The narrator decides to murder the old man because he is crazy. I can tell this because he does not like the old man's eye. He calls it a vultures eye even though it is just a normal eye that has gone blind. Also, many times he tries to prove himself that he is not crazy. He even starts the first sentence of his story by asking the readers that why would we think that he has gone mad. It states in the first sentence, "TRUE!—NERVOUS—VERY, very dreadfully nervous I had been and am; but why will you say that I am mad?" Furthermore, he says for himself that he wanted nothing from his gold or anything like that, he just did not like his eye. In the text it states, "He had never wronged me. He had never given me insult. For his gold I had no desire. I think it was his eye! yes, it was this!" Later, he thinks he can hear the old man's heart, and since he thinks that others can hear it too. Therefore, he kills the old man to protect himself from being discovered. This can be seen in the passage, "But the beating grew louder, louder! I thought the heart must burst. And now a new anxiety seized me—the sound would be heard by a neighbour!" From the textual evidence we can certainly infer that the narrator has gone extremely mad.
