On Divine Simplicity

“I am that I am.”

Ex. 3:14




God: Pure Act



Order of Contents

Early & Medieval Church  18
Post-Reformation  6
Modern  14+

Encyclopedia Articles  2
Historical Theology  8

Simplicity & Trinity  2
God’s Essence & Existence: Same  4
Divine Persons: Really Distinguished, but not Person & Esssence  3
Manifold Attributes of God in Relation to his One Being & Will  1
Latin  6+



Early Church

Melito – Fragment 14  in ed. Stuart G. Hall, Melito of Sardis on Pascha & Fragments  in Texts & Translations  (Oxford: Clarendon Press, 1979), p. 81

Melito of Sardis (d. 180)

Irenaeus, Against Heresies, bk. 2, ch. 13, sections 3-5  also see bk. 4, ch. 38, section 4  in ANF 1.373-4, 522

Irenaeus (c. 130 – c. 202)

Clement of Alexandria, Stromata4.255.12  in ANF 2.438-9, 462-4

Clement of Alexandria (c. 150 – c. 215)

Origen, On First Principles1.1.6  in ANF 4.243-44

Origen of Alexandria (c. 184 – c. 253)

Lactantius, Divine Institutes1.9  in ANF 7.52-6

Lactantius (c. 250 – c. 325)

Eusebius, The Theophaneia or Divine Manifestation of our Lord & Savior Jesus Christ  trans. Samuel Lee  (Cambridge Univ. Press, 1843), 1.27-29, pp. 17-19

Eusebius of Caesarea (260/265 – 339/340)


Against the Heathen28  in NPNF2 4.18-19

Athanasius (c. 296–298 – 373)

Defense of the Nicene Definition10-11  in NPNF2 4.156-7

To the Bishops of Egypt16  in NPNF2 4.231

Against the Arians4.1  in NPNF2 4.433

Gregory of Nyssa

Answer to Eunomius1.19  in NPNF2 5.56-8

Gregory of Nyssa (c. 335 – c. 395)

Answer to Eunomius’ Second Book, 2  in NPNF5.254-55

Great Catechismch. 1  in NPNF2 5.474-76

Basil the Great – Letter 234, to Amphilochius  in NPNF2 8.274

Basil of Caesarea (330–379)


City of God, 11.10

Augustine (354-430)

On the Trinity, 6.3-8; 15.5.8  in NPNF1 3.99-102, 203

Rufinus – On the Apostles’ Creed4  in NPNF2 3.543-4

Rufinus (344/345–411)



Medieval Church

Aquinas, Thomas

Summa, pt. 1, question 3, ‘On the Simplicity of God (8 Articles)’

Contra the Gentiles, bk. 1, ‘God’, ch. 77, ‘That the Multitude of the Objects of the Will is Not Opposed to the Divine Simplicity’

Compendium of Theology, pt. 1

ch. 9, ‘Simplicity of God’

ch. 24, ‘God’s Simplicity Not Contradicted by the Multiplicity of Names Applied to Him’






Becanus, Martin – ch. 2, ‘On Divine Simplicity’, pt. 12  in Summa Theologiae Scolasticae  (d. 1624; Leiden, 1683),   tr. Michael Lynch

Becanus (1563-1624) was a Romanist Jesuit and professor of theology.

Walaeus, Antonius – ‘On the Simplicity of God’  (d. 1639)

Davenant, John – Question 24, ‘In the Divine Essence there is Neither Diversity of Parts, Nor Anything Contingent or Adventitious’  in The Determinations, or Resolutions of Certain Theological Questions, Publicly Discussed in the University of Cambridge  trans. Josiah Allport  (1634; 1846), pp. 344-350  bound at the end of John Davenant, A Treatise on Justification, or the Disputatio de Justitia...  trans. Josiah Allport  (1631; London, 1846), vol. 2

Leigh, Edward – ch. 6. ‘That God is Great in his Nature, Works, Authority, a Necessary Essence, Independent & Wholly One’  in A System or Body of Divinity…  (London, A.M., 1654), bk. 2, pp. 152-60

Turretin, Francis – Question 7, ‘The Simplicity of God’  in Institutes of Elenctic Theology, ed. James Dennison, Jr., trans. George Musgrave Giger (Phillipsburg, N.J.: Presbyterian & Reformed Publishing Company, 1992-97), vol. 1, 3rd Topic, pp. 191-94

Heidegger, Johannes H. – ‘The Simplicity of God’  from The Marrow of Theology, 3.19-23  5 paragraphs



De Moor, Bernard – Continuous Commentary, ch. 4, ‘On God’ 

23. Arguments for the Simplicity of God: A Priori
23. A Posteriori
23. Against Gentile Polytheism
23. Against Tritheism
23. Against Manichean Dualism
24. Against Socinian Unitarianism
24. Against Composition in God
24. Divine Simplicity Defended against Socinians & Vorstius
24. Divine Simplicity Defended against Remonstrants
25. Against Pantheism
25. Not Composition of God with the Creature






Barrett, Matthew – ‘Divine Simplicity’  (n.d.)  18 paragraphs  at The Gospel Coalition

Rogers, Katherine – ‘The Traditional Doctrine of Divine Simplicity’  in Religious Studies, 32  (1996), pp. 165-86  Abstract

This article is not orthodox, but it will give you a view of the errors that unorthodox persons make on the issue.

Hurd, Ryan – ‘Simplicity & Trinity, Friends or Foes?  An Introduction to Complementary & Misunderstood Doctrines’  in Credo Magazine, vol. 11, issue 1  (2021)

Wagner, Christian B. – ’15 Arguments for Divine Simplicity’  (2022)  at Militant Thomist

This is a helpful, concise article summarizing the main metaphysical arguments of Aquinas for divine simplicity.  Wagner used to run Apologia Anglicana, but converted to Romanism in 2021.




Immink, Frederik Gerrit – Divine Simplicity  Ref  (Kok, 1987)  197 pp.



Muller, Richard – pt. 2, ch. 4.3, ‘Simplicity, Spirituality, Immutability & Related Attributes’  ToC  in Post-Reformation Reformed Dogmatics: the Rise & Development of Reformed Theology, ca. 1520 – ca. 1725, vol. 3, The Divine Essence & Attributes  2nd ed.  (Baker Books, 2003), pp. 271-325

Richards, J. Wesley – The Untamed God: a Philosophical Exploration of Divine Perfection, Immutability & Simplicity  Pre  (IVP Academic, 2003)

Sadler, Mark Davidson – Simply Divine: Simplicity as Fundamental to the Nature of God  Ref  (Southwestern Baptist Theological Seminary, 2004)  474 pp.

Gehring, Allen Stanley – Divine Simplicity as Actus Purus  Ref  (Texas A & M University, 2005)

“This thesis presents a case for the traditional doctrine of divine simplicity by construing it along the lines that God exists as actus purus.  My formulation of divine simplicity draws upon the medieval insight that God is what He is in virtue of what He does in one, eternal act of will with which He is identical.

In chapter I, I survey the contemporary literature on divine simplicity.  In chapter II, I critique Alvin Plantinga’s Platonic theory of the divine attributes…  In chapter III, I provide rejoinders to all of Plantinga’s defeaters against divine simplicity…  In chapter IV, I develop a viable theory of divine simplicity, given an actus purus conception of God, and I formulate a number of arguments supporting it…  As such, I seek to demonstrate that the traditional understanding of the divine essence is something that is worthy for theists to embrace and to explore…”

Dolezal, James E. – God Without Parts: Divine Simplicity & the Metaphysics of God’s Absoluteness  Pre  Buy  (Oregon: Pickwick Publications, 2011)  225 pp.

Duby, Steven J. – Divine Simplicity: a Dogmatic Account  PhD diss.  (Univ. of St. Andrews, 2014)  325 pp.  Here is the pubilshed version of this dissertation:  Divine Simplicity: a Dogmatic Account  in T&T Clark Studies in Systematic Theology, vol. 30  (Bloomsbury, 2010)  260 pp.

“This thesis offers a constructive account of the doctrine of divine simplicity in Christian theology.  In its methodology, the thesis aims to present this divine perfection as an implicate of the scriptural portrayal of God, to draw upon the insights and conceptual resources of Thomas Aquinas and various Reformed orthodox theologians, and to respond to some objections to divine simplicity….  The case for God’s simplicity is made by examining God’s singularity, aseity, immutability, infinity, and act of creation in Holy Scripture and then tracing the ways in which these descriptions of God imply that he is (negatively) not composed of parts.  Rather, he is (positively) actus purus and really identical with his own essence, existence, and attributes, each of which is identical with the whole being of the triune God considered under some aspect.

In light of the constructive work, this study then addresses the three most pressing objections to divine simplicity: (1) that it denigrates God’s revelation of his many attributes in the economy; (2) that it eliminates God’s freedom in creating the world and acting in history; and (3) that it does not cohere with the doctrine of the Trinity.”

Smith, Barry D. – The Oneness & Simplicity of God  Pre  (Pickwick Publications, 2014)

Schubert, Aaron Matthew – The Importance of Divine Simplicity  Ref  (Dallas Theological Seminary, 2014)  76 pp.

“The argument of this thesis is that the explanatory power of the doctrine of divine simplicity has significant ramifications on our understanding of other doctrines of God.  I argue that these ramifications can be seen in four distinct theological areas: the doctrine of divine aseity, the doctrine of divine immutability, God’s relationship with moral goodness, and in perfect being theology.”

Barrett, Jodan P. – Divine Simplicity: a Biblical & Trinitarian Account  Pre  Buy  (Fortress Press, 2017)

“…engages the recent critics and addresses one of their major concerns: that the doctrine of divine simplicity is not a biblical teaching.  By analyzing the use of Scripture by key theologians from the early church to Karl Barth, Barrett finds that divine simplicity developed in order to respond to theological errors (e.g., Eunomianism) and to avoid misreading Scripture.  Through close attention to Scripture, the work also argues that divine simplicity has two biblical roots: the names of God and the indivisible operations of the Trinity ad extra [outside of Himself]…  divine simplicity can be rearticulated by following a formal analogy from the doctrine of the Trinity–the analogia diversitatis (analogy of diversity)–in which the divine attributes are identical to the divine essence but are not identical to each other.”

eds. Joseph Minich & Onsi A. Kamel – The Lord is One: Reclaiming Divine Simplicity  Ref  Buy  (Davenant Press, 2019)  294 pp.

Includes chapters by Steven Duby, Steven Wedgeworth, J. David Moser, David Haines, Joe Rigney et al.

“…this volume presents exegetical, historical, and theological treatments of divine simplicity.  It argues the doctrine of divine simplicity is cogent and indispensable while also making space for historically marginalized or idiosyncratic articulations of it.”

Juliano, Chance – Divine Simplicity as a Necessary Condition for Affirming Creation Ex Nihilo  Ref  (Abilene Christian University, 2019)  83 pp.

“The heart of my argument will be to…  deduce that from such a [historically informed] notion of creation ex nihilo, that a God who creates ex nihilo cannot be composite.”

Platter, Jonathan M. – Divine Simplicity & the Triune Identity: A Critical Dialogue with the Theological Metaphysics of Robert W. Jenson  Pre  Buy  (De Gruyter, 2021)

“This book offers a theological defense of the doctrine of divine simplicity through careful reading of both exemplary historical theologians and Robert W. Jenson, an important American contributor to the trinitarian revival [in scholarly circles].”



Encyclopedia Articles


Stanford Encyclopedia of Philosophy – ‘Divine Simplicity’  82 paragraphs with a bibliography

Internet Encyclopedia of Philosophy, Peter Weigel – ‘Divine Simplicity’  52 paragraphs with a bibliography



Historical Theology

On the Early Church


Hill, W.J. – ‘Simplicity of God’  in New Catholic Encyclopedia, vol. 13  (1967), pp. 229-32

Osborne, Eric – pp. 31-78  of The Beginnings of Christian Philosophy  (Cambridge Univ. Press, 1981)

Stead, Christopher – ‘Divine Simplicity as a Problem for Orthodoxy’  in ed. Rowan D. Williams, The Making of Orthodoxy: Essays in Honor of Henry Chadwick  (Cambridge Univ. Pres, 1989), pp. 255-69

Krivocheine, Basil – ‘Simplicity of the Divine Nature & the Distinctions in God, According to St. Gregory of Nyssa’  in St. Vladimir’s Theological Quarterly, 21/2  (1977), pp. 76-104



Radde-Gallwitz, Andrew – Basil of Caesarea, Gregory of Nyssa & the Transformation of Divine Simplicity  in Oxford Early Christian Studies  Pre  (Oxford Univ. Press, 2009)


On the Medieval Church & the Post-Reformation

Muller, Richard – ‘antepraedicamenta’  in Dictionary of Latin & Greek Theological Terms: Drawn Principally from Protestant Scholastic Theology  1st ed.  (Baker, 1985)


On Anselm

Sadler, Gregory B. – ‘A Perfectly Simple God & Our Complicated Lives’  in The Saint Anselm Journal 6.1 (Fall, 2008)

“The first section of the paper presents five short Anselmian lessons about the divine attribute of simplicity.  The second section then frames and explores the problem.  The third and final section provides an Anselmian resolution to the problem.”


On Aquinas

Twetten, Walter S. – The Doctrine of Divine Simplicity in Thomas Aquinas & a Contemporary Defense  Ref  (Trinity Evangelical Divinity School, 1987)  182 pp.

Hughes, Christopher – On a Complex Theory of a Simple God: an Investigation in Aquinas’ Philosophical Theology  Pre  in Cornell Studies in the Philosophy of Religion  (Cornell Univ. Press, 1989)

Davies, Brian – ‘The Doctrine of Divine Simplicity: Preliminaries’  in The Thought of Thomas Aquinas  (Oxford: Clarendon Press, 1992), pp. 44-57

Dever, Vincent Michael – Divine Simplicity: Aquinas & the Current Debate  Ref  (Marquette University, 1994)

Weigel, Peter

Aquinas on Divine Simplicity: No Simple Matter  Ref  (Yale Univ., 1999)  488 pp.

Aquinas on Simplicity: an Investigation into the Foundations of his Philosophical Theology  Pre  (Peter Lang, 2008)


On the 1800’s

Parker, Jr., Gregory W. – Bavinckian Rhapsody: Herman Bavinck’s Doctrine of Divine Simplicity  ThM thesis  (Gordon-Conwell Theological Seminary, 2018)  96 pp.



On Simplicity & the Trinity


Aquinas, Thomas

Compendium of Theology, pt. 1

ch. 51, ‘A Seeming Contradiction in the Trinity’

ch. 52, ‘Solution of the Difficulty: Distinction in God According to Relations’

ch. 53, ‘Nature of the Relations whereby the Father, the Son & the Holy Spirit are Distinguished’



Samuel Rutherford

A Survey of the Spiritual Antichrist…  (London, 1648), pt. 1, ch. 32, pp. 275-6

“But in that chapter: 1. He [John Saltmarsh, an antinomian] denies the Trinity and makes the three Persons (as Mr. Beacon does, in his Catechisme also pp. 47-51) but manifestations of God.  Thus God be­ing infinitely one, yet in a threefold manifestation (says he) to us of Father, Son and Spirit, etc. a person is not a manifestation, but has need to be manifested to us…”



That God’s Essence & Existence are the Same, & are Only Distinguished Rationally


Muller, Richard

Dictionary of Latin & Greek Theological Terms: Drawn Principally from Protestant Scholastic Theology  1st ed.  (Baker, 1985)

‘essentia Dei’

pt. 2, ch. 4.1, ‘The Essence, Independence & Unity of God’  ToC  in Post-Reformation Reformed Dogmatics: the Rise & Development of Reformed Theology, ca. 1520 – ca. 1725, vol. 3, The Divine Essence & Attributes  2nd ed.  (Baker Books, 2003), pp. 227-46

See especially section B., p. 238.

Wanless, Brandon L. – pp. 72-80 & 84  of ch. 9, ‘Communicability & Incommunicability’  in Universality & the Divine Essence: St. Thomas Aquinas on the Unity Characteristic of the Trinitarian Persons  a Masters thesis  (University of St. Thomas, 2015)


Quote on Why the Divine Essence, which Subsists by Itself, is Not a Person

Geddes, L.W. & W.A. Wallace, “Person (in Philosophy)”  in New Catholic Encyclopedia

“The terms in which St. Thomas explained it [the definition of “person”], however, practically constitute a new definition [from that of Boethius].  “Individual substance” becomes, for him, a substance that is complete, subsists by itself, and is separated from others (Summa theologiae 3a, 16.12 ad 2).  When the remainder of Boethius’s definition is added to this, there are five notes that go to make up a person:

(1) substance—this excludes accident;
(2) complete—the person must have a complete nature, and thus that which is but part of a nature, either actually or aptitudinally, does not satisfy the definition;
(3) subsistent by itself—the person exists in himself and for himself, being the ultimate possessor of his nature and all its acts, and therefore is the ultimate subject of predication of all his attributes;
(4) separated from others—this excludes the universal notion of second substance, which can have no existence apart from the individual; and
(5) of a rational nature—this excludes all supposits that lack rationality.

To the person, therefore, there properly belongs a threefold incommunicability expressed in notes (2), (3), and (4)…  Lastly, the divine essence, though subsisting by itself, is so communicated to the three Persons that it does not exist apart from Them [contra (3) & (4) above]; it is therefore not a person.”



That the Persons of the Trinity are Really (Realiter) Distinguished, but Person & Esssence are Not (They being Distinguished, rather, Modally & Virtually)



Turretin, Francis – 27. ‘Can the divine persons be distinguished from the essence, and from each other, and how?’  in Institutes of Elenctic Theology, tr. George M. Giger, ed. James Dennison Jr.  (1679–1685; P&R, 1992), vol. 1, 3rd Topic, pp. 278-82



Muller, Richard – pt. 2, ch. 3.2, B, ‘Trinitarian Distinctions in the Godhead: Between Essence & Persons–Among the Persons’  in Post-Reformation Reformed Dogmatics: the Rise & Development of Reformed Theology, ca. 1520 – ca. 1725, vol. 4, The Triunity of God  2nd ed.  (Baker Books, 2003), pp. 189-96

1. ‘The Distinction Between Essence & Person–Rational or Modal?’, pp. 189-91

Note that terms are sometimes being used in different senses and ways.  Some of the reformed affirmed that the distinction is both modal and rational, which essentially equates to a virtual distinction.

2. ‘The Distinctions Between the Persons–Modal or Real?’, pp. 191-96

The difference between the distinctions here, modal and real, in their context, are nearly equivelent.  Some of the reformed affirmed modal so that the difference would not be real.  The term ‘mode’ though, does not seem not fully sufficient to describe the Persons of the Trinity.

The reformed who affirmed a real distinction (minor as opposed to major) between the Persons of the Trinity qualified this by asserting that it was not essentialiter, with a difference of essence.  Others defined the distinction as personal, which may be more accurate, but, without further elaboration, seems less informative.

Wanless, Brandon L. – ‘The Identity of the Persons & the Essence in God’, pp. 27-8  in Universality & the Divine Essence: St. Thomas Aquinas on the Unity Characteristic of the Trinitarian Persons  a Masters thesis  (University of St. Thomas, 2015)



On the Manifold Attributes of God in Relation to his One, Simple, Being & Will

Owen, John – pp. 90 (#16) – 91  in Exercitation 28  in An Exposition of the Epistle to the Hebrews…  vol. 2  ed. W.H. Goold  in Works  (Edinburgh: T&T Clark, 1862), vol. 19, Preliminary Exercitations



Latin Articles


Lombard – Sententiae in IV libris…  1, d. 8, chs. 5-8

Alexander Hales – Summa Theologica, part 1, inq. 1, tract 1, question 3, chs. 1-3

Bonaventure – In Sentent…  1, question 8  in Opera Omnia  (Quaracchi: Collegium S. Bonaventurae, 1882-1902), vol. 1

Duns Scotus, Ordinatio, 1, d. 8, q. 1

Ockham – In Sent…  1, d. 8, question 1  in Opera Philosophica et Theologica



Zanchi, Jerome – Of the Nature of God, or of the Divine Attributes, in 5 Books (Heidelberg, 1577)

Bk. 1, 8. ‘Whether so many various names which are spoken of God, may so far conflict with his unity & simplicity?’

Book 2, 2. ‘Of the Simplicity of God’

Zanchi (1516-1590) was an Italian, protestant Reformation clergyman and educator who influenced the development of Reformed theology during the years following John Calvin’s death.



Voet, Gisbert – Select Theological Disputations  (Utrecht: Waesberg, 1648), vol. 1

vol. 1, 13. ‘Of the One & Most Simple Essence of God’, pp. 226-46

vol. 4, p. 749  in 50. ‘A Disputation: Some Miscellaneous Positions’



Holtzfus, Barthold – 4. ‘Of the Unity, Simplicity, Spirituality, Invisibility & Ineffigability of God’  in A Theological Tract on God, Attributes & the Divine Decrees, Three Academic Dissertations  (1707), p. 30 ff.

Holtzfus (1659-1717) was a reformed professor of philosophy and theology at Frankfurt.




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