Whether or not Oedipus" downfall should be attributed to his own free will or that of the gods can only be established by the reference point it is to be analyzed from. In the time of Dionysus and the day for which Sophocles wrote this tragedy one would have to assume Oedipus's downfall was most likely meant to be attributed to the will of the gods. However, one must take into account the reference point of our modern thinking and knowledge of analytics and philosophy. From this vantage point it should only be reasonable that Oedipus's downfall could be that of his own free will. There are many instances within the text of the play itself that give way to this analysis. .
The play starts off with King Oedipus talking with the people of his kingdom who have come to seek his help with the plague that has fallen upon them. The priest who has been chosen to speak for the group asks of Oedipus, " O mighty King, we turn to you: Find us our safety, find us a remedy Noblest of men restore life to your city!" (Oedipus the King Prologue 43-46). Oedipus knows it is his obligation as king to help his people so he ensures them he has already sent Creon his brother-in-law to the Oracle at Delphi to seek out the remedy of the plague. Creon returns to tell Oedipus that Apollo has commanded he take revenge on whoever killed the former King Laios. As any good king should Oedipus promises, "You shall see how I stand by you, as I should, To avenge the city and the city's god By avenging the murdered king- (Oedipus the King Prologue 138-143). With the knowledge of the back story in mind this promise is obviously full of peripity and the first of the instances where Oedipus by his own free will leads himself to his eventual downfall. .
After the people of the land yield no clues to the identity of the murder Oedipus sends for the blind clairvoyant Teiresias, hoping he can shed some light on the identity of the murderer.