Superstition serves as a metaphor for the rigid and arbitrary rules of society.
Superstition is a running motif in The Adventures of Huckleberry Finn. It is used as an example of how the dogmatic ways of civilization can be nonsense. Just as the superstitions have the basis, the prejudices also have no purpose or reason.
In chapter 4, Huck consults a hair ball to find out what his father’s plans are.
Miss Watson's nigger, Jim, had a hair-ball as big as your fist, which had been took out of the fourth stomach of an ox, and he used to do magic with it. He said there was a spirit inside of it, and it knowed everything. (ch 4)
Obviously, something does not have magic powers just because it was in the stomach of an ox. For Huck to ask the hair ball for advice, and for Jim to give it to him, is just plain silly. Is that any sillier than thinking a person can be owned because of the color of his skin? Jim may use the hair ball, but he is not the only one who thinks it has powers. In this case, Huck thinks it has powers, and Jim is more or less fleecing him.
There are other examples of superstitions used to hide a person’s true intentions. When Jim and Huck find a dead man in the floating house, Jim tells Huck that looking is bad luck. He really does not want Huck to know it was his father, and does not want him to see his father in that condition. Huck is looking out for Jim.
For example, when Huck kills the snake and leaves it as a joke for Jim, the snake bites Jim even though it is dead.
And he said that handling a snake-skin was such awful bad luck that maybe we hadn't got to the end of it yet. (ch 10)
Obviously, they have already had “bad luck” from handling the snake. Huck’s juvenile prank could have seriously injured Jim. Huck is more concerned with how Jim looks at the moon, because “looking at the new moon over your left shoulder is one of the carelessest and foolishest things a body can do” (ch 10). Clearly, Huck has his priorities mixed up.
The use of superstitions is more than satire. Twain is not just making fun of poor country folk. He is explaining how human nature tends to attribute things for the wrong reasons. When we can’t explain things, we make things up to make ourselves feel better.