What is the Catastrophe (struggle that marks the ultimate fall of central character) in Julius Caesar? ?

I have always thought that Brutus was "too good" and was just not able to see the evil in other people. Because he was not able to see the bad in others he did things that were enabling to them, such as allowing Marc Anthony to speak at Caesar's funeral. He was unable to fathom the possibility that Marc Anthony might have ulterior motives because he did not have any. He was naive in the extreme.