Oedipus is “Son of Laios and Iokaste, father’s murderer, mother’s husband," but what is he in a psychological/ philosophical sense?
We all know that Oedipus is the stereotypical tragic hero--as the title is defined by Aristotle. We know who his parents were (and we know who he thought his parents were), and we understand his rise to power in Thebes. But essentially, Oedipus is a tragically flawed character--one whose hubris, or pride, is responsible for his tragic downfall. To audiences, Oedipus's story is one that evokes catharsis; we see a great man's fall from power because of fate. As Aristotle noted, an effective tragedy should evoke pity and fear in the audience. We feel pity for tragic heroes because their fall is so sudden and so dramatic, and we experience fear because, if someone so important and noble can experience such a downfall, so can we. Essentially, Oedipus's character is representative of these ideas.
I would look at the answer to this question as more of an existential one: all humans must come to terms with their true identity at some point, musn't they? It is the means by which we define our individual presence or "value" if you will, that provides us with a legitimate sense of self-awareness and/or understanding. Oedipus is, at this point in the play, in the early stages of "finding himself" and so he is still somewhat unprepared for the truth of his own participation in the death of Laios, but his psyche must already understand on some level, his culpability, so the psychological aspect has to do with the levels of human self-awareness also; what we consciously know of ourselves versus what we subconsciously know.
Oedipus questions who he is in all kinds of ways in this play. Is he really the true son of Polybus and Merope? Is he really the child supposedly left for dead on a mountaintop--at his parents' request? Is he really the brother/father of his children and the son/husband of his mother/wife? It's this search for self which initially motivates him and then spurs him on to the deeds which seal his fate. Who is Oedipus? His name means "swollen-foot," but he has become synonymous with "cursed one."