9. The Hypostatic Union and Unity of Person in Christ

Subscribe in Podcast App | Download Transcript

Lecture Notes

Main Topics #

The Hypostatic Union #

• The union of divine and human natures in Christ occurs in the person (hypostasis/suppositum), not in the nature
• This is called the “hypostatic union”—one person subsisting in two natures
• The two natures remain entirely distinct and unmixed after the union

Linguistic Precision and Heretical Dangers #

• Hypostasis (Greek ὑπόστασις): etymologically means “that which stands under”; properly names something subsisting in the genus of substance
• Suppositum (Latin): equivalent to hypostasis; the underlying individual substance
• Person: individual substance of a rational nature (Boethius’s definition)
• Confusing these terms historically led to Nestorian and semi-Nestorian heresies
• The distinction between alius/alium (masculine/neuter forms indicating personal vs. substantial distinction) is critical
• Custom usage of hypostasis in Greek theology sometimes conflates it with “person,” creating confusion in translation and doctrine

The Problem with Two Hypostases #

• If Christ’s human nature has its own hypostasis, it would have its own person (since hypostasis of rational nature = person)
• This would make Christ two persons—falling into Nestorianism
• Condemned by Council of Ephesus and Fifth Council (Second Constantinople)
• The Anathematism from these councils: if anyone introduces two subsistences or two persons in Christ, they are anathema

Operations and Properties Follow the Hypostasis #

• Only to the hypostasis can operations and properties of nature be attributed in the concrete
• Example: “This man reasons,” “This man is capable of laughter”
• If Christ had a separate human hypostasis, then some things could be predicated of the man Christ but not the Word (and vice versa)
• This would falsify: “God died for us” (Cyril’s anathema against Nestorius)

Key Arguments #

Article 3: Whether the Union Was Made in the Suppositum/Hypostasis #

Objection 1 - The Alius/Aliud Problem

• Alius and alius (masculine forms) indicate personal distinction (used in Trinity)
• Aliud and aliud (neuter forms) indicate substantial/essential distinction
• The objection argues that if the divine and human are aliud et aliud, they must be two suppositums
• Thomas’s Reply: The distinction between alius and aliud applies to created things regarding essential differences, but composition in created things cannot give the same thing two subsisting natures. In Christ, aliud et aliud signifies diversity of natures, not of suppositum. This follows Gregory Nazianzen: “Aliud et aliud are those from which the Savior is, but not alius et alius.”

Objection 2 - Another Substance in Christ Besides the Word’s

• Hypostasis is particular/individual substance (Boethius)
• Christ’s body, soul, and their composition seem to constitute another substance besides the divine Word’s hypostasis
• Thomas’s Reply: Hypostasis signifies particular substance not simply, but insofar as it is in completion. A hand is individual substance but not a hypostasis because it exists in something more complete. Human nature in Christ exists in the more complete divine person, so cannot be called a hypostasis or suppositum per se.

Objection 3 - Christ Under the Human Species

• The Word’s hypostasis is not contained in any genus or species (divine simplicity)
• But Christ as man is contained under the human species
• Therefore, there must be another hypostasis in Christ besides the Word’s
• Thomas’s Reply: A singular thing is placed in genus or species by reason of its nature, not by its individuating principle. Christ is in the human species by reason of his human nature assumed, not by reason of hypostasis.

Article 4: Whether Christ’s Person is Composite #

The Three Objections Against Composition

1. Simplicity Objection: Person = hypostasis of the Word; Word’s nature is simple; therefore person is simple. How can person be composed?

   • Reply: Person can be considered two ways: (1) in itself—absolutely simple like the Word’s being; (2) according to the ratio (meaning) of person as subsisting in nature—in this sense, composite

2. Parts Objection: Composition implies parts; divine nature cannot be a part (every part is imperfect); therefore no composition

   • Reply: This composition is not from parts but by reason of subsisting in two natures. Similar to how animal is composed of soul and body, yet neither soul nor body alone is an animal.

3. Homogeneity Objection: What is composed from things must be homogenous with them; body composed from bodies; therefore Christ from two natures would not be person but body

   • Reply: Not every composition requires homogeneity—only in continuous parts. Line is composed of lines (not points); animal is composed of soul and body (neither of which is an animal).

The Resolution - Composition in the Ratio of Subsisting

• The person of Christ is simple in itself (divine simplicity preserved)
• But has alia et alia ratio subsistendi (other and other way of subsisting)—subsisting in divine nature and in human nature simultaneously
• Not compositio ex partibus (composition from parts) but composition by reason of dual subsistence
• The one person is altogether simple as a being, but composite as to the notion of person (which pertains to subsisting in nature)

Important Definitions #

Hypostasis (ὑπόστασις) vs. Suppositum #

• Hypostasis: From ὑπό (hypo, “under”) + στάσις (stasis, “standing”)—that which stands under; a subsisting thing; particular individual substance
• Suppositum (Latin): Equivalent meaning; the underlying thing; that to which properties and operations are attributed
• In rational natures: hypostasis = suppositum = person
• Etymologically, both should apply to any individual substance, but custom usage often restricts hypostasis to persons

Person (Boethius) #

• “Individual substance of a rational nature” (substantia particularis rationalis naturae)
• Adds to the general notion of hypostasis the specification of rational nature
• What subsists per se in a rational nature

Nature #

• Signifies the essence or quiddity—what something is
• The principle by which a thing is placed in genus or species (not the individuating principle)

Examples & Illustrations #

The Point on Two Lines (Geometric Analogy) #

• Draw a line from point A to point B
• Draw a second line from point A to point C
• Point A is the same, simple, indivisible point
• Yet it is the beginning of line A and the beginning of line B
• If the second line had its own endpoint, there would be two points—two separate beings
• But drawn to the existing point, one point subsists in both lines
• Application: The human nature is “drawn” to subsist in the pre-existing divine person; it does not have its own person, but is assumed into the divine person

The Hand as Individual but Not Hypostasis #

• A hand is an individual substance (in the genus of substance)
• But it is not a hypostasis or person because it does not exist per se
• It exists in something more complete (the whole person)
• Similarly, human nature in Christ exists in the divine person, not per se

Linguistic Examples on “Nothing” #

• “Nothing is nothing”—affirmative statement (true)
• “Nothing is better than God”—appears grammatically affirmative but is logically negative
• “No thing is better than God”—clearly negative
• Grammar can be misleading; logical form requires careful analysis
• Example: “Anyone home?” refers to a person, not a chair, despite “anyone” etymologically fitting “any one thing”
• These confusions multiplied opportunities for heretics to misinterpret doctrine

Notable Quotes #

“In our Lord Jesus Christ, we recognize two natures. But one, what? Hypostasis.” - John Damascene, On the Orthodox Faith, Book III

“Aliud et aliud are those from which the Savior is, but not alius et alius.” - Gregory Nazianzen, Epistle to Celidonium

“If someone attempts to introduce into the mystery of Christ, right, two subsistences, right? Or two persons, such a one is cursed, right? Anathema.” - Council of Ephesus (quoted from Berquist’s text)

“The person is an individual substance of a rational nature.” - Boethius, De Duabus Naturis

“Person does not add above hypostasis anything except a determined nature… rational nature.” - Thomas Aquinas (paraphrased from Boethius)

Questions Addressed #

Q: Can there be one person if the divine and human are aliud et aliud (other and other)?

• A: Aliud et aliud signifies diversity of natures, not of suppositum. This is unlike the Trinity, where alius et alius signifies diversity of persons. In the Incarnation, one person subsists in two distinct natures.

Q: How can Christ be both God and man if they have different hypostases in creatures?

• A: In creatures, different substances have different hypostases. But in Christ, the human nature assumes existence in the pre-existing divine hypostasis rather than having its own. The human nature comes into union with something more complete (the whole Christ as God and man).

Q: If human nature in Christ has no hypostasis of its own, how is Christ truly man?

• A: Christ is man by virtue of his human nature, not by virtue of hypostasis. The hypostasis is what subsists; the nature is what defines what the thing is. Christ’s human nature makes him truly human; his divine person is what he subsists in.

Q: Why isn’t Christ’s person composite if he subsists in two natures?

• A: The person is simple in itself (divine simplicity). The composition is not in the being itself but in the ratio (meaning/description) of person—insofar as we understand “person” as that which subsists in nature. The one simple divine person subsists in two natures; this is not composition of parts but composition by reason of dual subsistence.

Q: Can properties of the divine nature be predicated of the human nature and vice versa?

• A: Yes, because both are predicated of the one person—the divine hypostasis. We can say “God died” and “the man rose from the dead” because in both cases we are predicating operations of the one person Christ, though through different natures. If there were two hypostases, we could not correctly say such things.