There are two bits of intellectual context that are essential for understanding the Metaphysics
. The first is the tradition of metaphysical investigation among earlier Greek philosophers, that is, the philosophers who are called the “Presocratics” because they lived before or at the same time as Socrates, and Aristotle’s teacher, Plato. The second is Aristotle’s own idea of a science, for he, like other Greek thinkers, regards metaphysics as a science.
First, though, let me make some general observations about Greek notions of science and metaphysics. Our word “science” comes from the Latin scientia, which is itself a translation of the Greek epistēmē. The latter can also be translated directly into English as “knowledge.” In other words, the same Greek term can be translated as “science” or as “[branch of] knowledge”: any branch of knowledge is called a “science.” Moreover, an art (technē), such as housebuilding, also counts as a branch of knowledge and, thus, as a science. It can be disorienting for contemporary readers to hear about a “science of metaphysics” or a “science of ethics,” but the term “science” should help to remind us that Aristotle assumes that knowledge must have a characteristic organization and structure. Both Plato and Aristotle distinguish branches of knowledge from each other by (1) their subject matters and (2) their principles. Physics, mathematics, ethics, and housebuilding all have different subject matters. The principles of these subject matters can be: (a) that within the subject matter in respect of which all else in the subject matter exists or is known (as the unit is the principle of number because all the counting numbers are composed of units), (b) those feelings, habits, and goals that motivate action (as happiness is a principle because it is the goal of all actions), and (c) the product the craftsman produces (as the finished house is a principle of the housebuilder because it determines the steps she needs to take to produce it).
It was Aristotle’s editor who gave the name “metaphysics” to the science he calls “wisdom,” “first philosophy,” and “the science of being as being.” Other Greek thinkers did not use any of these names, except perhaps “wisdom,” but they all had the concept of a branch of knowledge that differs from others because it seeks to know the first principles of all things. That is to say, its subject matter is all things, and its principles are that in respect of which all things are and are known. Plato thinks of it as the ruling science because it both rules the other sciences and fits a person to be a political ruler. Aristotle distinguishes the highest theoretical science, metaphysics, from the highest practical science, politics. It is not obvious that there are first principles and highest causes. Metaphysics must discover whether they exist and, if so, what they are. If there were no first principles, there would not be a science of metaphysics. Thus, in investigating whether there are first principles, metaphysics is investigating its own existence.
Greek philosophers assume that a cause is some sort of thing. This contrasts with modern thought where a cause is usually a law. Aristotle offers a famous account of the different sorts of causes, as we will see, in Metaphysics
A.3. All causes are principles, but some principles are not causes. Some readers take these latter principles to be laws, but Aristotle thinks they, too, must either be some sort of entity or somehow linked with an entity. Greek philosophers have no place for a principle that, like our principle of conservation of energy (energy is neither created nor destroyed), is a principle of everything without itself being anything.
Earlier Greek metaphysics
For Aristotle’s philosophical predecessors, the central metaphysical issue is the problem of the one and the many: are all things one or are they many? We can appreciate one version of this problem from modern physics, where it is posed as follows: are all things composed of many distinct elementary particles or are what appear to be distinct particles rather different states of a single entity? At one point, electrons, protons, and neutrons were thought to be the most elementary particles, but most physicists today think these are composed of still more fundamental constituents. Some claim that all these constituent particles are simply forms of energy and that, therefore, all is one. Analogously, ancient thinkers ask whether earth, air, fire, and water are distinct and irreducible elements of all things or whether all these are merely different forms of the same element, say, water. In either case, it is assumed that, by itself, each element is one and that, by being one, it is prior to any plurality formed from multiple elements.
There is another way that all might be one. Suppose that there is a single character that belongs to every being. (Such a character is called a “universal,” a “one [character] over many [things]”; a genus is an example of a universal because it belongs to each of its instances.) Then, everything that is would have the character, and everything that is not would not have it. All that is would, thus, have the same character, a character that would signify what it is to be, that is, the nature of being. A surprising consequence of this line of thought is that there would be no motion, for a motion occurs when something that is not comes to be, but whatever has the nature of being already is, and whatever lacks this nature and thereby is not, is nothing. It makes no sense to speak of nothing’s acquiring the nature of being or, indeed, acquiring any other nature. Furthermore, if there were a nature that were common to all beings, everything that is would have this nature and all would be one. This is the reasoning of Parmenides. Greek thinkers took these arguments to be so powerful that, after Parmenides, the central metaphysical issue was how there could be a plurality or a motion.
The ancient atomists are among those who offer an answer. They propose that there are indivisible bits of matter, atoms. Being consists of these atoms; not-being is the void. These philosophers concede that being does not change because individual atoms cannot alter their natures. However, motion and plurality are possible because groups of atoms do alter their positions relative to each other.
Plato and his school, the Academy, have a different response to Parmenides. Although there are some indications of this response in Plato’s dialogues, our principal source for it is Aristotle’s account in Metaphysics
books A, M and N. Since Aristotle recounts these doctrines in order to criticize them, some scholars argue that his reports are not reliable; all readers find them difficult to understand. Nonetheless, because he does propose, on behalf of the Academy, a response to Parmenides that he regards as important, readers of the Metaphysics
should appreciate it. According to Aristotle, Plato and the Academy try to construct things from both the character common to all beings, namely, “the one itself,” and its contrary. The contrary of the one itself is not “the many” as this latter is usually understood, for that many is a plurality of ones and, thus, presupposes the one itself instead of opposing it. Instead, they take the contrary to be an indeterminate many that lacks unity in any sense. They call it the “indefinite dyad.” This phrase is famously obscure, but the idea behind it is not. Think of a group of things that belong to the same class. They have something in common, the character that defines the class, but they must each also have some characteristic that distinguishes them from each other and from this common, defining character. Since the common defining character is a source of shared determination, the distinguishing character of each thing must be indeterminate. Thus, each individual is composed of the defining character and some indeterminate difference. Since the difference cannot be a single entity without partaking of the one, the Academy thinks of it as a dyad. Thus, it is possible to say that all things are composed of a determination and an indeterminacy or, as it is more typically put, of the one and the indefinite dyad. For Plato’s school, these latter are the principles of all things. Different people in the school worked out the details differently, proposing various hierarchical arrangements in accordance with different degrees of determinacy; but all seem to have thought that all things are, in some important sense, in the same class.
As such, all things come under a single science, that is, a single branch of knowledge. On the other hand, the Platonists also recognize the existence of particular sciences or arts. In his dialogue Philebus, Plato distinguishes the philosopher’s arithmetic from the arithmetic of the many (56d). In the former, all the units are equal; in the latter the units are cattle or armies or other things that are unequal. Whereas the philosopher counts equal units, the herdsman counts cattle, the general armies. Nonetheless, all the arts and sciences use counting and measuring, though some do so more than others. Thus, building and music depend heavily on mathematics, whereas military strategy and agriculture make less use of mathematics. Plato suggests a hierarchy of sciences based on the degree to which they use mathematics. At the top of the hierarchy is the philosopher’s arithmetic. It is followed closely by pure calculation (the science of making calculations with pure units) and geometry. Next are the arts like building and music that use mathematics extensively but impurely, and last the arts that make relatively little use of mathematics. It follows that someone who knows the philosopher’s arithmetic knows the basis of all the arts. If the one and the indefinite dyad are the principles of pure numbers, then the person who knows these principles knows all the arts and sciences. Conversely, knowing any particular science requires knowing something about number and measurement and, thereby, something about the first principles of all things. This account of the relationship between the one science (metaphysics) that knows all things by knowing the first principles and the particular sciences that know the principles of more limited subject matters is implicit in the Philebus.
In other dialogues Plato has Socrates raise questions about the relationship between a first science and subordinate sciences as objections to the existence of metaphysics. There are two sorts of objections: (1) If each subject matter is known by some particular science, there is no subject left for the highest science to know; but there is no science without its own proper subject matter. (2) If each science has a product (housebuilding produces the house, shoemaking the shoes, etc.), and the science that uses the product is higher than the science that makes it, then the highest science could not have a product. (If it did, then any science that used its product would be still higher, and we would have to inquire into the science that uses its product, and so on.) However, a highest science with no product would serve no end and, thus, be worthless.
Plato resolves these problems by identifying a distinctive subject matter for the highest sciences, separate forms. Since, as he argues, everything else imitates these forms, one who knows them knows something about everything else. He is able to produce things that imitate the forms, things like city-states, virtuous souls, and even physical objects. Again, there is a single generic science that knows all things by knowing their principles (that is, the forms) and specific sciences that each know a species of the genus of all things.
Aristotle argues against this account of the one and the many sciences, and he offers his own account in the Metaphysics
. However, it is important to realize that he recognizes the force of the problem. If there is to be one architectonic science of all things, it must somehow have its own subject matter, and it must somehow govern the other sciences. The problem of metaphysics is whether there is such a science. Hence, the problem of metaphysics is intrinsically a problem of how there can be one science that stands over all other sciences. Metaphysics is the only science that wrestles with its own existence, and its existence turns on finding some one thing or type of thing that stands over all other things and, thus, some one science that stands over all other sciences. Metaphysics is intrinsically connected with the problem of the one and the many that Aristotle’s predecessors address.
The term “science” is now often used loosely for an organized body of knowledge for which there is strong evidence, specifically the knowledge of nature and mathematical entities. Even though Aristotle uses this term for a broader range of subjects, he has more specific criteria for its application. A science (or, equivalently, “branch of knowledge”) (1) knows unchanging objects (2) that are grasped through their cause. The key to understanding how Aristotle meets these criteria lies in understanding the standard form of argument, the syllogism. The canonical syllogism, nicknamed “Barbara,” has the following form:
All M is P.
All S is M.
Therefore, All S is P.
M here is the middle term. We can say that we know that all S is P through M. Hence, M plays the role of a cause. The canonical scientific syllogism is a particular interpretation of the canonical syllogism. Here, S is the subject genus and P is an essential attribute. M is the essential nature of the genus. Hence, the syllogism shows that an essential attribute belongs to a genus because of the latter’s essential nature. A genus is a class of things that all have the same essential nature. For an attribute to belong to a genus is for it to be in each instance of the genus. For example: every rational animal is a being that is able to store food internally long enough to learn; every human being is a rational animal; hence, every human being is a being that is able to store food internally long enough to learn. Since the internal organ in which we store food is the long intestine, this syllogism is part of an Aristotelian account of why we have a long intestine.
It is often said that Aristotle does not follow his own scientific method in his physical and biological works. However, this remark misunderstands how Aristotle uses the syllogism. It assumes that he envisions science as a deductive enterprise, as if the essential attributes could somehow be deduced from a generic nature. Instead, Aristotle claims that scientific inquiry seeks the middle term, the M. That is to say, Aristotle uses the syllogism not to go from premises to conclusion, but to search in the opposite direction. His science begins from the observation that various attributes belong to a genus; that is, science begins from the conclusion of the syllogism. It aims to find the cause in respect of which the attributes belong to the genus; this cause is the genus’s essential nature. In general, scientific inquiry seeks to find the essential nature that defines its subject genus, the M. The syllogism directs the inquiry by showing what needs to be found. Sometimes Aristotle says that scientific inquiry begins from what is “prior for us” and finds what is “prior in nature.” The syllogism’s conclusion is prior for us because it is a matter of observation; the syllogism’s middle term is prior in nature. It is grasped through intellect. Thus, to return to the example of the previous paragraph, Aristotle begins with the observation that all human beings have long intestines, and seeks a cause, an M, that accounts for this fact. This cause is our rational nature, for to use reason we need extended periods of time when we are not eating and, thus, need an internal organ that can store food.
Aristotle’s account of science is more rigid than modern accounts because he is concerned to answer Plato’s contention that sensibles cannot be known. Both philosophers think that (a) the object of knowledge cannot change and also that (b) sensibles are always changing. These two assumptions lead Plato to conclude that sensibles cannot be objects of knowledge. Aristotle avoids this conclusion by arguing that these sensibles have unchanging essential natures as well as attributes that necessarily belong to them in respect of these natures. Thus, although individual sensibles change, their genera do not. (We will see later that he argues that sensibles have essential natures.) In other words, the syllogistic structure that Aristotle ascribes to science allows changing sensibles to be known by their unchanging natures, attributes, and genera.
Since metaphysics seeks the highest causes, we might think that it would seek that essential nature, M, that is the cause of the essential properties of all things. However, there is no genus of all things, as we will see later. Even if there were such a genus, its essential nature would not be the highest cause, but the lowest cause. To see why, consider the genus of animals. The generic nature of animals is the capacity for sensation. This character belongs to each instance of the genus, and it accounts for every animal’s having sense organs and, perhaps, for its being able to move itself. But each species of animal has its own sorts of sense organs and characteristic ways of movement. Whereas the generic nature of the genus animal accounts for characteristics common to all animals, the specific nature of, say, mammals, accounts for sense organs peculiar to mammals as well as hair, eyebrows, and other characteristics of this species. Each mammal has these latter essential attributes in virtue of its being a mammal. It has other, more general attributes insofar as it is an animal. Since each mammal is also an animal, the cause of its being a mammal is also the cause of its being an animal. So the essential nature of mammals is the cause not only of the essential attributes specific to mammals but also of the general attributes that belong to all animals. Insofar as the essential nature of mammals causes those attributes that are also caused by the essent...