Huck learns to decide for himself in various situations the right thing to do.
One of the central themes of the novel and of Huck's development relates to the notion of conscience. Huck is challenged to come to terms with society's moral code and/or balance it with his own native sense of morality.
Huck faces a dilemma with Jim that characterizes his larger moral conflict when he has to decide which side to choose - to agree with society, write a letter to Miss Watson and abandon Jim to captivity or to follow his own conscience, help Jim escape, and accept condemnation for his transgressive act.
Although Huck feels that helping Jim escape is the morally necessary act, he also believes that society will see him as a criminal. For Huck, being an abolitionist is identical with being a criminal, aiding in the theft of property.
Huck's development is largely effected by his growth toward independence in his moral thinking. As he develops, Huck becomes increasingly capable making up his own mind about what is right and what is wrong.