Is Atticus only defending Tom Robinson because he was appointed to do so by the court? Or does he aim to really defend Tom? Find a quote to support your answer.

As Atticus has explained to Scout many times about this, He is doing this because he values equality and justice. He believes that everyone is equal and therefore just because Tom Robinson is black, doesn't mean that he should not defend him. Atticus intends to give everything he has got to defend Tom.

if I didn't (defend Tom) I couldn't hold up my head in town, I couldn't represent this county in the legislature, I couldn't even tell you or Jem not to do something again."

What page number did you find your resourse?

Page numbers differ from the many publications of this book. Check out ch. 9.