 The introduction and discussion of the ad-arguments appears almost as an afterthought in Locke’s Essay. It is found at the end of the chapter, “Of Reason,” in which Locke devotes considerable effort to criticizing syllogistic logic. Reasoning by syllogisms, he maintained, was neither necessary nor useful for knowledge. Locke clearly thought that the three ad-arguments were inferior to ad judicium arguments, but he never used the term ‘fallacy’ in connection with them, although he did use it in connection with errors of syllogistic reasoning.