The standard text for anyone who wishes to analyse economic theory. Blaug takes the approach that an economic theory can be criticised on two levels. It may have a mismatch with the environment and or it may be internally flawed as a theory. By concentrating on theory Blaug helps the reader acquire their own critical faculties for assessing economic theories without getting bogged down on endless details associated with, "but things were different then," or with defendants of marxist economic theory, "but things would be different."