Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

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.