A major theme in Shakespeare's "Macbeth" is fate vs free will. On one hand, Macbeth was told it was his fate to become Thane of Glamis and Cawdor,...

The question of fate and free will is one which has puzzled philosophers and theologians in the western traditions since Aristotle. In Shakespeare's time, one of the most widely accepted solutions to this conundrum was the one found in Boethius' popular and influential book The Consolation of Philosophy. The key point it makes is the distinction between our point of view and God's point of view.

God exists within eternity, or sacred time, meaning...

The question of fate and free will is one which has puzzled philosophers and theologians in the western traditions since Aristotle. In Shakespeare's time, one of the most widely accepted solutions to this conundrum was the one found in Boethius' popular and influential book The Consolation of Philosophy. The key point it makes is the distinction between our point of view and God's point of view.

God exists within eternity, or sacred time, meaning that he sees all things we would consider past and future in a single glance. In a sense, this means that for God, time does not exist as we think of it; there is no past or future, but everything that ever has happened or will happen is immediately present to him. Thus from God's point of view, everything is "fated" and nothing is contingent. God sees all of Macbeth's life and actions at once, just as I see my entire computer screen at a single glance. The witches, through their magic, have a small glimpse into that future, like a mosquito landing on my computer screen might see one or two letters of an entire webpage. 

In one sense, divine foreknowledge means that from God's point of view, everything is fated and unalterable. Macbeth isn't God, though, and cannot see the future. Macbeth sees himself as making moral choices and as having free will. It is those choices which make him good or evil and the nature of his character that causes him to make those choices. A mundane parallel that might make this easier to understand is ordering pizza. My friends all have foreknowledge that I would never order pizza with anchovies because I dislike the taste of anchovies. Thus my friends could say they have foreknowledge that I will not order anchovy-laden pizza or that I am fated to order anchovy-free pizza. This is not because I lack free will, but rather because I have the sort of character that does not like anchovies. In the same way, Macbeth is free to choose not to kill Duncan, but his character is such that he cannot avoid the path that leads to power.