2.4 The point of the proof.
The proof in a nutshell is this: "If I am seriously trying to understand fully the world I live in, then I am already convinced that God exists." The peculiar force and power of the proof is exactly the force and power of the concrete judgment of fact underlying it; namely, the judgment achieved in Chapter 11: "I am a knower." Chapter 11 of Insight was focused on bringing the reader to make that concrete judgment of fact in the awareness that he or she could not reasonably help making it and could never reasonably go back on it. The same will be true of the conclusion finally drawn from it in Chapter 19.
There is, however, another side to this. Just as "I am a knower" has no binding force for other people, who do not know about me what I know about myself, so the same is true of a metaphysics built on "I am a knower.""No one can understand for another or judge for another. Such acts are one's own and only one's own. Explicit metaphysics is a personal attainment." --Insight, 396What Lonergan writes about explicit metaphysics is true about affirming the existence of God: "As each has to ask these questions for himself, so each has to answer them for himself" (329).
"[Explicit metaphysics] can exist only in a self-affirming subject, and the process can be produced only by the subject in which the result is to exist. It follows that the directives of the method must be issued by the self-affirming subject to himself" -- "Insight, 398.
Thus Lonergan openly makes the very focus of his proof that which John Hick would later describe as the hidden premise of all arguments for the existence of God: one's own conviction that the world is intelligible. Lonergan turns to those who claim to doubt that premise and invites them to ask themselves why they too spend so much time and effort trying to understand the world. His Chapter 19 is a metaproof.