Brutus makes a tragic error in killing Caesar because he has taken the law into his own hands while pondering over what if's...and maybes. Caesar may change, but what Brutus overlooks in making his decision is that everyone is prone to change. Eventually causing him his life, the error was made simply because Brutus looked out for the good of his country and for the good of himself. If Caesar had changed, and become unjust, his position in society could have been compromised, and people with high positions in society, don't particularly enjoy having thier positions in society compromised in even the slightest way. Cassius played on this while coercing Brutus to aide him in his plan, and suceeded, because another of Brutus's flaws was that he was too trustworthy, and noble. Knowing that his position in society could be easily disposed of, Brutus was convinced that he needed to act before it was to late, and what his he and is ancestors before him had fought for for generations would be deteriorated, and the way of life, and quality of life would change drastically. Deciding to kill Caesar seemed a easy, and immiediate solution to their plight, but not even one of the conspirators could have predicted what was to come. Even though predicting the future would, in reality have been impossible, the conspirators didn't think for the future, and plan for the worst, which was the cause of their downfall, and eventually demise.