When scout asks atticus if he is going to win the case, he tells her, "no, honey." she then asks him why he is taking on a case that cannot be won. what is his response, and what do you think he is referring to?

Atticus says, "Simply because we were licked a hundred years before we started is no reason for us not to try to win."

Answers may vary on the second part of the question. Example: Atticus is most likely
referring to the deep-rooted racism in Maycomb County, which goes back hundreds of
years. Although the novel is set nearly seventy years after the abolition of slavery, prejudice against black people is still very much alive in America, especially in Deep South states like Alabama. Atticus is saying that entrenched racism is what has already "licked" Robinson's chances of a fair trial. However, this is not going to cause Atticus to simply give up and not even try to win the case.   

source:https://quizlet.com/96831640/to-kill-a-mockingbird-chapter-9-flash-cards/

The answer is society was a caste like system with poor whites at the bottom of the white social ladder.