It is unclear whether Shakespeare intended Iago to appear as evil as he does but one thing is for sure; Iago remains one of Shakespeare's most debated villains. It is Iago's motives for scheming that continue to be the most intriguing aspect of his existence. Often critics tend to concentrate on discrediting his motives. Describing Iago's motives as being weak has almost become a given. There are two general ideas from the sources that I found. One of the ideas sees Iago as a conspicuous character whose sole purpose is to generate evil. Another analysis of Iago is that Shakespeare has created Iago to be a very dramatic villain rather than an evil one. These broad generalizations do not correlate in any kind of rationalization for Iago's demise. That is what my theory intends to elaborate on. .
By not establishing a clear motive, Iago's plan becomes so broad that he involves too many people for the result to be favorable to him. His aggression against Othello starts when Othello names Michael Cassio his lieutenant rather than Iago. This motive would have been valid if he had not involved Desdemona and Emilia. He could have easily gotten revenge at Othello and Cassio by just going after them. Another possible motive is that Othello has committed adultery with Emilia. This motive brings Desdemona and Emilia into Iago's plotting. He now feels he needs to involve everyone in his evil scheme. When Iago convinces Roderigo to start a fight with Cassio at a party, it appears obvious that Iago's plot to become lieutenant will come full circle. But Iago consulting Cassio after the altercation makes no sense for his motive to become lieutenant. .
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On a very surface level, Iago comes off as being just plain evil. Many critics would agree with this and would be content to think that Shakespeare created Iago to merely show evil. Richard Flatter feels that due to weak motives as a soldier and as an angry husband, Iago must be plotting just because he has a passion for scheming.