To what extent can we say Othello's tragedy is caused by jealousy in Othello?

On Othello's part, jealousy does not cause his
downfall. While Iago certainly demonstrates jealousy toward both Othello and Cassio and
uses that jealousy to propel his plot against the general and his lieutenant, it is
Othello's poor judgment in trusting Iago that leads to his downfall. He even tells Iago
that he is not a naturally jealous man and asks for "ocular" proof. If Othello had not
allowed Iago to mislead him, if he had not been conditioned by the culture of the time
to feel inferior because of his race, and if Desdemona would have defended her
reputation, then his tragic downfall could have been avoided--jealousy on Othello's part
does not play a part in the poor judgment, racial stereotypes, and naive timidity that
result in such a tragic ending.