of sensation. Second, forms are equally incompetent to explain how we arrive at knowledge of particular things. For, to have knowledge of a particular object, it must be knowledge of the substance which is in that things. However, the forms place knowledge outside of particular things. Further, to suppose that we know particular things better by adding on their general conceptions of their forms, is about as absurd as to imagine that we can count numbers better by multiplying them. Finally, if forms were needed to explain our knowledge of particular objects, then forms must be used to explain our knowledge of objects of art; however, Platonists do not recognize such forms. The third ground of attack is that the forms simply cannot explain the existence of particular objects. Plato contends that forms do not exist in the particular objects which partake in the forms. However, that substance of a particular thing cannot be separated from the thing itself. Further, aside from the jargon of "participation," Plato does not explain the relation between forms and particular things. In reality, it is merely metaphorical to describe the forms as patterns of things; for, what is a genus to one object is a species to a higher class, the same idea will have to be both a form and a particular thing at the same time. Finally, on Plato's account of the forms, we must imagine an intermediate link between the form and the particular object, and so on ad infinitum: there must always be a "third man" between the individual man and the form of man.

For Aristotle, the form is not something outside the object, but rather in the varied phenomena of sense. Real substance, or true being, is not the abstract form, but rather the concrete individual thing. Unfortunately, Aristotle's theory of substance is not altogether consistent with itself. In the Categories the notion of substance tends to be nominalistic (i.e., substance is a concept we apply to things). In the Metaphysics, though, it frequently inclines towards realism (i.e., substance has a real existence in itself). We are also struck by the apparent contradiction in his claims that science deals with universal concepts, and substance is declared to be an individual. In any case, substance is for him a merging of matter into form. The term "matter" is used by Aristotle in four overlapping senses. First, it is the underlying structure of changes, particularly changes of growth and of decay. Secondly, it is the potential which has implicitly the capacity to develop into reality. Thirdly, it is a kind of stuff without specific qualities and so is indeterminate and contingent. Fourthly, it is identical with form when it takes on a form in its actualized and final phase.

The development of potentiality to actuality is one of the most important aspects of Aristotle's philosophy. It was intended to solve the difficulties which earlier thinkers had raised with reference to the beginnings of existence and the relations of the one and many. The actual vs. potential state of things is explained in terms of the causes which act on things. There are four causes:

1. Material cause, or the elements out of which an object is created;
2. Efficient cause, or the means by which it is created;
3. Formal cause, or the expression of what it is;
4. Final cause, or the end for which it is.

Take, for example, a bronze statue. Its material cause is the bronze itself. Its efficient cause is the sculptor, insofar has he forces the bronze into shape. The formal cause is the idea of the completed statue. The final cause is the idea of the statue as it prompts the sculptor to act on the bronze. The final cause tends to be the same as the formal cause, and both of these can be subsumed by the efficient cause. Of the four, it is the formal and final which is the most important, and which most truly gives the explanation of an object. The final end (purpose, or teleology) of a thing is realized in the full perfection of the object itself, not in our conception of it. Final cause is thus internal to the nature of the object itself, and not something we subjectively impose on it.

God to Aristotle is the first of all substances, the necessary first source of movement who is himself unmoved. God is a being with everlasting life, and perfect blessedness, engaged in never-ending contemplation.

Philosophy of Nature. Aristotle sees the universe as a scale lying between the two extremes: form without matter is on one end, and matter without form is on the other end. The passage of matter into form must be shown in its various stages in the world of nature. To do this is the object of Aristotle's physics, or philosophy of nature. It is important to keep in mind that the passage from form to matter within nature is a movement towards ends or purposes. Everything in nature has its end and function, and nothing is without its purpose. Everywhere we find evidences of design and rational plan. No doctrine of physics can ignore the fundamental notions of motion, space, and time. Motion is the passage of matter into form, and it is of four kinds: (1) motion which affects the substance of a thing, particularly its beginning and its ending; (2) motion which brings about changes in quality; (3) motion which brings about changes in quantity, by increasing it and decreasing it; and (4) motion which brings about locomotion, or change of place. Of these the last is the most fundamental and important.

Aristotle rejects the definition of space as the void. Empty space is an impossibility. Hence, too, he disagrees with the view of Plato and the Pythagoreans that the elements are composed of geometrical figures. Space is defined as the limit of the surrounding body towards what is surrounded. Time is defined as the measure of motion in regard to what is earlier and later. it thus depends for its existence upon motion. If there where no change in the universe, there would be no time. Since it is the measuring or counting of motion, it also depends for its existence on a counting mind. If there were no mind to count, there could be no time. As to the infinite divisibility of space and time, and the paradoxes proposed by Zeno, Aristotle argues that space and time are potentially divisible ad infinitum, but are not actually so divided.

After these preliminaries, Aristotle passes to the main subject of physics, the scale of being. The first thing to notice about this scale is that it is a scale of values. What is higher on the scale of being is of more worth, because the principle of form is more advanced in it. Species on this scale are eternally fixed in their place, and cannot evolve over time. The higher items on the scale are also more organized. Further, the lower items are inorganic and the higher are organic. The principle which gives internal organization to the higher or organic items on the scale of being is life, or what he calls the soul of the organism. Even the human soul is nothing but the organization of the body. Plants are the lowest forms of life on the scale, and their souls contain a nutritive element by which it preserves itself. Animals are above plants on the scale, and their souls contain an appetitive feature which allows them to have sensations, desires, and thus gives them the ability to move. The scale of being proceeds from animals to humans. The human soul shares the nutritive element with plants, and the appetitive element with animals, but also has a rational element which is distinctively our own. The details of the appetitive and rational aspects of the soul are described in the following two sections.

The Soul and Psychology. Soul is defined by Aristotle as the perfect expression or realization of a natural body. From this definition it follows that there is a close connection between psychological states, and physiological processes. Body and soul are unified in the same way that wax and an impression stamped on it are unified. Metaphysicians before Aristotle discussed the soul abstractly without any regard to the bodily environment; this, Aristotle believes, was a mistake. At the same time, Aristotle regards the soul or mind not as the product of the physiological conditions of the body, but as the truth of the body -- the substance in which only the bodily conditions gain their real meaning.

The soul manifests its activity in certain "faculties" or "parts" which correspond with the stages of biological development, and are the faculties of nutrition (peculiar to plants), that of movement (peculiar to animals), and that of reason (peculiar to humans). These faculties resemble mathematical figures in which the higher includes the lower, and must be understood not as like actual physical parts, but like such aspects as convex and concave which we distinguish in the same line. The mind remains throughout a unity: and it is absurd to speak of it, as Plato did, as desiring with one part and feeling anger with another. Sense perception is a faculty of receiving the forms of outward objects independently of the matter of which they are composed, just as the wax takes on the figure of the seal without the gold or other metal of which the seal is composed. As the subject of impression, perception involves a movement and a kind of qualitative change; but perception is not merely a passive or receptive affection. It in turn acts, and, distinguishing between the qualities of outward things, becomes "a movement of the soul through the medium of the body."

The objects of the senses may be either (1) special, (such as color is the special object of sight, and sound of hearing), (2) common, or apprehended by several senses in combination (such as motion or figure), or (3) incidental or inferential (such as when from the immediate sensation of white we come to know a person or object which is white). There are five special senses. Of these, touch is the must rudimentary, hearing the most instructive, and sight the most ennobling. The organ in these senses never acts directly , but is affected by some medium such as air. Even touch, which seems to act by actual contact, probably involves some vehicle of communication. For Aristotle, the heart is the common or central sense organ. It recognizes the common qualities which are involved in all particular objects of sensation. It is, first, the sense which brings us a consciousness of sensation. Secondly, in one act before the mind, it holds up the objects of our knowledge and enables us to distinguish between the reports of different senses.

Aristotle defines the imagination as "the movement which results upon an actual sensation." In other words, it is the process by which an impression of the senses is pictured and retained before the mind, and is accordingly the basis of memory. The representative pictures which it provides form the materials of reason. Illusions and dreams are both alike due to an excitement in the organ of sense similar to that which would be caused by the actual presence of the sensible phenomenon. Memory is defined as the permanent possession of the sensuous picture as a copy which represents the object of which it is a picture. Recollection, or the calling back to mind the residue of memory, depends on the laws which regulate the association of our ideas. We trace the associations by starting with the thought of the object present to us, then considering what is similar, contrary or contiguous.

Reason is the source of the first principles of knowledge. Reason is opposed to the sense insofar as sensations are restricted and individual, and thought is free and universal. Also, while the senses deals with the concrete and material aspect of phenomena, reason deals with the abstract and ideal aspects. But while reason is in itself the source of general ideas, it is so only potentially. For, it arrives at them only by a process of development in which it gradually clothes sense in thought, and unifies and interprets sense-presentations. This work of reason in thinking beings suggests the question: How can immaterial thought come to receive material things? It is only possible in virtue of some community between thought and things. Aristotle recognizes an active reason which makes objects of thought. This is distinguished from passive reason which receives, combines and compares the objects of thought. Active reason makes the world intelligible, and bestows on the materials of knowledge those ideas or categories which make them accessible to thought. This is just as the sun communicates to material objects that light, without which color would be invisible, and sight would have no object. Hence reason is the constant support of an intelligible world. While assigning reason to the soul of humans, Aristotle describes it as coming from without, and almost seems to identify it with God as the eternal and omnipresent thinker. Even in humans, in short, reason realizes something of the essential characteristic of absolute thought -- the unity of thought as subject with thought as object.

Ethics. Ethics, as viewed by Aristotle, is an attempt to find out our chief end or highest good: an end which he maintains is really final. Though many ends of life are only means to further ends, our aspirations and desires must have some final object or pursuit. Such a chief end is universally called happiness. But people mean such different things by the expression that he finds it necessary to discuss the nature of it for himself. For starters, happiness must be based on human nature, and must begin from the facts of personal experience. Thus, happiness cannot be found in any abstract or ideal notion, like Plato's self-existing good. It must be something practical an human. It must then be found in the work and life which is unique to humans. But this is neither the vegetative life we share with plants nor the sensitive existence which we share with animals. It follows therefore that true happiness lies in the active life of a rational being or in a perfect realization and outworking of the true soul and self, continued throughout a lifetime.

Aristotle expands his notion of happiness through an analysis of the human soul which structures and animates a living human organism. The parts of the soul are divided as follows:

                    Calculative -- Intellectual Virtue
Rational
                    Appetitive -- Moral Virtue
Irrational
                    Vegetative -- Nutritional Virtue

The human soul has an irrational element which is shared with the animals, and a rational element which is distinctly human. The most primitive irrational element is the vegetative faculty which is responsible for nutrition and growth. An organism which does this well may be said to have a nutritional virtue. The second tier of the soul is the appetitive faculty which is responsible for our emotions and desires (such as joy, grief, hope and fear). This faculty is both rational and irrational. It is irrational since even animals experience desires. However, it is also rational since humans have the distinct ability to control these desires with the help of reason. The human ability to properly control these desires is called moral virtue, and is the focus of morality. Aristotle notes that there is a purely rational part of the soul, the calcu