In the play, Oedipus Rex, the main character (Oedipus) is a very misfortunate man. When he was born his father (Laius) was prophesized to be killed by the boy and his mother was prophesized to sleep with Oedipus. In the end the prophecy came true but Oedipus was in no way to blame. The Gods used him as a weapon to punish his parents, hexing him in the process. His parents tried to avoid their own fate by eliminating him from the picture and in doing so they actually gave him a roundabout way to bring his demise and their own.
Oedipus" misfortune was caused partially by his parents. They tried to avoid their fate by killing him. In doing this they made him not know his true lineage. This brought his demise by causing him to flee from his surrogate parents when he learned the prophecy, and run straight to his true parents. Jocasta didn't help him to realize the truth, so she just prolonged Oedipus" mental torture. By committing suicide instead of telling him of her suspicions, she made him more remorseful, causing his downfall. She had good intentions in not telling Oedipus what she had figured but instead got the opposite effect causing even more pain. .
The most powerful force in determining Oedipus" fate was the Gods. No matter how hard he tried to avoid his fate they held their ground. Once they saw how passionate he was about saving himself and his "parents", the Gods should have shown some compassion and kept him from his horrific future. He still couldn't escape the Gods though. They could have sent someone to warn him but instead he had to send for a prophet himself for information. (Which didn't help immediately, like an informant from them may have.) They didn't even give him a chance to escape his downfall and blinding.
In the end Oedipus did seem a bit ignorant. Though he was a little foolish, he still was not guilty. Some might say he earned his fate. They may even state that they have "proof" to back up their theory.