Hartsock, Mildred E. "The Complexity of Julius Caesar."
PMLA 81 (1966): 56-62.

Thesis: Towards the end of her essay, Hartsock writes,
The truth seems to be that there is no one truth in the play: no possibility of a single unifying approach. We believe Brutus when we hear him speak; we like or dislike Caesar as his image shifts; we are torn between Cassius the schemer and Cassius the suffering man and doughty Roman; we respond to Antony's rhetoric and cringe before his opportunism and perhaps leave the theater "sure" that his final estimate of the action must be the true one. We are fully committed at every point in the play to someone.  (61)
Hartsock's most persuasive evidence that Shakespeare intended us to have this varying response is her analysis of his treatment of his main source, Plutarch. In every instance which Hartsock cites, Shakespeare complicates something that is simple in Plutarch. For instance, Plutarch says that Caesar shows his arrogance in an insulting manner by failing to rise from his seat when honors are bestowed upon him, and as a result the people put messages in Brutus' seat, urging him to protect them against the tyrant. However, Shakespeare makes everything much more ambiguous. Shakespeare's Caesar is always gracious, even if pompous; the people in Shakespeare's play do not think of Caesar as a tyrant until Brutus tells them to; and the messages to Brutus are forged by Cassius. Hartsock's point is that as Shakespeare consistently complicates his source, he also consistently complicates our response to his play.

Bottom Line: Very persuasive.