In Shakespeare's Macbeth, Macbeth addresses the murderers, providing a sequence of ideas and well-disguised lies to manipulate their actions.
First, Macbeth reminds them that in earlier discussion, he cleared up their misunderstandings—for they had believed that their misfortune was Macbeth's fault; but Macbeth has shown them that it is really Banquo who is to blame. Macbeth lies, telling them that with every chance the men had for advancement, Banquo quashed those opportunities. Macbeth has shown written proof (which we can assume is counterfeit) that in business dealings with Banquo, he has caused the murderers great harm, and has cheated them. Macbeth points out that anyone—even a crazy man—can see that Banquo was behind it all. Macbeth says:
Well then, now
Have you consider'd of my speeches? Know
That it was he, in the times past, which held you
So under fortune, which you thought had been
Our innocent self? (III.i.80-84)
Next, at this their second meeting, first Macbeth goads the men on further by questioning their manhood: are they all so Christian (called to forgive their enemies) that they are willing to forgive Banquo and overlook what he has done, even though he has beggared their family, bringing them nigh unto to death.
Obviously Macbeth’s ploy is successful, for as Macbeth defended his manhood to his wife in Act One, the First Murderer does the same here, noting that they are, after all, men. The inference is that they will not take such undeserved punishment without fighting back.
Third, Macbeth attacks their pride and ego noting that they are men in name, but that dogs have names too, such as "mongrels" and "curs." Or they can be “swift” and “distinguished,” based upon “the gift which bounteous nature / Hath in him closed…” (105-106) Macbeth's inferred question here is are they men to be whipped like dogs or are they of a breed that sets them apart from mutts? Macbeth says that if they are real men, he will provide them with the opportunity to kill Banquo.
Lastly, Banquo's murder will not only destroy their enemy, but will also earn them special favor and consideration from their king.
…I will put that business in your bosoms
Whose execution takes your enemy off,
Grapples you to the heart and love of us... (111-113)
Each murderer declares that life has so beat him down with misfortune that he will do anything necessary to improve his situation. The first is angry at life’s blows, while the second is motivated by desperation.
In truth, it is easy to understand that Macbeth is not interested in either of these men. He has lied to them and is manipulating them to his own ends so that Banquo’s murder will not be traced back to him. And then, in sealing the deal, Macbeth appeals to their pride yet again by praising them:
Your spirits shine through you. (141)
The audience sees that step-by-step, Macbeth has convinced the men that he is not their enemy, but Banquo is. He questions their manliness by inferring that they can behave like men and punish Banquo or act like lowly dogs and forgive their enemy. Macbeth also appeals to the terrible weight of their poverty by offering the opportunity to improve their positions while also having the King indebted to them. Mere pawns, Macbeth orchestrates every detail so that these men will willingly kill Banquo and thereafter maintain Macbeth's anonymity when the murder is discovered.