Conceptual Change in the History of Science : Life , Mind , and Disease

INTRODUCTION Biology is the study of life, psychology is the study of mind, and medicine is the investigation of the causes and treatments of disease. This chapter describes how the central concepts of life, mind, and disease have undergone fundamental changes in the past 150 years or so. There has been a progression from theological, to qualitative, to mechanistic explanations of the nature of life, mind and disease. This progression has involved both theoretical change, as new theories with greater explanatory power replaced older ones, and emotional change as the new theories brought reorientation of attitudes toward the nature of life, mind, and disease. After a brief comparison of theological, qualitative, and mechanistic explanations, I will describe how shifts from one kind of explanation to another have carried with them dramatic kinds of conceptual change in the key concepts in the life sciences. Three generalizations follow about the nature of conceptual change in the history of science: there has been a shift from conceptualizations in terms of simple properties to ones in terms of complex relations; conceptual change is theory change; and conceptual change is often emotional as well as cognitive. The contention that historical development proceeds in three stages originated with the nineteenth-century French philosophers, Auguste Comte, who claimed that 2 human intellectual development progresses from a theological to a " metaphysical " stage to a " positive " (scientific) stage (Comte, 1988). The stages I have in mind are different from Comte's, so let me say what they involve. By the theological stage I mean systems of thought in which the primary explanatory entities are supernatural ones beyond the concept of fire was initially theological, as in the Greek myth of Prometheus receiving fire from the gods. By the qualitative stage I mean systems of thought that do not invoke supernatural entities, but which postulate natural entities not far removed from what they are supposed to explain, such as vital force in biology. Early qualitative concepts of fire include Aristotle's view of fire as a substance and Epicurus's account of fire atoms. By the mechanistic stage I mean the kinds of developments now rapidly taking place in all of the life sciences in which explanations consist of identifying systems of interacting parts that produce observable changes. The modern concept of fire is mechanistic: combustion is rapid oxidation, the combination of molecules. Much more will be said about the …