Why doesn't Alexandra want Atticus speaking about race in front of Calpurnia? Whom does Alexandra think it will encourage?

In Chapter 16 of Harper Lee's To Kill a Mockingbird, Aunt Alexandra expresses her point of view that white folks speaking of racial tensions before African Americans only leads to more racial tensions and eventually stirs up rebellion.

The scene opens at breakfast with Aunt Alexandra making known her disapproval of the children having sneaked out to the jailhouse at night to see if their father was in danger. When Atticus proclaims he was...

In Chapter 16 of Harper Lee's To Kill a Mockingbird, Aunt Alexandra expresses her point of view that white folks speaking of racial tensions before African Americans only leads to more racial tensions and eventually stirs up rebellion.

The scene opens at breakfast with Aunt Alexandra making known her disapproval of the children having sneaked out to the jailhouse at night to see if their father was in danger. When Atticus proclaims he was glad the children came along since they saved him, her retort is that "Mr. Underwood was there all the time" with his gun, ready to protect Atticus. But Atticus expresses his doubt that Mr. Underwood would have really taken action against the mob since Mr. Underwood "despises Negroes, won't have one near him." It's this comment that Aunt Alexandra expresses disapproval of Atticus having said in front of Calpurnia while she was serving breakfast.

Aunt Alexandra's argument is that talking about the disrespect of and mistreatment of the Negroes "encourages them," meaning encourages them to rebel against the white folks. As Aunt Alexandra sees it, the Negroes gossip about any racist event that occurs in Maycomb, which incites them to rebellion, as we see when she comments, "Every thing that happens in this town's out to the Quarters before sundown."

In contrast to Alexandra, Atticus shows he holds the right views about racism and racial tensions. Atticus argues that he would be showing Calpurnia disrespect if he didn't treat her as valuable enough to talk in front of her about the same problems of racism he spoke of in front of his own children. More importantly, he further argues that if the Negroes were not treated with so much disrespect, they wouldn't talk among themselves and feel the need to form a rebellion. Hence, Atticus demonstrates that a central difference between he and his sister is that he wants to address the problem of racial tension whereas his sister only wants to cover up the problem.