One thesis statement for Arthur Miller's "The Crucible" would be that the book uses the Salem witch trials to explore what happens when someone accuses someone else of treason or subversion without having proof. Another thesis would be that the play also shows the affect extreme behavior has on society and how quickly widespread fear and panic spreads.
To avoid punishment, several young girls caught conjuring spirits in the woods blame a slave woman for corrupting them. These girls also accuse other women in Salem of practicing witchcraft. With no one knowing who is and isn't a witch, despite no evidence that anyone is practicing witchcraft, the residents of Salem are soon gripped by fear and demand the accused be put on trial. "The Crucible" draws from the McCarthy hearings of the 1950s, where U.S. Senator Joseph McCarthy oversaw large-scale investigations into Americans accused of being communists.
These witch hunts hide several hidden agendas, much like the McCarthy hearings did. For example, Thomas and Ann Putnam use the paranoia in their community to increase their landholdings. They accuse their neighbors of witchcraft and buy their land after their executions. Abigail Williams, who spearheads the initial accusations, does so after her lover, John Proctor, ends their relationship. By accusing his wife, Elizabeth Proctor of witchcraft, Abigail clears the way to resume her relationship with John and ultimately marry him.
John Proctor is one of a few people who doubt the accusations. He worries about coming forward because he knows that Abigail will reveal their affair. He also fears her accusing him of witchcraft. He represents a common fear during the McCarthy era, where people feared retribution for coming forward and clearing the names of their neighbors.