Responsibility or the lack there of, is the underlying theme of "All My Sons." One good example of irresponsibility is when Joe insisted on claiming to George that it was his own father, Steve, who was the one responsible for the false plane parts. One example of responsibility occurs when Ann shows the letter to Kate. And a third example occurs when Joe kills himself and in doing so accepts the responsibility of killing the lives of all the twenty-one pilots.

Joe does not take responsibility for selling false plane parts for most of the play. In the end Joe finally takes responsibility for his crime. Joe is forced to accept responsibility - his suicide allows Chris to live free from guilt. At the end Joe finally explains to Chris what the truth is, and that, in fact, he did knowingly sell the false plane parts to keep...