Hale is presents an example of false humility when he arrives in Salem, overjoyed to be needed and admired. By the end of the play he is truly humble, repentent for playing a role in the condemnation and death of innocent people.
Hale learns a difficult lesson about himself and about the nature of hubris.
Hale is an earnest man who takes great satisfaction in knowing he is able to discern true witchcraft from silliness or fakery. He has stacks of great books which document, much like medical tomes, the signs, symptoms, and cures for witchery. Ironically, his books lead him to the conclusion that there is, indeed, witchcraft afoot in the town of Salem--yet by the end he's equally convinced that it is mischief and pride and other sins which have run amok in the town. Hale is a good man who values the truth, yet he leads the first victims--the girls and Tituba--exactly where he expects them to go by asking them leading questions. He expects witchcraft, so he finds it. In the end, though, this man of truth is willing to trade a lie for an innocent life. Proctor is not. Because he is a man of godly character, Hale no doubt lives with his guilt for the rest of his life.
Both amy-lepore and discussion are correct in their assessments of Reverend Hale. Hale is, by all accounts, a dynamic character. The irony of his transformation is that his morality and realization of the real TRUTH increases as his influence and popularity in the town of Salem -- and belief in a false "truth" -- decreases. Whereas Hale arrives to Salem confidently, claiming his books are heavy because they are "weighted with authority," (Act I), he realizes by the end of the play that the children are lying and that there is a different kind of authority in Salem now; he even disputes the "authority" of the court as Danforth and the other judges continue to dispute John Proctor and to believe Abigail's lies. By the end of the play, in Act IV, as Hale makes a final attempt to convince John Proctor to lie, he also has TRULY become the good person he THOUGHT he was when he first arrived in Salem.
Reverend Hale is a staunch believer in the system and that things are either black (completely evil/wrong) or white (completely innocent/right). By the time the fourth Act comes along, he is beginning to question the court and the witnesses, as well as his own beliefs. He has witnessed good people being accused and murdered without any tangible proof. He finds himself on the side of Rebecca Nurse and the Proctors who are accused and presumed guilty by the courts.
Hale is completely devoted to the truth in the beginning. He is depicted as very concerned with FACTS and JUSTICE. He promises to get to the bottom of the girls' afflictions and he is confident that science and the courts will prevail.
Ironically, by the end of the play, Hale has abondoned his devotion to truth and justice on that previous idealistic level. IN fact, he begs people to LIE and confess to witchcraft to save their lives. He admits JUSTICE cannot be obtained and says, "Give them their lie!"
Hale gives a very powerful speech near the end about how life is god's most precious gift and how it must be protected at all costs. He is no longer a black-and-white man of facts and justice. He realizes that the FACT that the accused people are innocent means little and that the JUSTICE of confessing to a lie to save your life is warped. His disillusionment leads him to quit the courts, and we can assume he is forever changed by the moral complexity of the situation.