In "To Kill a Mockingbird" Atticus says "There's something in our world that makes men lose their heads--they couldn't be fair if they tried?"What...

Atticus is speaking of Tom Robinson's case, and how unfortunate it was that despite all of the evidence proving Tom's innocence, people still found him guilty, because racism is such a strong and powerful emotion that fills people with hatred and fear, and takes over all else.  Atticus is referring to how normal, decent, hard-working people are turned into men who would show up at the jailhouse in great mobs, to violently attack someone just because they are black.  Atticus knows most of the people that show up in the mob outside the courthouse, but their fear has taken over; rational, logical thought isn't possible in the face of such racist mass hysteria.  That fear was what led the jury to decide as it did.  Atticus tries to be optmistic though; he feels that the jury taking so long was a good sign, a turn for the better.  At least he was able to make the men think for a bit before they turned their minds over to the fear.