The problem of what constitutes science is of considerable significance for the student of society: his work, both in its methods and its results, so far as it claims to be scientific, is regarded sceptically. Possibly in consequence he has tended recently to support a broad definition of science which identifies it with knowledge. Yet, leaving aside the difficult problems of what knowledge is, or what it is knowledge of, most of us would argue that, while knowledge may either be derived from science or lead to science, the two are not equivalent.