thatthe witches' control is limited. Think of what the witches do. They predict the future. This could be taken to mean that all of the events in Macbeth's life are preordained, and that his actions, too, have already been decided upon. However, even Macbeth considers that he has a choice when he says "if chance will have me King/Why chance may crown me/ Without my stir." He knows that if his destiny is determined, he does not have to take any action at all for it to come true. The fact that he does act after thinking this shows that he has freely decided on the action.

He is in control. The witches can predict, and they can suggest, but they don't necessarily control. There are, in fact, strict limits to what the witches can and cannot do. When the sailors' wife insults the second witch, they cannot kill her or her husband. All they can do is create chaos around him and toss his boat about in a storm.

Even in their final scene, they cannot control Macbeth's actions. Instead, they exploit his weakness and use his arrogance against him. Again, they have manipulated the situation, but it is Macbeth who chooses to interpret what they tell him in a way that gives him false hope and leaves him vulnerable. In each instance, they offer a path, but it up to Macbeth to decide whether or not to take it.

Macbeth is not without a mind. He repeatedly thinks of reasons why he should not perform the actions he does. He simply ignores his own reasons. To do so requires a choice, and to exercise a choice is to exercise free will.

Taken from criticism on Macbeth:

Macbeth is from the first entirely aware of the evil he embraces, and like Satan he can never renounce his free−willed moral choice, once it has been made. It is thus appropriate that the force of evil in Macbeth be symbolized by Satan's own sin of ambition. This sin for Shakespeare, as it had been for Aquinas, was an aspect of pride, the worst of the medieval seven deadly sins. In the neatly ordered and harmonious universe of which Renaissance man conceived, it stood for a rebellion against the will of God and thus against the order of nature.… Macbeth, through love of self, sets his own will against that of God, chooses a lesser finite good—kingship and power—rather than a greater infinite one. Shakespeare in Macbeth's moral choice is offering a definition of evil in fairly traditional terms.