How does The Crucible explore cruelty?

The play really shows that anyone can be cruel, that our capacity for cruelty seems to be a part of our human nature. Abigail Williams is cruel when she blames Tituba for her own devilishness; she accuses Tituba of witchcraft, knowing that she will be believed because Tituba is a black slave. Reverend Parris—a minister—is cruel when he tries to prejudice the court and the deputy governor against John Proctor and anyone who seems to present a threat to himself. He knows that people are being sentenced to death and that he is keeping secrets about his niece and her friends. He would rather see innocent people die than to lose his position in the community. Proctor behaved cruelly when he cheated on his wife with Abigail prior to the start of the play, and he yells at her in Act Two, insisting that he should have "roared [her] down" and refused to confess when she first brought her suspicions to him. Deputy Governor Danforth behaves cruelly when he refuses to postpone the hangings in Act Four because it would make him appear weak and would cause people to question him. From the high to the low, all are capable of cruelty.

The Crucible is seen as representing so many things by so many people. However, I tend to think that one of the most profound aspects of Miller's work is how it handles the issue of cruelty.
There is political cruelty in the accusations, the mass hysteria, the turning of neighbor upon neighbor, and the twisted way in which spirituality is used to repress and silence voice. What makes the drama profound is how this dynamic weaves its way into the private explorations of cruelty. The personal realm is where some of the most brutal displays of cruelty can be seen between husband and wife, minister and penitent, and between friends.
The moments in which Miller is able to capture the privatized sense of cruelty which manifests from a cruel political condition makes for some of the best dramatic literature. Miller was ahead of his time in illuminating how the true terror of the modern setting is how political and private cruelty converge to make individuals feel nothing but agonizing pain. It is here that The Crucible operates as literary text, historical document, and philosophical treatise.