What flaw does brutus reveal in act 3 act4?

In Act 4 of Shakespeare's "Julius Caesar," Brutus reveals his flaw of being overly idealistic and rigid in his principles. His insistence on maintaining honor and morality in the face of political turmoil leads to a lack of pragmatism, particularly when he dismisses Cassius's concerns about their strategies. This rigidity ultimately contributes to the discord among the conspirators, highlighting his inability to adapt to the complexities of their situation.