Hale recognizes that the judges are primarily concerned with protecting their authority and are not interested in discovering the truth. When John Proctor admits to lechery and Elizabeth lies in an attempt to save her husband's reputation, Reverend Hale realizes John is being honest and completely changes his position. Hale understands that John would never sacrifice his reputation. Ironically, Elizabeth dooms her husband by attempting to protect his name, and Danforth has Proctor arrested. Following Elizabeth's testimony, Reverend Hale says:

Excellency, it is a natural lie to tell; I beg you, stop now before another is condemned! I may shut my conscience to it no more—private vengeance is working through this testimony! From the beginning this man has struck me true. By my oath to Heaven, I believe him now, and I pray you call back his wife before we—

Reverend Hale then comments that Abigail has always struck him as false and denounces the proceedings. Overall, Reverend Hale changes his position on the witch trials when he recognizes the corrupt nature of the court officials and discovers that John Proctor is telling the truth. Reverend Hale regrets being involved in the witch trials, denounces the proceedings, and repents for his sins.

Reverend Hale undergoes a dramatic transformation between Act I and Act III.  Arriving in Salem as an authority on witchcraft,  he becomes a vital member of the court, assisting in the process of uncovering witches that are present in the village. Reverend Hale participates in the condemnation, along with the court, and signs off on the execution of 12 people. 

As the play progresses, particularly after John Proctor is arrested, Reverend Hale begins to see that the accusations of witchcraft are being used as a tool of  vengeance in the town.  He begins to doubt Abigail Williams testimony and when she is revealed to be a harlot, for having an adulterous relationship with John Proctor, Reverend Hale no longer believes that there are any witches in Salem.  He leaves the court and returns home.

At the end of the play, Reverend Hale returns to Salem with one purpose and one purpose only, to save as many of the accused as possible.  He goes about this process by begging those awaiting execution to confess to witchcraft in order to save their lives. 

His change has occurred as a result of a long period of meditation and fasting, he believes, now, that he is actually working for God, by trying to save innocent people from wrongfully being put to death for a lie.  He particularly wants to save John Proctor's life, but is unsuccessful. 

In Act 3 of The Crucible Reverend Hale serves as a liaison between the courts (Danforth, Parris, and Hathorne) and the accused (Proctor, Corey, and Nurse).  While Hale previously has been on the side of the courts, Hale now believes the trials are bigger than previously believed.  He begs Danforth to send Proctor home for a lawyer, but Danforth refuses to allow it.

Once Danforth tests Elizabeth about John's adultery, Hale again pleads with the court to understand.  Yes, Elizabeth lied, but "it was a a natural lie to tell." hale realizes that Elizabeth lies to save her husband's good name. As Reverend Hale transforms his character, Act III is pivotal is showing him the ugly truth behind the trials.  When he "quits the court" at the end of the act, it is because he believes that the courts are so biased that they cannot and will not listen to the truth.

Hale is a dynamic character in this story and learns much about himself and society during his time in Salem.  He comes to Salem with the arrogance of much intelligence, book learning, and some previous success.  He makes an assumption about the behavior of the girls based on this knowledge of witchcraft, and does not hesitate before plowing forth with the "discovery" of the devil at work.  His impetuousness is what causes events to get out of control. 

In Act II, Hale has a long talk with the Proctors and slowly begins to understand that there is more to these townspeople than meets the eye.  He sees that the Proctors are not immoral people, and is shocked when Elizabeth Proctor is taken.  He has spent time with her individually, and can see that she is not possessed of the devil or of evil doing.  The seed of doubt is planted.

However, it is the lack of legal proceedings in the court that really begins to change Hale's minds.  As an educated and fair-minded man,  he pleads with Danforth to take his time and get attorneys so that all the plaintiffs are represented in presenting their case against the list of townspeople.  Danforth's refusal, and the power Abigail is demonstrating in court, convince Hale that this investigation has turned into a war. 

Hale already has reservations about the witch craft trials by the time that Act 3 starts.  In Act 2, Hale went to visit the Proctor household and admitted that he was a little astounded at the number of accused.  He was also astounded at the women that were now being accused of witchcraft as well.  People like Rebecca Nurse were famous in the Puritan community for being good and wholesome.  

By the end of Act 3, Hale completely changes his opinion on the court proceedings.  He no longer believes that Abigail Williams is a trustworthy source.  He believes John Proctor is correct that Abigail is out for blood, because Hale sees that John is willing to throw away his good name in order to defend his wife.  Hale finally realizes that he was overzealous in his pursuit of witches, and he sees that innocent people are going to die.  

"I denounce these proceedings! I quit this court!"

By Act 4, Hale has come so far as to try and convince the accused to lie under oath in order to save their lives.  

"Why, it is all simple. I come to do the Devil‘s work. I come to counsel Christians they should belie themselves."

Hale's role in Act lV is made clear by Judge Danforth when he says:

Accept my congratulations, Reverend Hale; we are gladdened to see you returned to your good work.

The "good work" the judge refers to is the fact that Hale is counseling with those who have been arrested and is trying to persuade them to confess. This much was confirmed earlier by reverend Parris:

Now Mr. Hale's returned, there is hope, I think--for if he bring even one of these to God, that confession surely damns the others in the public eye, and none may doubt more that they are all linked to Hell.

Hale has not achieved much success in this regard and asks Judge Danforth to pardon them since "they will not budge." The request is rejected.

That Judge Danforth mentions that Hale has "returned" is a reference to the conclusion of Act Three when Reverend Hale, in a fit of anger and outrage, denounced the proceedings of the court and stated that he would no longer have any part in them. He walked out of the courtroom, slamming the door behind him.

Furthermore, Hale has clearly become much more of an adviser to the court in an effort not only to save the lives of those whom he clearly believes are innocent but to also ensure the peace and security of the village and the entire province.

The above indicates an obvious and dramatic change in Hale's attitude. Prior to his outburst at the end of Act lll, he was determined to find the Devil in Salem and root him out. He firmly believed that many had been involved and was skeptical about the innocence of the accused. He, much like the rest of the court, firmly believed that the girls were acting as God's agents and were innocent of any wrongdoing.

However, after he had heard John Proctor's dramatic confession about his affair with Abigail and Mary Warren's own turnaround when she was pressured by the actions of the other girls and accused John Proctor of doing the Devil's work, he realized that the girls were malicious liars. The court had been their puppet and he wanted nothing more to do with the proceedings and condemned them.

The text informs us that on his return:

He is steeped in sorrow, exhausted, and more direct than he ever was.

It is easy to notice Hale's change. He has been overwhelmed by the depth of malice and what he believes is the court's stubborn foolishness to see things for what they really are. He also experiences profound guilt for the role he has played in the execution of so many accused at this stage of events and states that there is blood on his head. Throughout Act lV, he consistently strives to make the court see reason. He mentions the threat of rebellion and refers to the confusion and chaos that have overtaken Salem.

Excellency, there are orphans wandering from house to house; abandoned cattle bellow on the highroads, the stink of rotting crops hangs everywhere, and no man knows when the harlots' cry will end his life - and you wonder yet if rebellion's spoke? Better you should marvel how they do not burn your province!

It is evident that the reverend is desperate and more outspoken. He plainly does not show the court the respect he had before. It is his sole purpose to bring to an end the slaughter of innocent citizens. He has become deeply immersed in fighting on behalf of those who have been accused and he is clearly sarcastic when Judge Danforth asks him why he returned to court.

Why, it is all simple. I come to do the Devil's work. I come to counsel Christians they should belie themselves.

It is tragically ironic that Reverend Hale's best efforts come to naught for, in the end, John Proctor, Rebecca Nurse, Martha Corey and other innocents are hanged for crimes they did not commit. The odds against the reverend were just too great--he had to deal with an arrogant, recalcitrant judge; a materialistic, fearful priest; ignorance and gullibility; and most importantly superstition and an irrational fear of the unknown.

At the end of Act Two, Reverend Hale -- though shaken by recent accusations against Rebecca Nurse and others -- still very much supports the courts in Salem. He tells John Proctor, Giles Corey, and Francis Nurse, "Let you counsel among yourselves; think on your village and what may have drawn from heaven such thundering wrath upon you all. I shall pray God open up our eyes." Though he seems to feel some "guilt and uncertainty," especially when Elizabeth Proctor is chained, he clings to his old beliefs because it is painful and frightening to abandon them.

In Act Three, he begs Danforth to allow Proctor and Corey to return with a lawyer since their evidence against the girls is so weighty.  When Elizabeth lies to save her husband's name, he says that "it is a natural lie to tell." He says, finally, "I may shut my conscience to it no more -- private vengeance is working through this testimony!" And when Danforth will not listen to him, he "denounce[s] these proceedings" and "quit[s] the court," leaving Salem.

When he returns in Act Four, several months later, he is a changed man. He says that when he came to Salem the first time, he

came into this village like a bridegroom to his beloved, bearing gifts of high religion; the very crowns of holy law I brought, and what I touched with my bright confidence, it died; and where I turned the eye of my great faith, blood flowed up.

Hale was arrogant before, and he felt that he knew all and could not be misled. He now understands that he was wrong, and so he has returned to "do the Devil's work [...] to counsel Christians they should belie themselves [...]." He believes that "There is blood on [his] head" because he signed the death warrants of many of the convicted, and he knows now that they were innocent. He has returned in order to convince the prisoners that they should tell a lie and confess to witchcraft because "no principle, however glorious, may justify the taking [of a life]." He is humble and guilt-ridden now where he was proud and righteous before.

Reverend Hale is summoned to Salem because he is a well-respected minister and an expert in finding witchcraft.  He carries with him huge books that show the type of devils and demons involved in witchery.  He takes his job seriously, and he wants to get to the bottom of the accusations spoken by Abagail and the other girls.  At first, he is enthusiastic about his conclusions and believes that witchcraft does indeed exist in Salem.  He gets caught up in the hysteria; however, as the trial goes on and after interviewing John and Elizabeth Proctor, Hale begins to doubt the girls’ stories.  He begins to see motivates behind the community’s accusations.  At the end of the play, Hale has lost all confidence in the trial and judges.  He begs John Proctor to save himself by signing the declaration of witchcraft because Hale feels that God will forgive John for lying and saving his own life.

Hale’s main characteristics include a sense of fairness and practicality.  He is able to read people well, and is not easily duped.  He is a sincere man who believes in the innocence of others.  Although proving witchcraft would make him well-known or famous, he does not have his self-interests in mind (like Reverend Parris) when he comes to Salem.   He believes in truth and justice.  Although he makes mistakes, he is able to find the truth and fight for the innocent.

John Hale in The Crucible by Arthur Miller epitomizes a dynamic character.  Throughout the drama, Hale evolves from a man with intentions to free the world from satanic influence to a person who realizes the Salem witch trials were based on lies and fakery. Reverend Parris asked Hale to come and assist in the pursuit of evil.

Hale is cautious in accepting situations that people believe have witchery involved. As a recognized authority on the devil and witchcraft, initially Hale appears arrogant and authoritative.  Although Hale had never really accused anyone of being a witch, he is ready to investigate and rid Salem of any demonic influences.    

Act I

Hale arrives with his weighty books of authority.  His idealism comes forth as Hale meets several of the characters involved in the night in the forest of naked dancing and flying: Abigail, Betty, and Tituba. 

In addition,  he is introduced to some of the well-known townspeople: John Proctor, Rebecca Nurse, The Putnams, and the Coreys.  Hale also observes some hysteria from the girls which increases his concern about the devil’s presence.  

Since Proctor has chosen not to attend church, Hale comes to question him by asking Proctor to repeat the Ten Commandments.  Proctor names all of them except adultery, which ironically is the one that he has broken.

Act II

Hale wants to find and prosecute witches.  He is willing to convict anyone that appears to have the devil within him/her.  Hale definitely believes that:

“…powers of the dark are gathered in monstrous attack upon this village. There is too much evidence to deny it.”

As the trial progresses, Hale begins to see some hypocrisy on the part of the court. He believes that the good people have nothing to fear because God will protect them.   The judges do not always give a fair hearing to people who have proof that they are not witches. In addition, there are people like Rebecca Nurse who is considered to be one of the godliest women in Salem accused based on the shady testimony of Ann Putnam.

Act III/IV

When Danforth fails to give a fair trial to Proctor, Hale doubts the purpose of the trials.  Up to this time, Hale had signed seventy-two death warrants.    Hale consistently challenges Danforth in his questioning of Mary Warren and John Proctor realizing that Proctor is telling the truth. 

When Abigail Williams does not deny her affair with Proctor and threatens the court, Hale calls this to the attention of the court, but the court ignores him.  Finally, when Proctor is sentenced to death, Hale denounces the court and leaves Salem.

After several months, Hale returns on the day of Proctor’s execution. His purpose is to try to get Proctor to sign the false confession to keep from being hanged.  Proctor does sign but refuses to give Danforth the copy of his signature. Hale begs Danforth for more time to convince Proctor to save his own life. Danforth refuses because it would make the court look bad. 

In addition, Hale asks Elizabeth Proctor to ask her husband to save himself.  She refuses because she believes that it is his decision.  Obviously, the Reverend Hale would like to relieve himself of some of the guilt for the innocent people who were hanged after he signed their death warrants.  Hale now knows that the entire proceedings have been a sham caused by silly girls and gullible adults with the devil and superstition on their shoulders.

In addition to the reasons outlined in previous answers, Hale is no longer comfortable signing death warrants for individuals convicted by this court. He says, in Act Three, that he has signed some seventy-two warrants, and he cannot sign more if he has any shred of doubt about the validity of these convictions. When Danforth is unwilling to allow John Proctor and Giles Corey to leave and return with a lawyer to help them present their evidence (and Mary Warren's deposition) to the court, Hale becomes very concerned that this court and its judges are actually corrupt. He believes, by the end of the act, that Mary Warren has gone wild and that the court should not be willing to accept her testimony against Proctor. However, Danforth's unequivocal trust in her words, as long as they support the other girls (who he believes are serving as God's voice in Salem), is too much for Hale, and he quits the court.

Hale quits the court in Act 3 because he no longer believes that the girls are telling the truth and feels that the judges are blind to the lies that they are telling.  John Proctor is not successful in convincing the court of his affair with Abigail; since Hale knows what kind of a person Proctor is, he now truly believes that he is being truthful and that the girls are fabricating the entire story.  Therefore, he quits the court.  In Act 4 Hale continues to play a part in the play when he tries to convince certain characters to confess to witchcraft ONLY because he does not want to see them get hanged.    

A dynamic character undergoes some change during the course of a novel, play, etc.

In The Crucible, Hale is dynamic because when he arrives in Salem, he's determined to investigate, solve, and prove the presence of witchcraft. However, by the play's end, Hale does recognize the truth which is that Abby and the other girls were lying all the time and that John Proctor is guilty only of adultery.

In the narrative that introduces Hale in Act 1, Miller notes that prior to his arrival in Salem, Hale had one experience with a witch. However, that woman turned out to be a "mere pest." Despite this experience, Hale remained determined that witchcraft did exist.

However, that experience never raised a doubt in his mind as to the reality of the underworld or the existence of Lucifer's many-faced lieutenants. And his belief is not to his discredit. Better minds than Hale's were--and still are--convinced that there is a society of spirits beyond our ken.

By the time Danforth has made up his mind not to retract any of the accusations, it is too late. Also, by this time, Hale has acknowledged that the girls were lying and he realizes that he has also played a part in contributing to the hysteria and false accusations.

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!! (Act 4, Scene 2)

Reverend Hale is one of the few characters who transforms throughout the play.

He starts as a firm believer in witchcraft, and by the end of Act III he has completely recanted his position and even tries to save the holdouts from execution. He represents the ability to look past bandwagon beliefs and form personal conclusions based on knowledge and observation rather than blind bigotry.

In an appeal to the immovable Danforth, Hale pleads,

"Excellency, it is a natural lie to tell; I beg you, stop now before another is condemned! l may shut my conscience to it no more - private vengeance is working through this testimony! From the beginning this man has struck me true. By my oath to Heaven, I believe him now."

While Hale can be credited for no longer turning a blind eye, his earlier convictions proved deadly for many a character, which shows the dangers of accepting the world around you before making investigations.

This can be related back to the real world with Miller's motivation for writing The Crucible:McCarthyism. Most people, even people who were powerful and would have been able to deter Senator McCarthy's agenda, did not speak out against him until the evidence of his fraud became too large to ignore. For many innocent citizens, it was too late as the modern "witch hunts" destroyed many a family and career.

Hale initially appears as an eager and erudite young man keen to use his religious learning to benefit the community. He is anxious to do things literally by the book, to call upon the powers of good against evil as instructed in the religious manuals that he brings along with him.

Hale comes across as a conformist at first, anxious to root out all disorderly elements in Salem, and convinced that malign supernatural forces are at work there. However, in Act II he shows that he does not blindly follow the hysteria that grips the town. He comes to visit the Proctors of his own accord, to give them warning that the court is on their trail. This shows how he can act independently and out of concern for individuals rather than condemning those accused out of hand. Indeed, as the play wears on he becomes increasingly dissociated from the court and all the official business that he took so much pride in at first; and he explicitly 'denounces' the court after seeing good people like Proctor and Giles condemned (Act III)

By the end of the play, Hale has become distrustful of the authorities. He is now said to be 'more direct than he ever was' (Act IV). All he wants now is to save lives from the scaffold, and he is deeply overcome with remorse over the people he has already helped to condemn:'Cannot you see the blood on my head!!' (Act IV).To this end, he pleads with Elizabeth to persuade Proctor to lie in order to save himself. He seems to abandon his former scruples, arguing unconvincingly that 'it may be that God damns a liar less than he that throws his life away for pride'.

Hale, then, misrepresents Proctor's refusal to lie as a sign of pride rather than of integrity, and he appears rather weak and inconsistent in this, but it really springs from his growing sense of compassion - he does not want any more innocent people hanged. In the end, it is his humanistic concerns that prevail; he is no longer the dogmatically religious figure that he was at the beginning of the play. 

Reverend Hale is one of the few characters in The Crucible who tries to do the right thing for its own sake. He starts the play as a character who believes that witches are real and that they deserve to die, but he is not a man without mercy or empathy. He is not as quick as other characters to dismiss the lives of people who have lived justly, and he is willing to listen to his gut feelings when it comes to judgments of people.

While he is the one who signs the death warrants and oversees the court proceedings at the start of the novel, he is quick to believe and advocate for John Proctor and Elizabeth Proctor. Despite listening to the girl's testimony, he doesn’t think that Abigail is as innocent or truthful as she seems, and he is willing to admit that he made mistakes to save people’s lives.

While he shows a willingness to do the right thing, or at least what he believes is correct, it is his ability to change based on new facts and evidence that makes him a symbol of integrity in the play. None of the other court officers are willing to dismiss the importance of the trial, and they feel that if people have died in mistake, others must too to uphold the honor of the court and its authority. Hale does not agree, and after hearing John Proctor’s confession of adultery, he is angry that the court would continue until the entire issue can be resolved. He leaves at the end of Act III saying,

I denounce these proceedings, I quit this court.

Hale goes from well kept and assured of his duty, to a man who feels the immense guilt of his actions by the end. At the end of the play, he is seeking to make up for his mistakes, even urging those accused to lie and admit false guilt so that they can save their own lives. Hale’s ability to change and the guilt he feels at his mistakes shows clearly the integrity he possesses.

When Reverend Hale first arrives in Salem, he says, rather importantly, that the many books he brings are "weighted with authority." He tells those gathered in Betty's room about the books:

Here is all the invisible world, caught, defined, and calculated.  In these books the Devil stands stripped of all his brute disguises.  Here are all your familiar spirits—your incubi and succubi; our witches that go by land, by air, and by sea; your wizards of the night and of the day.  Have no fear now—we shall find him out if he has come among us, and I mean to crush him utterly if he has shown his face!

Hale is tremendously confident, even perhaps somewhat arrogant, in his his own ability and power.  The pride that he takes in his education and discernment is clear, and he seems to have no fear that he might be up against an opponent that could best him.  While others quail before and fear the unknown, Hale seems to feel that there is no such unknown—he believes that his books contain everything he needs to know—so he has no fear.

In act two, when Francis Nurse arrives at the Proctors' home to tell John Proctor that Rebecca, Francis Nurse's wife, has been arrested, Hale says,

Let you rest upon the justice of the court; the court will send her home, I know it. 

He is clearly quite confident in the court's justice, and he is sure that there can be no corruption tolerated (or initiated) by Deputy Governor Danforth.  He is incredibly naive.  Further, he tells Proctor, in regard to Rebecca,

Man, remember, until an hour before the Devil fell, God thought him beautiful in heaven.

Hale is confident in the idea that there is a "misty plot afoot" in Salem, and he does not doubt the accusers' truthfulness or the honesty of the court.  Rather, he doubts the integrity of individuals who have been counted as honest and good for their entire lives.  He will not listen to Proctor, Giles Corey, or Francis Nurse, and he essentially sits by while their wives are carted off to jail.  This is why Proctor calls him "Pontius Pilate": the man seems to wash his hands, figuratively, of the blame being placed on these obviously innocent individuals.  His ultimate faith in the court trumps all else.

In act four, however, Hale returns (he quit the court at the end of act three), saying, 

I come to do the Devil's work.  I come to counsel Christians they should belie themselves.  There is blood on my head!  Can you not see the blood on my head!!

Hale now understands that the court is corrupt, that innocent people are being hanged for crimes they did not commit, and that the magistrates are more concerned about retaining their authority than the lives of the people who are scheduled to hang.  He is trying to get those people who have been convicted to confess and lie in order to save their own lives.  His confidence is gone, and he realizes the responsibility he bears in what has occurred. Hale tells Elizabeth Proctor, that if John, her husband, is executed, Hale will consider himself John's murderer.  Hale feels personally responsible for the hangings because he had assured these people that the court would find out the guilty parties and let the innocent go; this is not what happened.  Hale also tells Elizabeth Proctor,

Let you not mistake your duty as I mistook my own.  I came into this village like a bridegroom to his beloved, bearing gifts of high religion; the very crowns of holy law I brought, and what I touched with my bright confidence, it died; and where I turned the eye of my great faith, blood flowed up.

All of Hale's earlier confidence is gone.  He is no longer proudly arrogant concerning his powers of discernment, his education, or his books.  He feels now that he was totally mistaken in his "bright confidence" and recognizes the part he played in these deaths.

Hale's attitude toward studying witchcraft is that it should be studied and is important to study. If that wasn't his attitude, then he wouldn't study it and show up with books that are weighted with authority about witchcraft. Hale also believes that studying witchcraft will allow him to better find evidence of it and fight it off.

Hale, setting down his books: They must be; they are weighted with authority.

Parris, a little scared: Well, you do come prepared!

Hale: We shall need hard study if it comes to tracking down the Old Boy.

Hale's attitude is a clinically cold attitude. He passionately and emotionally feels that witchcraft is evil and should be gotten rid of; however, his pursuit of rooting it out is extremely logical. Miller is portraying Hale as something akin to a doctor seeking out signs and symptoms of an injury or disease. The books give him a base knowledge to compare individual cases of witchcraft against. Once Hale finds evidence of witchcraft, he then believes that cares and cures can be clinically administered so that the "disease" is expunged from a community and can't spread like any other kind of infection.

Audiences will see further evidence of Hale's clinical attitude and logical thinking when he goes to the Proctor house in order to test John and Elizabeth. He asks them a series of questions that are designed to supposedly call out potential signs and symptoms of witchcraft. It's very similar to the procedures I go through when I am called onto the football field to check an athlete out for a potential concussion. I am looking for specific physical things, but I am also quite dependent on how that athlete answers specific questions. Hale is doing the same thing with the Proctors, and it is a result of his studies on the subject.

Interestingly, Hale will begin to abandon his clinical and logical dependence on his studies as the play progresses. He abandons them in favor of what he feels is right, and he's even willing to try and get people to confess a lie in order to save lives.

Life, woman, life is God’s most precious gift; no principle, however glorious, may justify the taking of it. I beg you, woman, prevail upon your husband to confess. Let him give his lie. Quail not before God’s judgment in this, for it may well be God damns a liar less than he that throws his life away for pride. Will you plead with him? I cannot think he will listen to another.

Hale believes that witchcraft can be studied, discovered, and expunged much like a disease.  When he first comes to Salem from Beverly he arrives a student of witchcraft excited to practice his craft.  He is entranced is characterized by his weighty books.  These books are heavy in both weight and significance for it is with these books he will "discover" who and who is not affect by witchcraft in Salem. 

setting down his books: "They must be; they are weighted with authority."

This is important because Hale truly believes he is helping the people in Salem.  He believes that his study has prepared him for this task and that he is ready for it.

When we are first introduced to Reverend Hale, it is indirectly.  We learn from other characters that he "has much experience in all demonic arts."  Parris says this, only a few pages into act one (we probably don't have the same version of the play, so our page numbers will be different).  So, through other characters, we learn that Hale knows a lot about "demonic arts," meaning, the ways that demons and spirits of the devil work here on earth.

When Hale enters the scene, Miller, in a lengthy aside, gives us a lot of background information on him.  He says that Hale has spent a lot of time studing "the invisible world," and that he had ousted a witch in his own parish.  So, he had experience identifying and calling out witchcraft.  He was pleased to be called upon, and felt like his expertise was finally being recognized.  He brings many books on the subject, and refers to them in his diagnosis of Betty and others.  All of this information can be found nearer to the end of act one.

Reverend Hale also knows enough about the law to advise John Proctor, and others, to get lawyers to present their cases, in order to be fairly represented in court.  Near the middle of act three, Hale begs Danforth to let John get a lawyer.  He says,

"in all justice sir, a claim so weighty cannot be argued by a farmer...send him home and let him come again with a lawyer."

He obviously knows enough about the courts to know that lawyers represent people.  Also, throughout act three, Hale demands that justice be served, and that evidence be heard, even when the judges refuse to listen to it.  He is more willing to look at things objectively, and to take evidence based on facts and logic, as courts are supposed to do.  Because of the theocracy that the Puritans had, religious ministers were often involved with the execution of law, and Hale had also signed his name to many people's death warrants, making them valid and final.

I hope that those thoughts helped; good luck!

The previous answer was quite thorough.  I would only add that part of the reason that Hale does change is that he is forced to recognize the duplicity that exists within individual actions.  What would drive Hale to such a point could be summed up in a line from Yeats' poem, "The Second Coming:"

the best lack all conviction/ while the worst are filled with passionate intensity.

For Hale, he cannot understand how individuals with so much passion can represent the very evil he is committed to stamping out of Salem and of the world.  There is a singularity within Hale that is fundamentally challenged by the end of the play.  For example, in Act II, when Hale visits the Proctor home, he is about to leave before Francis Nurse and Giles Corey bust in with the news that their wives have been arrested.  Prior to leaving, Hale tells John and Elizabeth that the path to their salvation lies in showing deference to the church and Reverend Parris, attending it more often especially on the Sabbath, and having their last child baptized.  In Hale's mind, there is a convergence with religious purity and the institution.  He cannot fathom that there would be a disconnect.  It is this same reasoning that compels him to investigate Martha Corey after Giles talks about her reading.  Hale simply cannot see something wrong in an investigation as he believes it is being conducted by flatly religious people.  Hale changes in that he is forced to understand that there might be a disconnect in the psyche of individuals.  The most spiritual of people might not be the ones that are considered to be so and the ones who are considered to be so might not be.  Hale struggles with this, as he breaks from the court and seeks to pursue a more "grass roots" approach to ridding the town of witches in his desire to extract confessions.  It is for this reason that he seems to not want to understand Proctor's motivation at the end.  If he does understand it and accept it, the result would be a fundamental shift in that idea that there is a duality or a complexity within human nature and that the singularity that has dominated his life is not evident in an intricate setting.  It is here where Hale undergoes the greatest amount of change.

When Hale arrives in Salem at the beginning of The Crucible, he attempts to express a measured and scientific attitude toward witchcraft. He says that he refuses to assume that Betty's case is one of witchcraft until he has examined the evidence.

However, Hale almost immediately becomes satisfied that witchcraft is afoot in Salem based on flimsy and coerced testimony from Tituba. Readers see clearly that Hale was prepared to be convinced by even the slightest scrap of evidence. 

Though Hale is a man of mercy, he is willing to do whatever is necessary to purge Salem of witchcraft once he is convinced that it is going on in Salem. 

Ultimately, Reverend Hale is convinced that the trial is a fraud and that the accussations of witchcraft were personal attacks based wholly on lies. 

Hale's willingness to change his mind demonstrates a humility, which Danforth claims is a weakness and unbecoming to the court. Yet it is Hale's personal strength and tendency toward honesty that forces him to accept the truth. Far from being honored for his honest impulses, Hale is driven away from the court and loses all authority. 

Despite this admirable trait, he lacks the moral conviction to act against proceedings that will condemn innocents to death.

The truth alone is not enough to lend Hale the potency of moral spirit required to alter the course of the court. 

When Reverend Hale first appears in Act I, he is "a tight-skinned, eager-eyed intellectual. [Salem] is a beloved errand for him" (Miller). He believes firmly in what he is doing, and his belief is supported by some of the best scholars and religious figures of the day. The fight against the devil is necessary and all-important, as evidenced by his statements such as "[The books] must be [heavy]; they are weighted with authority" (Miller).

However, Hale strongly believes that his work is a scientific, exact matter that can be weighed and proven empirically. As he explains to Putnam, "Let me instruct you. We cannot look to superstition in this. The Devil is precise; the marks of his presence are as definite as stone, and I must tell you all that I shall not proceed unless you are prepared to believe me if I should find no bruise of hell upon her" (Miller). He carefully seeks evidence in all of his questioning, and he truly believes that what he is doing is right, empirical, and unbiased. Interestingly, many of his questions are biased and leading, and would therefore never be allowed by today's standards, such as when he says to Tituba, "When the Devil comes to you does he ever come - with another person? Perhaps another person in the village? Someone you know" (Miller). 

However, by the end of the play, Hale has seen his work turned into a series of wild accusations, and all power has been ripped from his hands. He no longer believes that the work he is doing is good, but likewise he no longer has the power to stop it. It is only once he sees someone else engaging in his "science" that he perceives its flaws. Over the course of Acts Two and Three, he seeks to mollify the bloodthirsty verdicts being passed down by Danforth, such as when he voices his reservation in Act III: "Your Honor, I cannot think you may judge a man on such evidence," to which Danforth chillingly replies, "I judge nothing" (Miller). Later in the same scene, he voices concern regarding the decisions of the court, noting that "it does not follow that everyone accused is part of [the witchcraft]," here using his scientific reasoning to point out a serious flaw: not everyone who comes to court should be found guilty, for this goes beyond the idea of chance and justice (Miller). Hale finally bursts out that he "dare not take a life without there be a proof so immaculate no slightest qualm of conscience may doubt it," clearly distancing himself from Danforth and the court, and ultimately exiting the scene with a cry of "I denounce these proceedings!" (Miller). 

By the final act, Hale has been reduced to sarcasm and panic. He presents a simple fact to Danforth: "You must pardon them. They will not budge," and later when asked why he has returned to Salem, he mockingly states, "I come to the Devil's work. I come to counsel Christians they should belie themselves," acquainting the Church and Court's demands that the accused confess to be saved with the sin of falsehood and the devil. Finally, when Proctor crumples his confession, Hale desperately pleads with him to sacrifice his honor and the truth for his life: "Man, you will hang! You cannot!" (Miller). 

Hale undergoes one of the most dramatic characterizations, evolving from a well-intentioned, well-educated religious man who believes that his mission is honest and true to a man who finally realizes the corruption and hypocrisy of the proceedings he has begun. 

At the beginning of the play, Reverend Hale is a man who is pleased to be helping the people of Salem.  He is a pretty confident in his skills as a diagnoser of spiritual woes, and feels pretty self-important and spiffy to be called into town as an "expert."  When he seems to uncover a nest of witches, he is even more pleased to be front and center in the verdicts and accusations.

As time wears on, and as more and more accusations come, he is still avid, but tired.  In Act Two we see him as a diligent man, trying to seek out truth, and trying to see the nature of people before they get to the courts.  He comes to the Proctor household and asks them some of the most logical questions of the entire play.  At the end, after hearing of Abby's statement to John, he gives John and the other concerned husbands advice.  He tells them that if it isn't witchcraft, then some other foul deeds must be going on--he encourages them to think of any possible reasons people might be accusing others of witchcraft to get them out of the way.  The men do this, and come prepared to the courts in Act Three.

In Act Three, we see Hale go through a transformation.  He is still there in the courts, but is questioning.  He tries to challenge Danforth and the others occasionally.  He is the only one that stands up for the logic behind Proctor's claims, the only one to defend Proctor, and the only one to point out the glaringly obvious fact that Elizabeth's lie "was a natural lie to tell" about her husband.  In Act Three, he is there, but doubting, and by the end of it, has had his eyes opened to the insanity of the courts.  It is then that he declares, "I quit this court" and walks away.

In Act Four, we see him weighed down with the guilt of having signed so many false death warrants.  He tries to assauge that guilt by getting people to confess, so that they won't die. He realizes that they were falsely charged, and realizes that they are being hanged for nothing.  He wants desperately to stem the tide of death, and goes about vigilantly preaching to help people feel okay with confessing.  From avid participant of the courts to avid protester of the courts, Reverend Hale goes through a complete turn-around in the course of the play.  I hope that helped; good luck.

As far as his behavior, when Reverend Hale first comes to Salem, he does so with tremendous confidence in his learning and ability to root out the Devil.  He later describes himself as having initially come to Salem "like a bridegroom to his beloved, bearing gifts of high religion [...]."  However his faith and his knowledge failed him and the villagers.  He should have said something sooner, before the trials were able to gather momentum.  Though he witnessed the arrest of Elizabeth Proctor "in a fever of guilt and uncertainty," he did nothing to stop it.  He continued to blame Salem for some possible transgression that had not yet come to light, suggesting that God was punishing Salem for these sins.  When, in Act Three, he expressed his concerns about the court and the evidence being provided by the girls, it was too late and he was not listened to, and so he quit the court and abandoned Salem.  

His function in the play is to point out that it isn't just the transgressors who are responsible for events like the Salem Witch Trials (or the McCarthy hearings), but the people who sit by and say nothing are just as responsible.  Even abandoning the court rather than staying and arguing for his perspective was a somewhat cowardly move, and, by the time Hale returns to counsel Salemites to lie and save their own lives, it is too little too late.

The case for Hale being a dynamic character rests in his expulsion from the hearings.  It is argued that after this, he operates not as an agent of the court of Danforth/ Hathorne, something that he sees as fundamentally misguided or simply wrong.  Rather, he seeks to counsel those who have been found guilty in order to placate his own misgivings about participating in such proceedings.  This is the basic element in pointing out how Hale represents a sense of the dynamic.  Yet, I would pivot in pointing out that this is precisely where he can be seen as a static character.  In the end, Hale still refuses to recognize a form of consciousness or being outside of established order.  Hale operates within this order and refuses to see any ambiguity outside of it.  Whether it is the legal/ social order of Salem in the start of the drama or the belief that life is the most important element ordained by the divine, it can be argued that Hale fails to become a dynamic character because he refuses to see the complexities or ambiguities that might exist in the strict belief of ordinance or the idea of a configuration.  Hale refuses to understand Proctor's motivation for sacrifice at the end.  He refuses to do so because in acknowledging this, he accepts that his world view is limited, the same reticence shown at the start of the drama.  In this, Hale can be seen as a non- dynamic character.