10. In Act 3, Scene 3, what weakness or incapacity of judgment does Othello betray? By the end of 3.3, what deterioration or contraction has taken place in Othello's outlook on his career and his marriage?
Passion is Othello's greatest strength and weakness. It is what allowed him to rise to success in Venice through difficult victorious battles, though he is an outsider; and it led to Desdemona's attraction to him. It is, therefore, logical that passion would be his intellect's defeat.
If someone were to try to undo him, as great a warrior as he is, challenging him would not be the way to do it. Rather, Iago cunningly slides right into Othello's weakness to destroy him by attacking him at his greatest passion: his love.
Since Othello experiences his emotions so strongly, it doesn't take much to plant the seeds of suspicion and jealousy into Othello's mind concerning the thing most precious to him: his wife Desdemona. All it took was one passing comment from Iago for Othello's nature to conveniently press and press him into a totally set up, false, reluctant confession of thoughts, which was the beginning of Othello's loss of peace of mind.
In act 3, scene 3, Iago casually asks Othello, "Did Michael Cassio, when you wooed your lady / Know of your love?" (96-97)
Iago's fishing tactic works well, as Othello continues on with the subject: "Why dost thou ask?" (98), "Why of thy thought, Iago?" (100), "Dincern'st thou aught in that?" (104), and "What dost thou think?" (108). Finally, after much pretend restraint mixed with dropping hints, Iago warns Othello of the very thing he intends to infect him with: jealousy.
"O, beware, my Lord, of jealousy. / It is the green-eyed monster which doth mock / The meat it feeds on." (169-171) And then continues: "Look to your wife. Observe her well with Cassio." (201)
Othello's undoing is now firmly in place, and so is Desdemona's. Othello will neither sleep nor take satisfaction in anything, nor will he find any virtue or hope in anything he does, which is reflective of how he compares his long military career and life success: "O, now for ever / Farewell the tranquil mind, farewell content, / Farewell the plum?d troops and the big wars / That makes ambition virtue! . . . / Farewell! Othello's occupation's gone." (353-355, 363) He wallows in obsessing, of which he has no control. He finds himself so vexed, that he wishes he had not known anything of Desdemona's alleged adultery. "I had been happy if the general camp, / Pioneers and all, had tasted her sweet body, / So I had nothing known. (350-352)
Othello's history of hard-won combat mixed with his experiences of racism also feeds into his paranoid thoughts of pain and betrayal. After all, he is a valued military leader who's staked his life in service to Venice, yet he would have been denied his choice of woman for marriage that would have been available to any other citizen of his high stature. It would make sense then that his anxiety of Desdemona's infidelity would be further fueled by an affair with a white foreigner — Cassio, who is Florentinian — and yet experiences acceptance taken for granted, something of which Othello has worked hard to earn, and remindfully had been denied. Consequently, the nature that compelled Desdemona to sneak away during the night to marry him now stings him in his doubts, and her father's words from act 1 haunt him: "Look to her, Moor, if thou hast eyes to see. / She has deceived her father, and may thee." (291-292)
Totally convinced by Iago that Desdemona has been unfaithful with the very man he promoted to lieutenant, he vows, with Iago by his side, that Desdemona and Cassio will die.
The murdering of a wife by her husband after making a cuckold of him fits into a couple genres: it is a literary convention and, in the context of male honor, this is necessary to restore respect both on the part of oneself and the surrounding community. "The cause" is something Othello will repeat later in act 5, which is a form of justice that trumps his love for her. But more importantly, from a character point of view, I feel that, again, it is Othello's passion which allows him to be the perfect lead character of this play, and which compels him to murder Desdemona. In this case, it is his fiery anger from the pain he feels of being betrayed by Desdemona. He can only satisfy it with revenge. The amount of hurt and anger he feels is directly proportionate with the amount of love he feels for Desdemona — which is why he becomes broken.