D.A. Carson observed at the 2010 NEXT conference that evangelicals tend to be relatively weak in the area of theology proper, or the doctrine of God. One aspect of the doctrine of God that has been a hallmark of patristic, medieval, and reformed thought, and yet tends to receive less attention today, is the doctrine of divine simplicity. Richard Muller has observed, “the doctrine of divine simplicity is among the normative assumptions of theology from the time of the church fathers, to the age of the great medieval scholastic systems, to the era of Reformation and post-Reformation theology, and indeed, on into the succeeding era of late orthodoxy and rationalism.” This post is a brief primer on the doctrine of divine simplicity, encouraging evangelicals to give greater attention to this part of our theological heritage.
What is divine simplicity?
Divine simplicity means that God is without parts, but utterly one and indivisible. Its opposite is not complex, but composite. In its strongest and most common version, what is sometimes called the identity thesis, divine simplicity means that God is identical with his attributes. Thus, God is not merely loving and righteous, but Love and Righteousness. God is what He has, and there is nothing within Him that is not wholly identical to Him.
Why is divine simplicity important?
Historically, divine simplicity has been used to protect other important components of the doctrine of God, especially divine aseity (that God exists through Himself) and divine immutability (that God cannot fundamentally change). If God merely instantiated or exemplified his attributes, then in some sense they would exist independently of Him, and God would not be utterly absolute and self-conditioned. He would instead be dependent on something outside of Himself. As Paul Helm puts it,
“In being the Creator, and not a creature, or creaturely, God does not depend for his existence on operations or forces working upon him. He is not fashioned or the product of parts forming themselves into a unity in an arbitrary fashion. He is necessary, self-existing. This means, for example, that God is not composed of elements that are more ultimate, in a logical or metaphysical sense, than he himself is. It is by attention to such considerations that the doctrine of simplicity has been developed.”
How is divine simplicity viewed today?
Since the publication of Alvin Plantinga’s Does God Have a Nature? in 1980, there has been a surge of critical treatments divine simplicity, both within and without evangelicalism. Some of the most common argument against divine simplicity include: (1) abstract properties cannot be identified with a concrete, personal God; (2) if God is identical to his properties, his properties are all identical to each other; (3) a simple God must either have only one property, or be a property, or both; (4) it is impossible to predicate diverse attributes of a simple God; (5) divine simplicity makes God unknowable; (6) divine simplicity denies God’s freedom; (7) divine simplicity is unbiblical; (8) divine simplicity is at odds with the doctrine of the Trinity. Increasingly, evangelicals are finding divine simplicity to be incoherent, unbiblical, and/or simply bizarre, despite its long standing in the thought and worship of the church.
What is at the root of the different treatments of divine simplicity by classical and contemporary Christians? Why do they tend to approach this doctrine differently?
James Dolezal claims that the common thread throughout the various criticisms of DDS is the assumption of a univocal relationship between God and creation, rather than an analogical relationship. In other words, the coherence of divine simplicity turns on a larger question: how are God and creation related? Differences between contemporary and classical thinkers on divine simplicity all too often boil down to differences on this more basic, ontological question.
A simple way to state the difference is this: much contemporary discussion of divine simplicity tends to approach God within a larger structure called reality, while its discussion in classical theology tended to approach reality itself as subsisting within the being of God. For classical theologians, God was not simply one existing thing among others, but utterly unique and transcendent. Classical theologians did not conceive of God and creation as two different items within the same genus or rank, and or even two different kinds of genus or rank, for the very potential for distinction between different kinds of reality was itself grounded in the being of God. For classical theology, God was not so much an existing thing as the ground of existence itself. Anselm, for example, prayed, “You, although nothing exists without you, do not exist in a place or a time; rather, all things exist in you. For nothing contains you, but you contain all things.” Or as John of Damascus put it, “[God] is not one of the things that are, but over all things.”
How does divine simplicity relate to the doctrine of the Trinity?
Divine simplicity is meant to exclude divisions, but not distinctions, in the being of God. As Herman Bavinck explains, “nor is simplicity inconsistent with the doctrine of the Trinity, for the term simple is not an antonym of ‘twofold’ or ‘threefold’ but of ‘composite.’ God is not composed of three persons, nor is each person composed of the being and attributes of that person, but the one uncompounded (simple) being of God exists in three persons.”
In recent years it is has become common to employ the notion of perichoresis – which means the interpenetration or mutual indwelling of the divine persons – to ground Trinitarianism within monotheism. Jurgen Moltmann’s influential social Trinitarianism, for instance, goes this route: “the unity of the triunity lies in the eternal perichoresis of the Trinitarian persons.” Though some theologians in church history used perichoresis in this way, the far more common approach was to use divine simplicity to ground the Trinity as monotheistic. Augustine, for example, repeatedly makes this move in his De Trinitate. A simple and compact expression of the reasoning can be found in this sentence from Basil the Great: “since the divine nature is not composed of parts, union of the persons is accomplished by partaking of the whole.” Countless patristic and medieval theologians, both East and West, made some version of this argument.
Perhaps the reason most theologians throughout church history have felt the need to use divine simplicity, not just perichoresis, to ground the Trinity as monotheistic is that they wanted to bind the three persons, not merely into each other, but into the one divine essence. Strictly on the grounds of interpenetration, we are left to further explain why the interpenetration of the Father, the Son, and the Spirit does not entail three interpenetrating gods. Why should interpenetration or mutual indwelling yield a unity, rather than some complex aggregate? What is needed is not simply a mechanism by which to bring the divine persons into proximity with each other in the “circulation of the divine life,” but a mechanism by which to unite the divine persons as one. Where perichoresis may make oneness among the three persons possible, divine simplicity makes it necessary.
What are some good resources to learn more about divine simplicity?
Let me recommend one contemporary book and two classics.
1) James E. Dolezal, God Without Parts: Divine Simplicity and the Metaphysics of God’s Absoluteness (Eugene: Pickwick, 2011).
This is perhaps the single best recent defense of divine simplicity on the market. Dolezal has an excellent overview of the historical reception of this doctrine in chapter 1, and his philosophical and theological analysis in the subsequent chapters is superb. He defends the strongest version of divine simplicity, tackling all of the objections listed above, and demonstrating the importance of this doctrine for the life of the church.
2) Thomas Aquinas, Summa Theologica, First Part, Question 1, Part 3.
Right after his famous “five ways” for proving the existence of God in ST I, Q 1, P 2, Thomas opens his treatment of God’s nature by expounding divine simplicity. Divine simplicity is foundational to Thomas’ theology, and his treatment of it is perhaps the most sophisticated in church history. Certainly it is the most influential. Many evangelicals have a caricatured understanding of Thomas because they have never read him. Dipping into the first three chapters of Summa Theologica, First Part, Question 1, would be a healthy and broadening experience, and it wouldn’t even take much time.
3) John of Damascus, An Exact Exposition of the Orthodox Faith, especially chapters 9-10
John of Damascus (sometimes called the final Father) was a 7th century Eastern theologian, often recognized for his role in the iconoclast controversy. John’s On the Orthodox Faith makes great use of the doctrine of divine simplicity. If Aquinas represents the zenith of the doctrinal development of divine simplicity in the West, John draws together the best of the earlier Eastern tradition. John follows earlier Eastern theologians (especially the Cappadocian Fathers) in opting for a weaker version of divine simplicity, which denied any physical or metaphysical composition in God, but did not explicitly identify God with his attributes. John’s On the Orthodox Faith is well worth a read for its clear exposition of this doctrine, and more generally for its value as an entrance into early Eastern Christian thought, a world often unexplored by evangelicals.
 Richard Muller, Post-Reformation Reformed Dogmatics: The Rise and Development of Reformed Orthodoxy, ca 1520. to ca. 1725, vol. 3 (Grand Rapids: Baker, 2003), 39.
 Paul Helm, Foreword to James E. Dolezal, God Without Parts: Divine Simplicity and the Metaphysics of God’s Absoluteness (Eugene: Pickwick, 2011), xii.
 Alvin Plantinga, Does God Have a Nature? (1980; reprinted, Milwaukee, Marquette University Press, 2007).
 John S. Feinberg, No One Like Him: The Doctrine of God (Wheaton, IL: Crossway, 2001), 330-335; Christopher Stead, Divine Substance (Oxford: Clarendon Press, 1977), 180-9.
 Richard M. Gale, On the Nature and Existence of God (Cambridge: Cambridge University Press, 1991) 24.
 Plantinga, Does God Have a Nature?, 47.
 Thomas Morris, Our Idea of God: An Introduction to Philosophical Theology (Notre Dame: University of Notre Dame Press, 1991), 117.
 Ronald H. Nash, The Concept of God: An Exploration of Contemporary Difficulties with the Attributes of God (Grand Rapids: Zondervan, 1983), 85.
 The discussion of Eleonore Stump, Aquinas (New York: Routledge, 2003), 100-127, is particularly helpful on this point.
 J.P. Moreland and William Lane Craig, Philosophical Foundations for a Christian Worldview (Downers Grove, IL: InterVarsity, 2003), 524.
 Christopher Hughes, On a Complex Theory of a Simple God: An Investigation in Aquinas’ Philosophical Theology (Ithica: Cornell University Press, 1989), 153-186, provides a good overview and response to this argument.
 Dolezal, God Without Parts, xvii-xviii, 29-30.
 Anselm, Proslogion 19, in Thomas Williams, Anselm: Basic Writings (Indianopolis: Hackett, 2007), 92.
 John of Damascus, On the Orthodox Faith 1.12 (Nicene and Post-Nicene Fathers, Second Series: Hilary of Poitiers, John of Damascus, 14 vols., ed. Philip Schaff, Henry Wace, vol. 9 [Peabody: Hendrickson, 1899, reprint, 2012]), 14.
 Herman Bavinck, Reformed Dogmatics, vol. 2, God and Creation, trans. John Vriend (Grand Rapids: Baker Academic, 2004), 149.
 Jurgen Moltmann, The Trinity and the Kingdom (reprint; Minneapolis: Fortress Press, 1993), 175.
 St. Basil the Great, On the Holy Spirit 18.23, trans. David Anderson (Popular Patristics Series; Yonkers, New York: St. Vladimir’s Press, 1980), 72.