"If I was still a preacher I'd say the arm of the Lord had struck. But now I don't know what happened. I been away. I didn't hear nothin'."
Whereas earlier in life Casy would've attributed the current condition of the Joad estate on supernatural forces, nowadays Casy admits that he doesn't have the answer. Perhaps the best way to adapt a non-teleoloical mode of thinking is admitting ignorance, because there are simply things that people cannot know.