4 Western Contemporary Explanations of the Trinity
4
Western Contemporary
Explanations of the Trinity
THE PREVIOUS CHAPTER PRESENTED the Arabic explanation of the Trinity among three Arab scholars who lived in the eighth, ninth, and tenth centuries. This chapter will discuss contemporary explanations of the doctrine of the Trinity in the West by engaging with many influential contemporary Christian scholars. The chapter will examine two types of explanations: the philosophical and the theological. While the philosophical Trinity is presented by Richard Swinburne, William Lane Craig, Brian Leftow, and Peter van Inwagen, the theological Trinity is presented by Paul Molnar, Kevin Giles, Bruce Ware, and others. More consideration and space will be given to the philosophical Trinity because of its apologetics value and contribution to non-Christians who are trying to understand the Trinity and Christians who are trying to learn how to defend it. This chapter is not intended to be a comprehensive study of all Western trinitarian thought. The purpose is to inform the reader of the most important trinitarian models and advance the dialogue between the monotheistic religions. This chapter will also inform the reader of the differences between the Arabic and Western explanations of the Trinity.
A SUMMARIZED HISTORICAL BACKGROUND
Throughout history, Western theologians advanced their theological and philosophical studies more than Arab theologians. Many reasons contributed to this fact, but the main reason remains obvious. No studies can be developed without freedom of expression and government support. Shortly after the invasion of Islam, Arab Christian theologians, unfortunately, lost the freedom to study, debate, and publish, whereas Western scholarship was progressing and flourishing.
Trinitarian theology was always important to Western Scholasticism, but it was not the only important topic that Western scholars discussed. Western Scholasticism developed and debated several topics and theological doctrines, such as different views on soteriology, eschatology, bibliology, and many more. Consequently, several types of theological discussions emerged after the patristic era. In the early history of the church, Christians had to fight against many heresies, such as Arianism, Sabellianism, Nestorianism, and others. In the fourth century, the Nicene Creed was created as a standard of faith for the purpose of defining what is orthodoxy and what is heterodoxy.
In medieval times, Scholasticism flourished in the Latin church. Great names, such as Thomas Aquinas, Peter Lombard, and John Duns Scotus (and many more theologians and scholars) never neglected the doctrine of the Trinity; on the contrary, it was at the heart of medieval theology. While the patristic period witnessed major debates on the nature of the person of Christ, medieval theology was drawn more toward soteriological questions. Many scholars during the thirteenth and fourteenth centuries treated the subject of the Trinity as if it was related to questions of theological epistemology; therefore, they were cautious about what role reason might play in order to help human beings learn about God and his nature.
Despite the importance that the doctrine of the Trinity enjoyed in the patristic and medieval eras, some modern philosophers saw no practical benefit to it. Whether people understood it or not was not an important issue to them. Immanuel Kant, for instance, states,
[The] doctrine of the Trinity, taken literally, has no practical relevance at all, even if we think we understand it; and it is even more clearly irrelevant if we realize that it transcends all our concepts. Whether we are to worship three or ten persons in the Divinity makes no difference: the pupil will implicitly accept one as readily as the other because he has no concept at all of a number of persons in one God (hypostases), and still more so because this distinction can make no difference in his rules of conduct. On the other hand, if we read a moral meaning into this article of faith (as I have tried to do in Religion within the Limits etc.), it would no longer contain an inconsequential belief but an intelligible one that refers to our moral vocation.
This thought is echoed by Friedrich Schleiermacher, who also did not see any practical and ethical benefit of this doctrine to the practical life of human beings. He states, “This doctrine itself, as ecclesiastically framed, is not an immediate utterance concerning the Christian self-consciousness, but only a combination of several such utterances.” Kant and Schleiermacher were interested not in the doctrine of God per se, but in the moral argument for God’s existence. It is sad to read their claims about the Trinity because it is not true that this doctrine has no benefits to the moral argument. On the contrary, the doctrine of the Trinity is the foundation of objective moral truth. Theism entails a loving perfect God who makes commands; therefore, He is the standard for human moral obligations. When Christians neglect the doctrine of the Trinity, they will neglect to learn about God and his nature. Consequently, this will affect their moral conduct. Unlike Arab theologians and philosophers—who dealt constantly with Muslims and had to develop convincing answers to defend the legitimacy of this doctrine—some Western scholars, unfortunately, saw no benefits of the doctrine of the Trinity.
Between patristic theology and medieval theology, two types of trinitarian models emerged in the West: the philosophical Trinity and the theological Trinity. These are not two trinities, but scholars developed different models based on their educational background (philosophical or theological), the opponents’ opinions during their times, and the need to answer those objections. The view that starts with natural theology will be called the philosophical Trinity. The view that starts with the nature of God, the Nicene definition, and the subordination of the Son will be called the theological Trinity.
PHILOSOPHICAL TRINITY
In the West, two types of philosophical Trinity were developed, the social Trinity and the Latin Trinity. The social Trinity can be traced back to the Cappadocian Fathers: Basil the Great, Gregory of Nyssa, and Gregory of Nazianzus. They were the first ones to formulate the distinctions between Father, Son, and Spirit, as defined by Christian orthodoxy. Their purpose was to preserve the distinctiveness and the coexistence of the three persons in the Godhead without jeopardizing the unity of the divine Being.
Gregory of Nazianzus offers a way of distinguishing the three Persons of the Trinity while maintaining their oneness. He states, “The very fact of being Unbegotten or Begotten, or Proceeding has given the name of Father to the First, of the Son to the Second, and [to] the Third . . . of the Holy Ghost, that the distinction of the Three Persons may be preserved in the one nature and dignity of the Godhead. . . . The Three are One in Godhead, and the One three in properties.” In a similar fashion, Gregory of Nyssa holds that the divine essence is common to the three persons. He goes a step further with the human analogy, which he applies in a strict fashion when he compares the inner life of the Trinity with three human persons sharing the one, indivisible human nature. He states, “Their nature is one, at union in itself, and an absolutely indivisible unit, not capable of increase by addition or of diminution by subtraction, but in its essence being and continually remaining one, inseparable even though it appears plurality, continuous, complete, and not divided with the individuals who participate in it.” After three centuries, the Nicene and post-Nicene fathers have come up with creedal confessions to preserve orthodoxy.
Some Western theologians did not find the Cappadocian fathers’ methodologies compatible with orthodoxy. They preferred to follow Augustine, who rejects the view that there is any sort of substrate in God, claiming the equality of the Father and the Son’s substance and function. To Augustine, God is just his nature, and the essence is somehow shared by the persons, and the essence of the Son is identical with the essence of the Father. The distinction that Augustine makes is in relation to “what relates to the form of God, in which He is equal to the Father, and what to the form of a servant which He took, in which He is less than the Father . . . for both the Son and the Holy Spirit, according to the form of God, are equal to the Father, because neither of them is a creature.” The distinction that is made between Father-Son is necessary to say that the Son is the one who was sent and the Father is the one who sent Jesus, “According to the form of God, He and the Father are one; according to the form of a servant, He came not to do His own will, but the will of Him that sent Him.”
Social trinitarianism in recent times. Ever since the formulation of the Nicene Creed, philosophers and analytic theologians have never stopped developing or reflecting on the mystery of the Trinity. Within the last few decades, responses to the logical problem of the Trinity have emerged in three main ways: The first one is known as social trinitarianism, which starts with explaining the three persons of the Trinity, then moves to the one-being theology (threeness to oneness). As McCall and Rea state, “The divine persons are numerically distinct, and that the unity of the Trinity can be understood by way of a ‘social analogy’: the divine persons are relevantly like a family, a supremely unified community of monarchs, or three human persons whose interpersonal relationships are so strong as to be unbreakable.” This school purports to present the teachings of the Cappadocian fathers of the fourth century and emphasizes its starting point in the works of the economic Trinity—the economy of salvation. Its primary aim is to secure an adequate distinction between the three persons within the Godhead. This chapter will use Richard Swinburne and William Lane Craig as examples of the social Trinity.
Latin trinitarianism in recent times. The second school is called the Latin Trinity, which goes back to the psychological trinitarian triads of Augustine of Hippo (such as intellect, memory, and will). Augustine was not comfortable with the concept of persons within the Godhead; therefore, he emphasized God’s unity over his diversity. This school starts with the one indivisible essence of God’s being subsisting in three persons. Latin trinitarians focus on one divine being or substance, and they tend to think of God as oneself, one “I”—(one-person perspective of God)—as relates to others. They also believe that God constitutes three persons. After starting with one being, they move from this oneness to explain the three persons of the Trinity.
Western scholars such as Michal Valčo rejected the Cappadocian fathers’ attempt because they tend to lose the distinction and coexistence of the three persons in the Godhead in the attempt to preserve the unity of the divine being, “either by speaking of chronologically distinct manifestations of God’s beings in three consecutive modes as the Father, Son, and Spirit; or to relegate the Son to an ‘adopted’ son of God (ontologically different from the Father) and the Spirit to an impersonal force.” Latin trinitarianism, therefore, emerged in the West, focusing on the single center of God’s power and will. Latin trinitarians need not believe that each person has his own intellectual power in order to use mental tokens that include terms such as I and me.
Latin trinitarians tend to believe that the numerical unity of God is secure, and the persons are distinct but not discrete. The divine persons do not share a common divine part among them, but each of them is God, whole and entire. The Latin trinitarians rarely express the relations among the three persons of the Godhead. Rather, they assert that some relation of numerical sameness holds between each of the persons and the Godhead. As Allan Coppedge states, “In the West an examination of the existence and the being of the one God is foundational. The discussion of the triuneness of God is secondary.” For the purposes of this discussion, it would be helpful to take Brian Leftow’s model as an example of the Latin Trinity.
Relative identity trinitarianism. In recent times, since approximately the 1980s, a third school has emerged, known as relative identity trinitarianism. It has its roots in a recent analysis of the relative identity theory. This approach is an attempt to reformulate the concept of numerical sameness without limiting it by absolute identity relations. Leibniz’s principle of the indiscernibility of identical states explains that if a is numerically identical with b, then a and b are indiscernible because every property of a is a property of b and vice versa. In other words, if a and b have exactly the same properties, including spatiotemporal properties, then they must be numerically identical. But the theory of relative identity tries to show that there are other properties that are not identical between a and b, and they try to apply this principle to the doctrine of the Trinity.
Using philosophical language, the logical problem of the Trinity (LPT) can be summarized as follows: “If there are x and y such that x is a God, x is not identical to y, and y is consubstantial with x, then it is not the case that there is exactly one God.” According to McCall and Rea, what sometimes goes unnoticed is that (LPT) is true only if (P) “x and y are not identical, then x and y are not numerically the same substance is true.” If (P) is false, “then it is possible that x and y are numerically the same but not identical. Thus, it is possible that the divine persons are genuinely distinct but yet, by virtue of their consubstantiality, one and the same God.”
According to some philosophers, the (LPT) can be solved and the Trinity can be understood with the help of relative identity theory. According to this theory, “it is possible for objects x and y to be the same F but not the same G—where F and G are sortals, and x and y are Gs as well as Fs.” In other words, sameness implies identity and identity is sortal-relative. Sortal means terms or quantifiable nouns, such as dog, table, man, and so on. So the philosophical concept of the sortal-relative of identity theory says, “Identity statements might be true relative to one sortal but false relative to another.” Relative identity theory denies classical identity, which says that every relative identity predicate dominates classical identity: that is to say, “for all sortals F, if x is the same F as y, then x = y.” According to relative identity theory, some R1 predicates do not dominate classical identity.
To better illustrate this concept, I will borrow an example from Harriet Baber about air travel, which best explains the relative identity theory. However, I will tweak this example to fit my agenda. I will use two terms: passenger and person. Supposedly, a traveler with dual citizenship is making two trips while using two passports with two names spelled differently. The first trip is between Germany and the United States. The traveler is going from the Dallas airport directly to Frankfurt, Germany (trip 1). The second trip takes place within the European continent. The traveler is going from Frankfurt to Athens, Greece (trip 2). The question under investigation is this: can the airline know that this passenger is the same person? From the airline’s point of view, they have two different passengers. It is very hard for the airline to know that the trips are done by the same person because he is using two different passports with two different names. But from the person’s point of view, he is the same person with dual citizenship. In this case, we have two passengers but one person who is taking two trips.
The Christian doctrine of the Trinity is committed to the idea that there is one God and three Persons—Father, Son, and Holy Spirit who are all God but are not identical. The Father is God, the Son is God, and the Spirit is God, but the Father is not the Son or the Spirit. The Father is the same nature as the Son, but the Father is not the same Person as the Son. To solve the puzzle, philosophers who follow the relative identity theory suggest that being is not identical to person—hence Father, Son, and Holy Spirit are the same being but not the same person. A later section of the chapter will explore Peter van Inwagen’s model of relative identity and the Trinity.
RICHARD SWINBURNE
The British scholar Richard Swinburne served as a visiting professor and lecturer in many British, American, and international universities, such as the University of Hull and the University of Keele. His expertise lies in the connection between science and philosophical theories. Swinburne seeks to demonstrate how scientific theories show how the universe operates in an orderly manner and metaphysical theories show the meaningfulness and justification of Christian theology. He has published several books on different philosophical topics, such as Space and Time (1968), The Concept of Miracles (1971), The Coherence of Theism (1997) (which he revised in 2016), The Existence of God (1979), Faith and Reason (1981), and many more.
A priori argument. Swinburne follows the Nicene Creed by stating that “God’s nature is three persons in one substance.” To explain this concept, Swinburne investigates this question: can there be two divine individuals? Then he explores the possibility of the Godhead having more than three divine individuals. He builds his argument on the basic assumption that “being divine should be understood as entailing and being entailed by being necessarily perfectly free, omniscient, omnipotent, and existing of metaphysical necessity.” However, could there be two or more individuals who are necessarily perfectly free, omniscient, and omnipotent? Swinburne explains that an omniscient and perfectly free individual will always be perfectly good. Such an individual might act according to his perfect goodness (act of essence) or according to his will (act of will). As Swinburne states, “A divine individual’s compatibilist power is his omnipotence, the power to do anything logically possible, if he so chooses; his absolute power is the power to choose and do, and that is limited not merely by logical possibility but by perfect goodness.” Each individual will be bringing about many goods, both within himself and in relation to the other individual.
If this analysis is true, could there be two omnipotent individuals bringing frustration to each other? Swinburne suggests that since each would recognize the other as having divine properties, it is plausible that each would now prevent or frustrate the acts of the other. For instance, if the first individual decides to create something, he is sure that the second individual will not object, and it would be good for the second individual to give it his backing.
Swinburne imagines that the only possible conflict that might arise between the two individuals is when one decides to create something according to his own goodness that is in some way incompatible with an act the second individual is simultaneously trying to accomplish. However, within the essence of the Christian God and the relationship between the Father and the Son, this is not an option. Swinburne states,
Such unity of action could be secured if the first individual solemnly vows to the second individual in causing his existence that he will not initiate any act (of will) in a certain sphere of activity that he allocates to him, while at the same time the first individual requests the second individual not to initiate any such act outside that sphere.
Since the two divine individuals are perfectly good, then the vow among them necessitates that no one initiates any act of will within the other individual’s allocated sphere of activity. The vow necessitates that they act according to their perfect goodness, which does not frustrate or even disagree with the other divine individual. In this case, their omnipotence is limited by their perfectly good nature.
Swinburne concludes that there can be more than one divine individual if it is necessary for the first one to bring about the existence of the second, but this can be only when the first divine individual has an overriding reason to bring about the existence of a second individual as an act of essence. In the same sense, there can be a third divine individual if the first and the second divine individuals have an overriding reason to bring about the third individual with the divine understanding not to initiate acts of will in a certain sphere and to confine his acts of will to the first and second divine individuals. This means the Father is the first divine individual. He actively causes the second and the third divine individuals to cooperate and relate to each other in love. Jesus, the second divine individual, causes the third divine individual. The third divine individual is the active cause of the existence of no other individuals.
The overriding reason for the first divine individual to bring about the second or the third is the nature of God himself. God is love. Swinburne believes that “Love involves sharing, giving to the other what of one’s own is good for him and receiving from the other what of his is good for one; and love involves cooperating with another to benefit third parties.” Love must share and cooperate in sharing, otherwise, it is not the best love. If there is only one divine individual, then there will be none other with whom to share. “So the love of a first divine individual G1 would be manifested first in bringing about another divine individual G2 with whom to share his life, and the love of G1 or G2 would be manifested in bringing about another divine individual G3 with whom G1 and G2 cooperatively could share their lives.” For love to be perfect, G2 and G3 would then cooperate in allowing G1 to continue in being.
Swinburne knows that his explanation might be limited by his human ability. So he does not neglect to suggest that the limitation he ascribes to the individual being is a matter of human limitation. He states, “I have presented a highly fallible human judgment as to what the best such mechanism (and so the one which would be adopted) would be . . . The ‘limit’ is a limit on the application of a human word to God; it is not to be understood as a constraint within a divine individual.” God cannot be limited because he is omnipotent. But there is a good chance that Swinburne is limited in his explanation, and this is why he calls his argument fallible.
The traditional doctrine. Swinburne concludes, “If there is at least one divine individual, and if it is logically possible that there be more than one divine individual, then there are three and only three divine individuals.” The Counsel of Nicaea confirmed the belief in one God and three persons but denied that there are three independent divine beings, any of which could exist without the other or act independently of each other. Swinburne agrees with the Nicene Creed that the three divine individuals should be taken together as a collective source of being of all other things. The members of the Godhead are mutually dependent and necessarily jointly behind each other’s acts. The collective source is indivisible in its action because each member would back the causal action of the others. The collective source is causeless, and the members are not dependent for existence on anything outside the Godhead. The members of the collective have the divine properties of omnipotence, omniscience, and so forth. If all the members of the group know something, then the group itself is knowledgeable and aware of that thing. So the one God is to be read as the source of being of all other things; a collective source of being that has in it an indivisible unity.
Examining the claim that each of the individuals is God. Swinburne believes that there are differences among the divine individuals, both in respect to which depends on which and in respect of function. The divine names help us distinguish between them. “Father seems a name appropriate to the original source.” The Son is the only member who is incarnated, and the Spirit takes a primary role in sanctification. The Son is called by this name because the Father is the one who begets, and the Son is the one who was begotten. The Spirit does not beget nor is begotten, but he proceeds from the Father and the Son. Swinburne interprets the creed saying,
The Council may be saying this: the Godhead is not just three individuals, each with its thisness, who have common essential properties. Rather, it is exactly the instantiation of the same essence of divinity which makes the Father God, as makes the Son God, as makes the Spirit God. They would be the same individual but for the relational properties which are distinct from the divine essence and which distinguish them.
Swinburne admits that this part of his argument is not in the area of reason and does not go beyond any ecclesiastical tradition.
WILLIAM LANE CRAIG
William Lane Craig is named by the Best Schools as one of the fifty most influential living philosophers. He is notable for his work on the kalām argument and the existence of God, philosophy of time, and the historical Jesus. He has authored and edited over thirty books, including Assessing the New Testament Evidence for the Historicity of the Resurrection of Jesus (1989), Divine Foreknowledge and Human Freedom (1990), Theism, Atheism and Big Bang Cosmology (1995), The Kalām Cosmological Argument (2000), Time and Eternity: Exploring God’s Relationship to Time (2001), and What Does God Know? Reconciling Divine Foreknowledge and Human Freedom (2023). Craig has also published over a hundred academic articles in different philosophical journals.
Craig is a strong advocate of social trinitarianism. He provides a model that captures the central commitment of this view. Usually, social trinitarians believe that “in God, there are three distinct centers of self-consciousness, each with its proper intellect and will.” In contrast, the central commitment of anti-social trinitarianism is that “there is only one God, whose unicity of intellect and will is not compromised by the diversity of persons.” Craig’s trinitarian model supports social trinitarianism because it focuses on the persons of the Trinity rather than the unity within the Godhead. It is worth mentioning that Craig believes there is no reason to think there is a perfect analogy to the Trinity among created things or among ideas related to creation. The analogies might be helpful as a springboard for philosophical reaction and formulation, but they are not to be taken literally and in exact similarity to the divine concept.
To expound on the Trinity, Craig borrows a mythical creature from Greco-Roman mythology who guarded the gates of Hades, the three-headed dog named Cerberus. Craig supposes that Cerberus has three brains, three distinct states of consciousness, and three wills. While Cerberus is a sentient being, he does not have a unified consciousness. The three heads are three centers of consciousness, and they are even named Rover, Bowser, and Spike. Since they are discrete, they might come into conflict with one another. One wants to move in one direction, but the other wants to move in a different one. One wants to sit while the other wants to stand or sleep; however, for Cerberus to make a move or to stand, the three have to agree on the decision. The three must cooperate in order to function. If Rover wants to sleep and Bowser and Spike to walk, then Cerberus will not be able to move or guard the gate as he was designed to. As Craig puts it, there must be a considerable degree of cooperation among Rover, Bowser, and Spike for them to work properly.
Despite the diversity of his mental states, Cerberus clearly is one dog. As Craig explains, “He is a single biological organism exemplifying a canine nature. Rover, Bowser, and Spike may be said to be canine, too, though they are not three dogs, but parts of the one dog Cerberus. If Hercules were attempting to enter Hades, and Spike snarled at him or bit his leg, he might well report, ‘Cerberus snarled at me’ or ‘Cerberus attacked me.’” What makes Cerberus one being is that he has a single body, and what makes him multiple is that he has triple heads.
The question of what makes several parts constitute a single object rather than distinct objects is a difficult one, but Craig wants to study the nature of the soul to get some insights. The souls of human beings and animals are immaterial substances. Craig explains that souls come in different variations of capacities and faculties. The human soul is the highest on the spectrum because what makes the human soul a person is that it is “equipped with rational faculties of intellect and volition which enable it to be a self-reactive agent capable of self-determination.”
Craig believes that God is a soul; he does not have a body. Normally, the human soul is equated with rational faculties, and it is considered an individual person because each soul is equipped with one set of rational faculties sufficient for being a person.
Suppose, then, that God is a soul which is endowed with three complete sets of rational cognitive faculties, each sufficient for personhood. Then God, though one soul, would not be one person but three, for God would have three centers of self-consciousness, intentionality, and volition, as Social Trinitarians maintain. God would clearly not be three discrete souls because the cognitive faculties in question are all faculties belonging to just one soul, one immaterial substance. If this is true, then God would be one being which supports three persons, just as our individual beings each support one person.
Craig’s way of explaining the formula of the three persons in one substance is related to the soul of that being (animal, human being, or divine being) and how well-developed this being is on the spectrum of creation. This is to say, the soul might have several faculties that are related to the being, and there is no reason that might prevent us from thinking that the divine soul is not so richly endowed, as they possess three sets of cognitive faculties sufficient for personhood. If the being is an animal, then his soul is primitive on the spectrum of abilities and faculties. Human beings have more advanced souls that allow them to become rational persons, and God’s soul is at the top of the spectrum. It possesses three sets of cognitive faculties sufficient for personhood.
BRIAN LEFTOW
Leftow is an American philosopher who specializes in the philosophy of religion, medieval philosophy, and metaphysics. He has many academic honors, such as the Brackenridge Distinguished Resident in Philosophy from the University of Texas/San Antonio and Distinguished Scholar Fellowship from the Center for Philosophy of Religion, University of Notre Dame. Leftow has authored and edited many books, three of which are published by Oxford University Press: Anselm’s God, Anselm’s Proofs, and God and Necessity. He wrote Aquinas: Questions on God, and The Cambridge Companion to Anselm, both of which are published by Cambridge University Press. He also has published and reviewed more than hundreds of academic articles, including “Time-Travel and the Trinity,” “On Hasker on Leftow on Hasker on Leftow,” and “A Latin Trinity,” which were published in the Faith and Philosophy Journal.
Unlike Swinburne and Craig, Leftow follows the Latin Trinity model of the doctrine of the Trinity. He prefers this model because it has fewer difficulties explaining the Trinity, especially since the three persons are not discrete. In a nutshell, Latin Trinity can be defined in the following way: “There is just one divine being (or substance), God. God constitutes three Persons. But all three are at bottom just God. They contain no constituent distinct from God. The Persons are somehow God three times over.” Within this view, God is one divine substance, not three centers of consciousness as in the social Trinity. Monotheism is preserved because the life of God is composed of “three event-based persons who exist simultaneously.” The doctrine of the Trinity is likewise preserved because the three-persons view is similarly retained.
To explain his model of the Trinity, Leftow makes sure he stays within the limits of orthodoxy. Therefore, he lays his arguments on two foundations. (1) The Athanasian Creed, which acknowledges the three persons of the Trinity and their divinity. It states, “We are compelled by the Christian verity to acknowledge every Person by Himself to be both God and Lord.” (2) The Latin Trinity model of Thomas Aquinas, which concentrates on the divine nature, not the three persons of the Trinity. Aquinas states, “Among creatures, the nature the one generated receives is not numerically identical with the nature the one generating has. . . . But God begotten receives numerically the same nature God begetting has.” These two concepts will be the foundation of Leftow’s model of the Trinity.
Leftow introduces a new term, trope, to explain the doctrine of the Trinity. This word means “an individualized case of an attribute.” To explain this concept, Leftow gives the example of Abel and Cain. Even though they were both human, they were different. Cain’s humanity was not identical to Abel’s because each had distinct tropes of human nature. The same concept pertains to the Trinity: “while Father and Son instance the divine nature (deity), they have but one trope of deity between them, which is God’s. While Abel’s humanity ≠ Cain’s humanity, the Father’s deity = the Son’s deity = God’s deity. But bearers individuate tropes. If the Father’s deity is God’s, this is because the Father just is God: which last is what Aquinas wants to say.” By this same reasoning, Aquinas did not believe that the Father alone is God, but the Son and the Holy Spirit are God as well.
Time-travel model. Leftow invites his readers to imagine themselves watching a musical play in which Jane is dancing on the stage. Jane can time travel. She goes to the stage on the left side, performs her dance, and then time travels to the past and appears on the right side of the stage to perform another dance. Jane appears both on the left and right side of the stage simultaneously. She moves between the two points in a straight line. She appears to be in different places at the same point in our lives, but not at the same point in hers. From the audience’s perspective, Jane appears in different places on the stage at the same time; but from Jane’s perspective, she is not in many places at the same time; instead, she is in different events.
In this story, there is one trope of human nature, which is Jane’s trope. Leftow admits that this might sound like an odd example, but he hopes readers will concentrate on the dance or many dances of one substance. Each dancer is Jane, but these are many events; and Jane is there many times over. In this example, Jane has genuine personal interaction. “She leans on herself for support, smiles to herself, talks (and talks back) to herself. The talk may even be dialogue in the fullest sense. . . . The Wells-o-matic [the time travel machine] lets the one Jane be present at one time many times over, in many ways, as the leftmost Rockette, the rightmost, etc. It gives us one Jane in many personae.” Leftow believes the analogy makes sense in a metaphysically possible world containing backward time travel.
When we apply this example to the Trinity, we find both similarities and differences. In terms of similarities and the way this model applies to God, Leftow states,
God’s life has the following peculiar structure: at any point in our lives, three discrete parts of God’s life are present. But this is not because one life’s successive parts appear at once. Rather, it is because God always lives His life in three discrete strands at once, no event of His life occurring in more than one strand and no strand succeeding another. In one strand God lives the Father’s life, in one the Son’s, and in one the Spirit’s. The events of each strand add up to the life of a Person. The lives of the Persons add up to the life God lives as the three Persons. There is one God, but He is many in the events of His life, as Jane was in the chorus line: being the Son is a bit like being the leftmost Rockette.
However, along with these similarities, there are also differences between the doctrine of the Trinity and the time-travel model. While the life of God is represented in the successive appearances of Jane, with the divine, those appearances are not successive multiple lives. They are three discrete parts of God’s singular life. God always lives his life in three discrete strands at once. One strand is the Father’s life, the second strand is the Son’s life, and the third strand is the Holy Spirit’s life. These strands are not many (only three), and they do not appear after each other. God is one, but he is many in the events of his life.
Every event in God’s life is part of the Father, the Son, and the Spirit. In the example, it appears as the chorus line. God does not live as Father, Son, and Holy Spirit. He is not the Father in one life and the Son or the Spirit in another. Jane has just one life, with consecutive episodes. The Father, Son, and Spirit are not consecutive episodes in the divine life. This example does not include the entire life of Jane; whereas, God’s life consists of three other things which count as an entire, ongoing life. In other words, God’s life runs in three streams. Jane is limited in her movements and time. She dances in one spot, runs to the machine, and then dances in another spot. Not so for God: God always lives in all three streams. “God’s life always consists of three non-overlapping lives going on at once, none after the other, as the series of positive numbers consists of two non-overlapping series . . . ‘going on at once’ within the series, neither after the other.” As expected, the doctrine of the Trinity is hard to illustrate; therefore, many might find this example hard to understand.
Toward Latin Trinity. Leftow is against the social Trinity because, in his opinion, numbers matter, and the Latin Trinity secures the numerical unity of God. In the Old Testament, God said, “Hear, O Israel: The Lord our God, the Lord is one” (Deut 6:4). The unity of God should be understood in a numerical sense, and this cannot happen under the social Trinity. When it comes to divine actions, Leftow believes that “if the Persons are discrete, and only the Son died for our sins, then however much the Father and Spirit helped out, it seems that the Son did more for us than the other two, who neither bled nor suffered.” In the social Trinity, where the three persons are three discrete substances, it would be hard to explain the reason behind loving or being loyal to the Father as much as to the Son or the Spirit, especially since human beings did not see the Father working the human redemption, but only the Son who died for humanity’s sins. The Latin Trinity does not face such a problem because “there is just one substance to whom we owe anything for our salvation, God. There can be a question of unequal loyalty or debt to two discrete divine substances. There cannot be a question of unequal loyalty or debt to one and the same substance.”
Leftow believes that there are four ways to consider how the three discrete persons might participate in one divine action if a person does not wish to assign the persons fields of sole agency. (1) One of the three persons makes the largest contribution of the act, and the other two persons support him or cooperate with the act. (2) All three persons contribute partially but equally to the action. (3) The three persons overdetermine the divine action by each of them contributing on his own to fully account for the divine effect. (4) It could be, as Leftow states,
The three Persons together just are one agent, in the sense they make not three distinct contributions, however related, but just one contribution among them. So to say: the Father acts, the Son acts, and the Spirit acts, and yet there are not in any sense three acts, but one act. Any act-token which is the Father’s is equally and fully the Son’s and Spirit’s, without overdetermination, partial contribution, etc.
According to Leftow, the third and fourth options should be rejected because any equal or unequal partial action that each person performs will cause an equal or unequal part of the effect. If one of the persons rules one action, it seems to follow that that person is the ruler of the action and maybe the God of that action. Or it could mean that while no part of the effect is assignable to any one person alone, the three persons together participated in a single effect. This means no one individual has caused the action to succeed, and all together succeed to cause it.
Leftow is against the group-mind theory, in which the persons of the Trinity have fully submerged, composing a fully integrated mind, which accounts for mental acts. Within this theory, the mind of God (or the mind of the Trinity) is understood as a single human mind. Leftow believes that if every person of the Trinity makes a less-than-full contribution to any mental act, then no person accounts fully for the act; therefore, no person of the Trinity could be fully divine or fully perfect. In the Latin Trinity, the Son is not discrete from the other persons. Leftow explains, “For the Son to be in the forefront of an act is just for God to be more prominent in one role (or state, etc.) than he is in others. So thanking the Son is thanking the same individual God who is Father and Spirit. We cannot owe God more thanks than we owe God.” Leftow gives the example of parting the sea. It is not as if each person of the Trinity contributes one-third of the force needed to split the sea. God divides the sea by deciding that it shall be divided. The acts of God in the Latin Trinity model are just acts of God.
PETER VAN INWAGEN
Peter van Inwagen is an American analytic philosopher and the leading figure in contemporary metaphysics, philosophy of religion, and philosophy of action. While he works in a wide variety of areas of philosophy, his expertise lies in metaphysics, the philosophy of action, and the philosophy of religion. Van Inwagen published several books with academic publishers, such as Being, Freedom, and Method: Themes from the Philosophy of Peter van Inwagen from Oxford University Press; God, Knowledge, and Mystery: Essays in Philosophical Theology from Cornell University Press; and Thinking About Free Will from Cambridge University Press.
Van Inwagen admits that the Trinity is a mystery; however, he strives to provide a philosophical answer to refute the charges that Christians are either simple polytheists or that polytheism and monotheism are the same things. Van Inwagen is preoccupied with the divine love concept. He starts with this question: is salvation individual? He admits that maybe it is the case, but there is something more. The beatific vision of the saints enjoying their relationship with God is not just individual but corporate. He states, “The love we have for each other will be a restored image of the love that the Persons of the Trinity have for one another.” If salvation is restoring the image of God that has been distorted by sin, loving one another is part of that restored image. This idea of love motivates van Inwagen to come up with a sophisticated philosophical explanation of the doctrine of the Trinity. His main concern is the minimal Trinity—the belief that God being one in being and three in persons is logical.
After van Inwagen explains the relative identity theory, he turns the doctrine of the Trinity into philosophical equations to test its logical credibility. He starts by denying the classical identity theory (explained earlier in this chapter) and the expression “x is the same apple as y.” He also denies the expression “z is a horse & z = w.” This is the classical image of “z is the same horse as w.” The two horses might have similar descriptions, but they are two different horses. Generally speaking, relative identity is different from relative identity logic+, which is relative identity with extra data. Relative identity logic+ includes extra information that makes sense in one way and no contradictions can be deduced from it if all the set of data were examined.
Van Inwagen relies on the concept of dominance in philosophy, which can be explained this way: “Iaβ → (F . . . α . . . ↔ F . . . β . . . ) where F . . . α . . . is a sentence in which β does not occur, and F . . . β . . . is like F . . . α . . . except for having free occurrences of β at some or all places at which F . . . α . . . has free occurrences of a.” A relative identity predicate dominates predicate F if all sentences of the form “Iaβ → (F . . . a ← → F . . . β)” are true. If relative identity predicates dominate all relative identity predicates, then being the same H entails being the same F for all sortals F. However, some of the relative identity predicates are not dominant. Van Inwagen gives the example of two men, one of whom is called John Locke and the other Don Locke. Clearly, they have the same surname, but they are not the same person because surname fails to dominate a great variety of predicates, such as “‘is alive in the twentieth century,’ ‘has never heard of Kant,’ ‘is the same man as,’ and so on.” When this principle is applied to the Trinity, there are two undenied relative identity predicates—being and person. Is being the same as person? Van Inwagen does not assume that either of these predicates dominates the other, and neither of them is eliminable in favor of dominant relative identity predicates and ordinary predicates.
Van Inwagen believes that “being” has causal powers. Being can be a person because “A being is a person (something that is the same being as something is also the same person as something) if it is self-aware and has beliefs and plans and acts on the basis of those beliefs to execute those plans. (As Boethius says, a person is an individual substance of a rational nature.).” Absolute identity provides us with definitions of “x is the same being as x” and “x is the same person as x,” but allows us to deny that “x is the same being as y” or “x is the same person as y.” For instance, we can deny that “x has causal power.” Van Inwagen explains that if there is such a relation as classical or absolute identity, and this relation was subdominant, then we should believe that all relative identity predicates entail the conditional x is the same being as y → x=y. Trinitarians must either deny classical-absolute identity theory, or—if it exists—recognize that it is not dominated by “is the same being as.”
Van Inwagen takes the route of examining each predicate of the Christian belief of the doctrine of the Trinity to prove that if all the predicates are logical, then being is not the same as person, and it is possible to have one being and three persons without logical contradiction. Van Inwagen tests the predicate “x is divine,” explaining,
x is necessarily existent; essentially almighty, all-knowing, and perfect in love and wisdom; essentially such that nothing contingent would exist unless x willed it . . . CT1 Ⱥx (x is divine →x is a being & x is a person).
This is redundant to the consequent phrase, since any person is, necessarily, a being.
CT2 Ⱥx (x is a person → x is a being).
It follows from CT1 that something is a divine Person if and only if it is a divine Being:
CT3 Ⱥx (x is a person & x is divine ↔ x is a being & x is divine).
Van Inwagen assumes that “is the same being as” dominates “is divine.” He also assumes that CT4 ȺxȺy (x is the same being as y → [x is divine ↔ y is divine]). The most important consequence of CT4 is that if a being is divine, then any being who is the same being as that being is divine. Van Inwagen does not assume, however, that the same person dominates “divine” because the “‘same person’ is not dominated by such predicates as ‘is a man’ and ‘was born in the world. It follows from CT1 and CT4 that if x is a divine Person and y is the same being as x, then y is a person. It does not follow that y is the same person as x.” If this is true, then something is a divine person if and only if it is a divine being (CT3), which consequently is consistent with there is one divine being and three divine persons.
The example that van Inwagen uses to illustrate his idea is related to three dogs who are each a purebred dachshund for sale at different prices. This information about the dogs is not relative identity predicates. It should be taken as absolute identity, “is the same breed as” and “is the same price as.” All these sentences are examples of absolute identity, not relative identity. Therefore, they are not good examples to illustrate the Trinity regarding relative identity theory. As stated earlier, in metaphysics, absolute identity needs to be rejected to avoid asserting that there are three divine beings and three divine persons.
Van Inwagen wants to show that because of relative identity theory, we cannot deduce formal inconsistency or contradiction from S in relative identity logic. S is considered the set of sentences containing various information about three dogs. There are three dogs: A, B, and C. Dog C prances from A to B and does no other prancing, and nothing besides C prances. Suppose that Dog A is barking at B and at nothing else, and nothing else barks besides Dog A. Given these assumptions and the earlier ones about prices and breeds, it is easy to verify by inspection that all the members of S are true on the proposed reinterpretation. Van Inwagen believes that we can apply the same set of S to the trinitarian belief, and no formal contradiction can be deduced in that logic from a set of trinitarian set of sentences that are true on some interpretation, such as: God is the same being as the Father, God is a person, God is the same person as the Father, God is the same person as the Son, the Son is not the same person as the Father, and God is begotten.
THEOLOGICAL TRINITY
The immanent versus the economic view. The previous scholars can all be classified under the philosophical Trinity. These scholars use natural theology as their starting point (and many other methods) to understand the Trinity. However, theologians prefer to argue historically and biblically to explain the Trinity because they see the above models as speculative, historically untested, and deviating from Nicene trinitarianism. For instance, Paul Molnar, who based his model on Thomas Torrance and Karl Barth’s theology, emphasizes the distinction between the immanent Trinity and the economic Trinity. There are not two Trinities here, but one. Understanding the difference between the immanent and the economic is related to God in himself, his relation to creation, and how we understand him through his revelation.
The immanent Trinity, which is also called the ontological Trinity, uses terms that explore the internal relationship among the three persons of the Trinity. The language gives attention to the inexpressible mystery of what God is like within himself apart from reference to his works with creation. Thus, “the immanent Trinity is God-as-God-is throughout eternity.” It denotes the personal properties of the three persons of the Trinity: The Father begets the Son, the Son is begotten, and the Holy Spirit proceeds.
The economic Trinity, on the other hand, refers to “the manifestations of the three persons of the Trinity in relationship to the world, particularly in regard to the outworking of God’s plan (economy) of salvation and redemption.” It is the Father who sent the Son for our redemption, the Son who acquires the redemption, and the Holy Spirit who applies the redemption to us. Thus, the economic Trinity denotes the activities of God and the role of the persons of the Trinity regarding creation, salvation, and redemption.
Some theologians, such as Karl Rahner, Jürgen Moltmann, and Eberhard Jüngel, believe that the immanent Trinity is the economic Trinity and vice versa. They see God’s threefold presence in the history of salvation as identical to God’s own inner triunity. Moltmann, for example, states, “In order to grasp the death of the Son in its significance for God himself, I found myself bound to surrender the traditional distinction between the immanent and the ontological Trinity.” For Moltmann, the event of the crucifixion is not only an event of the economic Trinity but also an event within the eternal Trinity.
Other theologians see the previous view as ambiguous and open to misunderstanding. Therefore they do not separate the immanent from the economic Trinity, but they make a distinction between them. Such theologians believe that we know the triune God through God’s relationship with his creation; however, this does not mean God became triune in his relation with the world. God himself was and is a triune God even before creating the universe. Hence, God reveals himself as a triune God through his economy because he is a triune God. As Seung Goo Lee explains, “We can recognize that God is the triune God in the process of examining God’s creation and redemption through Christ, especially, while examining the coming of Christ, his self-disclosure, the coming of the Holy Spirit to the New Testament church on Pentecost, the works of the Holy Spirit in the church, and the response of the church to the Holy Spirit (esp., Acts 5:1-16).” In other words, the trinitarian nature of God precedes his revelation and our knowledge of him.
One of the reasons these theologians rejected Rahner and Moltmann’s model is because it starts with human experience and moves up to understand God. As Paul Molnar explains:
The immanent trinity and the economic trinity could not be identified or confused but distinguished and united in a way analogous to the Incarnate Logos. Since the relation between God and creatures was irreversible, it could neither be seen nor described by looking at history as such; any such attempt would project our experience into the inner life of God, and re-define the immanent trinity by reason and not revelation.
In Molnar’s opinion, theology cannot begin with human experience and redefine God’s antecedent existence if the criterion is the human Jesus.
Molnar emphasizes the unity of the immanent and the economic Trinity to avoid stripping God of his freedom in creating human beings. God is God with or without creation; in contrast, Moltmann’s panentheism starts from human experience and reconstructs theology in a way that does not allow God to be God without the love that communicates salvation. God constituted the salvation plan not because he had to (forced by his love), but because of who he is as immanent Trinity out of pure freedom. As Torrance states, “God is therefore no blind fate, no immanent force acting under the compulsion of some prius or unknown law within his being.” There is no determinism in God’s being, but God was free to break the bondage of sin and start a personal relationship with human beings. This way of explaining the Trinity shifted the argument to issues related to the obedience, humiliation, and subordination experiences of the human Jesus to the divine Father and whether these actions were experienced by God the Son in his divine nature as well.
The gradational vs. the equivalence views. The eternal generation of the Son also led theologians to argue two different views about the Trinity, the gradational view and the equivalence view. The proponents of the gradational view argue that there is an eternal hierarchy of authority among the three persons of the Trinity. The Father is the supreme member of the Trinity with the highest authority. The Son and the Spirit are subordinate and submit to this authority. This gradational relationship has been in eternity past, during the earthly ministry of Jesus, and in the present ministry of the Holy Spirit in the life of the church. It will also be the same in the eternity future. Despite the gradational authority, there is equality of the being or essence among the three persons of the Trinity.
Bruce Ware is one of the proponents of this view. He believes in “functional hierarchy.” Quoting Philippians 2:9 he explains that “clearly, if the Father is the one who exalts the Son, and if the Father gives to the Son his all-surpassing name, then the Father has supremacy over the Son.” Any biblical reference to the Father’s superiority to the Son is to be referred to this temporary functional and missional subordination. Regarding the relationship between the Father and the Son, “the Son in fact is the eternal Son of the eternal Father, and hence, the Son stands in a relationship of eternal submission under the authority of his Father.” He adds, “Surely, they are not distinct in essence, for each share fully the identically same divine nature. Their distinction, rather, is constituted, in part, by taxis—the ordering of Father, Son, and Holy Spirit within the Godhead.” Ware believes that there is an order in the Godhead and it is reflected in creation and human relationships. This order is a built-in structure of authority and submission.
The equivalence view holds that the Father, Son, and Holy Spirit are eternally equal in authority. The subordination of the Son and the Holy Spirit is temporary and functional. “The temporary functional subordination of the Son and the Holy Spirit to the Father has been established for the purpose of carrying out a particular mission. But when that mission is completed, the three Persons’ full equality of authority will resume.” In other words, the submission of the Son is not eternal, but temporal for a particular purpose and a particular time. Once that purpose is accomplished everything goes back to its original status.
Stanley Grenz, with coauthor Denise Kjesbo, gave the major exposition of his view of the relationship between the three persons of the Trinity in a book on the role of women in the church. In this book, he explains the mutual dependence of the Son and the Father upon one another, stating,
Finally, the argument from Christ’s example often overlooks the deeper dynamic of mutual dependence within the Trinity. Jesus willingly submitted himself to the One he called “Abba.” Thereby he reveals that the Son is subordinate to the Father within the eternal Trinity. At the same time the Father is dependent on the Son for his deity. In sending his Son into the world, the Father entrusted his own reign—indeed his own deity—to the Son (for example, LK 10:22). Likewise, the Father is dependent on the Son for his title as the Father. As Irenaeus pointed out in the second century, without the Son the Father is not the Father of the Son. Hence the subordination of the Son to the Father must be balanced by the subordination of the Father to the Son.
Because of the equivalence view, Grenz believes in mutual dependence between the Father and the Son and he puts the traditional view in a linear way between the persons of the Trinity. There is no authority of the Father over the Son because the Father also is dependent on the Son.
Kevin Giles is a proponent of the equivalence view as well. He believes that the Son and the Holy Spirit have a functional submission to the Father for a certain period of time, or until the purpose of God is accomplished. Millard Erickson captures Giles’s position well, explaining that the three persons of the Trinity are
equal in their eternal authority. For a period of time and for a specific purpose within the redemptive economy of God, the Son and then the Spirit voluntarily assumed a position of functional subordination to the Father, and in the case of the Spirit, to the Son as well. At the completion of these respective redemptive tasks, however, the equal authority possessed in eternity past is reassumed and will continue to be possessed and exercised through all eternity future.
The proponents of this view believe in the equal and eternal authority of the three persons of the Trinity. They believe that on the gradation view, where the Son is necessarily subordinate to the Father (which means he cannot but be subordinate), the love of Jesus to humanity is distorted. If under all circumstances, the Father has authority and the Son is subordinate to the Father, then love is not real because it does not come from a free will decision. Jesus had to come to the world and sacrifice himself because of his subordination, not because of his love to humanity.
The followers of the equivalence view also believe that on the equivalence model, the quality of being subordinate is an accidental quality. It does not change the nature of the Son and who he is. On the other hand, to the gradationists, authority and subordination are essential properties. “If they were not possessed, the Father would not be the Father and the Son would not be the Son. . . . Authority is part of the Father’s essence, and subordination is part of the Son’s essence, and each attribute is not part of the essence of the other person.” Erickson introduces a philosophical distinction: what something is, is different from what something does. On the gradation view, subordination is part of the divine essence, whereas, on the equivalence view, subordination is part of the divine work. If we say subordination is part of the divine essence, then Jesus cannot but be subordinate and this makes him inferior. If we say subordination is part of the divine work, then subordination is linked to the divine will and any subsequent act belongs to the will of God, not to his essence.
In the West, scholars are free to choose and develop whatever model they think is biblical. There are no limitations, prohibitions, or restrictions to how scholars understand and think about God, except for the limitations they choose to apply (historical, creedal, or biblical). There is no scholar that will be persecuted because of her views. Moreover, criticism is not considered personal, and despite the differences among scholars and the many views explained earlier, I have not come across a scholar calling his opponent a heretic. Scholars understand that where there is freedom, there are differences. It is good to agree to disagree.
The most important note to add here is that despite all the differences among these views, none of them make a separation between the three persons of the Trinity within the Godhead. Instead, they all believe that the three persons share the same divine essence and they are distinguished in role. Theologians are not suggesting that the Son is inferior to the Father because of his eternal subordination, but he is equal in nature and distinct in role. In a similar fashion, philosophers are not trying to redefine the Trinity, claiming to be infallible, and insisting that their model is the right one. On the contrary, they all admit fallibility. What is more important is that all Christians around the world believe that the Trinity is a mystery. Those who claim to understand God fully are indirectly claiming to be gods.
CONCLUSION
Though some Western philosophers were not interested in the doctrine of the Trinity because they did not see any value in it for their studies, many other Western philosophers delved into this doctrine to answer their opponents’ objections, especially the claim that the Trinity is not logical. Moreover, explaining this doctrine in the West took a different turn than in the Middle East for different reasons. First, the nature of Western objections was different from Islamic objections. Muslims thought that the Trinity is not logical, but only a few of them provided philosophical reasons for their objections. The majority of them thought the Qur’an provides a different explanation of the Trinity than what Christians are thinking. Early Western Christians, on the other hand, faced philosophical objections to the Trinity, but they did not have to deal with different accounts of the Trinity. All they needed to do was to follow, expand, and defend the patristic creeds.
Modern Western Christians have always enjoyed the freedom of thinking, studying, and debating, a dynamic that has contributed to the development of many arguments. Christians in the Middle East, however, have historically lacked such freedom. Many of them wrote defenses that could not be published for the public. Yaḥya Ibn cAdī, for instance, is not well known in the Middle East among layman Christians, even though he is a well-known philosopher. Most of his writings are circulated in academia among philosophy students, but churches do not discuss his works for different reasons.
This chapter presented different models of the Trinity in the West that scholars think share the idea of orthodoxy. I divided them into philosophical and theological models. The philosophical models are not an attempt to redefine the doctrine of the Trinity. Instead, philosophers exhibit their defense using metaphysical concepts. The scholars claimed fallible and limited knowledge when they spoke about God, but their purpose was to test and expand the orthodox Christian creeds and help others understand the God they worship. These scholars published many other academic papers in Christian journals evaluating and critiquing each other’s models, which gave them the opportunity to strengthen and clarify their arguments even more.
The theological Trinity got tangled with the doctrine of the eternal subordination of the Son; however, it is an attempt to explain the different views about how theologians can understand the relation between the three persons of the Trinity in relation to other doctrines, especially salvation and redemption. Despite the importance of these attempts, I believe the theological Trinity does not have a great apologetic value. Christians may benefit from the dialogue among the different views; however, the differences among the views might confuse non-Christians.
The development of the doctrine of the Trinity in the West has some similarities to the Arabic theological development, but it also has many differences, which makes it hard to classify Arab theologians under one or another model of Western trinitarianism. Many Arab theologians follow the gradational view. They would agree with certain aspects of social trinitarianism, such as starting with threeness before moving to oneness. They are preoccupied with discussing the relationship among the three persons of the Trinity and the unity of the Godhead. They understand the oneness of God to mean one divine being, one Godhead, one virtue, one will, one operation, one principality, one power, one domination, and one kingdom. This explanation seems to be closer to Latin trinitarianism.
Social trinitarians Swinburne and Craig develop their arguments with a contemporary touch. Swinburne focuses on the number of the divine persons and explores the reason behind them being three, no more or less. Craig focuses on the three centers of consciousness in the divine Godhead. Swinburne’s model might be accepted more among Arab scholars than Craig’s model of the mythical creature Cerberus. The main reason is culture. In Arabic culture, Christians do not prefer using myths to refer to God or to metaphysical concepts related to God because Muslims accuse them of being polytheists, reducing Greco-Roman gods to just three. Using a mythical example to refer to any idea related to God will risk the concept of the Trinity and reinforce misconceptions Muslims already have.
The relative identity model, especially van Inwagen’s version, seems to be very promising because first, it is an informative, crosscultural, and highly philosophical example. If readers do not like the example of three dogs in relation to the Trinity (because it might be perceived as demeaning), they can change it to something else or keep the philosophical equations because they are academically neutral. Moreover, the philosophical part of van Inwagen’s model is highly informative. Lay people might fall into the trap of classical identity and think that similarities entail absolute identity. However, explaining that this is not the only option available is a plus. The example that van Inwagen gives about the two people with the same last names but who are two different persons is very helpful. It shows that despite the highly philosophical approach of this argument, minimal Trinity can be illustrated with simple examples of the relative identity theory to prove that having one divine being and three divine persons is not a contradiction.
Numerical identity concerned Latin trinitarians; but Yaḥya, who is hard to classify as one, was concerned with wāḥid in his trinitarian argument as well. However, he took the numerical identity to the route of relative identity. I think he is one of the first philosophers to talk about the relative identity of the Trinity because he was one of the first to suggest that God is one in one sense and multiple in a different sense. Because of his philosophical background, he was able to understand and show that the concept of unity and multiplicity in different senses is not a contradiction.
Understanding this distinction and the different theological approaches is important; however, it is beyond the purpose of this book and the space dedicated in this chapter to explain all the views and mention all the Western theologians and methods. This chapter does not deal with the doctrine of the Trinity in relation to the Catholic church. Most of the scholars mentioned here belong to the evangelical school. If readers would like to learn more about the development of the doctrine of the Trinity, including among Catholics, they can research works by R. P. C. Hanson, Lewis Ayres, Matthew Levering, Gilles Emery, and Johannes Zachhuber.