This article discusses ‘The Black Cat’ and how the story proves to be ethical through evil. I am not entirely sure how it is ethical (I have to reread it), but so far, I think it is saying that the first cat only follows and mimics its owner because it is a pet; it doesn’t know better, it merely loves its owner. But the second cat, by making noises, seeks justice to reveal the corpse. Poe is hiding the ethical standpoint behind the surface, which is the evil of the story.
via Academic Article 1.