Arthur Miller’s play All My Sons is the story of the Keller family, which is comprised of the parents—Joe and Kate—and their two sons Chris and Larry. The play is set immediately post-World War II, and Larry has died in the war. Dr. Jim Bayliss is a friend of the Keller family.
During the war, Joe shipped engine parts that he knew were defective. The play, which is a drama, revolves around Joe’s growing realization that his actions contributed to the death of his own son—who essentially killed himself during a mission—and many other young soldiers. Joe eventually realizes that these boys were “all my sons.”
Jim's role in the last act of All My Sons is to serve as a foil to help advance the plot and let the audience understand what Kate is thinking. He also serves as an ethical voice of wisdom and honesty in the scene.
During the dialog between Kate (Mother) and Jim, Mother tells Jim that her son Chris “had an argument with Joe. Then he got in the car and drove away.”
Jim questions her. “What kind of an argument?” he asks. It seems clear to the audience that Jim might suspect the subject of the argument, although he asks, “They argued about Ann?” Then Jim alludes to the true topic and asks whether Joe told Chris the truth.
Mother: (stops rocking) Tell him what?
Jim: Don't be afraid, Kate, I know. I've always known.
Jim: It occurred to me a long time ago.
Mother: I always had the feeling that in the back of his head, Chris... almost knew. I didn't think it would be such a shock.
Jim: (gets up) Chris would never know how to live with a thing like that. It takes a certain talent...for lying. You have it, and I do. But not him.
[E]very man does have a star. The star of one's honesty. And you spend your life groping for it, but once it's out it never lights again. I don't think he went very far. He probably just wanted to be alone to watch his star go out.
Jim alludes to Chris's star going out as a way of saying that Chris has always been honest, but if he accepts his father's actions, he will lose his intrinsic honesty and so lose himself. Jim says of himself, “I can't find myself; it's hard sometimes to remember the kind of man I wanted to be. I'm a good husband; Chris is a good son... He'll come back.”
In the final scene, Joe realizes the full impact of his actions. Chris and Kate debate whether it would help anyone if Joe should go to prison. Joe then reads a letter from Larry and says,
Keller: (looking at letter in his hand) Then what is this if it isn't telling me? Sure, he was my son. But I think to him they were all my sons. And I guess they were, I guess they were.