In Twelve Angry Men, twelve jurors have to decide in a court of law whether they find the accused guilty or not. An initial ballot shows that the majority of jurors assume the accused is guilty. Only one juror, Juror 8, believes that the man is innocent.
Throughout the film, it appears that whilst most jurors do believe in the guilt of the accused, they struggle to back their view up with justifiable evidence or reason when challenged. Most jurors simply seem to be influenced by their own experiences, common clichés and racist views, rather than rational arguments to do with the actual case.
However, there are some arguments, which could be seen as at least partially valid reasons. For example, Juror #7’s verdict is heavily influenced by the fact that the accused already showed criminal tendencies in his younger years, which may make repeated criminal actions more likely. One could also argue that Juror #4 has a valid argument, as he keeps referring back to the clear facts: evidence and witness statements. He urges the others not to become too emotional, but to remain factual and objective. He seems initially convinced by the evidence presented, which therefore forms a valid argument until the point when the evidence suddenly appears less reliable and more questionable later on, which is when Juror #4 changes his opinion as a result.