126. The Commonality of 'Person' in the Trinity

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Lecture Notes

Main Topics #

The Problem: How Can ‘Person’ Be Common to Three Incommunicable Beings? #

• The fundamental tension: nothing is common to the three persons except the divine essence, yet ‘person’ does not signify essence
• ‘Person’ signifies relations, not essence directly
• The objection: if person is incommunicable, how can it be said of all three?
• Why this matters: essential distinction between understanding what something is versus how we know it

Community of Thing vs. Community of Reason #

• Community of thing (secundum rem): One thing genuinely common to many (e.g., humanity to Socrates and Plato)
• Community of reason (secundum rationem): A way of understanding that applies to many distinct things without being one common thing
• Thomas’s answer: ‘Person’ is common by reason, not by thing
• This is why three persons does not mean one person (which would be the case if it were community of thing)

The Paradox of Individuality #

• Every human being is individual/unique
• Yet ‘individuality’ or ‘uniqueness’ is common to all humans
• Similarly: being incommunicable is a way of existing that is common to all three divine persons
• The crucial insight: although person is incommunicable, the way of existing incommunicably can be common to three

Singular vs. Universal in Knowledge #

• Boethius: “a thing is singular when sensed and universal when understood”
• The senses know only the singular directly and cannot understand universality
• Reason knows primarily the universal but can understand singularity
• When reason understands singularity (e.g., “Socrates is an individual man”), it understands the singular universally without making the singular thing universal
• This is not false knowledge—the way we know need not be the way things are
• The Platonic error (answered by Aristotle): thinking that the way we know must be the way things are
• Boethius follows Aristotle on this point: God can know all things (past, present, future) in the eternal now without falsity in knowing

The Vagum Individuum (Indeterminate Individual) #

• ‘Some man’ signifies an individual substance in an indeterminate way
• Unlike ‘Socrates,’ which signifies determined particulars (this flesh, these bones)
• ‘Person’ is not imposed to signify individuals from the side of nature (like ‘some man’) but to signify a thing subsisting in such a nature
• Definition: individua substantia (individual substance) of a rational nature
• In divine context: the rational nature is the divine nature; substance means subsisting by oneself; individual means distinct from all others

Why Not Genus or Species? #

• A genus or species is “a name said with one meaning of many things, other in kind, signifying what it is”
• Person signifies directly the individual, not something common by genus or species
• In human affairs, persons are not related by genus/species either (I am a person, you are a person, but not through genus/species)
• In divine things specifically: the three persons have one being, whereas genus and species are said of many differing in their being
• Therefore, the community of ‘person’ cannot be of genus or species

Key Arguments #

Objection 1: Common Names Require Common Essence #

Objection: Nothing is common to three persons except essence; person doesn’t signify essence; therefore person cannot be common.

Thomas’s Response: The argument proceeds from community of thing. But person is common by reason, not by thing. It is not one common thing possessed by three, but a way of understanding that applies to each of them.

Objection 2: Person’s Definition Includes Incommunicability #

Objection: The notion of person includes being incommunicable (from Richard of St. Victor’s definition); if person cannot be communicated, how can it be said of three?

Thomas’s Response: Although person is incommunicable, the way of existing incommunicably can be common. Analogously: to be unique is incommunicable, yet uniqueness is common to all humans—each is unique in its own way.

Objection 3: No Universals in God #

Objection: There are neither universals nor particulars in God; if person is common by reason, wouldn’t it be a universal? But universal implies many differing in being, which God is not.

Thomas’s Response: Although this is a community of reason (like genus and species), it does not follow that person is a universal or that genus and species exist in God. Neither in human things is the community of person a community of genus or species. Moreover, divine persons have one being, whereas universals are said of many differing in being.

Important Definitions #

Indivisibility and Distinction #

• Incommunicable (from Richard of St. Victor): that which cannot be given to or shared with another
• Individual substance (substantia individua): subsisting by itself and distinct from others
• Rational nature: in human persons, a nature capable of understanding; in divine persons, the divine nature itself

Modes of Signification #

• In rectal (directly): directly signifying the thing itself
• In oblique (indirectly, per se): signifying something about the thing, such as relations or qualities
• Person signifies individual substance directly, but in divine context this carries implications about relations and subsistence

Examples & Illustrations #

The Uniqueness Example #

• You are unique; I am unique; each person is unique
• Yet uniqueness is something common—a common way of being
• Similarly, each divine person is incommunicable, but the way of being incommunicable is common to all three

The Man in the Shop #

• “Some man came into the shop”—uses the vagum individuum (indeterminate individual)
• Different from “Socrates came into the shop”—which specifies a determined individual with particular characteristics
• Person works like the vagum individuum: signifies individual substance in a common way

Socrates and Particulars #

• Socrates is determined individual: this flesh of Socrates, these bones of Socrates
• Emphasizes the concrete material particularity of a determined individual
• Contrasts with the indeterminate way ‘person’ or ‘some man’ signifies

The Nun Named Person #

• Anecdote: A nun with the surname “Person” jokes with a worker
• When he jokes “I didn’t know you were a person,” she responds about being more than just her name
• Illustrates how the word ‘person’ in ordinary language differs from philosophical usage
• Also illustrates the joke: “I’m not a nun, I’m a someone”—feminist nuns’ emphasis on personhood over role

Shakespeare’s Plays #

• Different Shakespeare plays can be classified into roughly four kinds
• Yet each play is unique in some respects
• Illustrates the subtle philosophical problem: can we speak of what is common to things while acknowledging each is unique?
• Shows how sophists can exploit this tension by claiming contradiction where there is distinction between ways of knowing

Notable Quotes #

“Although person is incommunicable, nevertheless, the way of existing incommunicably can be common to three.” — Thomas Aquinas (Berquist’s summary of the response)

“A thing is singular when sensed and universal when understood.” — Boethius (cited by Berquist)

“When it’s asked, what three? We say three persons, right? Because it’s common to them that which is a person.” — Augustine, On the Trinity, Book VII (cited by Thomas)

Questions Addressed #

Can ‘Person’ Be Common If Each Person Is Incommunicable? #

• Resolution: Yes, by community of reason. The term signifies a common way of existing (subsisting in the divine nature, distinct from others) rather than a common thing. Analogy: uniqueness is common to all humans even though each is incommunicable/unique.

How Do We Understand Singularity When Reason Knows Primarily Universals? #

• Resolution: Reason can understand singularity even though it understands in a universal way. This does not make the singular thing universal. The way we know (universally) need not be the way things are (singular). This is Aristotle’s insight against Plato.

Why Isn’t ‘Person’ a Genus or Species? #

• Resolution: Because person signifies the individual directly (like ‘some man’), not a common nature from the side of what things are. Moreover, divine persons have one being, while genus and species require many differing in being.

How Does ‘Person’ Signify Both Relation and Substance in God? #

• Resolution: Person signifies relation “in the manner of substance” (modo substantiae) because in God, relation and substance are identical. This is a unique way of signifying found only in divine things.

Contextual Flow #

This article is the fourth in the first four articles of Question 30, which deal with the general consideration of persons. The previous article established whether ‘person’ can be common to the three divine persons; this article argues that it can be, and explains the precise metaphysical mechanism by which this occurs. The lecture emphasizes careful linguistic and philosophical precision to avoid both Arian errors (suggesting three substances) and Sabellian errors (denying real distinction).