Methodological criticism may be defined as the critique of scientific practice in the light of methodological principles, and critical methodology as the study of proper methods of criticism; the problem is that of the interaction between the scientific methods which give methodological criticism its methodological character and the critical methods which give it its character of criticism. These ideas and this problem are illustrated by an examination of Karl Popper's critique of Marxian social science. It is argued that though Popper's (...) favorable articulations of Marx are valuable, his unfavorable criticism is invalid, the grounds of my argument being certain ideas in critical methodology relating to the distinctions between theory and practice, between inaccurate and invalid criticism, and between the justification of favorable criticism and the justification of unfavorable criticism. (shrink)