What is an example of irony in Oedipus Rex?
Irony is, in fact, a literary technique which originated in Greek tragedy. Most common is dramatic irony in which a character's actions or words are understood by the audience, but unknown to the character.
The drama of Oedipus Rex is based upon the psychological blindness of Oedipus who issues punishments for the murderer of King Laius, who ruled Thebes before King Oedipus. For, he is unknowingly that very murderer who is the cause of the suffering of the people in Thebes.
So, in SCENE I when Oedipus says,
I pray that that man's [the killer of King Laius] life be consumed in evil and wretchedness (234)
Oedipus ironically curses himself. This is an example of dramatic irony, because Oedipus at this point in the drama is unaware of his own guilt and what will become of him.
In another example of dramatic irony from SCENE III, a messenger arrives to inform Oedipus that Polybus "was not your father." For, a shepherd had given the baby Oedipus to this messenger, who in turn gave Oedipus to Polybus. Nevertheless, Oedipus fearlessly replies with great dramatic irony,
Am a child of Luck; I can not be dishonored.
Luck is my mother; the passing month, my brother,
Have seen me rich and poor. (1022-1026)
Of course, Oedipus is, indeed, greatly dishonored and cursed with his own words. And, because he was blind to the truth, he physically blinds and banishes himself.
Dramatic irony occurs in the story because the audience is aware that it is Oedipus that killed Laius, but Oedipus is unaware and demands that the murderer is found and punished.
The audience is also aware that Oedipus was adopted by Polybus and Merope. However, Oedipus unknowingly runs from his adoptive parents, believing that he is forestalling the outcome of the prophecy that he would kill his father. He later discovers that the man he murdered on the road was indeed his father and that his biological parents are Laius and Jocasta.
Oedipus mocks Teiresias’s blindness not knowing that the situation is quite the opposite. Although Teiresias is blind, he is aware of what Oedipus has done, but Oedipus himself has no clue of the impending disaster due to his actions. In the end, Oedipus turns blind after he damages his eyesight.
The audience is aware that Oedipus is the cause of the plague because he married his mother. Oedipus discovers the incestuous relationship much later in the story.