"Some structuralist arguments would appear to assume that the critic identifies the 'appropriate' codes for deciphering the text and then applies them, so that the codes of text and the codes of the reader gradually converge into a unitary knowledge."
Eagleton goes on to say that this is surely too simple of a conception of what reading really is. Even if it is simple minded, it is a good concept of what goes on when we are reading literary criticisms. We are attempting to figure out the code the critic used and then apply it when we read the text that is being criticized. I think that is the point of trying on different "lenses" when we read. Once we figure out how the critic is reading the text, we can look at whether we agree or not.