Why won’t Brutus swear an oath in Scene 1 of Act II of Julius Caesar and what does this reveal about Brutus?
If we look carefully at this scene when Cassius asks all the conspirators to "swear our resolution" together as a form of a pact, the response that Brutus gives is tremendously revealing in terms of what it shows about his character. Let us see how he responds to the suggestion of Cassius:
No, not an oath. If not the face of men,
The sufferance of our souls, the time's abuse--
If these be motives weak, break of betimes,
And every man hence to his idle bed.
You have to love the honesty and moral integrity of Brutus, even if it is a quality that is abused by Cassius and the other conspirators. He argues against taking an oath, because he argues that the honesty of their faces should be enough. If, he says, that actually they are not honest to unite together, then they should end this conspiracy now, because it is not worth proceeding with it because of their moral lack. However, if they are honest enough, the conspirators should need no oath to spur them on, only "their own cause," which Brutus obviously believes is for the ultimate good.
Clearly Brutus reveals himself here to be politically naive. He is a man of his word, and yet he is blind to how this is a weakness and a strength. His nobility and bravery and courage is clear from his speech, but at the same time we have already seen how easily an unscrupulous character like Cassius can manipulate him, which leaves questions in our mind about the characteristics that he dangerously lacks.