In Oedipus Rex, Sophocles comments on various characteristics of Greek society. Rather than focusing on Oedipus' personal validation of existence, I am drawn to the study of Greek culture as a whole, and its various validations.
One of the elemental validations Sophocles reveals is that of a loyalty to the Gods. By portraying Oedipus' misfortunes as a product of his hubris, Sophocles argues that men who think themselves equal to the Gods are doomed to an ugly fate. Though Jocasta urges Oedipus to stop questioning the oracle and accept ignorance, he continues to probe the blind seer, bringing about his eventual demise. This is one example of a man believing he is above the will of the Gods, a veritable sin in Greek culture. Sophocles uses Oedipus to caution Greeks against hubris, and to illuminate an integral validation of existence for the Greeks, loyalty and obedience to the gods.
Additionally, Sophocles characterizes honor as a validation. Though Oedipus's life became steeped in shame, his decision to exile himself, thus removing his burdens from his people, appears honorable to his fellow men and to the audience. In order to be validated in existence as a Greek, Sophocles argues that you must have a strong sense of honor.
The last great validation for Greeks is respect for the well-being of Greek society. Oedipus remains respectful of his people, understanding that his own happiness is subordinate to the happiness of his people. He is constantly working to improve the lives of his people. When he learns of the plague, his sole focus becomes solving this plague and freeing his people from unhappiness. For the Greeks, this loyalty to one's people represents strong leadership, and even strong citizenship.