One way in which Jane Austen challenges her readers to examine values is by pointing out the lack of principles and ethics in certain characters, which is especially seen in Mansfield Park. In Mansfield Park, the only characters that demonstrate an understanding of principles and ethics are Edmund and Fanny. Austen makes a point of portraying the other characters as vain, conceited, arrogant, and even extravagant.
Edmund is the only one of the family at Mansfield Park that is kind to Fanny. When he sees her crying soon after her arrival, he tries to find out what he can do for her, and when that fails, he takes her for a walk through the park, encouraging her to tell him about her family. He is humble, sincere, and generous, just as one ought to expect of one who aspires to be a clergyman.
However, all of the other family members are proven to have many character failings. The eldest son, Tom, is described as feeling "born only for expense and enjoyment" (Ch. 2). In conceit and vanity, her cousins, especially the two girls, are always commenting on how little Fanny has learned in her education and how "stupid" she is. But the greatest flaw Austen points out concerning most of the entire family is that they are "entirely deficient in the less common acquirements of self-knowledge, generosity and humility" (Ch. 2). In other words, the family members are incapable of the sort of self-reflection that would reveal their character flaws. They also fail to be giving, compassionate, and humble human beings. Instead, because Fanny comes from the poorer side of their family, they treat her as inferior and insist that she know she is not their equal. Not only that, because Sir Thomas, the father, is a very distant man, he fails to observe just how much his family lacks principles.
Hence, in Mansfield Park, Austen challenges her readers to examine values by pointing out the lack of principles in her characters, but also by pointing out that their lack of principles is primarily the father's fault.