You: If his mental orderliness is a brute fact, something that is true and requires no proof, then the universe itself might as well be a brute fact, existing just because it exists.

Aaron: You seem to think that there are certain things that are true without being proved, but I will not allow you to use such beliefs in our discussion. That would make it to easy for you to say "such and such is true because that's the way it is." We cannot have that or we would go nowhere.

Let me modify your argument by saying that God's mental orderliness is the ultimate fact, and it is from his thoughts that all things come. Now we have but one "brute fact" as you put it, and no other givens.