William Shakespeare | Why Does Macbeth Change His Mind About Killing King Duncan?

At end of Act I, Macbeth declares, “I am settled, and bend up/Each corporal agent to this terrible feat” (I, vii, ll.79-80). Given the witches’ prediction that he will become Scotland’s king, we have ample reason to believe that Macbeth and his partner in regicide, Lady Macbeth, will succeed in their enterprise of murdering Duncan. What is most remarkable is that just fifty lines earlier, Macbeth has flatly told his wife that they shall proceed no further in the bloody business at hand; in the midst of Lady Macbeth’s subsequent argument against such “unmanly” inaction, he commands her to hold her peace. Lady Macbeth defies him, and the spurs embedded in her reply tap deeply into Macbeth’s psyche. Most interpreters have focused on Lady Macbeth’s skillful manipulation of gender identities and the strong innuendo of sexual tension between the two in their explanations of why Macbeth changes his mind and decides to kill the king. But Macbeth is not merely a susceptible puppet of his wife’s finely-honed goading, for while she is the prime mover in the assassination of Duncan, the other murders in the play (of Banquo and MacDuff’s family) are exclusively Macbeth’s doing and this shows that he retains the capacity for independent action. Lady Macbeth’s influence is a catalyst, but Macbeth is a willing object of her persuasions, but the seeds of his decision are sown well before the end of Act I.

The witches’ promised intention to meet Macbeth aside, the first we hear of him is in Act I, scene ii, as a wounded sergeant reports that “brave Macbeth” swathed in the blood of the rebels, “unseam’d” the old Thane of Cawdor “from the nave to th’ chops” (I, ii., l.22) and then impaled his head upon battlements. The loyal

officer Rosse then says that Macbeth is “Bellona’s bridegroom” (I, ii., l.54), Bellona being the virgin goddess of war. Even before he arrives on stage, we know that Macbeth is capable of bloody deeds (in a good cause), while the figurative reference to Bellona will soon materialize in the character of Lady Macbeth. It is after this, in Act I, scene iii, the Macbeth and Banquo encounter the witches with their intriguing prediction that Macbeth will become Scotland’s monarch. Macbeth leaves open the normative question of whether this prediction is good or ill, but when he becomes Thane of Cawdor by “chance,” he speculates that it may be possible for him to become king “without my stir” (I, iii, l.143).

Macbeth’s hopes for a passive and legitimate route to the throne are dashed in the very next scene of the play. In Act I, scene iv, the good King Duncan tells Macbeth that he owes more to his loyal general than he can pay (l.20), and Macbeth then dutifully replies that the service and loyalty he owes to the king are payment in itself. This is somewhat illogical, but for a brief moment it appears that Macbeth might becoming king without “stirring,” that Duncan might name him as his successor. But after Duncan names his son Malcolm as heir apparent, Macbeth realizes that the prophecy that he will become Scotland’s monarch will not unfold without action on his part. He acknowledges that this will entail Duncan’s murder and that his ambitions have caused him to develop a still notional murder plan. Toward the end of the scene, Macbeth withdraws and, in a stage aside, he tells us the naming of Malcolm is a step that bars his ascent to the throne. His ambition is so powerful, moreover, that he fears that his evil intentions will be discerned, saying “Stars, hide your fires,/Let not light see my black and deep desires (I, iv, ll.50-51).

At the start of Act I, scene vii, Macbeth is considering the technical parameters of a hypothetical murder, finding “If it were done, when ti’s done, then ’twere well/It were done quickly” (ll.1-2). When his fears about the consequences of detection surface, Macbeth begins to list the reasons for not assassinating the king. He turns first to customary personal loyalty, observing that Duncan is a blood relative and, as such, that Macbeth should protect the king against knife rather than wield it against him. Secondarily, he says that Duncan has been a good king, against whom he has no grievance. But he fails to mention the most obvious reason for refraining from murder, that it is morally wrong, a cardinal sin that deserves damnation whether detected by human agency or not. Instead, he urns to making an inventory of the resources he would need, should he decide to move forward. On this count, Macbeth finds one thing lacking, “I have no spur/To prick the sides of my intent, but only/Vaulting ambition, which o’erleaps itself” (I, vii, l.25-27).

It is then that the “spur” appears (almost as if Macbeth had conjured it into being) as Lady Macbeth enters the scene. Initially, Macbeth is adamant in his rejection of the course that they both know must be taken if he is to become Scotland’s ruler, and tells his wife that they shall proceed no further in this business. Now Lady Macbeth launches into her argument, and the “spur” that has captured the critic’s attention is her charge that Macbeth is a coward. In fact, she does not directly say this (she merely asks if her is prepared to live like a coward), nor is it the crux of her case. Indeed, Macbeth has a rebuttal to the coward charge, asserting to Lady Macbeth, “I dare do all that may become a man;/Who dares do more is none” (I, vii, ll.46-47), and he then commands her to be silent. But Lady Macbeth need not heed her duty toward her husband, for there is a second plank to her counter-argument; she tells Macbeth that if he does not follow through on their developing plot then he has broken a promise to her. She first asks whether the “hope” that he raised for their royalty in the letter that he sent to her after meeting the witches was “drunk.” She then says that since the expectations he raised in this missive were false, she will accord his professions of love to her to be equally false. That being so, some “beast” must have egged Macbeth on to breaking the bonds of trust with his wife by making promises (the attainment of the throne) that are then withdrawn.

It is at this juncture that Lady Macbeth enters into her famous “phantom child” speech, saying to Macbeth: “I have given suck, and know/How tender ’tis to love the babe that milks me; I would, while it was smiling in my face,/Have pluck’d my nipple from his boneless gums,/And dashed the brains out, had I shown as you/Have done to this” (I, vii, ll.54-58). Although the attention of modern critics has centered upon the gender and sexual aspects of this speech, especially in conjunction with Lady Macbeth’s earlier “desexing” soliloquy in Act I, scene v, ll., the thrust of the argument pivots on trust, specifically the trust that unites husband and wife.

Lastly, Macbeth returns to practical issues of execution. He seems to seek reassurance rather than an opportunity to back out, having already determined that his bond to Lady Macbeth requires him to act, when he asks her “what if we should fail?” Lady Macbeth has her follow-on answer and the details of the murder plan set. She says that only fear will cause their plan to fail and then lays out plot that pivots around pinning the blame for king’s death upon “spungy officers” drugged into “swinish” sleep (her reference to “swine” creating one of many associations between Lady Macbeth and the witches). The irony here is Macbeth’s decision to murder Duncan rests upon what he sees as the dictates of his natural relation with his wife, but the relation between Macbeth and Lady Macbeth is no longer natural, but purposively unnatural, Lady Macbeth having shorn herself of maternal gender, Macbeth having entered into an unholy relation with the witches that will ultimately supplant his marriage to Lady Macbeth altogether.