In this chapter, I explore Jevons’s conception of logic and the social function he attached to it. I argue that Jevons’s logic performed a social function in two ways. First, it was meant to provide a unified framework for science, enabling the methods of the physical sciences to be applied to the social sciences. Second, it was meant to help to correct errors in ordinary reasoning. Through its social function, logic could provide a solid basis for action aimed at improving society, showing that Jevons’s view of logic was in line with his concerns as a social scientist. In order to establish his own scientific system based on logic, Jevons had to reject previous attempts to provide a unified system of science, particularly that of John Stuart Mill. Jevons criticised Mill for basing his system on induction, instead advocating the primacy of deduction. I will explain how, for Jevons, logic was the common ground that unified all branches of scientific enquiry and how it rooted in the mental faculties of the human mind. I will then explain how Jevons aimed to make his logic simple and natural in order for it to fulfil its social function.