I've read Oedipus at least three times now in my lifetime, and every time I read it I become even more convinced that the hamartia of King Oedipus' is his pride. When he learns that the curse on Thebes will only be lifted through finding and exacting justice for the murder of the previous king, Oedipus makes elaborate promises and takes upon himself the responsibility of finding the murderer/s, "I will bring this to light again" (133 emphasis added). He believes that as king, he has both the authority and power to do anything, invoking even the Gods to help him in this righteous endeavor. "Those who do not obey me, may the Gods grant no crops...nor children...! May a fate like this, or one still worse than this consume them" (269-272)! Oedipus puts a kind of Holy Grail value on his quest, ultimately sealing his fate with his own zeal.
Pride prevents Oedipus from accepting the truth. While at first he respects Teiresias for his wisdom, Oedipus quickly turns on the prophet when he finds himself accused. Angrily, he demands, "And who has taught you this truth?" (357), dares, "Tell me again that I may learn it better" (358), and jumps to conclusions by accusing Creon of "brazen-faced daring that...you tried, openly, highway robbery of my crown" (533-535). Pride causes most of the pain that comes as a result of the truth. Queen Jocasta hangs herself from shame (1256), Oedipus violently blinds himself (1268) and requests his own death and banishment (1410).
While we feel sympathy for the horrible nightmare Oedipus is forced to endure, the audience must also feel a certain disconnect -- Oedipus cannot side-step his fate as willed by the Gods, and his downfall is made all the more dramatic by his own flaw, his pride.
