UNIVERSITY OF NAIROBI DEPARTMENT OF PHILOSOPHY AND RELIGIOUS STUDIES STRUCTURAL REALISM VERSUS ENTITY REALISM: A CRITICAL EVALUATION A THESIS PRESENTED IN FULFILMENT OF REQUIREMENTS FOR THE AWARD OF THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE DEPARTMENT OF PHILOSOPHY AND RELIGIOUS STUDIES, UNIVERSITY OF NAIROBI /Ersity a r u n |d a t t a UNIVERSITY OF NAIROBI DEPARTMENT OF PHILOSOPHY AND RELIGIOUS STUDIES TOPIC: STRUCTURAL REALISM VERSUS ENTITY REALISM: A CRITICAL EVALUATION NAME: ARUN DATTA SIGNATURE: SUPERVISORS SIGNATURE: 2. PROF. J. A. ODHIAMBO SIGNATURE: u To my wife, Brij ui ACKNOWLEDGEMENT My sincere gratitude and ‘asante sana' go to my supervisor Dr. Karori Mbugua for his guidance and patience. Prof. Jack Odhiambo perused my work at different stages and gave his valuable advice and encouragement. Prof D.W. Waruta encouraged me to learn philosophy by registering for M.A. in philosophy in spite of my M.Sc. in physical sciences. I am indebted to him for his words of wisdom and facilitation. My thanks are due, to all the lecturers in the department who taught me at M.A. level. I visited London School of Economics and Political Sciences (LSE), where Prof. Nancy Cartwright, the head of philosophy department encouraged me with my research. I had discussions with her Ph.D students and one of them, Mr. E. Maro provided useful tips and suggestions on my topic. I am thankful to the L.S.E for letting me use their study and research materials and making me a member of their library. IV ABSTRACT The two partial scientific realist positions, called structural realism and entity realism make conflicting claims about our knowledge of the unobservable world. They appear to be mutually exclusive and create a tension in the scientific realist camp. In this dissertation I have attempted to reconcile the two as follows. In the first chapter, I state the problem and set the objectives o f the study. The second chapter gives an overview of the scientific realism debate, focusing on the epistemological dimension. I bring out the challenges facing scientific realism. The third chapter surveys the development o f structural realism and explains the stance put forward by John Worrall in defense o f scientific realism. I examine his arguments and show that they are valid only where the structural part of a theory can be expressed mathematically in classical physics. Worrall has appealed to history of science to argue that we cannot know the unobservable theoretical entities. I utilize the same case-study from optics to argue that the unobservable entity ether was never an accepted and empirically adequate theoretical entity. The fourth chapter presents the arguments put forward by two entity realists - Nancy Cartwright and Ian Hacking. They have argued that the theoretical entities, which cause a phenomenon, exist; and by establishing the causal link, we can know them. Further, the entities, which can be interfered-with and manipulated, can be know'n and this knowledge is independent of the theories. I have argued that knowledge of v unobservable causes is parasitic on theories putating them. Entity realists' arguments are valid only where causal links can be theorized and then established experimentally. Interference and manipulation reveal certain aspects of the nature of the entities and are not possible for all types of unobservable entities. The fifth chapter brings out the tension created by structural realism and entity realism. After analyzing their arguments, I show that they do not apply to the whole enterprise of science. In some areas of the enterprise, beliefs about unobservables are justified by mathematization whereas in some other areas by manipulation and by showing causal connection. Thus the two schools of thought do not contradict each other and can coexist. The tension created by the two partial realist positions, is thus shown to be a pseudo- problem and dissolved. vi CONTENTS ACKNOWLEDGEMENT IV ABSTRACT V CONTENTS vii OPERATIONAL TERMS xii CHAPTER ONE 1 INTRODUCTION 1 1.0 Background to the Study 1 1.1 Literature Review 4 1.2 Statement of the Problem 21 1.3 Research Objectives 22 1.4 Scope of the Study 22 1.5 Research Hypothesis 23 1.6 Methodology 23 CHAPTER TWO 25 REALISM VERSUS ANTI-REALISM 25 2.0 Introduction 25 2.1 The origins of the debate 26 2.2 The debate 27 2.3 Scientific Realism 29 2.4 Argument in support of realism 34 2.5 Scientific Anti-Realism 45 2.6 Arguments in support of anti-realism 53 2.7 Realism or Anti-realism ? 69 2.8 Challenges to scientific realism 71 2.9 The partial realist positions 72 2.10 Conclusion 73 CHAPTER THREE 74 STRUCTURAL REALISM 74 3.0 Introduction 74 3.1 Structuralism 75 3.2 From Structuralism to Structural Realism 89 3.3 Reconciling Pessimistic Meta-Induction and No Miracle Arguments 90 3.4 Theories about propagation of light 92 3.5 Worrall’s structural realism 103 3.6 Conclusion 118 CHAPTER FOUR 121 ENTITY REALISM 121 4.0 Introduction 121 4.1 Background to entity realism 121 4.2 The Entity Realist Positions 123 4.3 Nancy Cartwright’s Entity-Realism 127 4.4 Ian Hacking’s Entity Realism 153 VI11 CHAPTER FIVE 193 RESOLVING THE TENSION BETWEEN STRUCTURAL REALISM AND ENTITY REALISM 193 5.0 Introduction 193 5.1 The Tension 194 5.2 The contradictory assertions (A) 196 5.3 The contradictory assertions (B) 205 5.4 Chakravartty’s position (semi-realism) 216 5.5 Dissolving the Tension 218 CHAPTER SIX 224 GENERAL CONCLUSION 224 BIBLIOGRAPHY 231 IX OPERATIONAL DEFINITIONS 1. Scientific Theory A Scientific Theory refers to an unproven hunch or a conceptual device for systematically characterizing the state-transition behaviour of systems. 2. Theoretical Entity A theoretical entity is a concept devised to account for the observed phenomena. 3. Scientific Observation Scientific observation is more than a physical act of sensation, it must be an epistemic act as well, with sufficient meaning and credibility to contribute to knowledge. 4. Scientific Realism Scientific Realism asserts that the objects of scientific knowledge exist independently of the minds or acts of scientists and that the scientific theories are true of that objective world. 5. Scientific Anti-realism Scientific anti-realism asserts that science does not tell us anything about the unobservable part of the world. Xll 6. No Miracle Argument (NMA) Science is a successful enterprise. It would be a miracle if the scientific theories, on which science is based, were false. 7. Pessimistic Meta-induction Argument (PMI) Many empirically successful and accepted theories of the past have been found to be false. Our current accepted theories are empirically successful and by inductive reasoning, may be found out to be false too. 8. Under determination of Theory by Evidence (UDTE) The empirical evidence available, can be accounted for by more than one, mutually incompatible theories. 9. Structural Realism Structural realism is a view that science can tell us about the structural part of the unobservable world. 10. Entity Realism Entity realism is a view that the unobservable theoretical entities exist and that we can know them by scientific method. xm CHAPTER ONE INTRODUCTION 1.0 Background to the Study The aim of science is to increase our knowledge and understanding of the world wc live in. Science is distinguished from other fields of knowledge by its empirical method which proceeds from observation, experiment and theory. A scientific theory is put forward to account for observed phenomena and in general, is made up of two parts. One part consists of unobservable, theoretical entities for example, molecules, electromagnetic waves, atoms and ether, the second part is the structural part which tells how the entities are configurated and behave. There is an ongoing debate between scientific realists and anti-realists over the knowledge that science can provide (as detailed on page 26 of this dissertation). Scientific realists are of the opinion that science, through its theories, tells us a true story about both, the observable and the unobservable parts of the world and that our successful theories are, at least, approximately true. The scientific realists invoke the success of science in favor of their position. They claim that the success of science would be a miracle if the scientific theories were not true. On the other hand, the anti­ realists hold the view that science can tell us about the observable part of the world only and that our belief in scientific theories should be limited to what they tell us about the observables. Some anti-realists take the scientific theories as mere 1 instruments for systematization and prediction of observable phenomena, without attributing reality to the invisible entities they posit. The debate between scientific realists and anti-realists is far from settled. It seems unlikely that they have any final, knockdown arguments against each other. Two partial realist positions have been proposed to defend scientific realism. These are entity realism and structural realism. Some philosophers of science consider these two as among the most promising formulations of scientific realism. Entity realists claim that the unobservable theoretical entities that cause a phenomenon and can be manipulated do actually exist and can be known. It is important to note that the entity realists do not commit themselves to judgments concerning the truth of scientific theories. Structural realists on the other hand, commit themselves only to the structural contents o f scientific theories and not to the truth of the entities. The two views defend scientific realism by claiming that some unobservable component of a scientific theory can be known. The two scientific partial realist positions are incompatible with each other and could hardly disagree more as one commits to the theoretical entities while remaining agnostic about the structure and the other position is committed to the structure only, w'hile remaining agnostic about the entities.