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[Common Places] Pro-Nicene Theology: Divine Simplicity

Categories Theology Common Places


Our current series, Pro-Nicene Theology, offers doctrinal and exegetical entries to the key tenets of basic Trinitarian orthodoxy as developed in the early centuries of the church. For introduction to the series, see this first post.

A mainstay of catholic Christian teaching, the doctrine of divine simplicity has recently become a much debated topic in contemporary dogmatics and philosophical theology. Despite its historical importance and constructive fecundity, it is still often misunderstood today and merits careful attention as the relevant literature continues to grow. For many, simplicity remains, in the words of Alvin Plantinga, a “dark saying indeed,”[1] so in this post I aim to offer a brief dogmatic description of divine simplicity and to suggest some of the ways in which it explicates and enriches a Christian understanding of the triune God and his work in the world.

Simplicity indicates that God is (negatively) not composed of parts and (positively) really identical with his essence, existence, and attributes. Linking up with the doctrine of the Trinity, it stresses that the divine persons are not “parts” composing a greater divine whole but are, instead, three personal modes of subsisting of the simple divine essence. Various authors throughout the Christian tradition delineate different kinds of parts found in the created order, including integral or quantitative parts, essential parts (matter and form), metaphysical parts (act and potency, nature and suppositum, substance and accidents, and essence and existence) and logical parts (genus and species). Such parts cannot be found in God especially in light of his aseity: as the one who enjoys fullness of life in himself and is the Creator and provider of all that is other than himself (John 1:1-4; 5:26; Acts 17:24-25), he is not dependent on anything distinct from himself to be what he is, and he need not and cannot be composed by anyone or anything more ultimate than he is. He is “pure act,” with no unrealized or idle potency awaiting fulfillment. He is his own deity, having no nature distinct from himself that might constitute his being. He is each of his own attributes, for to be God just is to be infinitely wise, infinitely good, and so on. In us, wisdom, justice, goodness, and the like are qualities adjoined to our human nature; in God, his wisdom, justice, and goodness simply are his nature. He is his own existence, with no need to participate (like creatures do) in a being above himself. Put differently, God is subsisting being itself (ipsum esse subsistens). Crucially, though, this does not render God impersonal but in fact accomplishes quite the opposite: it confirms that there is no impersonal esse “out there” that governs the life of God and creatures alike, and it underscores that the only ultimate esse just is the personal triune God revealed to us in Holy Scripture.

Because it is commonly suspected today that divine simplicity does not cohere with the doctrine of the Trinity, it must be emphasized that it was never meant to eliminate all kinds of distinction in God. Above all, it negates any “real” distinction in God, or any distinction between one “thing” (Latin, res) and another in God. However, it embraces modal and relative distinctions in God, which are critical to a responsible articulation of the Trinity. In the context of a doctrine of God shaped by God’s simplicity, the Father, Son, and Spirit are distinct in relation to one another and as one mode of subsisting from another. This is not to be confused with modalism, for the persons are not serial ad extra iterations of one immanent mode of subsisting but are in fact three immanently, eternally distinct personal modes of subsisting in God’s one essence. Rather than compromising trinitarian teaching, divine simplicity and the prioritization of the modal and relative distinctions enable us to see that the persons are not three individual deities within a species of deity and are instead both distinct and co-equal, each being a subsisting mode of all that is included in the singular Godhead.

It is worth noting that this description of simplicity is indebted particularly to Thomas Aquinas and a number of early Reformed expositions of the doctrine.[2] We should therefore bear in mind that there are multiple expressions of divine simplicity in the Christian tradition. The Cappadocians, John of Damascus, Gregory Palamas, and Duns Scotus, for example, all would handle certain features of the doctrine in different ways. In addition, in a series on pro-Nicene theology, we should remember that, while patristic theology yielded excellent material for later scholastic discussion, the fathers did not operate with all the concepts and distinctions developed in the medieval and early modern periods. Yet, divine simplicity was deployed to great effect by the fathers in combating problematic construals of God’s relationship to the world and of God’s triune relations within himself. Athanasius, for example, displays the aseity of the true God over against pagan deities by affirming that he is not one part of a whole dependent on others, nor even the sum of all the parts of the universe. He is not composed of dissimilar elements but is the one who created these and set them in their cosmic order.[3] In describing God in himself, Athanasius argues that the Father and Son are not parts in God. The Son shares the one Godhead of the Father and is distinct from him as the Son but not as God. Significantly, it is the Arians who violate God’s unity and simplicity in claiming that the Son is a deity by possession of a Godhead other than that of the Father.[4]

What are some of the ways in which the doctrine of divine simplicity further illumines biblical teaching on God and God’s works? We could highlight many but will have to be content to mention two here. First, simplicity helps us to coordinate the incomprehensibility and the knowability of God. On the one hand, since all that is in God is God, whatever is known of God is ultimately incomprehensible. When we apprehend God’s eternity, his holiness, his triune existence as Father, Son and Spirit, we are reminded that these are not discrete traits of God subject to the command of the human intellect. Instead, each really is God’s whole being and is thus, in John of Damascus’ words, a “sea of essence infinite and unseen.”[5] On the other hand, God’s simplicity implies that whenever we apprehend the truth of God, we apprehend God himself. To be sure, we never grasp God’s essence as such and in its fullness, but, in knowing in a limited way God’s love, beatitude, and so on, we know that which is included in God’s own essence. Second, as Hilary of Poitiers discerns, given his simplicity, wherever God is—and he is everywhere—he is there in the indivisible fullness of his being.[6] This is a profoundly encouraging implication for the people of God whose daily sustenance is the gracious activity of God in the world and in the church. While no creaturely place or field of divine action can contain God’s simple essence, he is present and active among us in all his indefatigable wholeness, and we need not wonder whether God meets us as he truly is, even as we do not understand all his ways. These reflections hardly begin to draw out the bearing of God’s simplicity on the practice of theology and the life of the church, but it is to be hoped that future work on this will be undertaken based on scriptural exegesis and in dialogue with the fathers and later doctors of the church for the enrichment of Christian thought and worship.


Steven J. Duby (PhD, University of St. Andrews) is a member of the faculty at Grand Canyon University. He is the author of Divine Simplicity: A Dogmatic Account (T & T Clark Studies in Systematic Theology, 2016).


Common Places is a regular column on the Zondervan Academic blog with a focus on systematic theology. The loci communes or “common places” of Christian theology, drawn out of the Scriptures and organized in a manner suitable to their exposition in the church and the academy, have functioned historically as common points of reference for theological discussion and debate. This column will focus upon the classical loci of systematic theology, not as occasions for revision, but as opportunities for entering into the ongoing conversation that is Christian systematic theology. We invite you to join and dialog with us on the first and third Thursdays of every month. For more about Common Places, read the column introduction.

Our current series, Pro-Nicene Theology, offers doctrinal and exegetical entries to the key tenets of basic Trinitarian orthodoxy as developed in the early centuries of the church.

Michael Allen and Scott Swain, editors


[1] Does God Have a Nature?, pp. 27-8.

[2] For the essential components (no pun intended) of Thomas’ view, see Summa Theologiae, Ia.3.

[3] See Contra Gentes, 28.

[4] See the third oration of Contra Arianos (esp. 23.4-6 and 25.15-16 in vol. 4 of NPNF Second Series).

[5] Expositio Fidei, I.9.

[6] De Trinitate, II.6.

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