Discussions about the roots of criminal behaviour often lead to nature versus nurture debates. While these debates will likely continue, it is generally accepted that human behaviour is the result of the complex interactions between external and internal forces. That said, in the play Macbeth, Shakespeare demonstrates that despite the external factors that influence Macbeth’s decisions, it is Macbeth’s own character flaws- namely his ambition, insecurity, and weakness of morals, will, and mind- that ultimately lead him to commit his crimes.

Despite the influences of others, Macbeth’s ambition is the first critical factor contributing to his crimes. The witches actively start the mischief by delivering seductive prophecies to Macbeth during a cleverly timed appearance. First of all, because Macbeth is still in the mindset of battle, he is able to pay attention to the witches who do not “look… like the inhabitants o’ the earth” (1.3 42). Secondly, having more honourable titles would not seem unrealistic for Macbeth because he has just accomplished a military victory and is the new Thane of Glamis. More importantly, however, their prognostications are extremely tempting to Macbeth because they resonate with his ambitious tendencies. Macbeth has just been named the Thane of Cawdor and has gotten “golden opinions from all sorts of people” (1.7 35), but he still quickly refocuses his intentions into his seemingly more promising future. When two of the witches’ predictions come true and the possibility of becoming king seems to increase, Macbeth immediately “yield[s] to that suggestion whose horrid image doth unfix [his] hair” (1.3 144-145) as he fantasizes about killing Duncan. He self-acknowledges his desire to be King by describing Malcolm’s proximation to the throne as “a step on which [he] must fall down, or else o’er leap,/ For in [his] way it lies” (1.4 55-57). Macbeth becomes anxious as Malcolm poses a threat to his ambition. He summons darkness to conceal his thoughts and act of murdering from heaven: “Stars, hide your fires;/ Let not light see my black and deep desires:/ The eye wink at the hand!” (1.4 57-59). Although the witches’ prophecies are tempting, they never suggest to Macbeth to take actions, and yet Macbeth embraces his “vaulting ambition” (1.7 27) and murders Duncan to secure the crown.

The second crucial factor contributing to Macbeth’s crimes is his insecurities about his masculinity, a factor which also relates later on to the questionable legitimacy of his kingship. Men in Macbeth’s society are assumed to be and expected to be physically and emotionally stronger than women. Soldiers, especially, must have enough strength to “[unseam the enemy] from the nave to the chaps,/ And [fix] his head upon [their] battlements” (1.2 24-35). Lady Macbeth, however, is the archetype of the emasculating female. She wants to abandon all of her feminine qualities as she recognises that the characteristics she wants are not acceptable for females. She asks the spirits to “unsex” (1.5 46) her and to fill her “from the crown to the toe, top-full/ Of direst cruelty” (1.5 46). It is these masculine characteristics in Lady Macbeth that highlight Macbeth’s lack thereof. Indeed, Lady Macbeth’s words are particularly poignant for Macbeth because they attack his biggest insecurity- his masculinity. While at first Macbeth suggests that killing the King would make him less a man and cause him to lose his humanity, he changes his mind as Lady Macbeth proposes that a real man keeps his promises and acts on his ambitions: “When you durst do it, then you were a man;/ And, to be more than what you were, you would/ Be so much more the man” (1.7 54-56). Macbeth therefore murders Duncan to prove that he would be defeated neither by his fear nor his “milk of human kindness” (1.5 15). Furthermore, because Macbeth is trapped in his insecurity, he excludes Lady Macbeth from his plan of murdering Banquo- “Be innocent of the knowledge, dearest chuck,/ Till thou applaud the deed,” (3.2 50-51) he says; perhaps for him, murdering is a show where he can shine as a real man. In the same vein, Macbeth never feels secure about his kingship. He considers Banquo as a threat to his throne; he fears that Banquo will murder him in order for his descendents to become kings as foretold by the witches. For Macbeth, Banquo is “the torture of mind” (3.2 23). Moreover, it becomes clear that Macbeth feels inadequate due to his failure to sexually reproduce offspring. For a man without an heir, even the possession of the throne cannot truly fulfill his identity as a man. Macbeth says, “Upon my head they placed a fruitless crown,/ And put a barren sceptre in my gripe,/ Thence to be wrench’d with an unlineal hand,/ No son of mine succeeding” (3.1 65-68). To resolve his trepidation, Macbeth chooses to do “a deed of dreadful note” (3.2 48)- he hires murderers to kill Banquo. Macbeth projects his own insecurities of proper manhood onto the murderers, attacking their masculinity. In asking them, “Do you find your patience so predominance in your nature,/ that you can let this go?” (3.1 93-95), he suggests that murder is a show of masculinity for them to rise from “the worst rank of manhood” (3.1 111). Yet, throughout the play, other characters are able to interpret manhood with much more humanity. For example, for Macduff, a well-defined man does not necessarily possess a vengeful attitude against every situation; in fact, he must “feel it like a man” (4.3 259)- he must feel the compassion and grief- before he takes any actions. For Siward, it is the courage to confront his enemies without fear that defines a man. Nonetheless, Macbeth decides to commit crimes to secure his throne and to satisfy his search for the “undaunted mettle [that] should compose/ Nothing but males” (1.7 81-82).

The last key factor that contributes to Macbeth’s crimes is his weakness of morals, will, and mind. It is true that Macbeth’s environment is conductive for any man that has a desire to murder. As a lord of noble birth, Macbeth is in a powerful position to commit crimes with impunity. Because Duncan is a king who builds “an absolute trust” (1.4 15-16) with his lords, it is easy for Macbeth to assassinate him. Finally, a king possesses all power to control his subjects and to compel them to murder for him, if he so desires. It is, however, Macbeth’s weak moral fibre that makes him see this as a tempting environment. After encountering the witches, he devotes all his thoughts to them because he approves of their “instruments of darkness” (1.3 133). In fact, as he thinks that he is “yet but young in deed,” (3.4 175)- still new to crime- he voluntarily seeks advice from the witches despite their reputation for evil. Moreover, Macbeth makes few moral reflections and decides to continue to compromise everything with criminal actions: “I am in blood/ stepp’d in so far, that, should I wade no more,/ Returning were as tedious as go o’er” (3.4 167-169). This results in the slaughter of Lady Macduff and her son, a woman and child scarcely in a position to interfere with his plans. In addition to his moral weakness, Macbeth is easily persuaded because he lacks judgement and has a poor will. Although he has given himself good reasons not to kill Duncan, his mind switches quickly as soon as Lady Macbeth starts provoking him. He does not attempt to think about the flaws of Lady Macbeth’s plan; he simply follows orders. Perhaps this is why he had such success in the military, as soldiers take orders from superiors and act as parts of a unit, not as individuals. Not only is he easily manipulated by others, Macbeth also has an unstable mind: he is easily disturbed and has little self-control. For instance, when a crisis arises for him, he yells angrily at his servant, calling him a “cream-faced loon” (5.3 11). His unstable nature is intensified as his mind begins to break from the stress of his crimes. At the feast, he sees “the very painting of [his] fear” (3.4 75), Banquo’s ghost, and yells fervently, “Hence, horrible shadow!/ Unreal mockery, hence!” (3.4 128-129) This instance fully demonstrates that Macbeth’s mind is never at peace; in fact, he is “cabin’d, cribb’d, confined, bound in/ To saucy doubts and fears,” (3.4 28-29). Perhaps, committing murders becomes the only logical result of the weaknesses that he permits to grow and that in turn become the primary determinants of his behaviour.

In the play Macbeth, the power of Macbeth’s internal flaws outshines the influences of his environment and finally contributes to his murderous crimes. Many external forces come to bear on Macbeth’s decisions, but evidently, homicidal plans are not the inevitable consequence of being in such situations- Macbeth’s actions require both his thought and his lack of it. Macbeth spirals downward in an increasingly uncontrolled murderous panic ultimately because, as he himself asserts, “O, full of scorpions is my mind…” (3.2 40).