As he owed his office mainly to the influence of the Rev.Increase Mather, and sat under the weekly ministrations of his learned son, Cotton Mather, the witch prosecutors had a very great hold upon him.

With a good natural intellect, Sir William had received a very scanty education; and was therefore much impressed by the prodigious attainments of such men as the two Mathers.

To differ with them on a theological matter seemed to him rather presumptuous.

If they did not know what was sound in theology, and right in practise; why was there any use in having ministers at all, or who could be expected to be certain of anything?
Then if Sir William turned to the law, he was met by an almost unanimous array of lawyers and judges who endorsed the witchcraft prosecution.
Chief-Justice Stoughton, honest and learned Judge Sewall--and nearly all the rest of the judiciary--were sure of the truth in this matter.
Not one magistrate could be found in the whole province, to decide as a sensible English judge is reported by tradition to have done, in the case of an old woman who at last acknowledged in the feebleness of her confused intellect that she was a witch, and in the habit of riding about on a broomstick: "Well, as I know of no law that forbids old women riding about on broomsticks, if they fancy that mode of conveyance, you are discharged." But there was not one magistrate at that time, wise or learned enough to make such a sensible decision in the whole of New England.
Thus with the almost unanimous bar, and the great preponderance of the clergy, advising him to pursue a certain course, Sir William undoubtedly would have followed it, had he not been a man whose sympathies naturally were with sea-captains, military officers, and other men-of-the-world; and, moreover, if he had not a wife, herself the daughter of a sea-captain, who was an utter disbeliever in her accused friends being witches, and who had moreover a very strong will of her own.
Of course if the Governor should come to Lady Mary's opinion, the prosecution might as well be abandoned--for, with a stroke of his pen, he could remit the sentences of all the convicted persons.

Left to himself and Lady Mary, he doubtless would have done this; but he wished to continue in his office, and to be a successful Governor; and he knew that to array himself against the prosecution and punishment of the alleged witches was to displease the great majority of the people of the province; including, as I have shown, the most influential persons.