Η αντίθεση ανάμεσα στον δεοντικό και περιγραφικό χαρακτήρα της επιστημονικής μεθοδολογίας
The problem of any theory of science, that is any theory of the history of science, or even more analytically, any theory of change of scientific theories, lies in a contradiction inherent in the nature of scientific methodology. This contradiction is the result of an inevitable interplay between a normative and a descriptive role that scientific methodology (as theory of science) is forced to have while setting up demarcation criteria for science and at the same time trying to be compatible with as much of actual history of science as possible. The normative character of scientific methodology concerns both the (scientific) behaviour of scientists (that is how and how honestly to set up experiments to test their theories) and the structure of theories upon which depends their empirical, verifiable or falsifiable character. A methodology therefore in its normative role demarcates on the basis of such criteria, a specific set out of the bulk of phenomena of the actual history, as genuinely scientific. However the need to allow for a critical comparison between different methodologies reverses the relationship between history and methodology. Normative methodology judges history demarcating scientific from non- scientific phenomena. But then, history judges normative methodologies in terms of the quantity of historical phenomena which are accounted by them. This is the only means to compare normative methodologies and that which as a result renders them descriptive. The descriptive character lies even deeper in the nature of methodology and is due to the fact that we have a vague notion of scientific rationality which we unconsciously describe while exercising the very normative role of methodology, that is setting up demarcation criteria for the «scientific». This is what makes the nature of methodology really contradictory and perpetuates debates in the history of science concerning the role of internal and external factors in accounting for theory change.