Hypostasis: What the Word Means in Philosophy, Theology and Medicine
In short. Hypostasis (Greek hupostasis) means underlying reality or substance. How Aristotle, the Neoplatonists and Christian theology used it, and what it means today.
Hypostasis (Greek hupostasis, ὑπόστασις) means, literally, “that which stands underneath”: hupo, “under”, and stasis, “standing”. In philosophy it names underlying reality, whatever genuinely exists in its own right and supports everything else, as opposed to what exists only in something else or only in appearance. In Christian theology it took on a second, narrower meaning: each of the three persons of the Trinity.
Most of the confusion around the word comes from mixing those two histories together. This essay takes them in order, then covers the word’s everyday meanings in medicine and genetics, which are what many people searching for it actually need.
Did Plato use the word hypostasis?
No, and this is the most common mistake made about the term. Hypostasis is not a technical word in Plato’s dialogues. In the Greek of his time it was an ordinary, even humble, word: Aristotle uses it in his scientific writings for sediment, the stuff that settles at the bottom of a liquid. Its philosophical career begins after Plato, with the Stoics, who used it to separate what really exists from what is only thought, and it reaches its height six centuries after Plato with a Platonist: Plotinus.
What is Plato’s is the problem the word was later recruited to solve: how the levels of reality are ordered, from shadows to physical things to the Forms, and what stands at the top. In the Republic (509b) Plato says that the Good is “beyond being”, surpassing it in dignity and power. Later philosophers drew centuries of consequences from that phrase, and the idea of a hierarchy of hypostases is one of them.
What are the three hypostases of Plotinus?
Plotinus (3rd century AD), the founder of what we now call Neoplatonism, made hypostasis a technical term. In his Enneads (V.1–2) the word names each of the three levels of divine reality from which everything else flows:
- The One (to hen): the absolute first principle, perfectly simple, beyond being and beyond thought. It is Plotinus’s reading of the Good “beyond being” in the Republic. Everything emanates from the One the way light spreads from a source, without the One moving or losing anything.
- Intellect (nous): the first emanation, and the home of the Platonic Forms. It is thought thinking itself, containing every intelligible reality at once.
- Soul (psuchē): the emanation of Intellect. It animates the cosmos as the World Soul, gives life to individual souls, and bridges the intelligible world and the physical one.
Each hypostasis subsists in its own right, which is why it gets the name, and each gives rise to the next without being diminished, like a spring overflowing. It is the most influential system Platonism ever received, and it is the system the word “hypostasis” has carried with it ever since.
How did hypostasis come to mean “person” in the Trinity?
Christian writers inherited the word early. The Letter to the Hebrews calls the Son “the exact imprint of [God’s] hypostasis” (1:3) and faith “the hypostasis of things hoped for” (11:1), where it means something like underlying reality, or assurance.
The word’s great test came with the Trinitarian controversies of the fourth century. Theologians needed to say that God is one in one respect and three in another, and Greek had two near-synonyms for “real, subsisting being”: ousia (essence, substance) and hupostasis. Early on they were used almost interchangeably, which caused real trouble. Latin translated hupostasis literally as substantia, so when Greek theologians spoke of “three hypostases”, Latin ears heard “three substances”, which sounded like three gods.
The solution, worked out by the Cappadocian Fathers (Basil of Caesarea, Gregory of Nazianzus and Gregory of Nyssa) and confirmed at the Council of Constantinople in 381, was to specialise the two words: one ousia, three hypostases. One divine essence; three distinct subsistences, the Father, the Son and the Holy Spirit. In Latin the hypostases became personae, which is why the creeds speak of three persons in one substance.
The shift is striking. In Plotinus the three hypostases are ranked: the One above Intellect, Intellect above Soul. In the Trinity the three are equal and coeternal, and orthodox theology rejects that kind of ranking outright. The Council of Chalcedon (451) then used the same word for the hypostatic union: the doctrine that in Christ a divine nature and a human nature are united in a single hypostasis, one person.
Hypostasis in philosophy vs theology: the short version
| Context | What “hypostasis” means | How many |
|---|---|---|
| Ordinary Greek (Aristotle) | Sediment; what settles underneath | n/a |
| Neoplatonism (Plotinus) | A level of divine reality that subsists in its own right | Three, ranked: the One, Intellect, Soul |
| Christian theology | A person; an individual subsistence of the divine essence | Three, equal: Father, Son, Holy Spirit |
The resemblance between the two “threes” is not an accident, since the Greek Church Fathers had read Plotinus. But it is not an identity either, and treating the Neoplatonic hypostases and the persons of the Trinity as the same thing is the classic error about this term.
What does hypostasis mean in medicine and genetics?
Outside philosophy and theology, the word keeps its old physical sense of “settling underneath”:
- In medicine, hypostasis is the pooling of blood or fluid in the lowest parts of the body under gravity, usually because circulation is weak. Post-mortem hypostasis is the reddish-purple discoloration that appears on the lower side of a body after death, also called livor mortis or lividity. Hypostatic pneumonia develops in the lower lungs of patients confined to bed.
- In genetics, a gene is hypostatic when its effect is masked by another gene. The masking gene is called epistatic, and the relationship is epistasis.
These are the same word as the philosopher’s, used in its most literal sense.
What does it mean to “hypostatize” something?
The word also survives as a criticism. To hypostatize (or reify) is to treat an abstraction as if it were a thing that really exists, for example talking about “the Market” or “History” as if it were an agent with its own wishes. The irony is hard to miss: the fallacy is named after the very move Platonism made into a system. Whether Plato’s Forms are discoveries about reality or abstractions wrongly hypostatized is, at bottom, the question Western philosophy has been arguing about for twenty-four centuries.
A note on references: Plato is cited by Stephanus number (509b) and Plotinus by Ennead and treatise (V.1). Both systems are the same in every edition and translation.
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