Commentaria in Summam contra Gentiles, Liber II

From what has been said there follows as a corollary that the soul is not of the same species as the separate substances ¹. I. It is argued thus, first: the difference between the human soul and a separate substance is greater than the difference between one separate substance and another. Therefore etc. The consequence is evident from the preceding chapter, namely because all separate substances differ in species. Second ²: the esse of the human soul and of a separate substance is not of one kind, because in the one case body can be shared in, but in the other it cannot. Therefore etc. The consequence is proved because each thing has its own esse according to the account of its species; for those things whose mode of being differs are of different species. II. Concerning this argument two things must be noted. The first is that, as was said above ³, esse of actual existence, since it is the ultimate actuality of a thing, cannot be determined by another act or another difference, but receives its determination and limitation from its recipient, namely because this is the esse of this nature and that is the esse of another: just as the esse of man and the esse of horse are distinguished because this is the esse of human nature and that the esse of equine nature, which are natures specifically distinct. On this account St. Thomas rightly says that each thing has its own esse according to the account of its species, and that things whose mode of being differs—that is, whose esse belongs to different accounts—are of different species. 2. The second is from the teaching of St. Thomas, II Sent., d. III, q. 1, art. ult., that, since the essential differences of things are unknown to us, especially those of immaterial things, as is said in VII Metaphysics ⁴, we designate them by accidental differences caused by the essential ones, just as we demonstrate a cause through its effect. Hence it is that sometimes multiple differences are assigned to certain things, insofar as many things follow upon their proper and essential differences. Nevertheless, among these, prior is that difference which is taken from properties proceeding more immediately from the essence and nature of the thing. This difference, then, assigned here between separate substances and the soul on account of the diverse mode of being, is not an essential difference: because the esse of a created thing is not of its essence itself, but follows upon the essence; and it follows each species and nature as an esse distinct from the esse of another nature, just as the accounts of those natures themselves are diverse. Hence to argue from the specific distinction of esse to the specific distinction of natures is not to argue a priori but a posteriori. Yet this difference, taken from the diversity of being, seems to precede the other differences assigned, for instance that of being cognitive with discourse and being cognitive without discourse, and that of having mutable choice and having immutable choice: because the specific difference of simple substances is taken according to their degree of potentiality; and from the greatest potentiality of the intellective soul within intellectual nature—since it holds the last degree in it, just as prime matter holds the last degree in sensible nature—it immediately follows that its esse is communicated to matter, which does not befit the esse of separate substances. From this difference, then, the others assigned by various doctors follow. 3. From these things it is evident that Scotus does not proceed according to the mind of St. Thomas when, in II Sent., d. I, q. VI ⁵, he attacks the first root of the distinction between a separate substance and the soul as being that which we say is unifiable with a body, and not being unifiable with a body. For although St. Thomas holds that these substances are distinguished specifically by being unifiable and not unifiable with a body, he nevertheless does not say that this is the first root of the distinction, as if unifiable and non-unifiable signified relations. Rather, as is gathered from his words in II Sent., at the place cited above, this distinction presupposes another essential distinction, which, because it is unknown to us, we circumscribe by means of this and other differences.

III. Third. A separate substance has a species through itself. The soul, however, does not; rather, it is part of a species. Therefore, etc. — The consequence is proved. Because that which has a species according to itself cannot be of the same species as that which does not have a species according to itself, that is, which according to itself is not a complete species, but part of a species. Fourth. There is an altogether different mode of understanding in a separate substance and in the soul. Therefore, etc. — The antecedent is clear. Because the soul understands by abstracting from phantasms; a separate substance, however, does not, since it does not have bodily organs. — But the consequence is proved. Because from a thing’s proper operation its species is perceived. IV. With regard to this argument a difficulty arises. For if a diverse mode of understanding indicates a specific diversity of intellectual natures, one or the other of two things follows: namely, either that the separated soul is of another species than the conjoined soul; or that when separated it has the same mode of understanding that it has when conjoined, namely, by abstracting from sensibles and phantasms. But each of these is impossible, as is openly clear. Therefore, etc. The doubt is also increased. Because in Qu. de Anima, a. 15, ad 10, it is said that the species of intellectual operation are not diversified by this, that things actually intelligible are taken from phantasms or from elsewhere. Therefore from this diverse mode of understanding a specific diversity of intellectual nature cannot be argued, as is done in this argument. V. For the evidence of this, one must consider that in this place Saint Thomas argues for the specific distinction of substances from a diverse mode of understanding, not from just any mode whatever, but from a natural mode, which, I say, naturally follows a nature absolutely considered. For just as determinate and proper passions follow each nature, so too determinate operations follow, distinct from the operations that follow another nature. Therefore from the diverse character of proper operations that follow a nature, a diversity of natures can be argued, just as it is also argued from the diversity of other properties. Since, therefore, the mode of understanding through abstraction from phantasms, and the mode of understanding through connatural and inborn species, are diverse modes of cognizing and of different characters, the nature whose proper and connatural mode of understanding is through abstraction from phantasms must be of another species than the nature whose proper mode of understanding is through connatural and inborn species. And since one of these modes is connatural and proper to the soul, while the other is connatural to separate substances, those natures must be specifically distinct. 2. To the first argument, therefore, to the contrary, the consequence is denied. For neither of those follows. For we have said that from those modes a specific diversity of intellectual natures is then argued, when each of them [is] proper and natural to the intellectual nature to which it is attributed, as happens in the case of a separate substance and the soul. Now, both of these modes are not attributed to the conjoined and separated intellectual soul as proper and natural to the soul itself considered according to its own nature; rather, to understand through abstraction from phantasms is natural to it, just as being in a body is; but to understand through species participated from the divine light is not natural to it, as is said in the Prima, q. LXXXIX, a. 1, and as was shown above ⁶, but belongs to it accidentally insofar as it accidentally is separated from the body and participates in the nature of separate substances. Therefore this diverse mode of understanding does not indicate a specific diversity of the intellectual soul and the separated soul, although it does indicate a specific diversity between the soul and a separate substance. I say, however, that although, absolutely speaking, to understand through infused species is beside the soul’s nature and accidental to it, just as it is accidental to it to have being separated from the body; nevertheless, considering the soul itself as it has such being, namely, abstracted and separated from the body, this is natural to it. And therefore the nature of the soul itself need not be diversified while it is conjoined and separated; rather, the mode of being must be diverse, and of one and another character. Hence in Qq. de Verit., q. xix, a. 1, ad 5, it is said that, although the nature of the soul before death and after death is the same as to the character of species, nevertheless the mode of being is not the same, and consequently neither is the mode of operating the same.

3. For the declaration of the second argument, it must be noted that these modes of understanding can be compared to two things: namely, to the object known, and to the knower. If they are referred to the object known, they do not diversify the species of the intellectual operation as such: because, since an operation takes its species from its object, so long as the formal object of the operations is the same, those operations will be specifically the same, however much the intelligible species are received from different things. But if these modes are referred to the knower, then, since as such they require diverse natures to which they belong (if, I say, they are proper and natural modes of understanding for them), the intellections must also be specifically distinguished insofar as they flow from that very nature. For it is not unfitting that operations be diversified in species when compared to their agents, even though objectively they are of the same species: just as the vision of a man and the vision of a horse are of the same species objectively and inasmuch as they are visions; but insofar as they are referred to man and horse as their active principles, they are of different species, because different accidents and different operations follow upon different species. Hence Albertus also, in I De Anima, chapter penultimate ⁷, proves that the sensitive powers in man are of another species than the sensitive powers in brute animals, on account of the specific diversity of the souls to which they belong. And yet, as the powers are compared to objects, they are of the same species, on account of the formal unity of the object.

The mind of St. Thomas, therefore, is that the species of intellectual operation is not diversified, insofar as the operation is related to its object, on account of a different reception of intelligible species: since, notwithstanding this, it can have the same object. But this is not contrary to what is said in this argument. For it does not conflict that intellectual operations, insofar as they are compared to objects, be of the same species; and yet they are distinguished in species insofar as they are compared to intellective natures, one of which has as natural to receive the species in one of the said ways, the other in another: since these diverse modes of understanding, following from nature absolutely considered, can only be attributed to diverse natures; for there is but one natural mode of acting and operating belonging to one nature, just as there is one natural mode of being.