Commentaria in Primam Partem Summae Theologiae

In the title, note that the question here is not whether there could be more than three divine persons: for this was discussed in qu. XXX¹ Rather, the only question here is whether the formal principle of some person can be multiplied, so that, namely, there would not be only one Son or one Holy Spirit; and thus this question differs from that one in that there the question concerns the plurality of persons simply, whereas here it concerns the plurality of persons of the same formal principle.

Now we can imagine such a plurality in two ways. First, that there be several Sons, none of whom is the Father or the Spirit. Second, that there be several Sons, such that the Holy Spirit too would be a Son by another filiation. And similarly a distinction can be made concerning two Holy Spirits: namely, either that neither be the Son, or that the Son too would be the Holy Spirit by a passive spiration other in number. For in both ways there would be several Sons and several Holy Spirits. And in one way, there would be more persons than three; in the other way, however, not. Wherefore, if this question is considered carefully, it stands together with the Trinity of persons; and therefore it was placed after the determination of the number of persons. Nor does it pertain to it to examine anything except a plurality purely numerical, or individual.

II. In the body there is a single conclusion, from the Creed of Athanasius: In the divine there is only one Father, one Son, and one Holy Spirit. - And it is proved in four ways. And although the arguments in the text are sufficiently well formed, since they are nevertheless attacked, they will be examined one by one.

III. The first argument, therefore, founded on the principle that the form of one species is not multiplied except according to matter, has many opponents, namely Scotus, Aureolus, Adam, etc.² Their objections consist in this: that a multiplication of accidental forms is found in the same matter. And they bring forward light, the species in the medium or in the eye, and relation. For in one and the same part of the diaphanous we see many lights, according to the multitude of illuminating bodies, as the opposing multitude of shadows and illuminations testifies. – In the same medium there is also the species of both walls of the same quantity, color, figure, etc., so that there is no ground of specific diversity. – Every white thing has many likenesses to the other white things; and likewise one father is referred by several paternities to several sons; otherwise the relation would remain after the corruption of its term.

They also bring forward other arguments against this reasoning, which you may see, if you wish, in Capreolus, on the seventh distinction of the First Book³: every ambiguity will indeed be resolved from what is to be said.

IV. Scotus also argues, in the Quodlibet, question II⁴, directly and in several ways that the immateriality of a form is not the reason why it is of itself this, or unmultipliable in number. First thus: By that which something is first in act outside cause and intellect, by that is it first this: but every absolute entity is first of itself outside cause and intellect: therefore. – The major is proved: because being outside cause and intellect does not belong except to this.

And it is confirmed. A thing is not this by that which is not of itself the cause of it: but matter is not the cause of form, according to Avicenna⁵: therefore form is not this by matter.

Furthermore, it would follow that Gabriel would be a being from himself here: and consequently, without contradiction, there could not be posited a universal, predicable of many things, etc.

Furthermore, against this proposition there are the articles condemned at Paris: If forms admit of division only according to matter. Error, etc.⁶

And finally he infers that it is not, according to⁷ sound doctrine, to hold so certain and necessary a conclusion by way of propositions that are too general, and with so many instances.

V. To make this evident, note first that by the name matter is understood in this passage every receptive principle. For it is clear that charity is a form of one species multiplied among the multitude of blessed angels and men: and yet there is no matter, which is a part of the composite, in the will, but only a receptive power. Hence the sense of the proposition is that a specific form is not multiplied except according to what is receptive. And he means that if a form is receptive of being received, it is multiplied according to the multiplication of its receivers actually or potentially (which I say on account of intellectual souls); but if it is unreceptive, it is thereby incapable of multiplication.

Note secondly that, as is clear from Book V of the Metaphysics⁸ (where the foundations of every science are set forth, since we possess the seminal principles of all things), things are one in number when their matter is one. Numerical identity, therefore, is grounded in the unity of matter: nor can numerical plurality of forms of the same species stand together with the unity of matter.

VI. And therefore, following Aristotle, we deny all that was assumed in the instances⁹. For it stands that the form is one in its being (esse), and multiple in depending, or representing, or regarding, or other things of this kind. And thus the likeness of white to all white things is one relation in being (esse), and multiple in regarding. But concerning the defect with respect to the defect of the term, distinguish: what is lacking is the defect of the term adequate to it, not however of the inadequate, such as are the singular respects had from one thing. For the singular falls short extensively: and therefore, when one remains, it does not suffice for the relation which was to it to be absent; but only for it to cease regarding it. – Likewise the species in the medium, even with respect to objects more and less intense, is unique according to its being (esse): but multiple in representing and depending. And therefore, as the intention is of this object, it leads to this; and as of that, to that. – And the same holds for light: for there is one light according to its being (esse), and multiple in its dependencies. And therefore many illuminations are granted: and it is granted that it is multiple according to its ways or tendencies, and obstacles. And therefore many shadows appear.

The proposition, therefore, stands firm in its strength, as established in the treatise on the Angels¹⁰

VII. To Scotus's first argument, however,¹¹ it is said first that he did not understand the proposition he attacked with such zeal. For it is not immateriality, that is, the absence of matter which is one part of the composite; but immateriality, that is, the absence of matter, that is, of receptive potency, of which the Author speaks, as we have shown¹², and as even the text itself suggests here in the example of whiteness if it subsisted. – And therefore he vainly adduces the Parisian articles, which speak of matter as matter: since, according to the truth of the matter, matter as receptive potency is what is meant, formally speaking, in this proposition. Yet, lest the same arguments be brought against irreceptibility, a reply is made to each one.

To the first: the major premise is false. For each thing is first outside cause and intellect by the esse signified by the second adjunct, and yet it is not this. – The proof, moreover, is worthless, even on the face of it, from the fact that only in a singular do two things coincide, namely esse outside intellect and cause and esse this, inferring the formal identity of each whereby.

To the second objection, that we never even dreamed that a form existing in matter is this through matter intrinsically or formally, but rather causally. – And although matter, according to Avicenna, is not the material cause of the form, but of the composite, because "material cause" names an intrinsic cause; nevertheless matter is the cause of the form in the genus of material cause, for it is educed from it as from matter; and this suffices.

As for what is touched upon concerning the angels, this will be treated in its proper place; and it was said in the Commentaries on Being and Essence De Ente et Essentia¹³, where we also glossed the Parisian articles.

And note that this doctrine, as it has been handed down, is not new, but perhaps ascends to the depth of the intention of St. Thomas. He called irreceptibility immateriality, partly because in the separate substances irreceptibility signifies nothing other than immateriality subsisting in species, and partly because receptive potency is grounded on the side of matter, and it was therefore easy to understand the latter from the former. – And thus is clear the first reason, taken from what is common to all subsisting forms whatsoever that are immaterial.

Nor is it unfitting that she has been led to the personal properties. Indeed it was necessary: since these themselves are of the number of such things, and we do not know them in themselves, but from creatures, as far as we are able, we ascend to them; so that we may hold a conclusion certain and necessary, from a most certain proposition common to all philosophers—indeed common to the conception of the wise.

VIII. The second argument¹⁴ is drawn from the mode that specifies the processions, namely, by way of word and love. And it rests upon the unity of the act of understanding, and the unity of the act of loving, in the divine.

Against this argument some object as follows. If the unity of the act of understanding entails the unity of the Son, you are speaking either of real unity or of unity according to reason. If of real unity, then the real unity of the act of intellect and will in God would entail the unity of the person produced. If of unity according to reason, then a distinction according to reason would entail a distinction of persons: for as unity is related to unity, so distinction is related to distinction.

IX. Scotus, however, in the Quodlibet cited above¹⁵, says against this argument that it is not valid, because it rests upon this proposition: Where there can be only a single act of understanding, there cannot be more than one act of speaking and one Word. This proposition is indeed true in us, on account of matter, because in us every act of understanding is expressed through an act of speaking; but it is not so in God, etc. — And briefly, he says, from the unity of the absolute form of the same nature one cannot infer universally, and in every case, a unity of production and of term: therefore, from the unity of intellection there does not follow, on account of form, a unity of speaking and of Word.

X. To this it is briefly answered that the discussion here concerns numerical unity, which presupposes formal unity, as is clear from Book V of the Metaphysics, chapter on the One¹⁶: for the question is only about the numerical multiplication of persons. Thus the argument stands thus: God's intellection is one in number, therefore the Word is one in number. And if there were several of God's intellections according to number, there would be several words according to number.

To the argument, therefore, it is said¹⁷ that he is concerned with formal numerical unity, that is, the unity which entails formal unity; but not with identical numerical unity, such as exists between the act of the divine intellect and of the divine will. And for this reason the inference is denied. – How, however, from the formal distinction according to reason between intellect and will there is inferred a distinction of persons was explained in q. XXVII¹⁸; and it was said that this does not follow immediately, but mediately through the order of origin.

XI. To Scotus's objection,¹⁹ it is said that the argument of the text is not founded upon that proposition, but upon this: that where there is only one act of understanding, and a saying adequate to it, there there is only one saying and one Word. That this is true is evident: for another saying would be superfluous. – And likewise, from the unity of the absolute form, the unity of the respective form, or of the action adequate to it, is most fittingly inferred. And to intimate this adequation, it is said in the text that God understands all things by one simple act, and therefore speaks them.

XII. The third argument²⁰ is taken from the common mode of proceeding, which is truly a mode, namely that they proceed naturally, as distinguished from freely. And it is founded on this, that nature is determined to one thing.

Some also object against this argument. Either you mean that a nature is determined to one in number: and this is false, even in limited natures. Or to one mode of producing: and this is false in an infinite nature. Therefore in neither way does the argument have any force.

XIII. To this it is briefly replied that he intends the third mode, namely, that nature is determined to one formally. For under this is subsumed, and rightly, that a nature communicable in several ways, being one and the same nature, is determined to one formally of each mode according to each mode: and consequently that this nature, according to this mode, is determined to this one. And thus is concluded the numerical unity of what is produced in one way. – This argument was introduced to show the difference between a natural agent and a voluntary agent in bestowing numerical unity upon an effect while acting with a single action. For from a voluntary agent several things can be produced at once, as Averroes says, comment. XLIV on XII Metaphysics: but from a natural agent, only one thing from one. – And from these things the answer to Scotus's objection, where above ²¹, which also seeks to undermine this argument on the ground that nature is not determined to one in number, is clear.

XIV. The fourth reason²² is drawn from the divine perfection. It rests on this, that every divine reality possesses whatever can be found within the breadth of that formal notion. From this it plainly follows that it does not admit of division of itself, and consequently not of plurality either.

But against this argument it is also objected that it is worthless: because from it there would follow that only one thing is produced in the divine. – And the consequence is proved: because what is produced is a divine reality, and thereby possesses whatever can be found within the breadth of the thing produced; and so it excludes its own multiplication. But if this does not hold here, then neither does it hold in your argument.

XV. To this it is briefly answered that that foundation is to be understood of the divine reality which is one by the mode of a most special species, and not of the divine reality which is one by the mode of a genus: for under a species only material difference remains, whereas under a genus many things lie hidden. And thus it directly serves the purpose at hand: since what is in question is numerical plurality, as has already been said ²³. – And the objections cease: for productum signifies not a specific but a generic notion, while Filius signifies a specific one; and therefore the argument holds concerning filiation, but not concerning production.

XVI. And note this argument: since it concludes universally that no specific predicate, whether absolute or relative, is multiplied in God. Hence it is clear that Scotus's instance is of no force, where above²⁴, against this argument, because the Son is perfect God, and yet does not have deity in every mode of having it; therefore filiation can be perfect, and yet had by one from another. For there is no similarity, as is evident: because the Son is perfect God, it follows: Therefore he has whatever is within the breadth of the divine being (esse), and consequently he is incapable of being multiplied according to the divine being (ens).