His own criterion

"Theologians have usually treated aseity as a metaphysical attribute, that is, one that focuses on the independence of God's being over against other beings. It seems to me, however, that the same basic concept is equally important in the epistemological and ethical areas. That is to say, God is not only self-existent, but also self-attesting and self-justifying. He not only exists without receiving existence from something else, but also gains his knowledge only from himself (his nature and his plan) and serves as his own criterion of truth. And his righteousness is self-justifying, based on the righteousness of his own nature and on his status as the ultimate criterion of rightness." (Frame, John. The Doctrine of God. New Jersey: P & R Publishing. 2002. 602)