16.1 Aquinas’s General Approach to the Trinity in SCG 4,2–26
16.1 Aquinas’s General Approach to the Trinity in SCG 4,2–26
Since Aquinas denies that the doctrine of the Trinity can be proved by philosophical reasoning, his discussion of it in SCG 4,2–26 amounts only to a defense of it based on biblical texts together with arguments intended to suggest that the doctrine is not intrinsically absurd. In grounding his account of the Trinity on Scripture, Aquinas is aiming to refute those who reject what he takes to be orthodox Trinitarian doctrine while taking their stand on the Bible. In arguing that the doctrine of the Trinity is thinkable or not incoherent, however, he seems to have a more philosophical readership in mind.
In accordance with what he takes to be Christian orthodoxy, Aquinas holds that God is Father, Son, and Holy Spirit.9 He believes that, though there is but one God, there is also distinction within God. He takes the Bible to teach that Jesus is divine and is the Word that is God from eternity (see John 1:1–14). He also takes the Bible to teach that Jesus spoke of God as his father so as to teach that Jesus and his father are distinct, while also being one in some sense (see John 10:30). In addition, Aquinas thinks of the Bible as telling us that there is that which is divine though distinct from God the Father and God the Son—this being the Holy Spirit (see John 15:26 and John 16:1).
Aquinas does not mean that there are three Gods. He believes that the divine nature is shared by three who can be distinguished from each other without implying the truth of polytheism and without implying that the three that constitute God are three parts of God or three distinct features possessed by God. Yet what three does Aquinas take there to be in the one God? His answer, derived from the theological tradition he inherited, is “Three persons.” God, for him, is a trinity of persons: Father, Son, and Holy Spirit.
Aquinas does not think that the persons of the Trinity are three human beings, or even three distinct centers of consciousness, as three people might be thought to be. His approach to divine simplicity clearly prevents him from doing that (see chapter 4 here). So he argues that “person,” when it comes to the Trinity, signifies a relation. He says that the divine persons are subsistent relations that exist in God. In doing so, he thinks of God the Son as what God the Father has eternally conceived as knowing the divine nature. And he thinks of God the Holy Spirit as the love that is eternally there in God as God knows and wills the divine nature.
If I form a concept of myself, that concept is in me, as would be my willing or loving of myself based on that concept.10 Aquinas does not think that God forms concepts as we do or that God wills as we do. He does not, for example, think of God forming concepts or willing over time while being able to lose concepts or to lose the ability to will or love. He does, however, think that God understands the divine nature and is drawn to it. So, with the doctrine of the Trinity in mind, he speaks of the eternal life of God with respect to understanding and willing. He says that God from eternity knows and wills the divine nature (see SCG 1,45–48 and 1,74). He also suggests that, though God is entirely simple, God’s knowledge and will exist in God and are not just constructions of our minds when thinking about God. So, he argues, God’s knowledge of God and God’s willing of God can, in the light of divine revelation, be thought of as relationally distinct.11 Yet given his thinking on divine simplicity, which entails that all that is in God is God, he also argues that what is relationally distinct in God is God. On this basis, he maintains that distinction can be intelligibly thought to be in God (albeit eternally) as God knows and loves what is divine. And he takes the doctrine of the Trinity as teaching that this is so. His view is that God is Father, Son, and Holy Spirit insofar as there are real relations in God. As I noted in chapter 9, section 3 here, Aquinas holds that “relations predicated of God in reference to creatures do not really exist in him” (SCG 2,12). So he is obviously prepared to distinguish between real and nonreal relations. Yet he takes the persons of the Trinity to be real relations, ones that exist in God.
When it comes to relations predicated of God with respect to creatures, Aquinas seems to be saying that, though God makes creatures to exist, God is not modified because changeable creatures exist over time as created by God. Aristotle’s Categories provides a famous and influential discussion of relations, but it does not consider them with an eye on what Aquinas takes God to be considered as the first cause of things in all their ways of being.12 Aquinas thinks that creatures undergo real changes and can be thought of as related to God on that basis since we can talk of them in sentences that use tenses. So Moses might have said “God is creating me,” and I might say “God was creating Moses.” But do these statements imply that God has undergone a change between being the creator of Moses and being the creator of me? Aquinas thinks not. He holds that God, though unchangeable, can be talked of by us as if undergoing change, as if coming in and out of various relationships between things. So, he thinks, we can truly say that God came to be my creator when I came to exist, or that God became incarnate at some time while not having been incarnate beforehand. But he does not think that God undergoes any real change as history proceeds. Even when it comes to the Incarnation of God in Christ, he insists that the change here is on the side of what is created. For him, “The Word became flesh” (John 1:14) does not mean that the Word went through a process. It means that something unprecedented occurred in the world: the birth of a child united to God in a special way, as the Son of God incarnate.
Yet Aquinas does think that there can be real relations in God, and he begins to defend himself by noting how it is that will and knowledge can exist in us while being distinct. My knowledge of you can be distinguished from my delight in you, my loving of you. So Aquinas thinks that there can be knowledge and will in God even if God has no creaturely objects to know and to deal with providentially. And he thinks that there being knowledge and will in God, without reference to creatures, is reason to think that the doctrine of the Trinity is not nonsensical. He argues that God can know and love God. He thinks that knowledge and will in God can be directed only to what God is. But, since he thinks that God’s knowing and willing are not distinct from what God eternally is, he argues that God’s knowledge and love of God cannot be anything other than God. He holds that all that is in God is God and that real relations in God are God.
We commonly take there to be relations insofar as certain physical things in the world are connected to each other in various ways. Hence, for example, we can readily speak of my heart as related to my hands since it pumps blood through my body. Again, I might be thought of as related to my cat as being its owner, or I might be thought of as related to you with respect to spatial position: me standing on your right, say, while you are to my left. Yet again, I might be related to someone by being that person’s child, or I might be related to you as being the person to whom I owe money. However, there are other ways in which things can be thought of as related to each other. For example, the number 4 is related to the numbers 3 and 5 by being the successor of the former and the predecessor of the latter. Not all relations are between physical objects, and Aquinas holds that the persons of the Trinity can be thought of as distinct insofar as the relations between them are real, insofar as each person of the Trinity exists as related in some way to the others. This distinction between the divine persons is not, he says, such as to make them three Gods or three aspects of God. The divine persons are distinct as real and subsistent relations.
How are they distinct? Aquinas’s answer is: (1) the Father is distinct from the Son because the Father brings forth (or, as Aquinas says, “generates”) the Son; (2) the Son is distinct from the Father because the Son is generated by the Father; and (3) the Holy Spirit is distinct from the Father and the Son because the Holy Spirit is the love between the Father and the Son. Aquinas makes these points while appealing to the notion of procession. If X proceeds from Y, then X comes from Y in some sense. But Aquinas cannot possibly think of there being a coming forth of one thing in God from another as, say, there is a coming forth of a human child from its parents. So he takes procession in God to be eternal and not a matter of one thing bringing about another new individual thing distinct from itself, as is the case with human generation. For Aquinas, procession is internal to God and is nontemporal. The Son, he says, eternally proceeds from the Father as the Father eternally forms something like a concept or idea of the divine nature. And, he adds, the Holy Spirit eternally proceeds from the Father and the Son as being the love between them produced by them.13
In saying all this, Aquinas is drawing on what he takes to be inadequate analogies: knowledge and love in people. We can come to know by understanding what something is. So, says Aquinas, we can think of God as knowing what God is. We can also come to love what we know. So, says Aquinas, we can think of God as loving what God is. Yet he is very much aware that these comparisons between people and God are seriously flawed when used to articulate the doctrine of the Trinity. I can come to know or form concepts; but only as a creature, which God is not. Again, I can come to love; yet Aquinas does not think that my knowledge and my love are me. He thinks that they are aspects or properties of me (in his terminology, they are accidents in me), and he thinks that they are temporal, transient, and finite, as God is not. Nonetheless, despite the inadequacy of the comparisons he draws on when talking about the Trinity in SCG 4,2–26, Aquinas regards them as adequate enough to sustain the conclusion that people are not talking nonsense when professing the doctrine of the Trinity.
His reasoning is: (1) knowledge and will (love) exist in people; (2) there is, from eternity, knowledge and will in God to be distinguished from God’s knowing and willing of creatures; (3) this knowledge and will is the divine nature, not attributes of it to be distinguished from the individual that God is; (4) nothing in God is distinct from the divine nature that God is; (5) so knowledge and will in God can be “internal” to God, and both are what God essentially is; (6) in knowing the divine nature, God must love it since the divine nature is pure goodness that has to be loved by one who is perfectly good and who truly knows all that can be known; (7) it is not contrary to reason to suppose that, in knowing the divine nature, God knows it and loves it; (8) since all that is in God is God, it is also not contrary to reason to suppose that there could be relations in God between God as knowing and loving God and between what God knows when knowing God and what God loves when loving God; (9) these have to be real relations in God if what God knows of God comes from God’s knowledge and if God’s love of God comes from God’s knowledge; (10) a real relation, however, is a relation to something else; (11) so it is not against reason to suppose that in God there are real and distinct relations that are divine, though there is nothing in God that is not God.
Once again, I should stress that when arguing in this way, Aquinas is not trying to prove that the doctrine of the Trinity is true. He does not think that it is entailed by anything he has said in SCG 1–3. He is only saying that it is not refutable by reason. He believes the doctrine of the Trinity to hold that the Second Person of the Trinity proceeds from God the Father and that the Holy Spirit proceeds from God the Father and God the Son. That there should be such proceeding, amounting to three eternal divine persons, is not a conclusion that he holds to be rationally demonstrable. In SCG 1–3 we see what he views as knowable about God by reason, and the doctrine of the Trinity does not feature in these books.14 It emerges for discussion only in SCG 4,2–26, in which Aquinas defends it by means of quotations from the Bible and by arguing that it is not contrary to reason. His SCG discussion of the Trinity does not spring from his natural theology. It is prompted by his Christian belief, based on his reading of the Bible, that God is somehow both one and three. It is also, of course, prompted by his belief that the doctrine of the Trinity comes with impeccable ecclesiastical credentials as enshrined in texts such as the Nicene-Constantinopolitan Creed.
Can we summarize Aquinas’s SCG teaching on the Trinity in terms that he would have ratified? We can, since he provides such a summary himself in SCG 4,26. Here we read:
One must hold that in the divine nature three persons subsist: the Father, the Son, and the Holy Spirit; and that these three are one God, distinguished from one another by relations only. For the Father is distinguished from the Son by the relation of paternity and innascibility (being unbegotten); the Son from the Father by a relation of sonship; the Father and the Son from the Holy Spirit by spiration, so to say; and the Holy Spirit from the Father and the Son by the procession of love; by this the Spirit proceeds from each of them.15