In some stories (think stories by Ernest Hemingway) drinking has both positive and negative effects on the drinkers. Not so in "The Black Cat." The unnamed narrator of this grim tale claims he began abusing his wife and pets when his drinking got out of control, wrecking his personality. Some readers think this is a "temperance" narrative, a popular genre in Poe's day. "Temperance" in this context means "sobriety." The Temperance Movement focused on educating the public on the perceived dangers of drinking, and pushing legislature prohibiting the manufacture, use, and sale of alcohol. In a temperance narrative alcohol is the major issue, and is to blame for all the bad things that happen in the story. Here, alcohol fades out of the story just when things get bad, suggesting that alcohol is only one of many factors in the narrator's moral breakdown.
"The Black Cat" parodies traditional temperance narratives that hold alcohol up as the only cause of the characters' problems, while at the same time seriously questioning issues of alcohol abuse.
The narrator uses alcohol as an excuse for his bad behavior.