The tone of Othello largely reflects Iago’s worldview, which is characterized by cynicism and suspicion. Iago expresses his cynicism frequently, and particularly in the play’s opening acts. When Roderigo, sorrowful at losing his chance with Desdemona, confesses, “it is my shame to be so / fond, but it is not in my virtue to amend it” (I.iii.), Iago has none of it. Iago responds that one’s “virtue” (or character) is not so static or predetermined as Roderigo’s conventional expression would suggest. “Virtue? A fig! ’Tis in ourselves that we are thus or thus. / Our bodies are our gardens, to the which our wills are / gardeners” (I.iii.).

Iago’s horticultural metaphor forcefully rejects the idea that a person’s character is set in stone; one can cultivate the attributes that are helpful in achieving goals, and suppress attributes that are harmful. Iago’s cynical philosophy of life prevents him from feeling remorse for his actions. From his perspective, he simply exercises his will on others and cannot be held accountable if those others lack his innate distrust and suspicion. To Iago, Othello’s naïve belief in an “honest Iago” is the real problem—not Iago’s treachery.

Iago’s cynicism sets the stage for the paranoid tone of the play’s second half. As Othello gradually falls under Iago’s sway, he too begins to utter suspicious comments that echo Iago’s cynical worldview. In particular, Othello adopts Iago’s misogyny. Not only does he begin alluding to the falseness of women, but he eventually calls his wife a “whore” to her face. His intensifying doubt reflects an all-consuming paranoia that stokes the fires of jealousy. As he grows increasingly paranoid, he descends into a nearly schizophrenic confusion.

In a moment of unreason he posits: “Nature would not / invest herself in such shadowing passion without some instruction” (IV.i.). Othello is saying he would not feel so deeply disturbed if nothing had really happened between Cassio and Desdemona. Therefore, since he does feel disturbed, the charge of adultery must be well founded. Othello, usually so reasonable, well-spoken, and self-assured, now employs a confused logic that showcases the tone of paranoia that overtakes the play.