1. Dramatic Irony: It is the device of giving the spectator an item of information that at least one of the characters in the narrative is unaware of (at least consciously), thus placing the spectator a step ahead of at least one of the characters. Dramatic Irony is a literary term that defines a situation in the play where the reader knows more than the character does. This is the one of the most common types of irony used by Shakespeare and there are many instances of it in Macbeth.E.g. “Fair is foul, and foul is fair” is the motto of the witches, something that Macbeth unknowingly echoes in his first line, “So fair and foul a day I have not seen”.
This indicates to the audience that Macbeth and witches are already connected in spirit before they have even met. Duncan says, referring to the Thane of Cawdor, that “There’s no art/ To find the mind’s construction in the face./ He was a gentleman on whom I built/ An absolute trust.” This is ironic because after Macbeth becomes the Thane of Cawdor, the same words may be applied to him and he becomes a “most disloyal traitor”, just as the previous Thane of Cawdor was. When Duncan visits Inverness, he says that the castle has a “pleasant seat” and Banquo is quick to agree, saying that the “air is delicate”, neither of them knowing that Macbeth is planning to murder Duncan in this castle.
After the murder of Duncan, Macbeth says that his “hand will rather/ The multitudinous seas incarnadine” but Lady Macbeth scoffs at this and says, “A little water clears us of this deed.” The irony of this is only brought to light in Act 5, Scene 1 when Lady Macbeth, while sleepwalking, constantly washes her hands and says, “Here’s the smell of blood still; all the perfumes of Arabia will not sweeten this little hand.” In Act 2, Scene 3, or the “Porter’s Scene”, the porter imagines that he is a “porter of hell-gate”, not knowing that the castle, due to the murder of King Duncan by one of his loyal subjects, have become a hell on earth.
2. Irony of Fate: It stems from the notion that the gods, or the Fates, are amusing themselves by toying with the minds of mortals with deliberate ironic intent. In Macbeth, it is the witches who toy with Macbeth to deliberately mislead him. E.g. When Macbeth meets the witches for the second time and they show him the apparitions, the words of the apparitions are deliberately designed to make Macbeth overconfident and think that he is invulnerable.