Tragedy, Fate And Hamartia:
The most common definition of tragic hamartia is "tragic flaw", but we need to be careful with this term and understand what the Greeks meant by "flaw" and how it relates to a broadly defined sense of "fate": Through hamartia, the tragic hero visits his own fate upon him or herself. In this way, "fate" is transformed from some metaphysical concept -- "the will of the gods," "the divine order of the cosmos" etc. -- to one in which we see our fates as tied to inherent elements of our selves, of our psyches, that ordain our destinies.
To put it in a simplistic way, hamartia means "no matter where you go, there you are"; there are elements of our selves from which we simply cannot escape, and, for the Greeks, these elements are "inherited" and will sometimes determine the course of our lives.
Oedipus has long offered the classic example. At first glance the story seems to argue that we are all bound to an inescapable fate, a destiny beyond our control, and that it is folly to try to escape it, but a deeper reading reveals that it is the very same elements of Oedipus' personality that have made him a hero to the people of Thebes that will ultimately lead to his downfall; in other words, he has led himself to his own undoing.
Consider Romeo and Juliet as "star-cross'd lovers" ultimately undone by their own hamartia; although they are somewhat "doomed" by the bigoted Veronese social order, ultimately their own, impatient adolescent passions rush them toward death.
If Romeo And Juliet were a medieval Christian play, or if it took place in Hebrew scriptures, we'd probably interpret their hamartia as "sin"; they have not honored the will of their parents and they have violated their communities' morals, so clearly they've been punished by God. But Shakespeare's Renaissance view of tragedy is principally Greek, not Judeo-Christian, and we are left seeing their destructive passions, their youthful, idealistic, impatient love, as tragically beautiful. It is a painful beauty, but it is beauty none-the-less.
And this is how we should approach Oedipus; fate, the will of the gods is a metaphor for the workings of both those social and natural forces beyond our personal control and the inescapable elements of our own psyches -- our own selves that both make us heroic and tragic, and thus make us beautiful.
...and "flawed" or, most telling, in Oedipus' and Romeo and Juliet's cases, doomed by ignorance, knowledge and experience.
Hamartia And Hubris
At this point you've probably guessed the close link between hamartia and hubris, for what makes us great often leads to our own downfall when it is excessive.
Tragedy and Celebrity Hubris
Remember that these plays are likely, loosely based around actual, historical figures, so in many ways they are an artistic representation of reality. In our culture these same "tragedies" play out nearly identically in the media's treatment of, say, Whitney Houston, Amy Winehouse, Heath Ledger, Kurt Cobain, Marilyn Monroe etc etc.
Fate As Metaphor
Death: It's worth remembering that the word "fatal", meaning "deadly" is rooted in the word "fate". Life is fatal: it ends in death, inevitably. There is no escaping this fact. Thus, each and every life carries a tragic fate: we all fall from a great height, despite all of our greatest efforts.
Gilgamesh wrestles with this: he must make his peace with mortality. Achilles wrestles with it. Adam and Eve's ejection is fated and tragic: it seems bound to happen given human nature, and to be human they cannot eat of the Tree Of Life and thus become immortal.
Family: Both Greek and Shakespearean drama roots tragic fate in family. It reminds us that although we remain free to determine the course of most of our lives, much of who we are fated to become is tied to the choices our parents, and their parents, and their parents' parents etc. made: the future is inexorably connected to the past: the past determines the future.
We Americans like to pretend that we will reap the rewards of our own labors, but how much of who you are was determined by those who chose to emigrate to this country, or live in the town(s) you grew up in? How much was determined by your race or the language that you grew up speaking at home?
Or from another, more personal, angle, at some point we must make our peace with who we are: we cannot escape our heritage or those elements of ourselves we find repugnant: tragedy reminds us there is no escape. As teenagers many of us vow to never become like our parents, to make their mistakes and live their dull lives. And then you have your own children and one day look into the mirror to find your father or mother's face staring back at you. Orestes and Oedipus remind us all that there is no escape from who we are, and much of who we is who our pasts -- especially our family -- once were.
This suggests we might see hamartia as "layered", like an onion: on the surface, fate seems beyond one's control and "the will of the gods", but dig deeper and we find we will our own fates through our own personalities and character traits, but dig deeper still and we find our character traits were in turn formed largely by luck: you did not choose your parents; you did not choose your DNA; you did not choose what continent you were born on or in what century you found yourself.... You did not choose your skin color or how others perceive that color; you did not choose to be born, say, to a parent who would be killed in war or to be born to one who inherited tens of millions of dollars and sent you to the best private schools.... In short, fate determines your character, and your character then determines your fate.
Tragic Irony and Negative Capability:
Such truths are inherently ironic, in the literal term, which is to say that involve an order, a logic, but it is an inverted logic: the events unfold in the *opposite* manner than intended or expected. (Eric McMillan)
Our brains are wired for logic and seeing and remembering patterns is of great evolutionary value – we remember that when the sun goes down “over there” it will rise again after night on the opposite side of our periphery; we note that spring follows winter and summer spring and we must plant seeds in early spring if we want to harvest food in the summer or fall etc.
But life seems to unfold at times with an illogical logic: an ironic, inverted logic, wherein the opposite of what we expected and plans happens, often with the most ironically tragic outcome (witness Oedipus).
Thus there is a disjoint between our logical minds and this illogical existence. Religion expresses that disjoint via faith and divine will; as God says, “I am that I am,” meaning, my order is a mystery beyond your comprehension.
Art expresses this disjoint via tragedy, which is inherently ironic, and what Keats called Negative Capability, which our logical minds can only somewhat grasp, or glance. Math can express order, but art can express disorder – art can give us an understanding of that beyond understanding.
Negative Capability: “that is when man is capable of being in uncertainties, Mysteries, doubts, without any irritable reaching after fact & reason…” Letters. Allowing rationally contradictory ideas and/or sensations to exist at once. As a key piece in all modern poetry, philosophy etc. -- (over) simplified as “paradox”. Negative capability is associated with The Sublime. We can achieve the sublime through language only by breaking down binary (either/or, yes/no) rationality. ...in many ways this is what we mean by "romanticism": a renewed embrace of emotional and even spiritual knowledge privileged over rational, Enlightenment knowledge.
" . . several things dovetailed in my mind, & at once it struck me, what quality went to form a Man of Achievement especially in Literature & which Shakespeare possessed so enormously--I mean Negative Capability, that is when man is capable of being in uncertainties, Mysteries, doubts, without any irritable reaching after fact & reason…”
Letters, December 21, 27 (?), 1817