Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

Logical genus is defined by Porphyry: “That which is predicated of many things differing in species in answer to ‘what?’” In this definition three points are explained:

FIRST is the character common to every predicable, in the words “that which is predicated of many”; for this is common to every predicable. Hence you will understand that the universal is not defined here materially, as a substrate, but according to the very character of universality, because that common predicate, namely “being predicated of many,” is not a nature but universality.

SECOND, what is explained in the definition, is what belongs specifically to the character of genus on the side of the term to which it is related; for relations are specified by their term. Thus the phrase “of many things distinct in species” is included, since generic universality regards these as its term.

THIRD, finally, what is explained in this definition is the mode or character of predicating, namely “in answer to what.”

As to the FIRST PHRASE: what it is to be predicated of many has been sufficiently explained above, for it belongs to the character of universality. What it is for something to be predicated of many as an essential defined thing, to which this definition belongs essentially, we will say in the next article. Hence, to explain this definition exactly, it is enough here to explain the two phrases “of many things differing in species” and “in answer to what.”

Accordingly, concerning the first phrase, “of many things differing in species,” we must say that although other predicables can be said of many things differing in species—for example, some generic differences and even generic properties are said of subjects differing in species—this is material to those predicables. Only genus, however, is predicated formally and per se of many things differing in species. For although other predicables can be predicated of many things differing in species, they are also preserved without being predicated of many things differing in species, as is clear in specific differences and properties. Thus the inferiors of such predicables need not differ in species merely because they are their inferiors. Genus, however, simply by being genus, has inferiors that differ in species, because the intrinsic character of genus expresses something contractible and divisible through specifically diverse differences. These differences are contained potentially in the genus itself and originate from it, as Cajetan rightly noted, following Albert the Great, in his commentary on this chapter on Genus¹. Hence, by its very formal character, genus requires inferiors distinct in species.

The SECOND PHRASE, namely “to be predicated in answer to what,” explains the mode and formal character of the predication of genus, insofar as it is genus.

To understand this, one must note that the phrase “in answer to what,” as St. Thomas often teaches, can ask either about a supposit or about a nature. For example, if someone asks what swims in the sea, we answer “a fish”; if someone asks what a human being is, we answer “a rational animal.” Here, when it is said that genus is predicated “in answer to what,” the second sense is meant, not the first.

Second, one must see how predication in answer to what differs from predication “as a what-sort,” not only when the latter is accidental, which is obvious, but also when it is essential, as when difference is predicated. We should not say absolutely that difference is predicated “in answer to what,” as some recent authors allow. Rather, genus is predicated “in answer to what,” and difference “as a what-sort”—that is, genus is predicated in a substantive, quidditative mode, while difference is predicated even essentially in an adjectival mode, as St. Thomas notes at the end of his treatise on Genus, chapter 2 of opusculum 48². Therefore difference is said to be predicated as an essential what-sort, or a quidditative what-sort. For although difference is essential, it nevertheless performs the office and predication of difference by way of inherence, not in the mode of a substantive, which pertains to “what.”

The reason is that the office of difference is not to provide the first foundation of quiddity, but to come to the genus and determine it so that a species is constituted. Hence it never functions as the first foundation and first character of quiddity, but as a character that contracts and comes to something else, determining it. Its mode, therefore, is to determine and actualize something previously presupposed and contractible, as genus is. Thus the substantive mode belongs to genus, while the qualificative or inhering mode belongs to difference: the former is called “what,” the latter “what-sort.” When the Philosopher said in Topics VII, ch. 3³ that both parts of a definition are predicated in answer to what a thing is, the sense is that both parts are predicated essentially, but in different modes: genus in answer to what, and difference as a what-sort.

A third distinction is considered in the very mode of predicating in answer to what: the way genus is predicated in answer to what differs from the way species is. Species is predicated in answer to what completely, because it predicates the entire and complete character of quiddity; genus is predicated in answer to what incompletely, because it predicates a constitutive part of the essence, which is potential and prior, as the foundation of the contracting difference. Both modes of signifying, however, are substantive and in answer to what.

The reason for this is that substance is signified as a whole and a complete being, since it belongs to substance to have the character of a whole and supposit. Likewise, it belongs to the mode of substance to be, as it were, underlying or foundational to other things, and to have the character of what is first in some order. From this comes the likeness by which things signified as a whole or as the foundation and first in some order are said to signify in a substantive mode. Species signifies in the mode of “what,” or in a substantive mode, because it signifies what is integral and complete in the character of quiddity. Genus, too, signifies in the mode of “what” and in a substantive mode, because it signifies in the mode of the first predicate, which is the foundation and root of the others. The definition itself explains all this when it says that genus “is predicated in answer to what of many things differing in species,” that is, as something contractible through specific differences. What is contractible is the first predicate, containing those differences potentially. The definition of species, however, says “in answer to what of many things differing in number,” thereby designating the integral character of quiddity, no longer contractible through formal and specific differences, but multiplicable through singular differences, which are material.

IF YOU ASK whether this definition of genus is essential or descriptive, the reply is that, as Porphyry presents it, it is descriptive, as he himself indicates, and St. Thomas calls it so in opusculum 48, chapter 2⁴. For the essence of genus consists in the character of universality, which regards its inferiors in such a way that they are distinct in species and are related in the mode of “what.” Its definition, however, is given through predicability, which is a property of the universal. Therefore it explains the nature of genus through a property, which makes it descriptive. It can nevertheless be reduced to an essential definition by saying: “Genus is a universal that regards (or is apt to regard, if it is defined fundamentally) many things distinct in species in answer to what.” Here the definition is given through a higher or generic predicate, namely, “universal,” and through an intrinsic difference, namely, to regard in such a way—that is, in answer to what—and to have such a term, namely, many things distinct in species.

THE ARGUMENTS ARE ANSWERED.

Against the phrase “in answer to what” it is argued: it belongs to things other than what is defined, even if predication in answer to what of many things differing in species is taken into account; and predication as a what-sort can belong to genus. Therefore the phrase is wrongly included.

The antecedent, as to its first part, is proved as follows. Being is predicated in answer to what of many things differing in species, for it is a quidditative predicate, being imbibed in the very quiddities; yet it is not a genus, since it is analogical. Definition itself is also predicated in answer to what of the defined thing; for to someone asking what a human being is, one rightly answers “a rational animal.” Difference itself, too, since it is nobler than genus, ought to be predicated in a nobler mode. But the nobler mode is predicating in answer to what—that is, predicating substantively rather than as a what-sort, which is adjectival predication in the mode of an accident. Therefore this mode ought to belong to difference as well, and not only to genus.

The second part is proved because, in the category of substance, genera and species are called secondary substances. In the chapter on Substance⁵, however, the Philosopher says that these signify a “what-sort,” and adds that genus and species determine quality with respect to substance. Therefore genus is predicated as a what-sort. Further, this predication of genus—such as “Whiteness is a color”—is nevertheless predicated through “colored,” which is predicated as inhering and consequently as a what-sort. Therefore predication in answer to what is not of the character of genus.

THE REPLY: The antecedent is denied.

To the first part the reply is that being is not a quidditative predicate, but a transcendent one, imbibed in every thing, whether or not it pertains to quiddity. Hence what is common to quiddity and non-quiddity cannot constitute a quidditative concept. The transcendent concept is therefore presupposed to the concept of quiddity; it does not constitute it, nor does it pertain more to “what” than to “what-sort.” For just as when we say “What is a human being?” and the answer is “a being,” so too, when we say “What sort is a human being?” one can answer “a being.” Moreover, because being is analogical, it is not predicated in answer to what simply and according to one character, but according to several, and only according to one proportionally; genus, by contrast, is predicated in answer to what simply and as one.

As for what is said about definition, the reply is that a definition is a complex “what” and contains not only the character of “what,” but also that of “what-sort.” For it consists of genus and difference, and is not predicated in answer to what as genus is, but in the mode of species, as an integral quiddity that it explains.

As for what is said about difference, the reply is that although it is nobler than genus on the side of the thing signified, on the side of the mode of predication it is not predicated in answer to what, because the mode of predication does not follow precisely the mode of being in the thing, but the mode of conceiving. St. Thomas teaches this in Metaphysics VII, lecture 1⁶ and opusculum 42, chapter 19⁷. Difference is conceived in the mode of what determines and actualizes, while genus is conceived as determinable and contractible. Thus genus grounds predication in answer to what in the explained mode, while difference grounds predication as a what-sort.

To the second part of the argument the reply is that the Philosopher calls secondary substances a “what-sort,” and says that they determine quality, not with respect to nature and quiddity, but in comparison with primary substances, which signify a supposit that supports them. For in relation to a supposit, species, genus, and the other higher grades all have the character of a predicate and of a form supported by the supposit. But in comparison with the nature and essence they constitute, one constitutive part, namely genus, is said in answer to what, and the other, namely difference, as a what-sort. On this solution see Cajetan on chapter 5 of the Categories.

Hence the other objection is also resolved: genus functions as a form in relation to the inferior of which it is predicated; therefore it is not predicated in answer to what, but as informing. The reply is that genus functions as a form not on the side of the thing it explains, nor in comparison with the nature it constitutes, but on the side of its mode of being a predicate, which takes on the mode of a form in relation to its subject, and in comparison with the primary substance by which it is supported. In this sense St. Thomas says in Summa theologiae I–II, q. 18, art. 7, ad 3, that genus is compared to species as something more formal, insofar as it is less contracted.

To the final proof the reply is that in the predication “White is colored,” the word “colored” is taken substantively in relation to white, although it is an adjective in relation to a body or subject of color. Hence, in relation to the subject, the predication is denominative and adjectival; in relation, however, to white, which is its inferior, it is a quidditative predication by reason of the form it signifies.

Second it is argued against the phrase “of many things differing in species.” Genus is also predicated of many things differing in number, as “animal” is of Peter and Paul; therefore the adequate term of genus is not explained in the definition.

If you say that only the immediate term is explained, which is species, an objection is raised against the predication of genus of generic individuals. For example, when “animal” is predicated of this animal and that animal, it is then predicated immediately of individuals, not of species; therefore the definition is incomplete. Also, genus can be predicated of many things differing not only in species but also in genus, as the highest genus is predicated of many intermediate genera, which are subordinate species. Therefore the phrase “of many things differing in species” does not sufficiently explain the character of genus in general.

THE REPLY is that genus is predicated of many things differing in number mediately, namely, precisely because it is predicated of many things differing in species. For since individuals are contained under a species, and whatever is predicated universally of something is predicated of everything contained under it by the principle “said of all,” genus is consequently also predicated of many things differing in number, though not as the lowest species, which is predicated immediately of them.

To the objection about generic individuals, the reply is that genus is also predicated of them mediately, whether they are contained in the same lowest species or in different ones. Generic individuals express a generic grade individualized, without expressing the specific grade through which they are contained under the generic grade. Because they do not express the specific grade but nevertheless include it, and through it belong under the generic grade, they are said to be contained mediately, although it is possible for such generic individuals to belong to different species by reason of including those species. The generic grade is always predicated of them, insofar as they are individuals, only mediately, because it is contracted and belongs to individuals mediately, even if sometimes only the generic grade is expressed and the specific grade is omitted; in this way those generic individuals are predicated.

To the second part of the argument, it is said that the highest genus is predicated of many things differing in genus, not insofar as they are genera, but insofar as they are subordinate. A genus subordinated to another, higher genus is subject to it insofar as it is a certain species, because it is subject to it insofar as it consists of that genus and a difference, which is to be a species. Hence genus is predicated of many insofar as they differ in species, because they are subject to it as species. Therefore only things that differ in category are said to differ in genus. For things within the same category differ through contracting differences and consequently constitute some species; every difference, in fact, constitutes a species.

Finally it is argued to prove that this definition is essential, because the intention of predicability is included in the character of this intention, which is genus, as St. Thomas says at the end of chapter 4 of On Being and Essence⁸. There he also adds that being predicated belongs to genus per se, since it is placed in its definition. Therefore he thinks predicability belongs essentially to the essence of genus, especially since this treatise deals per se with predicables. Thus things, insofar as they pertain to this treatise, are essentially defined when they are defined through predicability.

THE REPLY is that the meaning of St. Thomas is clear: predicability belongs to the nature of genus and belongs to it per se—either essentially, when predicability is taken as its root rather than as its own formal intention. The root of predicability, however, is universality. Or, if predicability is taken formally, it is understood to belong to genus per se and to be included in its character through per se predication in the second mode, as a property, not through per se predication in the first mode, as an essential predicate. In this treatise Porphyry deals with predicables not insofar as they are distinguished from the universal, but insofar as they are rooted in it, including the very character of universal rather than excluding it. Hence their essential definitions must also be given through the very character of universal.

THE POINT OF THIS DIFFICULTY has often been touched upon by us, and depends on that common difficulty concerning the definition of accidents in the concrete. For since, in the concrete of an accident, we find the subject denominated by the form, the form denominating it, and a constituted thing or composite of both, it is difficult to assign a proper and per se defined thing to which the definition belongs essentially. For if, for example, we say that in this definition of genus the defined thing is the subject itself, or the nature to which the intention of genus belongs, the definition does not belong to it essentially. For animal, for example, does not have it as its essential account to be predicated of many, although it is that which is predicated of many. Nor can the defined thing be the intention itself, or generic form: for this is not that which is predicated, but that by which some nature is predicated of many. Nor can it be the thing constituted from nature and intention: for this constituted thing is not predicated of many specifically different things, since the composite of real nature and a being of reason does not descend to the species themselves; nature alone does so.

This difficulty has twisted many minds and divided them into VARIOUS OPINIONS: some say that in these definitions the defined thing is the subject, insofar as it expresses an order to the form; others, on the contrary, say that it is the form, insofar as it expresses an order to the subject; and others finally, especially among certain more recent authors, say that the thing constituted from the subject and the accidental form is defined as that to which the definition belongs essentially, while the subject itself, or supposit, is defined only denominatively.

On this point we have often rejected as contrary to Aristotle and St. Thomas the claim that a composite of subject and accident can be defined as something per se one. For the opposing authors agree in understanding by that constituted or composite thing of subject and accident a certain quiddity resulting from subject and accident as constituents of a third thing, which has the subject as a part of itself; hence it is not predicated of that subject, since a whole is not predicated of a part. And when one says, “A human being is white,” this is verified adjectivally of the supposit itself, not essentially and substantivally of that third constituted thing. We therefore say that from these two, subject and accident, there does not result something per se one and definable by a single definition, but rather a being per accidens, as we explained at length above, q. 5, following the mind of St. Thomas.

The point made there is further explained: no per se one quiddity that is neither substance nor accident can result from substance and accident. For there is no middle between substance and accident: they are divided by modes that express a contradiction, namely, being per se and being in another. Therefore, the third thing that results, since it has both substance and accident as parts of itself, cannot be a quiddity that is substance alone or accident alone; a middle between these two is impossible. It is therefore not a per se quiddity, but a being per accidens. If you say that it is not one quiddity that is neither substance nor accident, but one quiddity that is both, this is just what we intend: if that quiddity, or composite, is at once substance and accident, it cannot be so by passing into one per se quiddity distinct from both, which would be neither per se accident nor per se substance, since no such thing exists. It is therefore only substance and accident joined by an accidental union, not essentially and per se. Things accidentally united are a being per accidens, even if they coincide in the same subject; they are one not constitutively, but denominatively.

BUT SOME REPLY that the concretes of accidents can be taken either adjectivally or substantivally: adjectivally, they are subordinated to several concepts and are not a being per se; taken substantivally, they are said to be one per se, because they are conceived and presented as one, whereas adjectivally they present subject and form as several. Hence whether they are a being per accidens or per se depends on the mode of conceiving. Others say that no one per accidens results from accident and subject, because they have a true union with one another and compose something true. Others say that even if it is a being per accidens, it can be defined, as a commonwealth, an army, a people, and other similar things, which have less unity, are defined.

But the first solution makes an unsuitable distinction between a name taken adjectivally and substantivally with respect to whether it is a being per accidens or per se. For a name is taken adjectivally insofar as it is signified as applying its adjacency to another; substantivally, one thing is signified as carrying with it the supposit to which it is in reality adjacent and inheres. Whether something is a being per accidens or per se, however, depends on the unity and identity of the thing that results from combining the two. This quiddity or unity that results is not per se one, whether it is signified as applying its adjacency to another or as carrying the supposit with it. Whichever way it is signified, the quiddity resulting from that form and subject arises from the accidental conjunction of the extremes. It makes no middle quiddity between substance and accident, since that is impossible, nor a quiddity that is substance alone or accident alone. Therefore it does not make something constituted per se, but something denominated accidentally, whether the name is taken adjectivally or substantivally.

The second solution fails because it thinks that a being per se one results from an accidental union. For although the union is real, it is not a per se union, but a qualified and accidental one. Therefore what results from it is one only in a qualified sense; the unity resulting from the union of the extremes will be of the same kind as that union.

Finally, the third solution is manifestly mistaken because definition concerns quiddity alone. A definition is one to the extent that it reaches and defines one quiddity. A being per accidens does not signify one quiddity simply and per se, but several quiddities that are one only per accidens; hence it is not definable by a single definition. For a definition defines through genus and specific difference. Where there are several quiddities, there are several genera and differences, and therefore several definitions. This argument is taken from the Philosopher, Metaphysics VII,¹ lecture 12, as cited by St. Thomas.²

From these points, then, I resolve the proposed difficulty.

AND I SAY FIRST: The defined thing of genus is not a thing constituted from subject and the intention of genus, nor can the definition belong to that thing essentially.

So says Cajetan in his commentary on the chapter “On Genus,” and the Thomists commonly agree. This follows clearly from what has been said, since the intention of genus is an accidental predicate with respect to the subject, and consequently no nature or quiddity per se definable results from it and the subject.

I SAY SECOND: In this definition, and in the definitions of other accidents, the formal defined thing cannot be the nature or subject itself insofar as it is clothed with and subject to the intention.

THE REASON IS that the formal defined thing must be what is designated formally and per se by the very name. But “white,” for example, does not signify the subject formally and per se, but as connoted and consequently; therefore.

The minor is proved from St. Thomas, Metaphysics V, lecture 9,³ where he says: “Nor is what Avicenna says true: that predicates belonging to the genera of accidents signify substance principally and accident secondarily, as in what I call ‘white.’ For ‘white,’ as it is spoken of in the Categories, signifies quality alone. But this name ‘white’ signifies the white subject consequently, insofar as it signifies whiteness in the manner of an accident.” So St. Thomas. The reason is that the concrete term of an accident agrees with its abstract term in what is signified formally and per se; for it takes from the latter the form by which it is denominated and which it concerns. Therefore the concrete term signifies the same thing as the abstract term on the side of the denominating form, although applied to the denominated subject. The formal signified of the abstract term is the form; therefore the formal signified of the concrete term is also the form, although it adds the form’s mode of existing in the denominated subject. The subject, however, is imported only as sustaining and receiving the form, not as belonging to the form’s quiddity. Definition intends to explain for us the quiddity of the form received and signified in the concrete, not the subject that receives it; much less does it intend to declare the very nature of the receiving subject. For when I define “white,” I define not the nature of a body, but the account of white.

I SAY FINALLY: The formal and quidditative defined thing in this definition (and the same holds for other accidental concretes) is the second intention of genus. But that which supplies the supposit to the defined thing, or is denominated by it, is the subject of this intention, and so is imported in the defined thing itself consequently and as connoted.

This is Cajetan’s view in his commentary on the chapter “On Genus” and chapter 4 of On Being and Essence, and the Thomists commonly follow it. Thus, in these definitions, the formal defined thing is one thing, and that which supplies the supposit to the defined thing is another. In this the accident differs from substance: in substance, the defined thing has its supposit and the account of quod from itself, whereas an accident begs that from outside itself. This conclusion is evident from St. Thomas, who says that the concrete term of an accident signifies the form alone—“white,” for example, signifies quality—and does not have the subject as a part of its signification, as is clear in Metaphysics V, lecture 9,⁴ VIII, lecture 4, § Determinat,⁵ and VII, lecture 1.⁶

Nor is it enough to reply that Aristotle and St. Thomas intended the concrete term of an accident not to signify this or that subject determinately, but in a confused way, while signifying the form determinately; for it cannot be denied that the concrete term of an accident represents the subject to us, and not the form alone. But this solution cannot stand, because St. Thomas does not deny that the subject is signified by the concrete name; he says that it is not signified principally, but consequently, as is clear in Metaphysics V, lecture 9,⁷ against Avicenna, and that it is not signified on an equal footing or as a part of the signification, in Metaphysics VII, lecture 1.⁸ Therefore, whether or not it signifies the subject in common, still, according to St. Thomas, that which is imported as subject by the name “white” (and it is certain that no determinate this or that subject is signified, but a subject in a confused way) is signified not principally but consequently, as a subject sustaining the form. It is therefore not the principal and per se defined thing, but that which supplies the supposit to the defined thing and is imported consequently.

Finally, one may see how lucidly St. Thomas sets out this conclusion in chapter 7 of On Being and Essence,⁹ where he says: “Since essence is signified through definition, accidents must have essence in the same way in which they have definition. But they have an incomplete definition, because they cannot be defined unless the subject is posited in their definition; this is because they do not have in themselves an absolute being per se apart from a subject.” St. Thomas then sets out the difference between substantial and accidental form: the former, when it comes to matter, constitutes a certain essence, and therefore “form is a part of a complete essence.” Accidental form together with the subject, however, “does not make one per se, but per accidens; and therefore no essence results from their conjunction, as it does from matter and form. Hence an accident neither has the account of a complete essence nor is a part of a complete essence; but just as it is a being in a qualified sense, so it has essence in a qualified sense.” Thus, for St. Thomas, the definition of an accident is always incomplete, just as its essence is, because it is an essence dependent on something outside itself, namely, the subject that supplies a supposit to the defined thing; the subject does not belong to or enter into the quiddity of the defined thing. This is why accidents are said to be defined by addition, as the Philosopher puts it in Metaphysics VII, chapter 5,¹⁰ lecture 4 according to St. Thomas,¹¹ because they are defined through something outside the essence of the defined thing, namely, the subject. For in accidents “what it is” is distinguished from “that of which it is,” as Aristotle says in the same place, text 20,¹² and St. Thomas in lecture 5.¹³ Therefore, in concrete accidents, the formal and quidditative defined thing is one thing, and the supposit of the defined thing another.

From this is drawn the BASIS of the conclusion: the quidditative and formal predicates of an accident terminate in the accidental form itself, and the subject does not belong to the quidditative predicate, although it sustains and receives that form. Therefore the quidditative and formal defined thing in these definitions does not pass over to the subject, but terminates in the form itself; for the formal and quidditative defined thing is that in which formal quidditative predicates are included. But since such a form and its quidditative predicates are not defined in a state of separation and abstraction from the subject, but together with their mode of existing in the subject, the subject is therefore posited consequently in their definition as supplying a supposit to the defined thing, not as its quidditative predicate. Thus the quidditative and formal defined thing is one thing, and that in which this defined thing is found and which supplies its supposit is another. The latter is the subject or nature; the former is the form or intention in this definition of genus.

THE ARGUMENTS ARE RESOLVED.

First, one argues from the argument set out above in the introduction to the difficulty: the intention of genus is not that “which” is predicated essentially of many species, since it does not descend to them, but is that “by which” a nature is predicated. Therefore the definition given does not belong to it. Hence also, when I say concretely, “Peter is white,” I do not predicate whiteness of him, but predicate “having whiteness.” But what has whiteness is not quality alone, but a subject affected by a quality. Therefore that is the defined thing, just as it is what is signified by the term “white.”

THE REPLY is that the intention is not that which is predicated as the supposit of such an intention and as the thing predicated; therefore the definition belongs to it not as the supposit of the definition, but only as the account or form by which one predicates of many. Hence in definitions of concrete accidents the defined thing is not found essentially as quod, but denominatively, when the supposit is supplied to the defined thing through something extrinsic. Nor do accidents themselves carry their supposits, which is why their definitions are given by addition: in them “what it is” is one thing, and “that of which it is” another, as we said above from the Philosopher and St. Thomas.

Why, then, are these definitions given through that which is denominated such, and not through that by which it is such, when the definition belongs essentially to the latter alone, and that alone is the formal defined thing? The reason is that accidents have an incomplete being, dependent on the denominated subject and not subsisting in themselves. Hence this dependence and imperfection of an accident is better expressed by defining it through the subject, which is such denominatively, than through what is signified by itself alone as that by which. See St. Thomas, Metaphysics VII, lecture 4,¹⁴ and chapter 7 of On Being and Essence.¹⁵ A further reason is that this accords with the very mode of signifying. For when an accident is defined concretely, where the subject is signified as supplying a supposit to the defined thing, it would be less suitable to say that what is signified in this way is that by which something is such—where only the abstract account is signified—than to say that it is that which is such, even though the definition belongs to it only denominatively. When one says “Peter is white,” the term “white” does signify “having whiteness,” not whiteness in the abstract; but it does not signify both equally. Rather, it signifies whiteness formally, while the subject, which is the one having it, is connoted and taken materially. For this reason the predicate is verified accidentally of the subject to which it is applied, because it is identified with that subject in the supposit. Likewise, “having whiteness” is the defined thing, but not on an equal footing: whiteness is so formally, while “having” is so denominatively and enters the definition by addition.

Second, one argues from the argument made above, q. 5, art. 5, which some use here: “White” is well defined as “a body that disperses sight” or “that which has whiteness”; therefore not quality alone, but the thing constituted from quality and subject is definable. See the solution at the cited place, final argument.

Third, one argues: In the definition of genus, one subject cannot be imported; therefore it imports a subject neither principally nor consequently.

The consequence is clear: if the subject of the intention of genus is imported not as one but as many, then it is not properly defined in the manner of one by saying “that which is predicated”; rather, there will be many things that are predicated.

The antecedent is manifest: that which underlies the nature of genus is not one and cannot be conceived by a single concept. For both a real being and a being of reason, both an accident and a substance, underlie the intention of genus. Therefore there is not one subject.

THE REPLY is that many are troubled by this argument. Nevertheless, in my view, it must be resolved in every position, whether the subject is imported on the side of the principal defined thing or as denominatively defined and imported consequently. The same difficulty can be found in any concrete term that imports a very broad subject, such as “true,” “good,” “intelligible,” and so on, whose subject is found in real beings as well as beings of reason, in substance and in accident. I say, then, that in such a concrete term one subject is not imported by unity of nature or being, but by unity of capacity and receptivity for that form or intention. For whatever has the capacity for that form in the manner of one subject—that is, of one receptive thing—is signified, even if the natures are very diverse. Thus theologians say that in the words “This is my body,” by “this” is understood what is contained under the species, that is, whatever can be under those species, whether it is a living or dead body, bread or a human being. So, by the name “substrate of genus,” we understand whatever is capable of genericity, whether real or not, provided it agrees in this account of capacity, even if it does not agree in the quiddity and unity of nature.

Fourth, one argues: If we understand that what is defined here is the very thing constituted from subject and form, everything pertaining to the account of genus is explained essentially: both the thing predicated denominatively and the form by which it is made predicable are explained. Therefore such a composite fits better as the defined thing of the entire definition.

This is confirmed because that whole constituted thing is subordinated to a single ultimate concept; therefore it is one definable thing. The consequence is clear: a being per accidens is not definable for the reason that it is not one quiddity, but several. Conversely, then, if it is one, being subordinated to a single concept, it is definable per se. The antecedent is proved both because this concrete term, “white” for example, belongs to one concept, and so too does the thing itself constituted from whiteness and body—for no more things are found in the concrete term than in the constituted thing—and also because both that accidental concrete and the constituted thing can be ordered to a single operation: white to dispersing, hot to heating. Therefore it can be subordinated to a single concept.

THE REPLY is that the whole which is in the genus is indeed explained in that constituted thing, but not on an equal footing or as belonging essentially to the genus itself: the subject is there as denominated, and the intention as the form by which genus is constituted formally. But that one third quiddity should result from these two and be definable essentially by this definition of genus is impossible, as we have said. Nor does such a composite explain the defined thing of genus better or fit the definition better: it is neither that which is predicated, since the intention does not descend with the nature to the inferiors, nor that by which it is predicated, since the nature does not belong to the form by which something is made predicable, but to the thing predicated. Hence from nature and intention there is made neither a quiddity that is genus as that which, nor one that is genus as that by which. Both are explained, however, when one does not take them as a constituted whole, but takes the form partially and the subject denominatively.

In reply to the confirmation, one says that the concrete term of an accident is subordinated to a single concept, importing subject and form not as equally principal, but the form essentially and formally, and the subject materially and as denominated. Thus it can be defined under this concept, and it will not behave as a being per accidens, but will be defined in the manner in which it is subordinated to that concept: the form will be the formal defined thing itself, and the subject denominative. But the thing constituted from whiteness and body, from form and accident, includes both equally essentially and thereby constitutes a third thing. In this way it is a being per accidens, because it results from extremes accidentally united; no one quiddity can result that is neither substance nor accident, but it is both together. The concrete term, however, does not express some resulting quiddity, but the very formal quiddity of the accident, which has the subject not as a part or an extreme composing it, but as something material denominated by it, in which it has its mode of being not abstractly but concretely.

Finally, one argues: Nature alone is what is predicated of inferiors, or nature considered in itself, as St. Thomas says in chapter 4 of On Being and Essence.¹⁶ Therefore, although such a nature has a relation and intention of genus, nevertheless the defined thing directly will be the very substrate of the intention, since the definition belongs essentially to this alone, namely, to be predicated of many. Nor can one say that predication belongs to it denominatively, not formally and essentially; for a generic nature, “animal,” for example, is predicated essentially, not denominatively, of inferiors.

THE REPLY is that it is entirely true that nature is that which is predicated essentially of inferiors on the side of the thing predicated. Nevertheless, predicability itself and the state of universality by which it is predicated of many belong to nature denominatively. The appellation changes, however, when one says: “It is not predicated denominatively, but essentially; therefore it does not belong to it denominatively to be predicated of many.” For it is one thing how predicability belongs to nature, and another how nature is predicated of inferiors and belongs to them. Nature does not belong to the inferiors denominatively; nevertheless, predicability or universality belongs denominatively to nature itself, so that it may be predicated essentially of inferiors—not with respect to the thing predicated, but in the mode of a universal and superior, while the essence is found without that universality. With respect to the thing that is predicated, however, St. Thomas says that nature considered in itself is predicated of inferiors.

For a nature to be a genus, it requires certain CONDITIONS, which we must explain in this article: First, that it stand as a whole in relation to its inferiors. Second, that it not state the whole nature actually and explicitly, but only a part. Third, that it state the more potential part of the nature, by reason of which genus is called a potential whole. Fourth, that it be drawn from matter, while difference is drawn from form.

HOW GENUS IS A WHOLE AND A PART.

Two things must be observed: THE FIRST is that, in universals, the notion of whole and part is considered in two ways: first, from the mode of conceiving; second, from the side of the thing conceived and signified. From the side of the mode of conceiving, every universal states the notion of a whole, and not of a part, in relation to its inferiors, since it must be conceived in such a way that it can be predicated of each inferior. If it were conceived as a part in relation to them, it could not be predicated of them, because every whole is greater than its part, and every part is less than its whole. Hence, if something is signified as a part in relation to something, by that very mode of signification it is signified as less than it, and consequently is not that whole; accordingly, it is not predicated of it. For predication is signified by the verb “is,” insofar as this is that. Such a notion of a whole, then, must be common to every universal and every predicate by reason of its mode of conceiving, and so it does not belong specifically to the notion of genus.

From the side of the thing signified or conceived, however, the notion of whole and the notion of part are considered insofar as they constitute the quiddity itself, or insofar as the quiddity itself is considered as constituted. In this way, the notion of whole and part is found only in the first three predicables, because genus and difference concur in composing the species and therefore designate its parts, whereas the species is the whole and integral quiddity itself, constituted from genus and difference. Hence, although genus and difference, as universals, have the notion of a whole by their mode of conceiving, from the side of the thing they explain they do not explain the whole quiddity, but a part.

THE SECOND thing we observe is that, strictly speaking, in metaphysical composition there are not parts as there are in physical composition, but grades. In physical composition two separable parts are joined, as is evident: matter is now under one form and now under another, and the rational form also exists without matter. Thus a whole is composed from these parts in such a way that one part is not included in another, nor predicated of another or of the whole; for we do not say that the soul is a body, or a human being, or vice versa. But metaphysical parts are not distinct things composing one whole; rather, they are diverse designations of the same thing as more or less determined, as St. Thomas teaches in chapter 3 of On Being and Essence.¹ Since these metaphysical grades differ only in designating the same thing more or less determinately, they cannot properly signify parts really distinct from one another, but the same whole designated and determined to a greater or lesser degree. Thus the same thing, or the same whole, insofar as it expresses or designates the less determined notion of animal, and that same whole insofar as it designates rationality, the more determined notion, compose the human being, which expresses the integral notion of human quiddity. In this sense we must understand the same Doctor in Sentences I, distinction 25, question 1, article 1, reply to objection 2,² where he says that a human being is not made from animal and rational, but is an animal that is rational: that is, it is not made from these as distinct parts, but indeed as grades that designate the same thing in different ways.

From this it follows that genus is not called a physical part, but a metaphysical one, which can at the same time be a whole: it is a part insofar as it explains and designates only one constituent of the specific quiddity; but it is a whole insofar as, by its very mode of signifying and conceiving, it implicitly states the whole that is in the inferior of which it is predicated. For example, from the side of the thing signified, animal designates and explains only the sensitive nature, and does not explain everything belonging to the essence of a human being, a horse, or the other species; nevertheless, it implicitly states whatever is in a human being or a horse. For it states the sensitive form by explaining only the notion of the sensitive, without excluding anything else that can be joined to such a sensitive form. Thus it states any form that is sensitive, whether it is merely sensitive or has something more. Its not excluding everything else that can be joined to a sensitive form is what makes it contain that other thing implicitly. If that animal form or generic nature were signified with such precision that it excluded anything other than the sensitive form—as when it is signified by the abstract term “animality”—then it could not be predicated concretely of its inferiors, as we explained at length above, question 5.

This resolves the question whether genus is predicated of its inferiors as a whole or as a part. From what has been said, it is clear that genus is predicated as a whole from the side of the mode of conceiving, but from the side of the thing predicated it explains only a part of that thing’s quiddity. When I predicate animal of a human being, what is explained by the name “animal” is the notion of sensitive form, while the mode of its predication is to state, without qualification, the whole that is in the human being: implicitly, it includes not only the sensitive form with the exclusion of any further perfection, but whatever is sensitive even if it has something further. In this respect it is simply the whole. Thus the opinions that seem opposed on this point are reconciled, and the arguments for either side prove nothing further.

HOW GENUS IS A POTENTIAL WHOLE.

To prevent confusion over the name “potential whole,” we must observe that here “potential whole” is not taken as distinguished from an essential whole, in the sense in which a potential whole is said to be divided into potential parts, of which it is not predicated, while an essential whole is divided into subjective parts, of which it is predicated. Rather, genus is called a potential whole as opposed to an actual whole, because it does not explain the whole as actually constituted, but a part of it that can be further actualized and contracted, and hence is potential.

Two things remain to be explained about this potential whole: First, in relation to what genus is said to be potential and implicit, and consequently whether this potentiality belongs to it insofar as it is a whole or insofar as it is a part. Second, what is the actuality in comparison with which genus is called potential.

To the first, we reply: FIRST, genus is said to be potential insofar as it signifies some common nature that can be contracted by the addition of a difference, which is not actually included in that superior nature, but is included in it potentially. This is common to every univocal, including a species, as distinguished from transcendentals and analogues, which are imbued in the differences themselves. Hence nothing is added to transcendentals as something extraneous, because they are included in every thing precisely as transcendentals. For this reason, they do not abstract perfectly from their inferiors, as we shall say in question 13. A univocal, however, because it is abstracted perfectly from its inferiors and is not included in their differences, is said to remain in potency to those differences.

SECOND, genus is said in a special way to be something potential with respect to metaphysical composition, because in the specific quiddity genus designates a part contractible by a difference, and thus one that is more indeterminate and potential. Difference, by contrast, states the part that contracts and determines; therefore it is predicated in the manner of a quality, though essentially, because what determines and affects something else, as it were, qualifies it. Thus genus is potential in relation to the contracting difference, as matter is in relation to form, and as the incomplete is in relation to the complete whole constituted from them.

From this it is clear whether genus should be called a potential whole or a potential part. It should be called both, according to different considerations. Since metaphysical parts are not properly parts but grades, and are in reality the whole itself implicitly, though not wholly explained in its quiddity as the species explains it, genus, when considered as a part, is also a whole. Yet of that whole it does not explain the whole, but a part or grade that can be completed by a further actuality, namely the difference. Thus, from the side of the quiddity it explains, in comparison with the difference it is a potential part; but in relation to the inferior species it is a potential whole, that is, the whole present in the species, not wholly designated and explained, but taken indeterminately.

To the second point we proposed for explanation, we reply that the actual predicate in relation to which the greater or lesser potentiality of genus is measured is the ultimate specific difference. This renders a quiddity so formed and determined that it can be contracted no further except by individual differences, which do not make a formal and quidditative difference, but a material and numerical one, as will be explained further in question 9.

WHAT IT MEANS FOR GENUS TO BE DRAWN FROM MATTER AND DIFFERENCE FROM FORM.

This is a familiar axiom, although it cannot be applied in the same way to every nature that falls under the notion of genus. Some natures are composed of form and matter. Some are forms alone, although dependent on matter, as accidents are. Others have neither composition from matter nor any order to it, as angels do. How genus in all these cases is drawn from matter and difference from form is discussed by St. Thomas in chapters 6 and 7 of On Being and Essence,³ On the Nature of Genus, chapters 4 and 5,⁴ Summa theologiae I, question 50, article 2, reply to objection 1, and Question on Created Spirits, article 1, reply to objection 24,⁵ as well as Metaphysics VII, lecture 9,⁶ Metaphysics VIII, lecture 3,⁷ and frequently elsewhere.

We must therefore consider that when we say genus is drawn from matter and difference from form, we do not mean that genus states matter alone and difference form alone; rather, form is the principle of the difference from which it is drawn. It is like saying that the principle of individuation is designated matter: this does not mean that individuation formally consists in designated matter, but that it is drawn from matter as from its root, as St. Thomas notes in chapter 6 of On Being and Essence.⁸ This is plainly evident, because genus, as often proved, states the whole essence of that of which it is predicated. Therefore it does not state matter alone, nor does difference state form alone. Otherwise metaphysical parts would not differ from physical parts.

In generic and specific or differential grades, then, we must distinguish what they have of potentiality from what they explain of actuality, just as the soul, for example, actually explains the sensitive form and potentially involves what is joined to such a form.

I say, then, that the generic grade itself does not signify pure potentiality, as prime matter does, but also signifies some determinate actuality and quiddity, although not one wholly complete and determined. Therefore the generic notion is not to be drawn proximately from matter alone, which is a physical part, but from what is material or potential in each thing, whether composite or simple.

Hence, even in composite things, we have said that all the grades are drawn from the same form, while matter does not supply a grade but receives it and is informed by it. In composite things, however, genus can be drawn remotely from matter insofar as matter is the principle of all potentiality. Thus a form that informs matter according to a perfect grade while leaving it informable by a further grade is called the root and principle of genus, as is the corresponding informability on the side of matter itself. This is taken from St. Thomas at the cited passage in Question on Created Spirits,⁹ where he says that “genus is taken from matter, provided that by matter we do not understand prime matter, but matter insofar as, through form, it receives a certain imperfect and material act of being in relation to the specific act of being, as the act of being of animal is imperfect and material in relation to that of a human being.” Likewise, in chapter 6 of On Being and Essence,¹⁰ he says: “In sensible things genus is taken from what is material in the thing, while difference is taken from what is formal in it. Hence Avicenna says that, in things composed of matter and form, form is the simple difference—not that the form itself is the difference, but because it is the principle of the difference.” Thus genus is not taken from bare prime matter alone, but from matter insofar as it has an imperfect act of being through form; matter so possessing an imperfect act of being is called material in relation to a more perfect grade. For genus states a certain determinate nature, though one not yet complete in every perfection, whereas matter in itself states no determinate grade or actuality; it is in potency to every substantial actuality, as will be proved more fully in the Physics. Even if matter has some substantial actuality, it is nevertheless clear that it receives from form not only its ultimate actuality and grade, but also diverse grades and perfections, more or less determined. Therefore those genera that correspond to these more imperfect grades cannot be drawn from bare matter, but from matter informed according to an imperfect grade and nature, and thus informable by that matter in a more perfect grade and nature.

WHEN, however, St. Thomas says in On the Nature of Genus, chapter 5,¹¹ that “the potentiality of the whole composite in material things comes from matter, and therefore genus is taken from it; the perfection of the whole, however, comes from form, and therefore difference is taken from form”; and in Summa theologiae I, question 50, article 2, reply to objection 1, he says that “in material things one thing determines the specific grade, namely form, and another is determined, namely matter”; he therefore seems to affirm that genus is taken from matter alone and difference from form alone.

We reply that the meaning of St. Thomas is clear from his words: in composites, matter is the first root of potentiality. Thus, although the generic grade is taken from form insofar as the grade states actuality, its potentiality is traced back to matter as its root, even though it is drawn proximately not from bare matter, but from what is material in relation to what is more formal and perfect. St. Thomas calls this material aspect “matter” and the more formal aspect “form”; he does not mean bare matter to be what genus is taken from.

In things that are not composite, however—namely angels, who do not share matter with bodies and are therefore sometimes said to differ from them in genus, that is, in physical genus—it is not true even remotely that genus is taken from matter, since they lack matter. Rather, it is taken from what is more potential and quasi-material in such substances. As St. Thomas says in chapter 6 of On Being and Essence¹² and Summa theologiae I, question 50, article 3, reply to objection 1, this is intellectuality or immateriality itself, taken precisely or indeterminately: that is, insofar as it is finite and limited intellectuality, in potency to being more or less perfect through greater or lesser access to, and participation in, pure act. This provides the notion of difference and of graded perfection, insofar as one intellect understands in a more uniform way than another and is thus more like God and comes closer to him.

Finally, in accidents genus is likewise not taken from matter intrinsic to them, since they lack it, but from their diverse relation to substance, as we shall say in the Antepredicaments;¹³ thus quantity is named from its relation to substance by measuring it in the manner of extension, quality by affecting it in the manner of power or adornment, and so on. We draw the differences from which proper accidents arise either from the effects of such accidents, as it were a posteriori, because we do not know their proper differences. See St. Thomas, On Being and Essence, chapter 7.¹⁴

YOU WILL OBJECT: Genus and individuation cannot be drawn from the same principle and root, since genus is maximally indeterminate, while an individual is ultimately determined. Therefore it is inappropriate to say that genus is taken from matter, since, in St. Thomas’s view, individuation is also taken from it.

We reply that both belong to matter according to different relations and considerations. Matter is related to form as a first and potential subject, namely as that which is in potency to receive the form and its grades; matter itself, however, has no further subject in which it is received. Thus, in relation to form, its potentiality leaves it indeterminate and indifferent to receiving the imperfect grade of one form and then another, more perfect grade, up to the ultimate one. In this respect matter is the root and principle of genus. But because, in receiving a form, matter is the ultimate subject and is not further communicable to another subject, it is the principle of individuation by reason of this ultimate incommunicability, since it is no longer common or communicable to many.

WHICH NATURES ARE CAPABLE OF HAVING A GENUS.

I reply: All those that can directly exist in a category, whether real or of reason, whether they are accidents, modes, or substances. Thus every being that has the mode or notion of a whole, consisting in metaphysical composition, is capable of having genus and difference, so that genus predicates a quidditative part of it in the mode of a whole. Things that are only simple parts—whether physical parts, such as matter and form, or integral parts—and likewise differences, do not have the notion of genus in their own right, but only by reduction. This is the view of St. Thomas in Sentences III, distinction 6, question 1, article 1, reply to objection 1,¹⁵ and On the Nature of Genus, chapter 10,¹⁶ as well as Cajetan in the chapter on Species and others.

The REASON for excluding physical and integral parts is that these parts cannot have a supreme genus; therefore they cannot have a subordinate genus either, since genera cannot proceed to infinity and must come to a stop at one, which will be the supreme genus.

The antecedent is proved as follows. If they had a supreme genus, it would either be complete substance, which is the supreme categorical genus, or incomplete substance. It cannot be complete, because complete substance is not truly predicated of parts and therefore is not predicated of them generically. Nor can it be incomplete, because the incomplete is imbued in every difference, and so it is imbued even in the differences of the parts, since they too are something incomplete. Thus it is present transcendentally, not in the manner of genus, which must be outside the concept of the differences. A similar argument can be made concerning body, living thing, and so forth. In the case of accidents, this argument is not needed, because they have no parts but are simple forms; if they did have parts, the same argument would apply.

The REASON for excluding differences from the notion of genus is that an infinite regress would follow. For if, for example, rational has a genus, it must contract it by another difference, since every genus is contractible by a difference. Again, the difference that contracts it would itself have a genus—there is no greater reason for one than for the other—and so it would be contracted by another difference. That difference in turn would have another genus and difference, and so on to infinity. Therefore differences do not directly have a genus, but are subordinated to one indirectly.

Do not infer from this, however, that abstract terms for substances are not genera and species. Although they are signified in the manner of a part, they are nevertheless total forms and have composition from genus and difference, as humanity has in relation to animality and rationality. Thus the same difficulty that arises with other parts does not follow.

But if you object: These parts and differences have certain superior quidditative predicates besides being; for they have greater agreement with one part than with another, as the form of a lion agrees more with the form of an ox than with the form of a stone. Therefore they can have a genus, which is a superior predicate as that in which they agree, and likewise their own difference.

This is confirmed as follows: celestial and sublunary matter differ in species, according to St. Thomas’s view in Summa theologiae I, question 66, article 2. Therefore each has its own distinct species and, consequently, they have a genus in which they agree and a difference by which they are divided.

WE REPLY that these parts have superior quidditative predicates, but because they are not of themselves a whole and complete thing, they do not directly constitute a species and consequently do not directly have a genus; rather, they have these by reduction, as the incomplete is reduced to the complete. Indeed, such predications of parts and incomplete beings are more transcendental than generic, because they are included in the differences themselves, which is not true of genus. Thus having superior quidditative predicates is not enough for them to be generic: they must be non-transcendental and stand outside the differences.

And if you ask whether the predication “this form is a form,” “this hand is a hand,” and so forth, is predication of a species of an individual: we reply that it is so only in a qualified and reductive sense, as when one says, “this person is a person,” or “this individual is an individual.” For in these cases a nature is not predicated, but something belonging to a nature; and although the predication is essential, it is incomplete and consequently belongs by reduction to complete predication.

To the confirmation, we reply that celestial and sublunary matter are of different species in an incomplete sense, namely because they do not state an order and capacity for the same forms, and so one matter does not pass from one form to another. This diversity of capacities nevertheless adds no difference that, in the manner of actuality, determines and constitutes matter, since both are pure potency. Thus the very potentiality that constitutes matter in general is included in the differences of each kind of matter, while the substance predicated of them is incomplete substance, which is predicated more transcendentally than generically, as was said. Matter’s having the notion of a nature, and the other quidditative predicates, is understood in the same way: incompletely and transcendentally, not generically.