Themes are the fundamental and often universal ideas explored in a literary work.

The Discomfort of Uncertainty and Doubt

Throughout the play, many jurors struggle with uncertainty, often stretching reality or bending the truth in order to avoid doubt. The goal of the jurors is to determine if the accused can be convicted beyond reasonable doubt, and many of them begin deliberations certain that the case against the boy is iron-clad. Therefore, when the 8th Juror starts reexamining the case and expanding the realm of what could possibly have occurred, they respond with anger, frustration, and avoidance. For example, the 10th Juror is convinced that the verdict should be "guilty" and unequivocally asserts the boy’s guilt from the start. He is quick to rage and uses overgeneralizations to avoid uncertainty. In one of their first interactions, when the 8th Juror points out inconsistencies in his thinking, the 10th Juror has to be physically restrained.

The 3rd Juror also gets easily frustrated with the 8th Juror’s meticulous questions and pushes back with anger, jokes, and distractions. For example, when the 8th Juror expresses doubt about the woman witnessing the murder through the window of the train, the 3rd Juror starts playing tic-tac-toe. One of the last jurors to change his mind, the 4th Juror holds on to an unshakeable certainty throughout the proceedings up until the very end. He is more capable of engaging with the facts of the case and less inclined to the emotional antics that his fellow jurors rely on. However, he clings to certainty and is unwilling to interrogate whether or not the witness’s testimony could be wrong. He argues that the case is built on facts and facts alone, but the 11th Juror points out that facts too can be colored by other people. This suggests that so-called facts are not always infallible, and all of the above events highlight the lengths to which some jurors will go to avoid the discomfort that often accompanies doubt.

The Power of Racism to Obscure the Truth  

Throughout the play, the characters most staunchly convinced of the boy’s guilt also espouse racist and classist ideas about the boy’s character. While those who vote "not guilty" early on see the boy as an individual, the 4th and 10th Jurors characterize the boy in terms of the groups that he belongs to. For example, the 4th Juror, who otherwise adheres to the facts of the case, argues that people who grow up in slums are more likely to be criminals. He believes that this is a fact of life; it never occurs to him that it's just a racist and classist idea that impairs his ability to see the boy clearly. The 10th Juror refers to people of the boy’s race as “those people” and says that they let their kids “run wild.”  He also claims that people of the boy’s race don’t value human life, implying that the boy’s race and upbringing are to blame for his alleged actions. These beliefs cause the 10th Juror to dehumanize the boy and see him not as a teenager but as a member of a group who are a threat to his own existence. In his final monologue, during which he argues that the jurors should seize the opportunity to literally kill the boy, he says that he doesn’t care about the law. This illustrates that he is unfit to be a juror because he’s more interested in carrying out a racial crusade than in achieving justice. In contrast, the early proponents of a "not guilty" verdict argue against prejudice. After the 10th Juror espouses racist beliefs, the 9th Juror says that the 10th Juror is just an ignorant man who believes he has a monopoly on the truth. Those whose perspectives are unclouded by overt racism are better equipped to carry out due process and defend the boy against wrongful conviction.  

The Vulnerability of Old Age 

The two elderly characters in the play illustrate the vulnerability of old age. The old man who serves as a witness for the prosecution seems to be both physically and emotionally weakened by his age. He walks with a limp, which casts doubt on his testimony that he ran to the door. The 9th Juror hypothesizes that the old man’s loneliness and need for validation may have affected his testimony. He convinced himself that he saw something important because his need to feel important was so intense. Similarly, the 9th Juror is often shouted down or dismissed throughout the proceedings. This bullying becomes so pronounced that the 6th Juror becomes the 9th Juror's de facto defender against the younger jurors who disrespect him. 

The 9th Juror’s familiarity with the vulnerability of old age makes him a keen observer of the old man on the witness stand. The 9th Juror seems to also feel cast aside, a fact that is emphasized when the 10th Juror immediately disregards the 9th Juror’s observations. When he tries to push back against the bluster and racism of the 10th Juror, the 9th Juror appears to falter and wishes aloud that he were younger. This suggests that his ability to be heard in the jury room, and maybe even outside of it, is undermined by his advanced age.