Greatly different in personality, Aunt Alexandra holds to the conservative and more traditional attitude of a Southerner in the 1930s whereas Atticu Finch is extremely liberal-minded and "progressive" in his thinking for his environment. So, in Chapter 16 of Harper Lee's novel as Atticus and his sister are at breakfast and Calpurnia serves them coffee, Alexandra waits until Calpurnia goes into the kitchen before she scolds her brother, "Don't talk like that in front of them." She refers to Atticus's remark about Mr. Underwood despising Negroes; she does not think it appropriate to discuss what a white man thinks of black people before a person of color. For one thing, she fears that doing so will encourage black people to discuss whites and be more discontent.
However, Atticus disagrees; he sees the problem as greater than that perceived by Alexandra. Keeping them quiet and non-rebellious is less the problem to Atticus than the injustices that are perpetuated. He retorts,
"....Maybe if we didn't give them so much to talk about, they'd be quiet."
Further, Alexandra scolds her brother about the children's involvement in the scene at the jailhouse. While Atticus is proud that the children made the mob become human again, Alexandra expresses her disapproval of Atticus's personal support in the Tom Robinson affair,
"You see, don't, you...what comes of things like this. Don't say I haven't told you."
Aunt Alexandra wishes to remain with the status quo of the Jim Crow South and take a traditional approach to race matters, while Atticus considers people on an individual basis and does not define people as black or white or "just a nest of those Cunninghams."