Iago is motivated by the desire to know and show what Othello is really like

-          W H Auden

To what extent do you agree with this view?

Argument; disagree.
It is not Iago’s desire to reveal Othello’s true character that motivates him, but rather on a more profound level we see that lago's true motive is his blatant love of evil. Iago is using jealousy and anger as excuses to perpetrate evil. Even if Iago had received the promotion; even if he had no suspicions or jealous feelings, he would invent other motives to provide the framework for the diabolical mischief he must create. To Iago, the ruination of Othello is a game:
Quotes in chronological order to support the idea of Iago’s true evil nature:
One Michael Cassio, a Florentine
(A fellow almost damn'd in a fair wife),
That never set a squadron in the field
But he, sir, had th' election ... (1.1.20-27)
Here it is evident this is an unsatisfactory reasoning for bringing about the tragic ending of the play, thus leading us to conclude that Iago himself must be mentally challenged through his desire to perpetuate evil constantly.
... I hate the Moor;
And it is thought abroad that 'twixt my sheets
'Has done my office. I know not if't be true;
Yet I, for mere suspicion in that kind,
Will do as if for surety. (1.3.378-82)
Again, his evil intentions are highlighted here as it is apparent he does not believe these rumours are true; there is a deeper meaning to his schemes.
Let us be conjunctive against him. If thou canst cuckold him, thou dost thyself a pleasure, me a sport. (1.3.363)
Honour, loyalty, reverence, and fidelity - the highest and the holiest virtues of humanity - are but base commodities to be bought and sold. Iago is "an unbeliever in, and denier of, all things spiritual, who only acknowledges God, like Satan, to defy him" (William Robertson Turnbull, Othello: A Critical Study, 269).
In act 3 scene 3 Othello demands ocular proof, Iago brings out the handkerchief, the magical symbol of Othello's manhood and source of his jealousy:

I know not that; but such a handkerchief--
I am sure it was your wife's--did I to-day
See Cassio wipe his beard with.

Upon proof that Cassio has the handkerchief, Iago gets Othello to effectively divorce Desdemona and align himself with Iago.  His plan to kill her is not only persuasive but very clever: he knows that Othello will be put to death for the crime.  Othello says,

Damn her, lewd minx! O, damn her!
Come, go with me apart; I will withdraw,
To furnish me with some swift means of death
For the fair devil. Now art thou my lieutenant.

Proof of Iago's evil is easy to come by, but he is no more evil that when he uses his wife as a pawn in his twisted revenge plot.  In act 5 scene 2 he calls her a ‘Villanous whore!’ and ‘Filth, thou liest!’ he then he stabs her.  Pure evil.
Possible counter-argument; rather than Iago’s evil nature that possesses him and causes the ultimate tragedy of the play to occur, it could be credible to believe that Iago merely desires to show Othello’s true qualities. Othello often relies on stories such as those that won over his gentle Desdemona, similarly those he attempts to use to persuade the state that his love should be accepted because of the acts of magnitude he has committed in the past e.g. ‘shall outongue his complaints’. Iago may believe Othello is a threat to society with such a high status for a Moor whom cannot possess that much authority and remain sane. Hence his reasoning for his what appears an evil plot; he succeeds in displaying how easily Othello can be led astray.Conclusion; therefore it could be credible to formulate an argument based around the ideology that Iago has no conscience, no ability to perform good deeds. Iago is a psychopath, and is not capable of forming affectionate relationships or feeling guilt and concern over his behaviour. Unlike Othello, Iago does not have the free will to refrain from wickedness. His nature does not enable him to see the goodness in anyone or anything; he is driven by a lust for evil beyond his control, as opposed to a quest to reveal Othello’s true nature as Auden suggests.

Psychologically Iago is a slighted man, powerfully possessed by hatred against a master who (as he thinks) has kept him down, and by envy for a man he despises who has been promoted over him.

Neville Coghill

To what extent do you agree with this view?

Argument; agree.

Iago uses the power of his hatred to guide the play along the tragic route it follows. Iago claims the reason for his hatred is that Cassio has been promoted over him –

One Michael Cassio, a Florentine
(A fellow almost damn'd in a fair wife),
That never set a squadron in the field
But he, sir, had th' election ... (1.1.20-27).

Counter argument: it is not just this reason that Iago 

2 paragraphs from internal exam

The fact that the extract is set in a dark location which lacks daylight, indicated by the mention of ‘torches’ emphasises the duality of night and day. The darkness introduces an eerie feel and a certain disorder rules over the proceedings. With the torches that illuminate the scene, there is a corresponding call for some kind of order; darkness vs. light and order vs. disorder are important juxtapositions within the play. This theme will appear again at the end, as the play returns to darkness, and also to chaos. The darkness also suggests the attendants that hold the torches are attempting to illuminate the truth, it is tragic in which the noble manor Othello responds to these abrupt demands of the truth in comparison to less noble manor in which his characters begins to act in as the play continues – such as the equivalent of modern day swearing ‘fire and brimstone’ in Act 4 Scene 1.

This extract is also tragic in relation to the play as a whole as it demonstrates not only the duality of night and day but also the duality of Othello’s character. ‘Shall out-tongue his complaints. ‘Tis yet to know – Which, when I know that boasting is an honour, I shall provulgate’ indicates this as it is evident that Othello is both an insider because of his status in the military as a ‘worthy general’, but similarly how he is an outsider because of his race as a ‘moor’. Othello is confident his past service to the state will counteract any negative emotion society will feel upon his love for Desdemona. Othello depicts this view through his talk of stories, similar to his stories that he states enabled him to win the love of his wife. This correlates to McEvoy’s view that Othello ‘lives according to a set of stories’, it is tragic that he believes these stories that won ‘thee gentle Desdemona’ will also win over society. Arguably it is not society that needs to be persuaded of the legitimacy of their love, but Othello himself as he so easily allows his mind to be poisoned by Iago; thus contributing to the tragedy of the play as a whole.