In Macbeth, how is humor or comic relief used in Act 2 and 3?
Comic relief is used in the scene with the porter because it is silly, and in the banquet scene because Macbeth makes a fool out of himself.
All dark plays need some sparks of humor to break the tension. This is known as comic relief. In this case, the extreme tension of the murders in Act II, Scene 2, there follows complete silliness in Scene 3.
The porter serves little purpose other than to characterize Macduff, because this is our first real interaction with him. The porter tells Macduff that drink provokes three things, and Macduff can’t help but as what three things.
Marry, sir, nose-painting, sleep, and urine.(25)
Lechery, sir, it provokes and unprovokes: it provokes the
desire, but it takes away the performance. (2:2)
Macduff finally gets frustrated and asks to come in. In the meantime, Macbeth has had plenty of time to get away with murder.
The scene in Act III, Scene 4 is a little more serious but still plenty funny. Macbeth throws a banquet for the nobles after having Banquo murdered. He asks why Banquo does not show up; keeping up appearances because he knows Banquo is dead. Yet Banquo does show up—as a ghost!
The scene is comical in many ways. Macbeth sees the ghost, but no one else can. The guests are confused, and try to act as if nothing is wrong. Lady Macbeth makes excuses.
Ross gestures at Macbeth to sit down, and he replies, “The table's full.” He then proceeds to ask which one of them did it, and then argue with the ghost.
Thou canst not say I did it: never shake
Thy gory locks at me. (3:4)
He laments about how it used to be that without brains a man would die. Eventually, Lady Macbeth cannot take it anymore and shoos the others out before Macbeth makes more of a spectacle and has them doubting his sanity.
Although the scene with the porter is funny, the banquet is much more important. It demonstrates Macbeth’s shaky grasp on reality, and how guilt and paranoia are beginning to set in. It also could be a vision sent by the witches, meaning they are not done with him yet. Killing Banquo is going to continue to haunt him.