Point to details in "The Tell-Tale Heart" that identify its speaker as an unreliable narrator.
The narrator begins the story by insisting that he is sane before telling his audience, "I heard all things in the heaven and in the earth. I heard many things in hell" (1). The reader initially questions the narrator's sanity after his admission that he hears things in heaven and hell. Also, a reliable narrator would typically not attempt to prove his sanity before telling a story. As the narrator continues, he mentions that he loved the old man yet was willing to take his life because the man's pale blue eye bothered him. This admission indicates that the narrator is both unreliable and insane. There is a clear conflict between the narrator's admission that he loves the old man and his willingness to murder him.
The narrator continues to plead his case by telling his audience how he cautiously stared at the old man in his sleep for seven nights in a row without the man knowing. The narrator believes that since he acted cautiously and carefully planned his attack, his sanity is justified. However, the reader is aware that insane individuals have the capacity to act cautiously and with foresight. Following the murder, the narrator once again attempts to convince the audience of his sanity by demonstrating the "wise precautions" he took to conceal the body. The narrator proceeds to dismember the body and hide it underneath the floorboards. The fact that the self-proclaimed "sane" narrator dismisses his brutal, inhumane actions is further evidence that he is unreliable.
The last piece of evidence that proves the narrator's unreliability is when he admits to hearing the sound of the dead man's heart beating through the floorboards and believes the police are mocking him as they laugh. His inability to identify the sounds he thinks he hears as hallucinations resulting from his extreme guilt is additional evidence that proves he is insane and unreliable.
The narrator is indeed insane, which makes him an unreliable narrator. The narrator begins the story by saying ‘‘True!—nervous—very, very dreadfully nervous I had been and am, but why will you say that I am mad?'' We know he is crazy because he has no real reason to murder the old, defenseless man other than the fact that he has a peculiar eye. The palish-blue eye taunts and irks the narrator to the point of insanity. The man decides to murder the bearer of the eye but cannot do so when his eyes are closed. The insane narrator rationalizes that his crime must be committed when the eye is in view because he is in fact antagonized by the eye and not by the old man. This rationalization, although perfectly normal to the story teller, makes no sense to a sane person.
For eight nights, the madman stalks his victim as he meticulously plans his crime. Ironically, this carefulness to him is a sign of his sanity, and he assures the reader that no madman would be able to be so keen. However, the reader sees the man's reasoning of the ploy as utterly lunatic, and we watch the narrator on his path through madness.
All the signs that point to his insanity and instability also clue us to the fact that he is an unreliable narrator. He does not see things the way a normal person would and distorts reality to suit his needs. This is the epitome of that an unreliable narrator is.