In Othello, Iago suffers from any combinations of the following:
1. Jealousy that Othello is General and he is not. This stems from an overdeveloped sense of male reputation from an honor culture (military rank and Great Chain of Being).
2. Jealousy that Cassio is appointed as Lieutenant and he is not
3. Jealousy that Othello has married Desdemona, a senator's daughter. He is jealous that Othello's wife is more desirable than his own.
4. Sexual jealousy that Othello has "done his service betwixt the sheets"--that Othello has seduced Emilia. Fear that a black man is superior to a white man in bed.
5. Fear that Black men are all out to seduce white women. Iago is a protector of racial purity (white virgins).
6. Racism against Othello as a black man
7. Fear of Islam, as Othello is a former Muslim
8. Pure evil. Iago is a Satanic / Vice figure who represents unmotivated guile. As such, he is an agent of chaos.
9. Homosexuality. Iago suffers denial regarding his sexual attraction to other men (soldiers), namely Othello.
Iago does evil because he is an evil personfied by Shakespeare. Some time he seems jealous, some time racist and some time exploiting the difference of culturs. He tries to find reason of his action afterwards. This is the way of devil.
Evil incarnate, racism, jealousy