Where part i left us
Part I established the theological tension: if God is essentially perfect love, then God cannot be a solitary, unipersonal deity whose love only “switches on” once creatures exist. Part II makes this intuition precise through possible-worlds reasoning. The key insight: if love is essential to God, it must characterize God in every possible world where God exists. But if creation is contingent, there exist possible worlds where God exists and no creatures exist. Therefore, if love requires a genuine “other,” a unipersonal God cannot be essentially perfect love.
The modal toolkit
Before proceeding with the formal argument, we need minimal modal machinery:
A possible world represents a complete way reality could have been. □P (“necessarily P”) means P is true in every possible world. ◇P (“possibly P”) means P is true in at least one possible world. An essential property: P is essential to x if and only if in every possible world where x exists, x has P.
These are logical devices for tracking necessity and possibility—not commitments to multiple universes.
The argument in natural language
The argument unfolds through eight steps:
First, if God is maximally great, God possesses the great-making moral perfections essentially. Second, perfect love constitutes one of those perfections. Third, perfect love, in its highest form, is irreducibly interpersonal: it involves an actual lover-beloved relation to a distinct personal other—not mere self-relation, not merely “readiness to love.” Fourth, creation is contingent: God could have created nothing. Fifth, therefore there exists a possible world where God exists but no creatures exist. Sixth, if God were unipersonal, then in that world there would be no distinct personal beloved—so God would not be actually instantiating perfect interpersonal love there. Seventh, but if perfect love is essential to God, God must instantiate it in every world where God exists. This generates a contradiction. Therefore, God is not unipersonal; there must be eternal intra-divine personal plurality.
The formal modal argument
Key predicates
Let:
G = God exists
U = God is unipersonal (exactly one divine person)
PL = God is perfectly loving (in the strong, interpersonal sense)
C = Creatures exist
Beloved = there exists a distinct personal beloved of God
The premise set
Perfect-being theology provides our foundation.1 If God exists, God has essential great-making moral perfections; perfect love is one of them. We capture the “essential” component as:
(E) If PL is essential to God, then □(G → PL)
Read: Necessarily, if God exists, then God is perfectly loving.
Perfect love requires a distinct personal beloved:
(R) □(PL → Beloved)
Creation is contingent, so possibly God exists with no creatures:
(K) ◇(G ∧ ¬C)
If there are no creatures and God is unipersonal, then no distinct personal beloved exists:
(S) □((¬C ∧ U) → ¬Beloved)
Thus, if there are no creatures, then the only candidate “other” would have to be internal to God; but if God is unipersonal, there is no internal personal other.
The derivation
Assume, for reductio, U (God is unipersonal).
From (K): ◇(G ∧ ¬C). So consider a possible world w where G ∧ ¬C holds.
From (E): □(G → PL). Since G holds in w, PL holds in w.
From (R): □(PL → Beloved). Since PL holds in w, Beloved holds in w.
From (S): □((¬C ∧ U) → ¬Beloved). In w, we have ¬C; and by our assumption we have U; so ¬Beloved holds in w.
In w we get Beloved ∧ ¬Beloved. Contradiction.
Therefore the assumption U is false. So ¬U: God is not unipersonal.
Hence, if God is essentially perfect love and creation is contingent, there must be intra-divine personal plurality—at least Lover and Beloved eternally.
Why modal logic strengthens the argument
An appeal to aseity alone might elicit the response: “God doesn’t need creatures—God freely chooses to create, and then loves.” The modal version blocks this escape by shifting the question from need to essence. If perfect love is essential, it must characterize God in every world where God exists. Since creation is contingent, there are worlds where God exists without creatures. Therefore, if love requires a genuine “other,” that “other” must be available without creation. Aseity motivates the argument, but modal logic supplies the formal contradiction.
Critical pressure points
The argument is formally valid, so resistance must target a premise. Critics have four main exit strategies:
Deny (K): “God necessarily creates.” Some philosophers hold that creation flows necessarily from God, making no-creature worlds impossible. This emanationist view would prevent the argument from starting. However, classical theism typically treats creation as free, not compelled—and this argument addresses that tradition.
Deny (R): “Perfect love doesn’t require a distinct personal other.” A critic might claim self-love suffices, or that God loving God’s own goodness constitutes perfect love. But the argument targets paradigmatic perfect love as interpersonal communion—self-giving to a genuine other. If that’s what “perfect love” means as a great-making moral perfection, then (R) holds.
Deny (E): “Perfect love isn’t essential; it’s contingent.” Someone might argue God is morally perfect but not essentially loving. On perfect-being reasoning, however, if perfect love is a great-making moral perfection, denying its essentiality constitutes a major concession—and renders “God is love” less than fully literal.
What is established
The modal argument demonstrates something precise: an essential perfection must be instantiated in every possible world where God exists. If creation is contingent, there are worlds where God exists without creatures. If perfect love is essentially interpersonal—requiring a distinct personal beloved—then a unipersonal God would fail to be perfectly loving in those worlds. Therefore, if God is essentially perfect love, God cannot be solitary: the beloved must exist eternally within the divine life.
What is not established
This isn’t yet a full doctrine of the Trinity (moving to three persons requires additional argumentation), nor a complete metaphysics of how plurality and unity relate. It’s an argument for intra-divine personal plurality based on widely shared theistic premises about divine perfection, the nature of love, and the contingency of creation.
- Thomas V. Morris, Anselmian Explorations: Essays in Philosophical Theology (Notre Dame, IN: University of Notre Dame Press, 1987), chaps. 1–2. ↩︎