After cruising down the Mississippi with Jim on a raft, a situation that brings him the warmth of Jim's love and a peace from the natural beauty of the river, time and time again Huck Finn encounters the treachery, hypocrisy, and cruelty of society. Finally, he rejects this duplicitous society as he chooses to act according to his moral conscience and not allow the unconscionable act of the King, who sells Jim to the Phelpses, to send Jim back into slavery.
After getting to know Jim as a fellow human being, Huck cannot in good conscience relinquish his friend to a life of oppression and loneliness. For, from their travels together, Huck learns that Jim has tender feelings and is capable of deep love. When, for instance, Huck tricks Jim after they have become separated in the fog when Huck goes off in the canoe, he is later ashamed of himself as Jim cries with happiness when he is again reunited with Huck and becomes angry when he realizes that he has been tricked by Huck into thinking that Huck has been on the raft all along. Sorry for his trickery, Huck apologizes to Jim. This act of Huck's signifies his recognition of Jim as a man equal to him.
Because of this recognition of Jim as a man with feelings like himself, Huck Finn senses the moral torpitude of slavery. Therefore, he is right in rejecting the conventions of society:
...I see Jim before me, all the time, in the day, and in the night-time, talking, and singing, and laughing. But somehow I couldn't seem to strike no places to harden me against him, but only the other kind.....I'd see him standing my watch on top of his'n...and see him how glad he was when I come back out of the fog, and how good he always was....
"All right, then, I'll go to hell," Huck decides to reject a society that keeps a man like Jim as a slave. For, the others are the sinners and hypocrites, not Huck.