Pride is the main tragic flaw present in both Oedipus Rex and his daughter Antigone. A tragic flaw, or hamartia, is the defect in a hero's character that helps bring about his downfall. Both Oedipus and Antigone were so sure they alone knew the moral high road, even in the face of others' advice to them, that they did not always stop to think about all the possibilities.
Oedipus had been warned of his fate: he was destined to kill his father and marry his mother. He did not know who they were, but in his own feelings of self-sufficiency, he sought to escape his fate without trying to find the identity of his parents. He had so much pride in his ability to thwart his fate that he did not even think it was a possibility that the man he killed was his father. In the same vein, it never occurred to him that this older woman he married was his mother. In his pride he believed he was able to make things right and despite the warnings given him, he was determined to find the killer of Laius and vowed the murderer's destruction.
Antigone also believed she knew what was right. When the king ordered that her brother not be buried, her loyalty prevented her from accepting that edict. In spite of her sister's pleas, she was determined to do what she thought was right with little thought to how her actions affected her sister or her fiancée. Her speech to her uncle, the king, was defiant and prideful. She did not even try to approach him from a more humble standpoint.
The pride in both of these characters led not only to their own downfall but to that of others as well.