What are the main themes of "All My Sons"?
American Dream: Joe Keller, a simple, blue-collar worker, who has made it to business owner, sacrifices everything to maintain his version of the American dream. He surrenders his integrity, he lies, he chooses to act outside of morality.
Duty and Responsibility, Joe Keller tells us that he had no choice but to ship the faulty parts. If he had pulled them and started over he would have lost the contract, resulting in his business failing, he felt compelled to honor the contract to secure his company. He says he needed to take care of his family.
Choices and Consequences, Joe Keller makes a deadly choice and the consequences result in the deaths of several pilots and his own son, Larry.
Guilt, Revenge and Punishment, Steve Deever is made out to be the bad guy by Joe Keller, who puts all the blame on him. His son George, when he learns the truth, comes to the Keller's house seeking revenge. Steve has been in prison, while Joe has been free.
Death Kate won't accept the death of her son Larry. She desperately tries to maintain a false reality where Larry is still alive.
Forgiveness and Atonement, Joe Keller commits suicide at the end of the play when he realizes that his decision resulted in his own son's death, also a suicide. He wants Kate and Chris to forgive him.
Idealism Chris Keller, who believes that his father is an upright and honest man, discovers the truth, and is devastated.
I would just like to add one additional thought to those that pmiranda has already posted and that is the totally unforgiving society that made a "mistake" impossible. If there had been any forgiveness, and drop in the relentless demans to produce or go out of business, then none of what happened would have come to pass. I think the pressure of a capitalist society, the demand that you succeed economically, is a character in some of Miller's play, perhaps most obviously this one and "Death of a Salesman." It may help explain Miller's fascination with the Socialist/Communist model of the state.
Although a lot of the blame for what happens seems to fall on Joe, without the relentless pressure of the system, none of this would have happened, so one of the themes would be a cricitism of the capitalist system.
I would just to add ...
Each character in the play has a different experience of blame. Joe Keller tries to blame anyone and everyone for crimes during the war, first by letting his partner go to jail. Later, when he is confronted with the truth, he blames business practice and the U.S. Army and everyone he can think of--except himself. When he finally does accept blame, after learning how Larry had taken the blame and shame on himself, Keller kills himself. Chris, meanwhile, feels guilty for surviving the war and for having money, but when the crimes are revealed, he places the blame squarely on his father's shoulders. He even blames his father for his own inability to send his father to prison. These are just a few examples of the many instances of deflected blame in this story, and this very human impulse is used to great effect by Miller to demonstrate the true relationships and power plays between characters as they try to maintain self-respect as well as personal and family honor.
The American Dream
Miller points out the flaw with a merely economic interpretation of the American Dream as business success alone. Keller sacrifices other parts of the American Dream for simple economic success. Has he given up part of his basic human decency (consider the pilots) and a successful family life--does he sacrifice Steve or Larry? Miller suggests the flaws of a capitalist who has no grounding in cultural or social morals. While Keller accepted the idea that a good businessman like himself should patch over the flawed shipment, Miller critiques a system that would encourage profit and greed at the expense of human life and happiness. The challenge is to recover the full American Dream of healthy communities with thriving families, whether or not capitalism is the economic system that leads to this happy life. Economic mobility alone can be detrimental--consider George's abandonment of his hometown for big city success. There is a rift in the Bayliss marriage over Dr. Bayliss's desire to do unprofitable research, because his wife wants him to make more money instead of do what he enjoys and what will help others.
ONE of the main themes of the play is the pursuit and consequences of the American Dream
crime and punishment ,it is the general idea of the play.