At the beginning of Act Two, Brutus contemplates assassinating Caesar. As was mentioned in the previous post, Brutus's motivations are honorable and just. The fact that he weighs the pros and cons of assassinating Caesar reveals his sincerity. Unlike many of the conspirators, who want to murder Caesar because they are jealous or ambitious, Brutus has honorable intentions. In Brutus's soliloquy, he mentions that he has no personal reason to harm Julius Caesar but wants to act in the best interests of the Roman citizens. Brutus believes that Caesar wants to become king, and he fears that Caesar will change once he is given that extraordinary power. Brutus reasons that if Rome were to crown Caesar king, they would be giving him the power to do damage. He decides that killing Caesar would be a necessary preventive measure that would stop Caesar's ability to rule Rome like a tyrant. Since Brutus is acting in the best interests of the people, his intentions are honorable and sincere.
Throughout the play, many characters come to a conclusion that Caesar must be killed, Brutus included. However, Brutus is the only conspirator in the play who acts entirely out of sincerity. While the other conspirators seek to gain power by eliminating Caesar, Brutus honestly believes that Caesar's climb in authority would be bad for Rome. In this scene, Brutus mulls over his dilemna, weighing out the facts for himself. While he is still loyal to Caesar, he also fears that Caesar would become corrupt by a gain in power or status.
After Brutus's servant enters and delivers the letter, Brutus finds that his first impressions were solid. He believes that the letter details the wishes of the Romans to be rid of Caesar; since Brutus always tries to act in the best interests of Rome, he determines that he must follow through with the conspiracy plot. Once he measures the pros and cons of the situation, Brutus comes to a decision that Caesar must die, for the good of Rome.