Hi.
CCC says the persons’ distinction lies in their relations. Why we can’t imagine two gods who their distinction lies in their relation?
We need to take a step back and recall some basic Aristotelian metaphysics, to understand the terminology that the Church uses for the Holy Trinity.
Trees, moths, stones, men, and angels are beings that have a separate, concrete existence. They can stand alone. This kind of being, Aristotle calls
substance or
essence.
On the other hand, the greenness of trees, the ability of moths to fly, the hardness of stones, and the intellects and wills of men and angels are also beings, but each of them depends radically on a
substance in order to exist. There is no greeness without a green
substance to go with it, and so on. Aristotle calls this kind of being, which has no independent existence,
accident.
Among the many accidents that a substance can have are its
relationships with other substances. For example, I am a
son, and sonship is a relationship that refers me to my
father. (Therefore, fatherhood is also a relationship, one that relates my father to me.)
So far, I think things are fairly easy to understand. Here is where it gets complicated: you see, creatures are really distinct from their accidents. A tree is not the same thing as its greenness; I am not the same thing as my intellect, and so on. Much less am I identical with my sonship.
However, with God, things are different: God is utterly one. There can be no division whatsoever in Him. It follows that God cannot possibly have any “accidents”—or else, put another way, the sorts of things that would be accidents in creatures are actually perfectly identical in God to His Substance.
Thus, for example, God is not simply just and merciful; He is Justice and Mercy Itself. He is not just good; He is Goodness Itself. And so on.
The same thing goes for the relationships that are intrinsic to the Holy Trinity. Whereas my father is really distinct from his fatherhood, God the Father is not in any way distinct from His Fatherhood. And likewise for the other persons.
The three Persons are really distinct from
one another, but none of them is distict at all from the Divine Substance or Essence. (Said in simpler words, all of them are perfectly and fully God.)
The problem with positing several “gods” is that you would be assuming that there can be many “members” of the “species” called “god.” However, having many members of the same species, or genus, can only apply to a creature. It would mean, basically, that there is more than one possible way to be a “god,” which is a condition that is impossible for the Creator, the First Cause. (After all, there is no one to constitute
Him as God.)
Undoubtedly, creatures can, and do, have relationships among themselves, but the Creator can only (strictly speaking) have relationships within Himself—namely, the four relations that constitute the Trinity: Fatherhood, Sonship, Spiration, and Procession.
[Note that three of the relations are identical to a Person. Spiration, which is proper to both Father and Son, is not.]
