Following the angry discussion with Aunt Alexandra that ends in her calling Walter Cunningham Jr. "trash," Jem and Scout discuss the differences in some people. Jem states that there are four kinds of people in the world: People like the Finches and their neighbors; poor, honest folk like the Cunninghams; dishonest people like the Ewells; and Negroes. Scout disagrees. She tells Jem
"... there's just one kind of folks. Folks."
But Jem wonders aloud that if this is so, then
"... why can't they get along with each other?"
Jem has learned a great deal about people in this chapter (Chapter 23). Bob Ewell has made a threat against Atticus' life; Jem discovers that one of the Cunninghams was the holdout on the jury; he learns that women cannot serve on juries; and he has heard his aunt's rant against young Walter.
"If they're all alike, why do they go out of the way to despise each other?... I'm beginning to understand why Boo Radley's stayed shut up in the house all this time... it's because he wants to stay inside."