Are the events in Macbeth predestined (under the influence of Fate), or would you say that the witches manipulated Macbeth?

Concerning Shakespeare's Macbeth, the
answer depends largely on the beliefs you bring to the
play.

With a modern mindset, which you probably possess,
you probably, following a thorough reading and study of the drama, would insist that
Macbeth has free will and makes choices, then suffers the
consequences.

For an Elizabethan, or someone who believes
in predestination, however, plenty of evidence exists in the play that could convince
such a person that predestination, or fate, as you call it, is at
play.

For instance, if the witches know the future, do they
just know it or do they cause it?  Is there a line between knowing the future and
causing it?  Even if one finds rational explanations for the predictions concerning
Macbeth (he'll be Cawdor, king, Birnam Wood will move, a man born of a body instead of a
woman will kill him), one is still left with the prediction that Banquo's heirs will be
kings.  How do the witches know that?  And, again, if they know it, does a supernatural
force cause it?

And free will and predestination were
contemporary issues in Elizabethan England, brought into focus by the Protestant
Reformation.

In short, Shakespeare is often ambiguous, and
this issue, as it is presented in Macbeth, is no exception.  You
can make a case both ways.  My modern mind tells me that the witches are manipulative
and Macbeth obsessively ambitious, and he makes choices to get what he wants.  But I can
argue the opposite, as well.