Appearance vs. Reality
This theme is especially relevant to the issue of Iago's character. For although he is called "honest" by almost everyone in the play, he is treacherous, deceitful, and manipulative. This also applies to Desdemona, as Othello believes that she is deceitful and impure, although she is really blameless and innocent. This theme contributes greatly to the tragedy, as Iago is able to engineer his schemes due to the perception of others of his honesty. Othello's decision to murder his wife is hastened by a conversation in which Cassio speaks of Bianca; Othello assumes the man is talking about an affair with Desdemona.
Misrepresentation allows Iago to gain trust and manipulate other people; he is able to appear to be "honest," in order to deceive and misdirect people. Although the word "honest" is usually used in an ironic way throughout the text, most characters in the play go through a crisis of learning who and who not to trust. Most of them, unfortunately, trust in Iago's honesty; this leads to the downfall of many characters, as this trust in Iago's "honesty" became a crucial contributor to their undoing. Discovering or uncovering reality would have changed the course of the play.
Race
Race is an extremely important theme, as it leads to Othello's insecurity, which Iago is able to manipulate. Despite his standing and military prowess, Othello never feels comfortable in Venice because of his otherness. As a Moor, he is constantly stereotyped as "savage" or "animal", even though he speaks eloquently and displays more gentlemanly qualities than those who judge him. Thus, Othello perceives himself to be a rough outsider, though he is nothing of the sort. Othello's race sets him apart, and makes him very self-conscious; it makes him work hard and look carefully after his reputation, so he is regarded as equal to the white people that surround him. This has perhaps led to his success, but the prejudice that surrounds him - especially with respect to his marriage to Desdemona - has tragic consequences.
Pride
Othello is defensively proud of himself and his achievements, and especially proud of the honorable appearance he presents. The allegations of Desdemona's affair hurt his pride even more than they inflame his vanity and jealousy; he wants to appear powerful, accomplished, and moral at every possible instance, and when this is almost denied to him, his wounded pride becomes especially powerful.
Magic
Othello is charged with using magic to woo Desdemona, merely because he is black, and therefore, "pagan." Yet, Othello does have real magic, in the words he uses and the stories he tells. Magic also reappears when Desdemona's handkerchief cannot be found; Othello has too much trust in the symbolism and charm of the handkerchief, which is why the object is so significant to him.
Order vs. Chaos
As Othello begins to abandon reason and language, chaos takes over. His world begins to be ruled by chaotic emotions and very shady allegations, with order pushed to the side. This chaos rushes him into tragedy, and once Othello has sunk into it, he is unable to stop his fate from taking him over.
Self-Knowledge
Othello's lack of self-knowledge makes him easy prey for Iago. Once Iago inflames Othello's jealousy and sets the darker aspects of Othello's nature in motion, there is nothing Othello can do to stop it, since he cannot even admit that he has these darker traits. Even after he has murdered his wife, and has learned that Iago set a trap for him, Othello is unable to acknowledge the character flaws that were manipulated. He asserts he is "honorable" even in murder. This theme is related to pride, as Othello's pride blinds him to his weaknesses, precipitating his downfall.
Good vs. Evil
Iago's battle against Othello and Cassio certainly counts as an embodiment of this theme. Iago and his evil battle to corrupt and turn the flawed natures of other characters, and he does succeed to some extent. By the end of the play, neither has won, as Desdemona and Emilia are both dead, and Iago revealed and punished. Othello is a tragic character, but one that is neither good nor evil. His flaws are easily manipulated, and he is unable to see the truth while blinded by pride. He is a good soldier and a good man, but this good is twisted and he commits an evil act.
Desdemona is the embodiment of goodness in the play, as she has done no wrong and seeks only to love and to help her friends. However, she resigns herself to her death out of this goodness. The ruin of innocence is a key ingredient to tragedy, but one could interpret that Desdemona did not have to suffer her fate. Othello represents a grey area between good and evil, where self-interest clouds even the best intentions, and people on both sides end up dead.
