His arrogance is what led him to take the evidence given to him at face value. Hale was so determined to uncover the witchcraft occurring in the community, and did not have time to carefully examine the evidence of "witchcraft" that the townspeople had provided him. Hale's arrogance comes into play because he truly believed he knew everything there was to know about witchcraft. Therefore, he never second-guessed himself or tried to dig deeper into the case. This is why innocent people were sentenced to death. Hale's arrogance and "intellectual" attitude made him believe he didn't need to delve into any of the allegations made. If he had simply spent more time on his investigation rather than his reputation, he might have seen that the evidence didn't line up