The witches tell Macbeth that he will be king. The question that moves the entire play is: do they announce a destiny that has already been written, or do they just name a desire that was already there? Shakespeare's response decides whether Macbeth is a victim or a defendant.
Prophecy does not oblige
At no point do witches order people to kill. They tell you what will be, not what to do. The best proof is in the play itself: Banquo hears the same prophecy, that his descendants will reign, and does not kill anyone. Same prediction, opposite choices. If the oracle determined the action, both men would suffer the same fate. The difference is not in the prophecy, it is in the will of those who hear it.
Prophecy as a mirror
What prophecy does is reveal. She illuminates a desire that Macbeth would rather not see. That's why he doesn't wait: "if luck wants me king, let luck crown me without me moving", he says, and then he moves. He believes enough to kill, but not enough to trust. Fate becomes an excuse for haste.
Gyges' ring
Plato, in the Republic, tells the myth of the ring of Gyges: a ring that makes one invisible. The question is simple and terrible: what does a man do when he is sure no one sees him? For Plato, the unjust surrenders to injustice as soon as he feels unpunished. Prophecy is Macbeth's ring. It does not make him invisible, but it convinces him that fate has absolved him beforehand. Once the brakes on consequence are removed, desire does the rest.
Destiny even keeps its promises. But he doesn't forgive anyone who tries to sign in his place.
Why does this matter in your life
Free will is the condition of tragedy: if everything were fate, there would be no guilt, and Macbeth would not be pursued by imaginary daggers and ghosts. The play insists he chose it. And the question comes back to us: when a voice assures you that what you want most is already yours, do you wait, or force the door? Trust is, deep down, an act of free will.
Related class
The myth of Gyges' ring, by Plato
The question about what we do when no one sees, explained on the channel Nous on YouTube.
Watch the class on YouTubeFrequently asked questions
Do Macbeth's witches control his destiny?
No. They predict, but never order the crime. Banquo receives the same prophecy and does not kill anyone. The prophecy reveals the desire that already existed in Macbeth, without suppressing his choice.
What is the relationship between Macbeth and Plato's Gyges' ring?
In Plato's myth, a ring that makes one invisible tests what someone does when they think no one sees. The prophecy is Macbeth's ring: it makes him believe that destiny has already absolved him, removing the moral restraint. The question is the same: who do you become when you think there are no consequences?
Does Macbeth have free will in the play?
Yes. The tragedy depends on this: if everything were fate, there would be no guilt. Macbeth chooses to hasten fate into his own hands, and is held responsible for it. Free will is the condition of tragedy.
Continue: The Anatomy of Fear in Macbeth · The influence of others: Lady Macbeth · Macbeth and Raskolnikov: the anatomy of guilt