Why does Malcolm misrepresent his character to Macduff in Act 4 of Macbeth?

The play is about betrayal and trust.  We see that Duncan made a fatal mistake in trusting Macbeth.  Malcolm does not want to make the same mistake in trusting Macduff, who wants him to return to Scotland.  Fearing a trap (Remember Braveheart?), Malcolm must test Macduff's loyalty.  After all, Macduff's presence in England is somewhat suspicious.  Malcolm wonders how Macduff could leave his wife and children to come to England.  Perhaps Macbeth sent him and has guaranteed protection for them. If Malcolm returns to Scotland with Macduff, how can he be sure that some sort of ambush is not awaiting him.  He knows that Macbeth would like to see him dead, and Macduff could be working for Macbeth.  So, he lies to Macduff and tells him that he is the worst kind of man:  greedy, lustful, devoid of kingly virtues.  If Macduff still wants him to return to Scotland, then Malcolm knows that it is a trap.  But when Macduff hangs his head and walks away in frustration, Malcolm knows that Macduff is sincere in his desire to have the rightful monarch on the throne of Scotland.

What does Malcolm's lie to Macduff in Act 4, Scene 3 reveal about his character in Macbeth?

In this scene, Malcolm deliberately lies to Macduff because he wants to test Macduff's loyalty and trustworthiness. Specifically, Malcolm falsely presents himself as a man with extreme sexual desires who is driven by the "cisterns" of his lust. In addition, he tells Macduff that he is very greedy and would deliberately cause arguments ("quarrels unjust") with his subjects so that he could confiscate their lands and "wealth."

No matter what Malcolm says, Macduff's loyalty does not falter. He defends each of Malcolm's lies and becomes even more determined to overthrow Macbeth.

That Malcolm lies to Macduff demonstrates that he is a cautious person who wants to know who he can really trust. He wants to surround himself with the right people because he knows that this is the surest way to guarantee success against Macbeth.

What does Malcolm's lie to Macduff in Act 4, Scene 3 reveal about his character in Macbeth?

This is a rather curious scene in this play where Malcolm shows his own character and ability to manipulate and test his subjects. In response to Macduff's claims that Macbeth must be deposed, Malcolm presents himself as an even worse king than Macbeth, saying, for example, that:

But I have none: the king-becoming graces,

As Justice, Verity, Temp'rance, Stableness,

Bounty, Perseverance, Mercy, Lowliness,

Devotion, Patience, Courage, Fortitude,

I have no relish of them; but abound

In the division of each several crime,

Acting it many ways.

He clearly exaggerates his own "evil deeds," lying to Macduff deliberately to test his loyalty to Scotland rather than to a specific person. When Macduff says that such a king should not be given power, Malcolm says:

Macduff, this noble passion,

Child of integrity, hath from my soul

Wip'd the black scruples, reconcil'd my thoughts

To thy good truth and honour.

Malcolm therefore quite coldly has tested Macduff to work out where he stands and if he can be trusted. The main function of this scene appears to be to assess the moral forces present in the drama that are opposed against the evil of Macbeth, however, rather worryingly perhaps, Malcolm shows himself able to manipulate others and test them for his own motives and reasons, which could either be shown as a sign of political maturity or a sign of potential evil to come.

In Act 4, Scene 3 of Macbeth, why does Malcolm lie to Macduff?

In Act IV, MacDuff has gone to England in order to get English military support and convince Malcolm to return to Scotland.  He has suspicions that Macbeth killed Duncan and knows that his is a tyrannical ruler who must be stopped.

Remember that after his father's death, Malcolm fled to England so that whoever killed his father wouldn't be able to kill him.  When MacDuff shows up saying that he wants to bring him back to Scotland in order to restore his role as king, Malcolm is not sure if he should believe him.  Malcolm lies about himself in order to test MacDuff's loyalties and ensure that they lie with Malcolm.  Before he will join MacDuff, he wants to make sure they are on the same side- a side that wants what is best for England.

It is myself I mean, in whom I know
All the particulars of vice so grafted
That, when they shall be open'd, black Macbeth
Will seem as pure as snow, and the poor state(60)
Esteem him as a lamb, being compared
With my confineless harms.

I grant him bloody,
Luxurious, avaricious, false, deceitful,
Sudden, malicious, smacking of every sin
That has a name. But there's no bottom, none,
In my voluptuousness Your wives, your daughters,(70)
Your matrons, and your maids could not fill up
The cistern of my lust, and my desire
All continent impediments would o'erbear
That did oppose my will. Better Macbeth
Than such an one to reign.(75)

Why does Malcolm lie about himself to Macduff?

The scene between Malcolm and Macduff in Act IV sc iii appears very confusing at first glance until we realize Malcolm is actually testing Macduff’s loyalty to Scotland.  Malcolm tells Macduff that he will be a far worse tyrant than Macbeth will:

“It is myself I mean: in whom I know
All the particulars of vice so grafted
That, when they shall be open'd, black Macbeth
Will seem as pure as snow, and the poor state
Esteem him as a lamb, being compared
With my confineless harms.”

At first Macduff does not believe him, since Macbeth is such an evil, treacherous leader. No one else could possibly be worse.  However, Malcolm claims he is extremely lustful, greedy, and unjust. He would deliberately abuse the powers that come with being king for his own pleasure and gain, completely opposing any action that would be for the good of Scotland. Macduff finally believes him and rebukes him for being such a vile son when King Duncan was such a noble father. He agrees that Malcolm should not govern Scotland, and he weeps because the country he loves has no hope of escaping oppressive tyranny.

At this point Malcolm confesses that everything he said about himself was a lie. He wanted to see how Macduff would react. If Macduff were fine with Malcolm becoming king even though he was as bad (or worse) for Scotland than Macbeth, Malcolm would know that Macduff did not truly love Scotland. Macduff would just be trying to gain advantage by aligning himself with a new tyrant, and therefore could not be trusted.

Macduff passes the test, showing that his love and loyalty are to his country above himself. When Malcolm sees this, he tells Macduff the truth and explains his current plans to dethrone Macbeth. The two become allies.