In To Kill A Mockingbird by Harper Lee, Atticus Finch tries to live an exemplary life, unaffected by the prejudices of others, particularly in his own community of Maycomb County. Atticus will defend Tom Robinson even though he knows that, as far as the community is concerned, Tom is guilty even though they have not heard the true facts of the case. In this quote, Atticus, in explaining to Scout why he is taking Tom's case, is alluding to the preconceived and racist ideals that exist. The people of Maycomb County may have "majority rule" but that can be ill-considered and will never change the truth. Having a majority say does not make something true. Atticus is exposing the pitfalls of operating according to an unfair system, regardless of how many people support it.
Doing what other people expect when a person knows that those people are wrong, may be the easiest choice but it will never replace the knowledge that, despite opinion, in this case, Atticus has done what he knows to be right, according to his conscience. He is not bound by others in forming his own conclusions. Atticus is quick to explain that, he respects the opinions of others, and reminds his daughter to do the same, but that, "before I can live with other folks, I've got to live with myself." Atticus cannot support a principle that he knows to be unjust and immoral.
Atticus is defending Tom Robinson, a black man who has been accused of raping a white woman. This accusation has left many residents in Maycomb shocked and appalled. Some are angry with Atticus for defending Tom. Scout has heard some people insult Atticus, which upsets her.
Despite this, Atticus explains to Scout that his conscience cannot allow him to stand by without trying to help Tom. Atticus believes the story about Tom raping Mayella has been fabricated and that Tom is an innocent man. Atticus tells Scout that he "'couldn't go to church and worship God if [he] didn't try to help that man'" (Chapter 11).
Scout tells her father that most people in town think he is wrong for feeling that way. She tells Atticus that those people think their own thinking is correct. Atticus tells Scout that everyone has a right to their own opinion. He also tells her that he cannot make decisions based on the opinions of others:
"Before I can live with other folks I've got to live with myself. The one thing that doesn't abide by majority rule is a person's conscience."
Atticus has to make his decision based on his conscience, rather than by how popular his decision is. He knows he needs to ignore what other people are saying.