His arrogance is what caused him to take the evidence given to him at face value. Hale was so determined to uncover the witchcraft going on in the community that he did not have time to carefully examine the evidence of "witchcraft" that the locals gave him. Hale's arrogance comes into play because he truly believed he knew everything there was to know about witchcraft. Therefore, he never doubted himself or tried to dig deeper into the matter. This is why innocent people were sentenced to death. Hale's arrogance and "intellectual" attitude led him to believe that he did not need to delve further into the accusations made. If he had simply spent more time on his investigation than on his reputation, he might have found that the evidence did not match his reputation.