Oedipus Rex: How did he determine his own downfall as oppose to fate?

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"Given our modern conception of fate and fatalism, readers of the play have a tendency to view Oedipus as a mere puppet controlled by greater forces, a man crushed by the gods and fate for no good reason. This, however, is not an entirely accurate reading. While it is a mythological truism that oracles exist to be fulfilled, oracles do not cause the events that lead up to the outcome. In his landmark essay "On Misunderstanding the Oedipus Rex",[15] E.R. Dodds draws a comparison with Jesus's prophecy at the Last Supper that Peter would deny him three times. Jesus knows that Peter will do this, but readers would in no way suggest that Peter was a puppet of fate being forced to deny Christ. Free will and predestination are by no means mutually exclusive, and such is the case with Oedipus.

The oracle delivered to Oedipus what is often called a "self-fulfilling prophecy", in that the prophecy itself sets in motion events that conclude with its own fulfilment.[16] This, however, is not to say that Oedipus is a victim of fate and has no free will. The oracle inspires a series of specific choices, freely made by Oedipus, which lead him to kill his father and marry his mother. Oedipus chooses not to return to Corinth after hearing the oracle, just as he chooses to head toward Thebes, to kill Laius, to marry and to take Jocasta specifically as his bride; in response to the plague at Thebes, he chooses to send Creon to the Oracle for advice and then to follow that advice, initiating the investigation into Laius's murder. None of these choices is predetermined.

Another characteristic of oracles in myth is that they are almost always misunderstood by those who hear them; hence Oedipus's misunderstanding the significance of the Delphic Oracle. He visits Delphi to find out who his real parents are and assumes that the Oracle refuses to answer that question, offering instead an unrelated prophecy which forecasts patricide and incest. Oedipus's assumption is incorrect: the Oracle does answer his question."

In the play it was fate because the Oracle told him what would happen. The irony was that by trying to avoid his fate he made it happen. This lesson applies more to understanding drama (specifically Greek Tragdedy) and less to understanding real life. You should read some version of the play, even a synopsis (look up synsopsis ) to get the important details.

By trying to run away from his fate, he instead ran into his fate.