Philosophical Arguments for the Trinity (Or Something Close Enough)
“All sorts of people are fond of repeating the Christian statement that ‘God is love’. But they seem not to notice that the words ‘God is love’ have no real meaning unless God contains at least two Persons. Love is something that one person has for another person. If God was a single person, then before the world was made, He was not love.” — C.S. Lewis, Mere Christianity (1952; Harper Collins: 2001) 174–176.
It is unanimously agreed upon Protestants, Catholic and Orthodox Christians that the Trinity is fundamentally an article of faith, indemonstrable by the light of reason, yet congruent with it. However, this has not prevented some philosophers and theologians from pursuing arguments for the truth of the Trinity of a probabilistic or abductive kind. Among such thinkers we find St. Bonaventure, Richard of St. Victor, and Richard Swinburne. In keeping with this tradition, here are three arguments for the Trinity — or something close enough.
Argument 1
1. Divine simplicity is true
2. Outwardly love involves the willing of the good of another
3. God creates and sustains the world out of outwardly love
4. Consequently, God is outwardly love (1,3)
5. Outwardly love involves a relationship between at least two persons
6. Consequently, God is at least two persons
The argument begins by presupposing the truth of divine simplicity, according to which God lacks both physical and metaphysical parts, and, consequently, is identical to his attributes.
In defense of premise 3 we may note, following Aquinas, that there is no extrinsic reason compelling God to create. God grants creation the gift of existence purely out of his own goodness, and this is plausibly understood as an act of love:
“The fact of saying that God made all things by His Word excludes the error of those who say that God produced things by necessity. When we say that in Him there is a procession of love, we show that God produced creatures not because He needed them, nor because of any other extrinsic reason, but on account of the love of His own goodness. So Moses, when he had said, “In the beginning God created heaven and earth,” subjoined, “God said, Let there be light,” to manifest the divine Word; and then said, “God saw the light that it was good,” to show proof of the divine love.” — Summa Theologiae I, Q. 32, A. 1, ad 3
Specifically, God’s act of love is an act of outwardly love, inasmuch as it has another as its object:
1. God is free to create or refrain from creating any world W.
2. In creating and sustaining W, God wills a fundamental good, namely, the existence and persistence of W.
3. Outwardly love involves the willing of the good of another. [¹]
4. Consequently, God creates and sustains W in existence out of outwardly love.
Premise 4 — “God is outwardly love” — follows from 1 and 3. If God has no metaphysical parts — such that he is identical with his attributes — and God creates and sustains the world out of outwardly love, then it follows that God is outwardly love. God does not create and sustain the world out of this kind of love, the way we often do things out of love as a contingent feature of our actions. Rather, God creates and sustains the world out of outwardly love, because he is outwardly love essentially, just as a triangle is a polygon with three edges and three vertices essentially.
Argument 1 — A Variant
1. Divine simplicity is true
2. Outwardly love involves the willing of the good of another
3. God creates and sustains the world out of outwardly love
4. Consequently, God is outwardly love (1,3)
5. Outwardly love entails a relationship between at least two persons
6. But the creation of the world is a contingent act
7. Consequently, God’s outwardly love entails a relationship between at least two persons prior[²] to his creative act
8. Consequently, God is at least two persons
Argument 2
1. Divine simplicity is true
2. God is love (1 John 4:8)
3. The greatest form of love involves the willing of the good of another.
4. Consequently, the greatest form of love involves a relationship between at least two persons.
5. God has the greatest form of love.
6. God’s decision to create the world is contingent
7. If God’s decision to create the world is contingent, then there is some possible world in which only God exists.
8. Consequently, there is a possible world in which a relationship between at least two persons obtains, sans the world. (4,5)
9. Consequently, there is a possible world in which God is at least two persons.
10. Each person that is God exists necessarily.
11. If x and y are distinct persons, then x and y are distinct in every world in which they both exist.
12. Consequently, God is at least two persons in every possible world.
In defense of 5, it seems prima facie clear that love of others is greater than love of self. It follows, then, that if God is that-than-which-no-greater-can-be-conceived (Anselm), then God exhibits the greatest form of love. But then, per divine simplicity, God is identical with his attributes, and hence God does not merely possess the greatest form of love; he is the greatest form of love.
Second, both Dietrich and Alice von Hildebrand persuasively argue that self-love runs the risk of collapsing into a kind of egoism. If God is perfectly good and perfectly loving, then God will exhibit — and therefore be, per divine simplicity — the greatest form of love, namely, love of another.
Third, if we suppose self-love is the greatest form of love, then it would be puzzling why God has created anything at all, given that he is all-perfect. But God has created things beyond himself, from which it follows A) that self-love is not the greatest form of love; B) God exhibits the greatest form of love; and C) God is the greatest form of love (again, per divine simplicity).
[1]: “I answer that as the philosopher says in Rhetoric Bk. II, “to love is to will the good for someone (amare est velle alicui bonum)”. In this way, then, the motion of love tends toward two things: namely, toward some good which one wills for someone, either for one’s self or for another; and toward that for which one wills this good. Thus one loves the good that is willed for the other with love of concupiscence, and that for which the good is willed with a love of friendship.” — (ST I-II, q.26, a.4)
[2]: By “prior” I mean logically prior
Additional readings:
Dietrich von Hildebrand, The Nature of Love (2009)
Alice von Hildebrand, “Problematic Self-Love” (2009)
