Adam Clarke on John 10:20

He hath a devil, and is mad - So, then, a demoniac and a madman were not exactly the same in the apprehension of the Jews; no more than the effect is the same with the cause which produces it. Some will have it that, when the Jews told our Lord that he had a demon, they meant no more than that he was deranged; but here these matters are evidently distinguished. They believed him to be possessed by a demon, who deranged his faculties, and that he must have been a wicked man, and a deceiver, thus to be put under the power of such a spirit.