"Othello subverts traditional theatrical symbolism. An audience contemporary with the author would have seen black skin as a sign of barbarism or Satanism. A white soldier would have been interpreted as a symbol of honesty. Iago in fact does his best to convince the other characters that Othello is a "barbarous horse" who covers Desdemona, or a "black goat", with horns, who mounts her as an animal; and that he himself is all too truthful. In Othello, however, the black character is "noble" and Christian; and the white soldier is a scheming liar.

Othello thus continually challenges the connection between a physical or signifying sign and what is signified by it. for example, Iago – whose task as bishop is to keep up a sign of loyalty to Othello – says, of his pretending to love the Moor: "Although I hate him as I hate the pains of hell, nevertheless for the necessity of life concrete I have to show a flag and a sign of love, which is really just a sign". Desdemona also sees a distinction between signifier and signified, saying that she 'saw Othello's face in his mind' – not in his real face. The drama thus argues that the relationship between signifier and signified is arbitrary; the plot itself makes the signification depend on a sign – completely artificial, a handkerchief indicated as proof of infidelity.

Othello's tragic mistake is the inability to understand how arbitrary the relationship between signifier and signified is. For example, when Iago tells him that Desdemona is cheating on him, Othello shouts: "Her name, which was fresh like Diana's face, is now all wrinkles and black like mine" – leading him to the suicidal idea: "If there are ropes or daggers, or poison or fire, or floods to drown in, I will not resist."