What is the role of the witches in Macbeth?
Some have seen them as being pure evil using Macbeth as a play thing if you will, while others see them as just supernatural beings that can see the future and give Macbeth these promises when he should have never been king in the first place.
The witches function on several levels in terms of their dramatic function. First of all, they allow the creation of a mystical and superstitious atmosphere, which is not only dramatically interesting but helps to underscore the dark motivations and trouble psyche of Macbeth himself. The fact that the witches claim to have knowledge of the future helps serve as a justification to Macbeth's actions, as if his acts are somehow fated or pre-determined. One central theme of the play is that Macbeth is himself not strong-willed enough to act on his own initiative, and thus is influenced by his wife and the witches. So the witches act as agents of influence, goading Macbeth to commit murder, but also reminding him that his status of king os a very fragile thing and this his actions will reap the appropriate reward or punishment. The supernatural quality the witches impart to the play also emphasize the obsessions with death and evil expressed by many of the characters.