INCONSISTENCY IN SCIENCE ORIGINS Studies in the sources of scientific creativity Volume 2 Managing Editor: Fernand Hallyn, University of Ghent, Belgium Editorial Board: Gillian Beer, Cambridge University, U.K. James J. Bono, State University ofN ew York, Buffalo, U.S.A. Marc de Mey, University of Ghent, Belgium Thomas Da Costa Kaufman, Princeton University, U.S.A. Peter Galison, Harvard University, U.S.A. Paolo Galluzzi, Istituto e Museo di Storia delle Science, Firenze, Italy Rom Harre, Oxford University, U.K. Peter Machamer, University of Pittsburgh, U.S.A. Arthur I. Miller, University College London, U.K. William Shea, University of Strasbourg, France Gerard Simon, University of Lille III, France Geert Vanpaemel, University ofL euven, Belgium Peter Weingart, University ofB ielefeld, Germany SCOPE The aim of the series is to present historical and theoretical studies on the sources of scientific creativity. The series provides a platform for various transdisciplinary viewpoints. Indeed, on the one hand, the origins of scientific creativity should be studied in the light of its relations with sources of creativity in other disciplines (literary, artistic), in order to illuminate the particular scientific element in the genesis of scientific in novation. On the other hand, the complexity of the topic necessitates a variety of approaches, where logic, cognitive studies, poetics, rhetoric, history of ideas and other disciplines meet in a common interrogation. In short, the series welcomes studies which integrate philosophy and history of science in a broad, diversified field of research, where there is room for a great va riety of perspectives with different methodological and conceptual references and where isolationism as well as reductionism are avoided. Inconsistency in Science Edited by JOKEMEHEUS Ghent University, Ghent, Belgium .... " Springer-Science+Business Media, B.V. A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN 978-90-481-6023-5 ISBN 978-94-017-0085-6 (eBook) DOl 10.1007/978-94-017-0085-6 Printed on acid-free paper All Rights Reserved © 2002 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 2002. Softcover reprint of the hardcover 1s t edition 2002 No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. CONTENTS Preface Vll From Copernicus to Ptolemy: Inconsistency and Method Thomas Nickles Inconsistent Reasoning toward Consistent Theories 35 Arthur 1. Miller Inconsistencies in the History of Mathematics 43 Jean Paul Van Bendegem Mathematical Change and Inconsistency 59 Otavio Bueno Approximate Truth 81 Bryson Brown Inconsistency in Science: A Partial Perspective 105 Newton da Costa and Steven French Inconsistency and the Empirical Sciences 119 Graham Priest v VI CONTENTS In Defence of a Programme for Handling Inconsistencies 129 Diderik Batens How to Reason Sensibly yet Naturally from Inconsistencies 151 Joke Meheus Why the Logic of Explanation is Inconsistency-adaptive 165 Erik Weber and Kristof De Clercq A Paradox in Newtonian Gravitation Theory II 185 John D. Norton Inconsistency, Generic Modeling, and Conceptual Change in Science 197 Nancy J. Nersessian INDEX 213 PREFACE Within traditional philosophy of science, the role of inconsistencies has largely been ignored. At best, inconsistencies were seen as a hindrance for good scientific reasoning. The reason for this is not difficult to understand. Until very recently, rationality has been identified with reasoning according to Classical Logic. And, as is well known, Classical Logic does not allow one to reason sensibly in the presence of inconsistencies. Today, it is generally recognised that almost all scientific theories at some point in their development were either internally inconsistent or incompatible with other accepted findings (empirical or theoretical). A growing number of scholars moreover recognises that inconsistencies need not be disastrous for good reasoning. Three developments were central for this change in attitude. First, there is the shift in attention from finished products to discovery processes. Whereas finished theories usually seem to satisfy the consistency requirement, developing theories typically do not. Next, there is the availability of case studies on episodes in the history of the sciences that involved inconsistencies. Finally, there is the study of paraconsistent logics' that started some fifty years ago. This study not only challenged the view that Classical Logic would be the appropriate tool for reasoning in all contexts, but also resulted in a variety of systems that are adequate for reasoning in inconsistent contexts. The prevalence of inconsistencies in the sciences raises a large number of interesting questions. How should 'logical anarchy' be avoided? Should one resort to a paraconsistent logic or to non-logical criteria? What about the acceptance of inconsistent theories? Are we ever justified to accept an inconsistent theory, and if so, can this acceptance be more than provisional? How does inconsistency affect our notion of truth? Should inconsistent theories at best be considered as 'containing some truth' or can they be considered as true in the same strong sense as consistent theories? Do inconsistencies exist in the world out there or only in the theories we , A logic is called paraconsistent iffit does not validate Ex Fa/so Quodlibet (A, -A f-- B). Vll Vlll PREFACE humans design about that world? The obvious importance of these questions certainly warrants to devote a series of studies to the theme. The incentive for this book was the First World Congress on Paraconsistency (Ghent University, Belgium, 30 July - 2 August 1997). At this congress, a workshop on The Role of Inconsistencies in the History and Philosophy of Science was organized. This was not the first meeting devoted to the theme. However, the Ghent workshop was at least for two reasons unique. Never before had a meeting on this subject been attended by specialists from all over the world. And even more importantly, never before had philosophers of science and historians of science met with logicians and computer scientists to discuss this intriguing theme. A selection of papers presented at this workshop is included in the present volume. In order to do justice to the variety of approaches, this selection has been extended with a number of invited papers. The book opens with two contributions from the philosophy of science, "From Copernicus to Ptolemy: Inconsistency and Method" by Thomas Nickles and "Inconsistent Reasoning toward Consistent Theories" by Arthur Miller. Nickles compares the standard theory-centred conception of science with newer pragmatic and model-based accounts of scientific inquiry regarding their methodological treatment of inconsistencies. Miller investigates different sources of inconsistencies, and draws some conclusions from this with respect to scientific progress. These are followed by two studies in the philosophy of mathematics, "Inconsistencies in the history of mathematics: the case of infinitesimals" by Jean Paul Van Bendegem and "Mathematical Change and Inconsistency: A Partial Structures Approach" by Otavio Bueno. Van Bendegem explores an alternative approach for limit analysis that solves the inconsistencies connected with infinitesimals; the case is further used to defend a contingent view on mathematical progress. Starting from da Costa's and French's partial structures approach, Bueno presents a framework for mathematical change that assigns a positive role to inconsistencies. He applies the framework to the development of set theory. Next, there are several analyses of inconsistencies in the empirical sciences that are based on a specific paraconsistent approach, "Approximate Truth: A Paraconsistent Account" by Bryson Brown, "Inconsistency in Science: A Partial Perspective" by Newton da Costa and Steven French, "Inconsistency and the Empirical Sciences" by Graham Priest, "In Defence of a Programme for Handling Inconsistencies" by Diderik Batens, "How to Reason Sensibly yet Naturally from Inconsistencies" by Joke Meheus and "Why the Logic of Explanation is Inconsistency-adaptive" by Erik Weber and Kristof De Clercq. The first three of these defend each a different realistic view on inconsistent theories. Brown presents an account of approximate truth that is based on a specific non-adjunctive approach to paraconsistency, and that aims at explaining the success of past and current (possibly inconsistent) theories. da Costa and French offer a model-theoretic account in which theories are regarded as partial structures. On this account, inconsistent theories (just like consistent ones) can be considered as partially true and accepted as such. Priest advocates the view that reality itself is inconsistent and that contradictions are observable. In line with this, he defends the idea that inconsistent theories can be considered as true in the strong sense of the word. The last three PREFACE IX papers in this group explore the philosophical foundations and some applications of inconsistency-adaptive logics. Batens spells out the philosophical programme underlying this family of logics; one of his central arguments is that handling inconsistent theories requires a logic that stays as close as possible to Classical Logic. Meheus argues that reasoning from inconsistencies requires an extremely rich inconsistency-adaptive logic, and presents a system that meets this requirement. Weber and De Clercq argue that inconsistency-adaptive logics are much better suited than Classical Logic to define the different types of explanation. The volume closes with two case studies, "A Paradox in Newtonian Gravitation theory II" by John Norton and "Inconsistency, Generic Modeling, and Conceptual Change in Science" by Nancy Nersessian. Norton provides a rigorous yet transparent demonstration of the inconsistency of Newtonian Cosmology, and defends the view that physical theorists handled this inconsistency by a content driven approach rather than a logic driven approach. Nersessian analyses Maxwell's construction of the laws of electrodynamics, and shows how generic modeling enabled him to tolerate several inconsistencies in his derivation. Acknowledgments The workshop The Role of Inconsistencies in the History and Philosophy of Science was organized by the international research community "Science and Culture" and was sponsored by the Fund of Scientific Research - Flanders. The editor is a Postdoctoral Fellow of the same Fund. The editor wants to thank the members of the organising committee of the First World Congress on Paraconsistency for their help in organising the workshop and Isabel D'Hanis for her help in preparing the manuscript. Joke Meheus THOMAS NICKLES FROM COPERNICUS TO PTOLEMY: INCONSISTENCY AND METHOD* Abstract: In recent years several philosophers and other science studies experts have adopted a somewhat more Ptolemaic than Copernican view of theories, models, and scientific research, namely, the "semantic" conception of theories and their applications. On the old, "Copernican" view, theories are deductively integrated, interpreted logical calculi, in standard symbolic logic, and science is a theory-centered enterprise that aims for a comprehensive, single picture of the universe. Accordingly, consistency becomes a hard constraint, a sine qua non of useful, rational inquiry. Proponents of the semantic conception are somewhat more "Ptolemaic" in treating theories as collections of models and in placing the solution of local problems in restricted domains ahead of grand, spectator theories of the universe. They focus as much on the process of inquiry as upon the logical structure of its products. Remarkably, in scientific practice we find inconsistencies and near-inconsistencies of various kinds apparently popping up everywhere, suggesting that one cannot lay a tight grid of standard logic over scientific practice. However, deflating unitary theories into collections of models makes inconsistency harder to define and locate precisely-but also less serious. Consistency often becomes a soft, negotiable constraint--one constraint among others. In practice, inconsistency rarely leads to complete disaster, for there are various ways to tame it. I urge paraconsistency and inconsistency-tolerant logicians to pay attention to real scientific examples of scientists' responses to inconsistency and quasi-inconsistency, e.g., conceptual incongruities such as conceptual "blowups" and pragmatic inconsistencies such as the simultaneous use of mutually inconsistent models. 1. INTRODUCTION Methodological treatments of (in)consistency in the empirical sciences usually take for granted a theory-centered conception of inquiry according to which theories are the primary units of and for analysis. Theories are supposed to provide correct (realist) representations of the universe or at least unified engines of prediction and explanation for a universal domain of phenomena. Since the 1960s, however, this Copernican paradigm (as we may call it) has been challenged by numerous studies of historical and contemporary scientific practice, especially experimental practice. Some science studies experts now favor something closer to a Ptolemaic paradigm, according to which the theories (if any) of a scientific field are tools in a toolbox alongside various other tools for solving the variety of problems that arise in that field. Such a view is more characteristic of those who take a pragmatic, problem solving approach to scientific work than of those who take a universal-truth-seeking, * Acknowledgement. I thank the U.S. National Science Foundation for support on projects concerning heuristic appraisal and knowledge pollution. Thanks also to Joke Meheus for helpful suggestions. She is not responsible for infelicities that remain. J. Meheus (ed.), Inconsistency in Science, 1-33. © 2002 Kluwer Academic Publishers.