Rule Against Duncan's Constitutionally Transferring the Throne by Abdication

The Rule Against Duncan's Constitutionally Transferring the Throne by Abdication is a constraint on succession that Banco identifies when reckoning with Macbett’s rise. In Banco’s account, Duncan cannot simply abdicate in Macbett’s favor; because that lawful route is closed, Macbett’s accession requires Duncan’s death or the seizure of the throne by force. The rule turns succession into a political dead end—and helps explain why a murder that Banco regrets becomes part of the path to power.

Formulation and Scope

The play states the rule through Banco’s private reflection, not through a formal decree or an extended account of constitutional procedure. Looking back on the witches’ predictions, Banco reasons that Macbett could become king only if Duncan died or abdicated in his favor, and that abdication was constitutionally impossible. The evidence establishes the prohibition but does not specify its legal source, procedures, or penalties; its force in the drama lies in the closed option Banco describes.

The rule concerns transfer of the crown, not every exercise of Duncan’s authority. When Macbett reports that a rebel has been captured, he explains that he has not killed the prisoner because he was waiting for Duncan’s orders. Duncan immediately commands the prisoner’s execution and asks what has been done with Glamiss. The exchange presents Duncan as able to issue decisive commands, while leaving the constitutional route of voluntarily passing on his kingship unavailable.

Succession and Force

Banco sets out the practical consequence of the rule: if Duncan cannot abdicate to Macbett, then the existing king must die or be displaced by force before Macbett can take the throne. Banco acknowledges that he himself had a hand in Duncan’s murder, and connects that act to the political outcome he now resents. The rule does not make the murder lawful or excuse Banco’s participation; it clarifies the succession logic through which he understands how Macbett could become king.

That logic also sharpens Banco’s sense of unequal reward. He observes that Macbett is to become king after having been Baron Candor and Baron Glamiss, while Banco expects nothing comparable. The witches’ predictions have, in Banco’s view, come true one by one, but they did not mention Duncan’s murder. His account therefore joins prophecy to political action: the predicted accession is not achieved by constitutional handover, but through a violent break in the existing order.

Royal Discretion and Political Limits

The play distinguishes the transfer of kingship from the granting of lesser rewards. Banco complains that Duncan has not given him the promised title or lands, and says that Duncan cannot do this to him. Macbett responds that he and Lady Duncan have intervened on Banco’s behalf and proposes using more forceful arguments if their attempts remain unsuccessful. These exchanges show a court where titles and lands can be the subject of promises, appeals, and pressure; they do not suggest that Duncan can similarly transfer the crown by abdication.

The contrast gives the rule its dramatic significance. Duncan’s commands can direct immediate action, and his favor is sought over rewards, but the crown cannot be handed over through the constitutional means Banco considers. In Banco’s reasoning, that limit narrows the route to succession until political ambition and violence occupy the space a lawful abdication might otherwise have filled.