Council, Norman. " Julius Caesar :   The Honourable Brutus."
When Honour's at the Stake: Ideas of honour is Shakespeare's plays. New York: Barnes & Noble, 1973. 60-74.

Thesis: Council, in the opening chapter of his book, surveys Elizabethan writings about honor and comes to the conclusion that the dominant notion of honor was that it is the reward of virtue, not a guarantee of virtue. Brutus, in Council's opinion, made the mistake of believing that his honor guaranteed the virtue of his actions, and so he murdered a friend and then asked the Romans to "believe me for mine honor, and have respect to mine honor, that you may believe" (3.2.14-16). Here is how Council sums up his argument:
Shakespeare . . . makes Brutus' singular dependence on his sense of honour, which becomes self-protective and isolates Brutus from the reality of the world around him during the course of the play, the cause of his tragedy. Shakespeare also, of course, asserts Brutus' stature in every scene, providing a dual judgment of his protagonist which is necessary to the structure of the play. In a manner prophetic of the mature tragedies, the source of Brutus' nobility— his honour—is the source of his tragedy. Shakespeare places Brutus in a world compelled by the demands of honour, and he is at once the noblest citizen of that world and the most pitiable subject of its inverted ideals. After the decision to kill Caesar, each of these important scenes of the play dramatizes Brutus' moral and intellectual decay as being a direct consequence of his commitment to the name of honour, and each maintains the tragic irony of the play by surrounding Brutus with characters who all share some form of Casca's belief that honour, 'like richest alchemy', can change offence to virtue.  (73)

Bottom Line: Solid analysis