Macbeth should not kill Duncan to try and assume position as the King. For one Duncan is Macbeth's cousin. "O worthiest cousin", states that not only that Duncan considers Macbeth worthy, but it's not an unknown fact that they are cousins. There is a difference between being a blood cousin or being a blood but a recognized cousin. The crown is already spoken for anyways, "Our eldest, Malcolm, whom we name here after the Prince of Cumberland." So even is Macbeth does kill Duncan, Malcolm would get the throne. Macbeth's grand ploy may not be as great as he thought…
