What rhetorical devices does Shylock use?

Shylock's rhetoric is displayed most prominently in his famous monologue, known commonly by the phrase, "If you prick us, do we not bleed?" The speech can be found in the first scene of the third act.

The rhetoric of this passage appeals to the common humanity of men, suggesting that the distinctions of class and race are superficial in comparison with the underlying common nature shared by all.

Shylock does not claim common humanity to argue for more enlightened relations, however. Instead, he uses the proposition to argue his just right to revenge.

This passage has several parts: (1) catalog of abuses, (2) meditation on a common humanity, (3) meditation on common responses to injustice.

These three division unite to conclude with the following proposition:

"The villainy you teach me, I will execute, and it shall go hard but I will better the instruction."

Shylock's rhetorical point is that cruelty begets cruelty.