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 …

This paper is an investigation of the degree of incommensurability between Western scientific medicine and traditional Chinese medicine, focusing on the practice and theory of acupuncture. We describe the structure of traditional Chinese medicine, oriented around such concepts as yin, yang, qi, and xing, and discuss how the conceptual and explanatory differences between Western medicine and traditional Chinese medicine generate impediments to their comparison and evaluation. We argue that the linguistic, conceptual, ontological, and explanatory impediments can to a large extent be overcome, and conclude that the dramatic differences between Western and traditional Chinese medicine do not provide insurmountable barriers to rational evaluation of acupuncture. We conclude with a discussion of the intentional and emotional aspects of conceptual change.

This chapter shows that belief revision about global warming can be modeled by a theory of explanatory coherence that has previously been applied to many cases of scientific belief change. We present a computer simulation of how current evidence supports acceptance of important conclusions about global warming on the basis of explanatory coherence. In addition, we explain resistance to these conclusions using a computational model of emotional coherence, which shows how political and economic goals can bias the evaluation of evidence and produce irrational rejection of claims about global warming. Finally, we argue that explanatory coherence gives a better account of belief revision than major alternatives including logicist and Bayesian theories.

Many disciplines, including philosophy, history, and sociology, have attempted to make sense of how science works. In this book, Paul Thagard examines scientific development from the interdisciplinary perspective of cognitive science. Cognitive science combines insights from researchers in many fields: philosophers analyze historical cases, psychologists carry out behavioral experiments, neuroscientists perform brain scans, and computer modelers write programs that simulate thought processes. Thagard develops cognitive perspectives on the nature of explanation, mental models, theory choice, and resistance to scientific change, considering disbelief in climate change as a case study. He presents a series of studies that describe the psychological and neural processes that have led to breakthroughs in science, medicine, and technology. He shows how discoveries of new theories and explanations lead to conceptual change, with examples from biology, psychology, and medicine. Finally, he shows how the cognitive science of science can integrate descriptive and normative concerns; and he considers the neural underpinnings of certain scientific concepts.

Many psychologists, philosophers, and computer scientist have written about mental models, but have remained vague about the nature of such models. Do they consist of propositions, concepts, rules, images, or some other kind of mental representation? This paper will argue that a unified account can be achieved by understanding mental models as representations consisting of patterns of activation in populations of neurons. The fertility of this account will be illustrated by showing its applicability to causal reasoning and the generation of novel concepts in scientific discovery and technological innovation. I will also discuss the implications of this view of mental models for evaluating claims that cognition is embodied.

What is the relation between coherence and truth? This paper rejects numerous answers to this question, including the following: truth is coherence; coherence is irrelevant to truth; coherence always leads to truth; coherence leads to probability, which leads to truth. I will argue that coherence of the right kind leads to at least approximate truth. The right kind is explanatory coherence, where explanation consists in describing mechanisms. We can judge that a scientific theory is progressively approximating the truth if it is increasing its explanatory coherence in two key respects: broadening by explaining more phenomena and deepening by investigating layers of mechanisms. I sketch an explanation of why deepening is a good epistemic strategy and discuss the prospect of deepening knowledge in the social sciences and everyday life.