Increase Mather was born in Dorchester, Massachusetts on 12 June 1639. He was ordained in 1664, and by the time of the Salem witchcraft trials was a prominent Boston minister. He had previously been the first President of Harvard College, and had headed a commission sent to England to negotiate for a new charter for the colony. It was unprecedented for a clergyman to perform such an important civil function, and he was widely praised for his efforts.
Increase was the father of Cotton Mather, who was also a minister, although with a radical and oversexed theology compared to that of Increase. Both Mathers, however, developed doubts as to whether the witchcraft trials in Salem were achieving justice, and warned against the admission of spectral evidence. Much of the negative history surrounding the Mathers comes from Cotton's early writings on witchcraft which are widely seen as having inspired the initial diagnoses of witchcraft affliction in Salem. In addition, another writer of the period, Robert Calef, gleefully libeled and slandered both father and son (while acknowledging, on occasion, that much of what he wrote was not entirely true).
Although Increase was one of the few ministers to associate sexual activity with witchcraft, he flatly rejected such tests for accused witches as reciting the Lord's Prayer, swimming, or weeping (superstition was the witches lacked these abilities). In 1684, he published An Essay for the Recording of Illustrious Providence, a lengthy defense of the existence of apparitions, witches, diabolical possessions and "other remarkable judgements upon noted sinners." In it he reasserted puritan views of witchcraft and also asserted his belief that the sins of the population had brought on the Indian wars, the unusual thunderstorms, and other judgements of God upon New England. He warned his readers of the dangers of Satan and urged them to change their sinful ways.
Despite doubts as to the trials, Increase would never denounce the judges, most likely because many of them were his personal friends. After receiving the petition of John Proctor, Increase and seven other ministers from Boston met at Cambridge on August 1, 1692. This meeting began the change in feelings towards the witch hunt. After the meeting, Increase attended the trial of George Burroughs at Salem, becoming convinced of his guilt. Increase visited many of the accused in prison, and several of them recanted their confessions to him. About the time rumors began that Increase's wife would be named a witch, he presented his "Case of Conscience," which represented a dramatic break from his former position on witchcraft. In it he publicly questioned the credibility of the possessed persons, confessed witches, and spectral evidence.
After the trials, Increase tried to resolve the dispute between Parris and his congregation. Increase recommended that Parris leave the parish, but he refused and kept the matter tied up in court for two more years.
Increase died on August 23, 1723.