Trinity and Economy in Thomas Aquinas Steven J. Duby Steven J. Duby is Instructor of Theology at Grand Canyon University in Phoenix, Arizona. He earned his PhD in Systematic Theology at the University of St. Andrews, St. Andrews, Scotland. He is the author of Divine Simplicity: A Dogmatic Account (T&T Clark, 2015) and various articles in journals such as International Journal of Systematic Theology, Modern Theology, and Journal of Reformed Theology. Dr. Duby’s primary research interests are in the doctrine of God and Christology. Introduction The doctrine of the Trinity is a catholic teaching, a common possession of Christ’s whole church which expresses our understanding of the one who possesses and keeps us by his redeeming grace. Yet this doctrine that ought to foster a sense of unity among all orthodox believers has been a point of contention in recent times, not least in the world of evangelical theology where questions about the nature of the Son’s submission to the Father’s authority have generated significant controversy.1 My task in this essay is not to address any of these recent proposals directly but rather to consider how one of the church’s greatest theologians, Thomas Aquinas, handles the doctrine of the Trinity and how reflection on his work helps to cultivate the kind of theological discernment needed for faithful articulation of trinitarian teaching today. I propose to do this by focusing especially on the way in which Thomas sees God’s triune existence shaping God’s action in the economy of salvation. More specifically, we will focus on the question of how closely God’s own triune being corresponds to his activity in the incarnation. To show how Thomas’s perspective provides a helpful pathway into this matter, I will seek to do three things. First, I will set forth the basic concepts and SBJT 21.2 (2017): 29-51 29 The Southern Baptist Journal of Theology 21.2 (2017) structure of Thomas’s trinitarian doctrine, particularly his understanding of the divine processions, relations, persons and personal properties. Second, I will examine how this view of the processions and mutual relations of the persons gives shape to Thomas’s view of the mission and incarnation of the Son. Finally, I will comment on the strength of Thomas’s position on the correspondence between God’s trinitarian existence and his activity in the incarnation in dialogue with two alternative approaches to the question (those of Karl Barth and some Reformed orthodox theologians). The Structure of Thomas’s Trinitarian Theology In his Summa Theologiae, Thomas begins his account of the Trinity with a discussion of the triune processions (i.e., the Son’s eternal generation by the Father and the Spirit’s eternal procession from the Father and Son), for, according to Thomas, the divine persons are distinct from one another by “relations of origin.” He distinguishes a catholic view of the processions from the Arian and Sabellian views by stressing that procession in God is neither the procession of an effect from a cause (as Arius understood the Son’s procession) nor the procession of a cause to an effect (as Sabellius understood the Father to “proceed” in assuming flesh and to be called the Son in that respect). To preserve both the true deity and genuine distinction of the persons in orthodox trinitarianism, Thomas explains that procession here is to be understood not as an outward act but rather as an inward act that “remains in the agent himself.” It is an origination or “emanation” after the manner of a concept proceeding from the intellect or a spoken word proceeding from a speaker.2 The procession of the Son in particular is called “generation,” not because the Son passes from non-existence to existence or from potency to actuality as in the generation of something corruptible, but because he is one living who proceeds from a “living principle.” Such a procession is properly called “birth” (nativitas), and, indeed, the particular birth of the Son is of the sort in which the one born is properly called “begot- ten,” for he shares the same nature as the one who begets him (God the Father).3 Thomas believes the procession of the Son (who is aptly called the “Word”) occurs in the manner of an “intelligible action” where the concept of the thing known remains in the agent knowing (here, the Father), while the procession of the Spirit occurs in the manner of a “volitional action” 30 Trinity and Economy in Thomas Aquinas where the object loved remains in the one willing and loving (in this case, two – both the Father and the Son).4 Yet Thomas is clear that the communi- cation of the divine essence to the Son and Spirit in their processions does not multiply the divine essence or yield multiple deities. It is not that the divine essence is generated by the Father; rather, the Son is generated and, in being generated, receives from the Father the same essence the Father has.5 The processions in God require discussion of the relations of origin among the divine persons. The relation of the Father to the Son is called paternity; the relation of the Son to the Father is called filiation; the relation of the Father and Son to the Spirit is called spiration; the relation of the Spirit to the Father and Son is called procession.6 Thomas clarifies that these are not just logical relations existing in the human mind as it compares one thing to another. In that case, God would not really be Father, Son or Spirit, which would result in the error of Sabellianism. Instead, these relations are “real,” since the Father and Son, for example, are in fact “ordered toward one another” and have an “inclination” toward one another. This is supported by the fact that the pro- cessions in God occur within a single nature and order of being so that the relations among the persons are mutually constitutive.7 The relation of one person to another in the Trinity is, for Thomas, really identical with (the same “thing” as) the divine essence itself. If it were not the divine essence, it would be a creature. Accordingly, the relations among the divine persons are not accidents added to God’s essence; rather, their being (esse) is just that of the divine essence. Yet, this does not mean that the relation is the essence con- sidered as such or absolutely, for what the relation is—in Thomas’s language, the proper ratio of the relation—is a reference or “habitude” toward another. Nor does it mean that the essence is reduced to a relation, for relation here does not signify all that the essence is.8 Thomas adds, against Sabellianism, that these relations are “really” distinct from one another—not as one “thing” (res) or being from another but as distinct in reality and not just in the human mind. For, if a real relation is present—a real “respect of one to another”—this assumes a real distinction between the one and the other. Thus, there is real distinction in God, not with respect to what is absolute (i.e., the essence) but with respect to what is relative (i.e., the persons). Indeed, though the relations are identical in their being to one and the same thing (i.e., the essence), they are not identical to one another since they are not identical to the essence absolutely but formally import or involve a respect toward another.9 31 The Southern Baptist Journal of Theology 21.2 (2017) The Concept of Person After dealing with the concepts of procession and relation in the Summa Theologiae, Thomas is ready to discuss the concept of person.10 He affirms Boethius’s definition of “person” (an “individual substance of a rational nature,” which Thomas takes to be equivalent to the Greek hypostasis) and argues that it is rightly used to designate the Father, Son and Spirit, as long as it is recognized that certain creaturely factors that might be associated with the definition do not obtain in the doctrine of the Trinity. For example, individuation occurs by matter in many created substances, and created substances are often called such because they “stand under” accidents, but neither is true of God.11 Thomas then asks whether persona in the Trinity signifies relation, anticipating some of the careful work he will do a few questions later in the Summa Theologiae in clarifying the relationships among the various features (relation, person, essence and so on) included in the doctrine of the Trinity. Persona is not one of the “essential names” (like wisdom or power) that are attributed absolutely to God’s essence and are thus one in God. Yet, in itself, “person” does not have reference to another as paternity or filiation does. Thomas prefers to resolve the matter by saying that persona signifies relation “directly” and the divine essence “indirectly.” For, on the one hand, person signifies something that is distinct in a given nature rather than the nature as such (this particular individual as distinct from others), and, as noted, the persons of the Trinity are distinct by their relations toward one another. This means that persona must directly signify relation in the case of the Father, Son and Spirit. Yet, as noted, the relations of origin in the Trinity are not accidents added to God’s essence but really are the divine essence itself as it subsists in the distinct persons.12 Persona thus signifies not merely a relation but rather the relation as subsisting. In light of this, when Thomas calls the divine persons “relations,” he is not reducing the meaning of person to a mere respect or habitude toward another. He does affirm that persona signifies a distinct individual and that the divine persons are constituted as distinct from one another just by the relations of origin in God, which entails that the denotative content of persona as applied to the Father, Son and Spirit gives special prominence to the notion of relation. At the same time, the relations in the Trinity really are the divine essence as it subsists in the Father, Son and Spirit, so person as signifying 32 Trinity and Economy in Thomas Aquinas a relation also includes all the fullness of God’s essence as it subsists in a certain manner. Persona thus does not signify relation as such but only as the constitutive, individuating principle of the hypostasis.13 Accordingly, given that hypostasis in God is really identical with God’s essence, persona may from another angle be said to signify the essence directly and relation indirectly as an individuating factor. Given his emphasis on persona being a name suited—not merely by amended usage but “by the fittingness of its own signification”—to the Father, Son and Spirit in their distinctness from one another, Thomas’s view of the term differs from that of Augustine, who did not view persona as especially suited to designate the Father, Son and Spirit. For Augustine, persona designates the three simply because something has to be said when someone asks “three what?” in discussion of the Trinity.14 However, with Augustine, Thomas can say that because persona is equivalent to hypostasis and because in God hypostasis (‘what is’) and essence (that ‘by which’ a hypostasis is) are really identical, the content of the term persona includes the divine essence.15 The Concept of “Notion” Another important feature of Thomas’s doctrine of the Trinity is the concept of a “notion.” By “notion” Thomas means an abstract representation of the distinct character of a divine person, by which the person can be readily identified by us. He draws attention to five notions that set forth the distinct subsistences of the Father, Son and Spirit. To the Father belong “innascibil- ity” (not proceeding from another person) and paternity (his begetting of the Son); to the Son belongs filiation (proceeding from the Father in a filial manner); to both the Father and Son belongs common spiration (eternally bringing forth the Holy Spirit); to the Spirit belongs procession (coming forth from the Father and Son in what Thomas regards as a volitional manner). Four of these are relations (innascibility expresses no relation of the Father to another person and so is the exception). Four of these are unique to one person (common spiriation belongs to two persons and so is the exception here), and these four are thus called properties (characteristics proper to just one person). Three of these are what Thomas calls “personal” in the sense that they are fundamentally constitutive of the persons: paternity, filiation, procession.16 Significantly, Thomas does not describe the notions or personal properties after the manner of creaturely properties, which are, in classical 33 The Southern Baptist Journal of Theology 21.2 (2017) metaphysics, accidents (things that inhere in another in order to exist) naturally and automatically adjoined to the essence of a thing (as risibility is to human nature). Instead, to uphold God’s simplicity and confirm that there are no accidents in the divine persons, he explains that the personal properties are really identical to the divine persons themselves. They simply prescind the peculiar relative manner of subsisting of each person and express it in the abstract as a formal ratio by which each person is distinct from the others. The function of the personal properties is therefore, by an alternative mode of signifying the persons, to provide an answer to the question of how (quo, “by what”) there are three persons in God.17 To connect this at a very general level to contemporary debates about the distinctions among the divine persons, it is worth noting that Thomas does not envision any faculties (intellect, will) or inhering features that might distinguish the persons, only their relations to one another. Any- thing included in the divine essence itself (e.g., intellect and will) is ruled out as an individuating factor that might distinguish the divine persons. The principles of individuation in the doctrine of the Trinity are strictly the persons’ relative modes of subsisting: begetting the Son (the Father’s mode of subsisting), proceeding filially from the Father (the Son’s mode of subsisting) and proceeding from the Father and Son (the Spirit’s mode of subsisting). Even the power by which the Father generates the Son, for example, is not a power unique to the Father but simply the common divine power as modified and eternally enacted by the Father under a relation to the Son.18 With this basic understanding of the structure of Thomas’s trinitarian theology in hand, it is now fitting to inquire about how he views the relation- ship between God’s own triune being and his activity in the economy. How do the processions, relations of origin and notions or personal properties give shape to God’s outward works, particularly the mission and incarna- tion of the Son? Do all the dynamics of the Son’s mission and incarnation (especially his submission to the Father) have an antecedent in the Son’s procession and eternal relation to the Father? These questions will occupy us in the next section. 34 Trinity and Economy in Thomas Aquinas The Mission, Incarnation and Submission of the Son It is relevant to our discussion of God’s activity in the incarnation that when Thomas discusses the individual persons in greater detail in the Summa Theologiae, he touches upon the equality of the Father and Son. He explores the question of whether the Father is rightly called a “principle” of the Son and argues that he is rightly called such because a principle is simply “that by which something proceeds.” “Principle” has a wider meaning than “cause,” which, though it is used by the Greek fathers in the doctrine of the Trinity, is imprudent to use in this case since causal language suggests a “diversity of substance.” While Thomas, quoting Hilary of Poitiers, is willing to grant a certain auctoritas (a word that may denote “authority” or “originating power”) to the Father in that the Father begets the Son, he refuses to allow any “subjection” (subjectio) or “minority” or “less-ness” (minoritas) pertaining “in any way” to the Son (or the Spirit). For, as he puts it, “every occasion of error should be avoided.”19 This links up with Thomas’s later discussion of whether the Son is equal to the Father in greatness (secundum magnitudinem). Philippians 2:6 is crucial here: the Son did not consider it “robbery” (rapina in the Latin text Thomas uses) to be equal to God the Father.20 For the Son receives from the Father the very nature of the Father, and greatness is nothing but the “perfection of the nature itself.” That the Son is indeed equal to the Father is further underscored by the fact that his generation is not like the tran- sition from potentiality to actuality that occurs in human generation; the Son is generated eternally by the Father, with no gradual development or perfection taking place over time. Thus, when Christ states that “the Father is greater than I” (John 14:28), this pertains to his human nature. So too 1 Corinthians 15:28 (“the Son himself will be subject to him who subjects all things to him”): “those words are understood as said about Christ according to the human nature, in which he is less than the Father and subject to him.” Thomas references Athanasius here, affirming that the Son is “equal to the Father according to divinity, less than the Father according to humanity.” He then references Hilary again, apparently conceding that the Father might be called “greater” just in the sense that he generates the Son and in so doing communicates the divine nature to him. However, the quotation of Hilary continues and affirms that “he is not less to whom the one being is given.”21 35 The Southern Baptist Journal of Theology 21.2 (2017) Thomas then includes another quote from Hilary where Hilary distinguishes between the subjection of God the Son and the subjection of creatures: “the subjection of the Son is a natural devotion (naturae pietas),” which is, according to Thomas, “recognition of the auctoritas of the Father,” “but the subjection of the rest is a matter of the weakness of creation.”22 That Thomas would not posit a subordination or obedience of the Son as God or in his eternal relation to the Father is clear not only from the strong statements already mentioned here but also from his Christology. In the third part of the Summa Theologiae, Thomas directly addresses the question of whether the Son is “subject” to the Father, and there the subjection and obedience of the Son are restricted to his human nature alone (or, better, to the Son only as he subsists and acts in his human nature). It is proper to humanity to be subject to God’s authority (potestas) and to be required to obey God’s commands. It is therefore according to his human nature that Jesus always does what is pleasing to the Father (John 8:29) and that he obeys the Father even unto death (Phil 2:8). In this article, Thomas takes into account an objection that might be raised on the basis of the fact that only creatures are subject to God. In response, Thomas does not argue that a divine person as such might be subject to another divine person. Rather, he accepts that only creatures are subject to God and then argues that while Christ is not a creature “simply” (without any added qualification), he is a creature according to his human nature and may therefore be subject to the Father according to his human nature. Indeed, Thomas writes, while it is permissible to say that Christ is subject to the Father and leave the qualifi- cation “according to his human nature” to be implicit, it is wiser to add the qualification in order to avoid the error of Arius, who held that the Son is less (minor) than the Father.23 The restriction of submission and obedience to Christ in his human nature appears in Thomas’s commentary on the Gospel of John. For example, in John 5:19-20 Jesus clarifies that he is not in competition with the Father by saying that he does nothing “from himself” but only what he sees the Father doing. Whatever the Father does, the Son also does, for the Father loves the Son and shows him what he is doing. Thomas takes it that these are works performed by the Son according to his divine nature and thus rules out that this passage might imply a minority of the Son in relation to the Father, for such a minority would be applicable to Christ only according to his human 36 Trinity and Economy in Thomas Aquinas nature. Drawing upon Augustine, then, Thomas argues that the Son never acting “from himself” refers back to his eternal relation to the Father. Just as the Son’s very being (esse) is “from the Father,” so too does he share in the one divine power and action “from the Father.”24 Thomas paraphrases: “the Son, as he does not have esse except from the Father, so he is not able to do anything except from the Father.” Likewise, that the Father “shows” the Son what he does indicates not that the Father acts and then the Son subsequently learns and imitates but rather that the Father has communicated the divine knowledge to the Son as he has communicated the one divine essence and power to the Son in his eternal generation.25 To be sure, Christ also uses the future tense and says that the Father will show him greater works (5:20b), but Thomas holds that this signals not that the Father is waiting to give the divine knowledge, power and authority to the Son in the future but instead that the Father will “show” the aforemen- tioned works to the Son (and to all who will marvel at them) in that he will execute these works through the Son at a time in the future and make them known to the world at that point. These greater works are epitomized in the resurrection of the dead, which the Father and Son accomplish together (5:21). The fact that Jesus says the Son gives life “to whom he wills” evokes Thomas’s comment that the Father and Son do not give life to different sets of persons. Rather, the Father and Son share the one divine will and the Father always works through the Son (though not as if the Son were a mere “instrument”). Jesus then says that the Father judges no one but gives all judgment to the Son (5:22). Thomas then notes two traditional expositions of this verse. Augustine’s exposition suggests that Jesus is no longer talking about himself acting according to his divine nature (in which he always acts with and “from” the Father). If the Son alone is acting in the judgment, it must be according to his human nature (compare Acts 10:42), which would be fitting since this means that those who receive damnation at the judgment will not see God in his divine nature and will not unjustly receive the beatific vision. The “more literal” exposition of Hilary and John Chrysostom differs slightly in positing simply that the Son has “judgment” from the Father in that he has the divine wisdom (as opposed to “judgment” in the sense of granting approval and condemnation to others) from the Father by which he performs his works.26 Later in John 5 Jesus says again that he does nothing “from himself” but 37 The Southern Baptist Journal of Theology 21.2 (2017) judges as he “hears” and that his judgment is just because he seeks not his own will but the will of the one who sent him (v. 30). Here Thomas com- ments that this can be taken with reference to the Son as man, in which case “hearing” would have the sense of “obeying.” In that case obedience could be intended because, if the text speaks of Christ in his human nature, it speaks of him in that respect in which he is “less” than the Father and could therefore receive a command from him. Christ’s human will, Thomas points out, is always “ruled” by the divine will. Alternatively, Jesus could be speaking of himself with regard to his being the divine Son, in which case the language of “hearing” is employed just because we receive knowledge often by hear- ing and Christ receives the divine knowledge from the Father in his eternal generation. If it is Jesus in his divine nature and action in view, then the text does not imply that the Father and Son have two distinct divine wills but rather reflects the fact that the Son has the divine will “from” the Father and therefore fulfills it as he has it “from another.” Thomas paraphrases Christ’s words: “I do not seek my own will, which is originally mine from myself, but [a will] which is mine from another, namely, the Father.”27 The key observations are (1) that Thomas believes that filial obedience applies to Christ only where the biblical text speaks of Christ in his human nature, for he is less than the Father and commanded by the Father according to that human nature alone, and (2) that he believes that Christ in his divine nature always wills and acts from the Father in keeping with his eternal procession from and relation to the Father. There is therefore in Thomas’s theology a significant dissimilarity between the dynamic of submission and obedience in the economy and the eternal relation of the Son to the Father. This is because in the incarnation Christ has a human nature and will as well as the divine nature and will and therefore can and does act in a manner (i.e., submissively) that does not apply to him in his divine nature and eternal relation to the Father. Yet, there is still an important correspondence between Christ’s divine action in the economy and his eternal relationship to the Father, namely, that he acts from the Father just as he eternally has the divine essence and power from the Father. In other words, his mode of acting corresponds to and derives from his eternal mode of subsisting in the Godhead.28 But, one might ask, what about the Son being sent of the Father? Does that imply that, even prior to his assumption of a human nature, the Son submits 38