Context: In a New York City courthouse, an eighteen-year-old boy from a slum is on trial for allegedly stabbing his father to death. Final closing arguments having been presented, a visibly bored judge instructs the jury to decide whether the boy is guilty of murder. If there is any reasonable doubt of his guilt they are to return a verdict of not guilty. The judge further informs them that a guilty verdict will be accompanied by a mandatory death sentence.The jury retires to a private room, where the jurors spend a short while getting acquainted before they begin deliberating. It is immediately apparent that the jurors have already decided that the boy is guilty, and that they plan to return their verdict without taking time for discussion with the sole exception of Juror 8 (Henry Fonda), who is the only "not guilty" vote in a preliminary tally. He explains that there is too much at stake for him to go along with the verdict without at least talking about it first. His vote annoys the other jurors, especially Juror 7 (Jack Warden), who has tickets to a baseball game that evening; and Juror 10 (Ed Begley Sr.), who believes that people from slum backgrounds are liars, wild, and dangerous.The rest of the film's focus is the jury's difficulty in reaching a unanimous verdict. While several of the jurors harbor personal prejudices, Juror 8 maintains that the evidence presented in the case is circumstantial, and that the boy deserves a fair deliberation. He calls into question the accuracy and reliability of the only two witnesses to the murder, the "rarity" of the murder weapon (a common switchblade, of which he has an identical copy), and the overall questionable circumstances. He further argues that he cannot in good conscience vote "guilty" when he feels there is reasonable doubt of the boy's guilt.Having argued several points and gotten no favorable response from the others, Juror 8 reluctantly agrees that he has only succeeded in hanging the jury. Instead, he requests another vote, this time by secret ballot. He proposes that he will abstain from voting, and if the other 11 jurors are still unanimous in a guilty vote, then he will acquiesce to their decision. The secret ballot is held, and a new "not guilty" vote appears. This earns intense criticism from Juror 3 (Lee J. Cobb), who blatantly accuses Juror 5 (Jack Klugman) who had grown up in a slum of switching out of sympathy toward slum children. However, Juror 9 (Joseph Sweeney) reveals that he himself changed his vote, feeling that Juror 8's points deserve further discussion.Juror 8 presents a convincing argument that one of the witnesses, an elderly man who claimed to have heard the boy yell "I'm going to kill you" shortly before the murder took place, could not have heard the voices as clearly as he had testified due to an elevated train passing by at the time; as well as stating that "I'm going to kill you," is often said by people who do not literally mean it. Juror 5 changes his vote to "not guilty". Soon afterward, Juror 11 (George Voskovec) questions whether it is reasonable to suppose the defendant would have fled the scene, having cleaned the knife of fingerprints but leaving it behind, and then come back three hours later to retrieve it (having been left in his father's chest). Juror 11 then changes his vote.Juror 8 then mentions the man's second claim: upon hearing the father's body hit the floor, he had run to the door of his apartment and seen the defendant running out of the building from his front door in 15 seconds. Jurors 5, 6 and 8 question whether this is true, as the witness in question had had a stroke, limiting his ability to walk. Upon the end of an experiment, the jury finds that the witness would not have made it to the door in enough time to actually see the killer running out. Juror 8 concludes that, judging from what he claims to have heard earlier, the witness must have 
 Question: Juror number eight believes the evidence is what?
Output: circumstantial