Abstract

This dissertation is an attempt to develop a model of rational theory change which can be used to elucidate the shift in theories which occurred in cardiology during the 1920s. I examine in detail the introduction of the coronary theory of angina pectoris, and the introduction of the disease entity acute myocardial infarction. With regard to angina pectoris, I argue that the chief rival to the coronary theory, an aortic theory proposed by such investigators as Allbutt and Wenchebach, was not refuted by the available experimental evidence during the 1920s. There were certain facts which this theory could explain, and which the coronary theory today can still not explain. This episode therefore exemplifies what has become known as Kuhn-loss. I make a similar claim with regard to acute myocardial infarction. ;Based on this case study I examine some recent theories of theory change, such as those of Lakatos and Laudan. I criticize these theories both because of certain inherent weaknesses, and because they cannot adequately account for the rationality of this particular episode in the history of cardiology. Then I develop my own account of theory change, based on recent work by Philip Kitcher. I introduce a notion of a 'scientific practice'. Scientific change can be analysed in terms of changes in, and interactions between, the various components of a scientific practice. In particular, I argue that a theory should be regarded as a pattern of reasoning which can be used to give the same general answer to many particular questions. If we examine the relationship between successive theories conceptualised in this way, we will be able to argue for the rationality of scientific change even in cases of Kuhn-loss. I indicate how this particular way of structuring a scientific field enables us to see both the strengths and weaknesses of current cardiology. ;I also examine a second case study: the development in the understanding of surgical shock during the first two decades of this century. I show how this case study can be illuminated by the model of theory change introduced here