The major theme of All My Sons is Arthur Miller’s belief that people have a wider responsibility to the society in which they live, and this is something that Chris, Joe's son, is aware of and believes in. Unlike his father, Chris feels society and other people play a main part in a person's responsibility, as when he finds the truth out about his fathers actions; he is horrified - "What the hell are you? You’re not even an animal, no animal kills his own, what are you? What must I do to you? I ought to tear the tongue out of your mouth, what must I do?" - and here it is possible Chris has become a sort of spokesperson for Arthur Miller in the play. Keller seems to still not understand his sons anguish, as his responses are "Chris...my Chris..."

Not until Larry's letter is revealed to him, does Keller finally see the point of view of the next generation. Only after hearing Larry's letter does he reply to Chris' question "Do you get it now!?" with "Yes...I think I do" and then lead into where the play's title comes from when Joe Keller eventually realizes that "they were all my sons" in one sense. Keller kills himself in the final few pages of the play, leaving Kate on her own, the one thing she has always been said to fear, but the truth seems to give her a sort of strength in itself, as she tells her hysterical son Chris in the last line of the play, to "live...forget now...live" - freeing him of the obligation of living with any feeling of responsibility for Keller's suicide, in which he shoots himself in the head.

All My Sons is a criticism of the American Dream. Joe Keller, a representative type who would be considered an ordinary American, has lived through the Depression and despite a lack of education he has been able to own a factory, which he hopes his son will inherit. However, Keller’s quest for money leads to his responsibility for the deaths of 21 American pilots.

Keller has apparently achieved the 'American Dream' - he lives in a 'comfortable' house despite being an 'uneducated man.' Miller is emphasizing the hollowness of the American Dream and that one should 'think about the consequences of our actions.' However, this material comfort which Keller has worked to provide his family with the very best is of little consequence. His strong family unit is an illusion - his wife is ill, Chris is discontent and Larry has committed suicide as a result of his father's narrow-minded and reprehensible decision. It is through the letter from Larry that Keller realizes that he has not only killed one son but all of his sons, a theme which is reiterated by the title of the play. In conclusion, the American Dream has become more like an American Nightmare. Chris shows moral responsibility while his father Joe shows intense family responsibility.

Another theme of All My Sons is wartime profiteering. As there were large contracts when America entered the war on two fronts, the conditions were created for what Arthur Miller described as profiteering on a vast scale. Chris Keller is particularly angry that his selflessness in fighting in the war is contrasted by the selfishness of those making money off the war.

Death is another key theme in All My Sons. Kate Keller refuses to accept her son’s death. She denies the possibility of this death for a long time. Recognizing the death of her son would mean that she recognizes that her husband was responsible. This is an issue that constantly weighs on Kate throughout the work. The tree is a symbol that represents that Larry is still alive, and when the tree gets knocked down Kate still refuses to believe that her son is in danger.

When Chris finds out his father is responsible for killing the 21 pilots, he replies "I was dying every day and you were killing my boys" - and it is very notable Chris refers to the pilots as 'his boys' and says 'I was dying every day'; making them closer to himself and trying to indicate to the audience the extent of which he feels he has moral obligation to society.

At the start of Arthur Miller's Collected Plays he commented on his feelings on watching an audience's reaction to a performance of his first successful play: