Three Persons, One Essence, & Simplicity
Question #11: How does the Church’s Trinitarian dogma–three distinct persons, one divine essence (CCC 249–256)–square with the claim of divine simplicity that “all that is in God is God”? This is a central question for me so I’m going to go a little longer than usual for this one.
A core affirmation of Catholic Trinitarian dogma, succinctly stated in CCC 249–256, is that the Father, Son, and Holy Spirit are three really distinct Persons sharing one undivided divine essence. On the surface, this may seem to clash with the principle of divine simplicity, which states that God has no composition–indeed, “all that is in God is God” (a phrase often traced back to fourth-century and later scholastic formulations). However, the Church reconciles these teachings by understanding the Trinitarian distinctions not as “parts” of God but as real, subsistent relations within the one, simple divine being.
1. Persons as Relations, Not Parts
In Catholic theology, the three divine Persons are not separate “entities” or distinct “parts” of the divine essence. Rather, they are “subsistent relations” (drawing on St. Thomas Aquinas’s terminology), meaning each Person is the one divine substance fully possessed in a unique relational mode. The Father, for example, is unbegotten, the Son is begotten of the Father, and the Spirit proceeds from the Father (and the Son, in Western tradition)–but these relations are internal and do not divide God’s essence. They mark how the one essence is “lived” or “expressed,” rather than multiplying parts within it.
2. No Composition from Relations
Because the essence and the relations in God are identical to God, the distinct Persons do not introduce composition. In other words, these relations are not “accidental attributes” added onto a core divine substance; they simply are the way in which God’s essence subsists in three relational modes. As Aquinas puts it, God’s essence is not partitioned by the distinctions of origin. Hence, “all that is in God is God” still holds: each Person is God entirely, without remainder.
3. Relational Distinctions Preserve Simplicity
The Church emphasizes that divine simplicity (no parts, no composition) and Trinitarian distinction (Father, Son, Holy Spirit) operate on two different planes of explanation. Simplicity addresses God’s lack of metaphysical composition, while Trinitarian doctrine addresses the eternal relational identities that wholly express the same nature. The real distinction among Father, Son, and Spirit arises from relational opposition–who is begetting, who is begotten, and who proceeds–without introducing anything extraneous into God’s being.
4. Unity of Essence, Plurality of Persons
Finally, “all that is in God is God” highlights that each Person is fully the one God; there is no “division” that carves God into three partial shares. Instead, the three Persons share the same undivided essence, so they are one God in three irreducible relations. This teaching, consistently upheld in Catholic tradition, preserves genuine distinction at the personal level while upholding the total simplicity and oneness of God’s essence. Thus, the Church’s Trinitarian dogma and divine simplicity remain in harmony: no parts in God, yet three fully distinct relational modes of the one divine nature.
I personally have dedicated significant research to exploring how divine simplicity and the Trinitarian doctrine–often seen as two potentially conflicting notions–can be reconciled through a relational perspective. In my work, I propose what I call the Self-Standing Givenness Theory (SSGO), which draws on the insight of Professor Jiri Benovsky that we can treat relational distinctions as metaphysical primitives. These primitives, rather than introducing extra “parts” into God, do the explanatory work of showing how three real Persons (Father, Son, and Holy Spirit) can each fully possess the one, simple divine essence without dividing it.
Below is a concise outline of the argument I develop in SSGO:
1. Absolute Simplicity
• Premise 1: According to classical Catholic theology, God is absolutely simple–no composition of parts, attributes, or unrealized potentials.
• Reasoning: If God had internal “parts,” He would be subject to potential change or dependency, contradicting the notion of actus purus (pure act).
2. Real Trinitarian Distinctions
• Premise 2: Father, Son, and Holy Spirit must be truly distinct Persons, not mere roles or modes of appearance.
• Reasoning: Scriptural and doctrinal sources (e.g., Nicene Creed) affirm that the three divine Persons are co-equal, co-eternal, and not reducible to one another.
3. No Composition in God
• Premise 3: Because God is simple, any real distinction cannot be the result of adding or subtracting “components” in the divine essence.
• Reasoning: If distinctions were “parts,” that would negate absolute simplicity. We need a way to have distinctions without composition.
4. Relational Modes as Primitives
• Premise 4: Distinctions in God can be understood as self-standing relational modes of the one essence, rather than as separate entities.
• Reasoning: Drawing on Benovsky’s notion of metaphysical primitives, SSGO posits that each Person is the one essence fully expressed through a unique, irreducible relational identity (begetting, begotten, proceeding).
5. No Additional “Parts” Introduced
• Premise 5: These relational modes do not fragment God; they describe how the same essence is “lived” or “expressed” through distinct, subsistent relations.
• Reasoning: Thus, relational identity provides genuine distinction (Father ≠ Son ≠ Spirit) without composition or partitioning.
Conclusion:
Because the Father, Son, and Holy Spirit are self-standing ways of fully realizing the one divine essence, SSGO resolves the apparent contradiction between Trinitarian plurality and divine simplicity. It demonstrates how a single, simple essence can be expressed in distinct, irreducible relational modes–each Person being wholly God–without compromising God’s oneness or compositional unity.
For a more thorough explanation of these points, including references to Benovsky’s work and my own discussion of how this theory relates to Catholic theological tradition, feel free to visit my website, [robertdryer.com](https://robertdryer.com), where I delve into SSGO in greater depth.
(see #1, #12, #13, #14 for more)