Macbeth: Act 1

Lady Macbeth becomes entirely unnatural and inhuman. Like the supernatural Weird Sisters with their beards, Lady Macbeth becomes something that does not fit into the natural world.  Lady Macbeth taunts Macbeth for his fears and ambivalence, telling him he will only be a man when he carries out the murder. She states that she herself would go so far as to take her own nursing baby and dash its brains if necessary. She counsels him to "screw [his] courage to the sticking place" and details the way they will murder the king (60). They will wait until he falls asleep, she says, and thereafter intoxicate his bodyguards with drink. This will allow them to murder Duncan and lay the blame on the two drunken bodyguards. Macbeth is astonished by her cruelty but resigns to follow through with her plans.

What argument does Macbeth use to convince the murderers to act?