Arguments from Irenaeus, Against Heresies, Book 2, Chapter 1,

 

There is nothing “beyond” God, creator of the world.

Why God has to be the fullness... We might begin with an ontological argument.

1. God is that than which nothing greater can be conceived.
2. Suppose that God is not the fullness of being.
3. We can conceive of something greater than God, namely, God as the fullness of being. 
4. But that's not possible. (see premise 1)
5. And so our supposition must be false. God is in fact the fullness of being.

I shortened the argument for brevity. There should be a premise (2a) stating that we can conceive of the fullness of being (undertand that concept) and another premise (2b) stating that it would be greater to be the fullness of being than not to be the fullness of being.

We might have gone with Aquinas instead. I wanted to show how an ontological argument might be useful.)

This is, in any case, the gnostic idea. ‘Pleroma’ means fullness. Irenaeus begins by showing that their god is not the fullness, beginning with their idea, he shows that their god is not God.

1. God is the fullness (Pleroma).
2. If something is bounded by something, it is not the fullness.
3. If something is bounded by something, it is not God. (1, 2)
4. The gnostic god (the Pleroma) is so bounded, namely, the world below.
5. The gnostic god is not God. (3, 4)

On Irenaeus’s usage, God contains all things just in case he is the source of the being of all things. The gnostic god does not contain the world of the Demiurge, which exists independently of him. There is literally a wall separating the fullness from the world.

There is a historical dependence. That’s another problem. The gnostics have a real problem of evil...

Ignoring the ontological argument above, why not admit that God is not the fullness, just the greatest?

1. If something is bounded at all, it is bounded on all sides.
• Whatever is bounded at all is finite.
• Whatever is finite is bounded on all sides.
2. The gnostic god is bounded.
3. The gnostic god is bounded on all sides. (1, 2)
4. If something is bounded on all sides, it is contained.
5. The gnostic god is contained. (3, 4)
6. If something is contained, it is contained by something.
7. The gnostic god is contained by something. (5, 6)
8. That which contains is greater than that which is contained.
9. There is something greater than the gnostic god. (7, 8)

And, by the way, an infinite regress of greater beings ensues.  

There is a problem with premise (4) as it stands. Ex hypothesi, the world of the Demiurge is bounded on all sided by the Pleroma but is not contained by it. So, premise (4) is false. Irenaeus can’t use it.

There is a solution. To avoid the infinite regress of circumscribing beings, we can suppose that one of the rings is bound by another which is not bound by it, i.e., we can suppose that one of the rings is circumscribed by another which contains it and all the rest.

This, I think, is how we understand God, in relation to the world.

This is the idea prominent in St. Thomas that an explanation has to be something outside of the set of things it is needed to explain...

• We need an uncaused cause to explain the caused causes.
• We need a necessary thing to explain the contingent things.
• We need something that transcends, which is an exemplar of goodness, beauty, being etc. to explain the gradations of these in the world.

Apparently, God cannot be limited as the gnostics suppose. 

DSMW