Research into eighteenth-century British social thought and discourses of social issues has identified two main vocabularies—that of jurisprudence and that of civic humanism. However, several social discourses in the late eighteenth century, such as Thomas Paine's, also contain some influence from the field of political economy. These elements do not fit comfortably in either of the two abovementioned categories, and consequently, they have caused many problems for attempts at classification. Preceding research on Paine clearly shows that the problem here is due to the absence of an appropriate category for this aspect of his work. This paper conducts an inquiry into the usages hitherto of the principal analytical categories mentioned above, then points out obscurities and problems in these usages, and finally provides a new analytical category—“the vocabulary of utility"—and a redefinition of “radicalism" drawing on the work of Michel Foucault.