Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

With this book the course of Peripatetic doctrine begins; its author and founder is Aristotle. Who he was, where he came from, or how he spent his life does not concern us, since we are not writing this man’s history but explaining his teaching. Aristotle therefore began the principles of his Logic and of his entire doctrine with this book, for the reason that here Logic begins to direct the operations of reason from the side of the subject matter proper to this art. Since its proper task is to direct the three operations of reason, the first of which is the simple operation that apprehends simple things, Logic must first set to work on this operation. Although, because it is simple, this operation may not seem in itself to need regulation, just as simple vision by an external power does not, yet—as Cajetan aptly observes in the prologue to this book—it greatly needs ordering on the side of its object, or of the proposition that expresses its object, because things pass from the senses to the intellect in a highly entangled and confused way. For example, through the eyes a colored thing is presented together with figure, quantity, relation, substance, motion, and six hundred other features, all presented at once in an entangled way. But for the intellect to reach the quiddity of things, know how to form definitions, and draw out properties from definitions by demonstrations, these things had to be separated and distributed into their own genera, as it were into classes, which we call categories, in Greek categories: that is, “series or coordinations of higher and lower predicates within each genus and class,” so that we may assign to each thing its own essential predicates and properties.

This book therefore considers the simple genera of things by separating and distinguishing them—not by considering their natures, which belongs to the metaphysician, but by considering the coordination of higher and lower predicates, which is the business of the logician. This consideration belongs to Logic not on the side of form and prior resolution, but on the side of matter and posterior resolution within this art, as we have often noted. Accordingly, in the book On Interpretation, where he treats of speech and proposition, the Philosopher takes up again the simple concepts that in this book he considered on the side of the object, as separable and distinguishable into various genera; there he considers them according to the relations among the parts of speech, namely noun and verb, or simple expression and term, as we said in part 1 of the Summulae, and as St. Thomas wisely observes at the beginning of book 1 of On Interpretation¹.

About to treat these genera or categories, into which all created things are distributed and contained, Aristotle divided the whole book into three principal parts. The first is called Pre-Predicaments and is, as it were, the head of the book. It contains four chapters in which Aristotle treats certain necessities and requirements for the notion of categorical being and for its coordination into its genera. For example, since the categories, or highest genera, contain above themselves only analogues or equivocal terms and below themselves only univocals, while, when one category is compared with another, they are related as denominatives, it was necessary to place beforehand, as pre-predicaments, a treatment of equivocals, univocals, denominatives, and the other rules required for coordinating the categories, as we explained in the following question, art. 1.

The second part is called Predicaments, as it were the body of the book. In the next five chapters, through and including chapter 9, it explains the ten genera or categories to which it reduces all created beings that can be known and distinguished by a simple concept: namely, substance, quantity, relation, quality, action, passion, where, position, when, and having, or clothing, or clothing.

In the third part, as it were the conclusion of the whole book, he treats the Post-Predicaments, that is, certain modes that follow upon either all or many genera and are, as it were, general properties, just as the pre-predicaments are certain prerequisites and preliminaries for establishing the categories or their coordination. These modes are five: opposition, prior, simultaneous, motion, and having; they are set out in five chapters. Their REASON IS that, since the ten genera are distinguished in order to discern and coordinate everything, opposition necessarily follows, and distinction is founded upon it. Coordination is also followed by prior and posterior; likewise, the simultaneity of some things is compatible with it, at least in time, just as there is priority and posteriority in order, causality, and nature. These three—opposition, prior, and simultaneous—follow upon all the genera. Motion or change per se follows upon four genera: substance, which is changed by generation; quantity, by increase; quality, by alteration; and where, by local motion. By accident, all the other genera are moved when these are changed. Finally, all genera that are accidents either have something—that is, properties and accidental predicates—or are had by substance, which receives them. Thus having follows upon all the genera, actively or passively. These are the topics treated in summary in this work.

Many ask whether the Philosopher treats in this book principally of the things signified, or of the significant words or concepts. But the question is not very important. He treats of things not according to their natures—for that belongs to the metaphysician—but insofar as they ground intentions of being coordinable, by which higher and lower predicates are ordered in their genera; he also treats of words and concepts as expressing things that have been ordered and distinguished. For Logic treats of the things signified while also ordering the concepts and words that it uses as instruments for coordinating things: by simple operation in the categories, by composition in propositions, and by discourse in syllogisms. Hence he treats words and concepts here as instruments for ordering the categories in no other way than there as instruments for ordering propositions and syllogisms.

SUMMARY OF ARISTOTLE’S TEXT ON THE PRE-PREDICAMENTS²

SUMMARY OF CHAPTER 1: ON EQUIVOCALS, ETC.

The chapter contains THREE DEFINITIONS. The first is of equivocals: Equivocal things are those whose name is common, but the account of the substance corresponding to the name is different; for example, “dog” is said of an animal and of a star, and “man” of a real man and a painted one. The second definition is of univocals: Univocal things are those whose name is common and whose account of the substance corresponding to the name is the same, as “man” with respect to Peter and Paul. The third definition is of denominatives: Denominative things are those that receive their appellation from something, differing only in grammatical ending; for example, “grammatical” is denominated from “grammar.”

These definitions concern equivocal terms used equivocally and univocal terms used univocally, that is, things that signify equivocally or univocally. For this reason the definition says “are called,” not “signify” or “are.”

SUMMARY OF CHAPTER 2: ON COMPLEX THINGS, ETC.

This chapter contains TWO PARTS. The first contains two divisions; the second contains one definition.

The first division is of things that are said. Some are said complexly, as “Man runs”; others incomplexly, as “man,” “stone,” and so on. The second division is of things that are, or of categorical things. Some are said of a subject and are in no subject—that is, they do not inhere—as universal substances, which are predicated or said of inferiors but do not inhere in them. Some are in a subject but are not said of a subject, as singular accidents. Others are neither in a subject nor said of a subject, as singular substances.

In the second part he gives the definition of things that exist in a subject: “I call that being in a subject which is in something, not as a part; and it cannot exist separately from that in which it is.”

SUMMARY OF CHAPTER 3: ON THE RULES

He gives TWO RULES that serve to identify the lines of the categories, both with respect to progress from higher to lower—which pertains, as it were, to the depth or height of a category—and with respect to progress toward things placed alongside them, namely differences, which pertains, as it were, to breadth.

First rule: When something is predicated of something as of a subject, whatever is said of the predicate is also said of the subject. For example, if “man” is said of Peter and “animal” is said of man, then “animal” is also said of Peter; and whatever is said of animal will in turn be said of man and Peter.

Second rule: When genera are not arranged subordinately—that is, one coordinated under another—their differences are different; but when they are arranged subordinately, their differences can be the same. For example, animal, which is in the category of substance, and knowledge, which is in quality, do not have the same differences; animal and body, however, which are in the same coordination, do.

SUMMARY OF CHAPTER 4

In this chapter he does TWO THINGS. First, he divides incomplex or simple things into the ten categories, namely substance, quantity, and so forth, which we listed above. Second, he proves that these expressions are simple: every speech is either true or false, but none of these incomplex expressions is true or false; therefore, it is not complex but simple.

SUMMARY OF ARISTOTLE’S TEXT ON THE CATEGORIES³

SUMMARY OF CHAPTER 5: ON SUBSTANCE

This chapter is divided into three parts. In the first, he divides substance into primary and secondary; in the second, he compares them with one another; in the third, he lists six properties of substance.

AS TO THE FIRST: He defines substance in this way: A primary substance is that which is neither in a subject nor said of any subject. For, because it is a substance, it does not inhere in a subject; and because it is singular, it is not said of an inferior. Secondary substance is defined in the plural: the genera and species under which primary substances are contained.

AS TO THE SECOND: He teaches that primary substances are more substances than secondary ones, for they underlie other things more. Among secondary substances, species are more substances than genera because they come closer to primary substances. Next he teaches that all lowest species are substances equally, since they are equally distant from individuals; and likewise that all primary substances are equal if compared with one another.

AS TO THE THIRD: The first property of substance is not being in a subject. The second is being predicated univocally. The third is signifying a particular individual. The fourth is that nothing is contrary to substance. The fifth is not admitting more and less. The sixth is being receptive of contraries.

SUMMARY OF CHAPTER 6: ON QUANTITY

This chapter is divided into two parts. In the first, Aristotle proposes certain divisions of quantity; in the second, he lists some of its properties.

AS TO THE FIRST: He gives two divisions of quantity. The first is into continuous and discrete quantity. Continuous quantity is that whose parts are joined by some common boundary; discrete quantity is that whose parts are joined by no common boundary. Under discrete quantity he places number and spoken discourse. Under continuous quantity he places line, surface, and body, as well as place and time, the last of which have successive continuity. The second division is this: Some quantity has position in its parts, while some does not. Line, surface, body, and place have position; number, discourse, and time do not, because their parts do not remain, although they have an order among themselves.

AS TO THE SECOND: Three properties of quantity are assigned. First, it has no contrary. Second, it admits neither more nor less. Third—and this is the most proper—it is according to quantity that things are called equal or unequal.

SUMMARY OF CHAPTER 7: ON RELATIVES

This chapter has three parts. The first contains the definition of relatives according to the opinion of the ancients. The second lists four properties of relatives. In the third, he rejects the ancient definition and introduces his own, and explains another proper attribute of relatives.

AS TO THE FIRST: The definition of the ancients was: Relatives are those things that are said to be what they are by being something belonging to another, or are said to be related to something in some other way.

AS TO THE SECOND: The first property the ancients assigned is having a contrary. The second is admitting more and less. The third is being said correlatively, because they explain one another in turn. The fourth is being simultaneous by nature, that is, existing in such a way that one is not the cause and prior to the other.

AS TO THE THIRD: He rejects the ancient definition because it also applies to some substances and other things that are explained by a transcendental order: for example, a head and a hand are said to belong to someone, yet they are not relations. Hence he gives his own definition: Relatives are those whose whole being consists in being related to something. It follows as a proper attribute that they are simultaneous in knowledge, that is, whoever distinctly knows one knows the other.

SUMMARY OF CHAPTER 8: ON QUALITY

In this chapter the Philosopher does four things. First, he defines quality and divides its species; second, he treats of the qualified thing in the concrete; third, he gives the properties of quality; fourth, he resolves a difficulty he has raised.

AS TO THE FIRST: Quality is that by which things are called qualified.

Quality is divided into four species, or rather four genera of two species. The first division is into habit and disposition. The second is into natural power and incapacity. The third is into affection and passible quality. The fourth is into form and figure.

Aristotle sets out the differences among them. A habit is a disposition that is difficult to remove from its subject, while a disposition is easily moved. Likewise, power is a natural ability or aptitude for something, while incapacity is a natural ineptitude by which something acts or resists with difficulty. An affection is a quality that passes quickly, either moving the sense or arising from motion; a passible quality persists for a long time and either moves the sense or arises from motion. Form is a quality resulting from the delimitation of quantity insofar as it is in some natural thing; figure is a quality resulting from the delimitation of quantity in itself, without reference to a natural thing, as a triangle, a circle, and so on.

AS TO THE SECOND: Qualified things in the concrete are defined as those that are said denominatively from qualities or in some other way. They are said denominatively, for example, when “white” is derived from “whiteness,” retaining the same word; they are said in some other way when “studious” or “virtuous” is derived from virtue.

AS TO THE THIRD: He lists three properties of quality. The first is having a contrary. The second is admitting more and less. The third—which belongs to quality in the fourth way—is that something is called like or unlike according to quality.

AS TO THE FOURTH: He raises this difficulty: Habit and disposition are counted among relatives in the preceding chapter; therefore, they should not be placed among qualities. He answers first that this applies to habits taken in general, not in particular. For example, the name “knowledge” expresses an order to that of which it is knowledge, whereas the name of a particular kind of knowledge, such as Grammar or Rhetoric, does not; here he intimates that only things relative according to what is said are at issue, and these do not belong to the category of relation. Or, second, he answers that they belong to two categories under different aspects.

SUMMARY OF CHAPTER 9: ON THE LAST CATEGORIES

Aristotle runs through the last six categories by enumeration, since he will treat them elsewhere. He assigns two properties to action and passion, namely having a contrary and admitting more and less; these are to be treated in book 3 of the Physics. He says that position is a denomination derived from the position of quantity. “Where” is like being in a lyceum or in the forum. “Having” is like being clothed or armed. “When” is like being at this or that time.