Substance

Substance is Aristotle’s most basic category of being: a self-subsisting thing that exists in its own right and underlies its attributes, as distinct from an accident, which exists only by inhering in something else.¹ Theology inherited the term and applied it, often alongside essence, to what is one in God, the Father, Son, and Holy Spirit sharing “one substance,” and, in Christology, to what is two, Christ’s undivided divine and human natures.² Applied to God himself, though, the term runs into its own definition: God has no accidents for a substance to underlie.³

Confessional Definition

The 1689 Second London Baptist Confession states that “there are three subsistences, the Father, the Word or Son, and Holy Spirit, of one substance, power, and eternity, each having the whole divine essence, yet the essence undivided.”² “Substance” here functions the way ousia does in the Nicene formula, naming the one, shared divine reality rather than Aristotle’s individual, accident-bearing subject; the confession is not calling God a substance in the strict philosophical sense so much as inheriting a piece of settled Trinitarian vocabulary.

Historical Development

Aristotle’s category of substance

Aristotle’s Categories sorts everything that exists into ten kinds or modes of being, substance foremost among them, alongside quantity, quality, and the rest; his Metaphysics makes substance the primary sense of “being,” so that the other categories (accidents, genus and species, whole and part) all get their own being only by reference to some substance.⁴ Aristotle went further still: reflecting on the world’s eternal motion, he argued that some eternal, immaterial, immutable substance must exist as its cause, and identified this first substance with God, so that “first philosophy” shaded into theology on Aristotle’s own terms, well before any Christian took up his vocabulary.⁵

Substance, accident, and divine simplicity

Patristic and medieval theologians who did take up that vocabulary immediately grew cautious about it. Augustine held that substantia is “properly applied to things that function as subjects in which other things exist,” something that “subsists under accidents” and is therefore “composite and changeable”; calling God’s substantia anything other than his own goodness, as though goodness were a quality added to his essence, would be “wickedness,” so Augustine preferred essentia for God and judged that substantia, if used of God at all, could only be used “improperly.”³ Boethius pressed the same worry further: of all the categories, substance is the most obvious candidate for describing God, yet in God’s case it “is not truly substance but beyond substance” (ultra substantiam), since God, unlike every other substance, has no matter, is his own form and essence, and so has no accidents either.⁶ John of Damascus defined substance, against accident, as “a self-subsisting thing not needing another for constitution,” the very “subject of those things that must inhere in another in order to exist”; yet God, he held, is not one of the “common beings” that exist this way at all, but is “above substance,” or “super-essential,” precisely because he is “essence itself,” the source of existence for everything else rather than one more instance of it.¹ Peter Lombard’s Sentences later carried the same Augustinian judgment into the standard medieval theology textbook: the Aristotelian categories generally “do not convene with the nature of God, which is subject to no accidents.”⁷

A modern debate over the fathers’ own categories

By the Cappadocian fathers’ time, ousia (essence, one) and hypostasis (person, three) had settled into the fixed Trinitarian pairing that resolved essence’s earlier terminological instability. Some modern historians nonetheless read the Cappadocians’ one-ousia-three- hypostases grammar through an Aristotelian “primary-secondary substance ontology,” and contrast it with Augustine’s own, more explicitly substance-based starting point in the West.⁸ Robert Letham describes how “the traditional emphasis on an abstract property or substance, or a divine essence, standing under God has come under scrutiny in recent Trinitarian studies,” warning that it can make God sound like “an isolated, solitary individual.”⁸ John Zizioulas presses a version of the same critique, arguing that the Cappadocian East began with the three persons and only then arrived at their unity, the reverse of Augustine’s own order, a starting point Zizioulas reads as avoiding the risk of reducing the Trinity to what other theologians in this debate have called “an arithmetic problem.”⁹ This is a methodological dispute over how to characterize the fathers’ own categories, not a live confessional disagreement.

Scholastic substance and accident: the Eucharist

Medieval scholastic theology put the substance/accident distinction to a further use beyond the Trinity and Christology, applying it to the Lord’s Supper. The Council of Trent defined transubstantiation as “a change of the whole substance of the bread into the substance of the body of Christ our Lord and of the whole substance of the wine into the substance of his blood,” while the bread and wine’s outward accidents, “quality and quantity,” remain unchanged.¹⁰ On this account a consecrated host is, in its accidents, still bread, but in its substance, the body of Christ. Louis Markos argues that this application of Aristotle’s own categories sits in tension with Aristotle’s own law of noncontradiction, since it treats the consecrated bread as bread and not-bread at once.¹⁰

Opposing Views

Roman Catholic transubstantiation. Rome teaches that the whole substance of the bread becomes Christ’s body and the whole substance of the wine his blood at the priest’s consecration, with only the accidents, the outward appearance, of bread and wine remaining.¹¹

Objections and Responses

If Augustine, Boethius, and John of Damascus all warned against calling God a “substance,” why does the confession itself say the three persons are “of one substance”? Because the confession’s “substance” plays the role ousia plays in the Nicene formula: naming the one shared divine reality all three persons possess in full, not Aristotle’s individual, accident-bearing subject the patristic writers were warning against.² Their caution concerned a narrower claim: that God is a “substance” in Aristotle’s technical sense, a subject that has accidents inhering in it. God has none, so that specific sense does not apply to him, even though the confession still uses “substance” as settled Trinitarian vocabulary.¹

If substance is defined as a subject that bears accidents, doesn’t calling the divine essence a “substance” commit theology to accidents in God, against divine simplicity? No; this is the same problem the patristic writers already answered by qualifying, not abandoning, the term. Boethius held that God is “beyond substance” precisely because he lacks the matter and accidents ordinary substances have, and John of Damascus called God “super-essential” for the same reason.⁶ Reformed theology inherited that qualification along with the vocabulary itself: calling the divine essence one “substance” states that Father, Son, and Spirit share one undivided reality, not that this reality is a subject bearing separable attributes.²

Related Doctrines

References

Steven J. Duby, God in Himself: Scripture, Metaphysics, and the Task of Christian Theology, Studies in Christian Doctrine and Scripture (Downers Grove, IL: IVP Academic, 2019), chap. 4, “Theology and Metaphysics Revisited,” 201, summarizing John of Damascus’s definition of substance (οὐσία) against accident (συμβεβηκός). ↩ ↩² ↩³
The Second London Baptist Confession of Faith (1689), chap. 2, “Of God and of the Holy Trinity,” para. 3. ↩ ↩² ↩³ ↩⁴
Duby, chap. 4, 200, summarizing Augustine. ↩ ↩²
Duby, chap. 4, 198. ↩
Duby, chap. 4, 198-199. ↩
Duby, chap. 4, 200-201, summarizing Boethius. ↩ ↩²
Duby, chap. 4, 201-202, summarizing Peter Lombard’s Sentences. ↩
Keith Wesley Goad, “East and West Compared,” in “Trinitarian Grammars: A Comparison of Gregory of Nazianzus and Some Contemporary Models” (PhD diss., The Southern Baptist Theological Seminary, 2010), 173, quoting Robert Letham, The Holy Trinity: In Scripture, History, Theology, and Worship (Phillipsburg, NJ: P&R, 2004), 184. ↩ ↩²
Goad, “East and West Compared,” 173-174. ↩
Louis Markos, From Aristotle to Christ: How Aristotelian Thought Clarified the Christian Faith (Downers Grove, IL: IVP Academic, 2024), “Preface: A Platonist Learns to Love Aristotle,” quoting the Council of Trent’s definition of transubstantiation. ↩ ↩²
Archibald Alexander Hodge, Outlines of Theology (New York: Robert Carter and Brothers, 1879), 637. ↩