Having sketched out, in general terms, the conceptual oppositions with which I am concerned, I shall now discuss in more detail three accounts of concept formation. These three (positivism, hermeneutics and various recent forms of rationalist and realist philosophy of science) represent clusters of views rather than clearly delimited and mutually exclusive positions. (1) I shall, in fact, argue that there is a close affinity between traditional Marxism and recent versions of realism and also that important elements of positivism are incorporated into verstehende social science, often in an unacknowledged form. However, I shall also suggest that the hermeneutic tradition encouraged a recognition of the importance of description, and a non-positivist account of explanation (2) which in turn have important affinities with realism.