What is Reverend Hale's role and significance in The Crucible?
Reverend Hale's character helps to show that those who wash their hands of responsibility of wrongdoing, so to speak, are just as responsible as those who commit the wrongdoing. Tellingly, at the end of Act Two, as Elizabeth Proctor is being arrested on suspicion of witchcraft, John Proctor, her husband, calls Hale "Pontius Pilate" and says that "God will not let [Hale] wash his hands of this!" In other words, John feels that Hale will not be able to rid himself of his responsibility to intervene by simply refusing to do so one way or the other. Hale has said, again and again, that the people of Salem can rely on the justice of the court. He claims that he has seen signs of witchcraft here, himself, but that if those arrested are innocent, then the court will find them to be so and send them safely home. During Act Three, Hale tries to assist John in bringing his evidence before the court, and it is obvious that he now has grave doubts about the guilt of those convicted, and yet, when Deputy Governor Danforth will not listen, Hale just quits the court and leaves Salem. Rather than continue to fight against the injustice he sees, he simply walks away, and by the time he comes back, it is too late.
When Hale returns in Act Four, he now realizes his own responsibility in the trials and in the executions of innocent people. He tries to reason with Danforth but to no avail. He now feels that there is "blood on [his] head," meaning that he bears some guilt for the hangings which have occurred and those that will occur. His character helps to illuminate the theme that doing nothing to stop injustice is as bad as participating in that injustice oneself.
In The Crucible, Reverend Hale is brought in as an expert on witchcraft. His job is to investigate the claims and interview all those involved. Hale takes this work very seriously and he intends to rid Salem of any instances of witchcraft. Hale does, however, go about his business with much more reason and calm than the fanatics who embrace the hysteria of the accusations of witchcraft.
In Act IV, we see the dynamic character of Reverend Hale. After trying to coerce more confessions (along with Parris), Hale reverses his stance and asks Danforth to pardon those who've been condemned (Danforth does not do this). Hale then actually tries to get the confessed to lie in order to save their own lives.
Hale represents the dichotomy of the witch trials. He is a part of the hysteria but he is also one of the characters who actually shows a reasonable, rather than a fanatic, conscience. Toward the end of Act IV, Hale begins to see the devastation of the accusations and his part in it:
Why, it is all simple. I come to do the Devil's work. I come to counsel Christians they should belie themselves. His sarcasm collapses. There is blood on my head! Can you not see the blood on my head!!
Shortly after this, Hale asks Elizabeth to get John to confess to save his own life. Hale is trying to do the right thing but he also feels guilty and if John is to be executed, Hale would feel responsible and acknowledges this responsibility to Elizabeth.