There are several conditions and elements of society which Mark Twain satirizes in The Adventures of Huckleberry Finn.
Mark Twain satirizes the belief that children always belong with a biological parent in the character of Pap. This is a man, a drunkard, who is physically abusive and cruel and neglectful. However, he is still able to lay claim to Huck because when Judge Thatcher and the widow both petition to be Huck's guardians, the new judge who does not know anyone rules that a child should not be taken from his biological parent (Ch. 3).
Twain ridicules the notions of mental simplicity and lack of humanity in African Americans with the character of Miss Watson's runaway slave Jim.
Jim, of course, proves to be possessive of common sense when he is not superstitious, and he displays a depth of feeling on several occasions. Certainly, Jim shelters Huck from witnessing several sights not fit for a child. First, he prevents Pip from seeing his dead Pa floating down the river; then he shields Huck from the evidence of depravity on the house that washes down the river. About a dead man inside he tells Huck, "Come in. . . but doan’ look at his face—"it’s too gashly” as he throws a cloth over the face.
Later, when the King and the Duke board their raft, Jim perceives that they are dishonest and selfish men, and he warns Huck about them.
Of course, the most telling incidence of the sense of right and wrong that Jim has, as well as the love he possesses for Huck, is in Chapter 15 after Huck, who takes the canoe, is separated from Jim in the fog. When Huck finds the raft in the morning, he sneaks onto it and lies down near Jim, who is still asleep. When Jim wakes up, Huck pretends he has been asleep on the raft all along. When Jim realizes Huck has played a trick on him, he scolds Huck:
Dat truck dah is trash; en trash is what people is dat puts dirt on de head er day fren's en makes 'em ashamed (Ch. 15).
Throughout the narrative, Twain pokes fun of Tom Sawyer's dreamy ideas of how to do things based on various stories he has read. In Chapter 3, for instance, Tom tells Huck about Don Quixote and how things are done by enchantment. Later, when Huck and Tom rescue Jim, Tom insists they use various means to free him based on a narrative he read, even though Jim has already freed himself.
In the chapters that describe the feud between the Grangerfords and the Shepherdsons, there is a romantic notion attached to the killings. Emmeline Grangerford keeps a scrapbook of obituaries as though her relatives are like the knights of the crusade.
Aunt Sally and the Widow Douglas, who purport to be deeply devout Christians, are both slave owners. Huck wrestles with his conscience and tries to make sense of things, but he cannot. In Chapter 31, Huck believes his quandary about not wanting to turn in Jim is sinful.
The more I studied about this, the more my conscience went to grinding me and the more wicked and low-down and ornery I got to feeling. . . here was the plain hand of Providence slapping me in the face and letting me know my wickedness was being watched all the time from up there in heaven, whilst I was stealing a poor old woman's nigger that hadn't ever done me no harm.
Finally, Huck decides, "All right, then, I'll go to hell," and he tears up the note to Miss Watson because he cannot betray his friend Jim, even if his behavior is considered wrong.