How does pride make for more action in Oedipus Rex?

In a classic such as Oedipus Rex, the action of the plot is arranged with the six elements of tragedy, as defined in Aristotle's Poetics in mind:

1. There is foreshadowing, clues as to what will happen


2. There is a tragic mistake, hamartia


3. Arrogance is demonstrated by a character as a result of his/her pride or passion


4. The climax is the highest point of emotional tension where there is a catharsis


5. This catharsis is the purification of a character's emotions and/or relief of emotional tension.


6. The denouement is the reolution of the conflict

The pride of Oedipus is what generates his arrogance which effects the hamartia, thus bringing about the catharsis and denouement.  In short, it is what drives the plot.

First of all, when Oedipus leaves Corinth, fearing the words of the oracle that he would kill his father and marry his mother, he is forced off the road by a charioteer.  In his pride, Oedipus strikes at the man.  When the "old man" in the chariot--who is Laius--strikes Oedipus with his "double goad," Oedipus kills him in his rage, thus unwittingly fulfilling the prophecy.

Then, after he has become king of Thebes and unknowingly married Jocasta, his mother, Oedipus, having been informed about the "pollution" of the town, again asserts his pride, or hubris, and tells the people that he will rid the town of the curse.  He sends for Teiresias and Creon; when the oracle hesitates, he impatiently confronts him. 

Because of his pride, Oedipus wishes to believe he is in control of his life, so he says "However base my birth, I must know about it" (1020). Oedipus curses the oracle,"Now twice you have spat out infamy. You'll pay for it"(348); he accuses Creon of wishing to usurp his throne, "all the world may see what treason means" (591); he will not accept his wife's advice, "A man should live only for the present day" (930). Thus, in his hubris, Oedipus insists upon hearing the truth repeatedly from the reluctant tellers who fear for their lives (the shepherd), for his life (Jocasta), and for the future of Thebes:

The tryant is a child of Pirde/Who drinks from his great sickening cup/Recklessness and vanity/Until from his high crest headlong/He plummets to the dust of hope. (Antistrophe1/Ode 2)

While it is his flaw of pride that causes the tragedy of Oedipus, it is also that which makes him a well-rounded character.  For, otherwise he would appear too virtuous.  But, the irony of his words, "I must bring what is dark to light" foreshadows his blindness and and the tragic pride are what lend verisimilitude, not only action, to this great work.