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NEW PERSPECTIVES ON THE OF WESTERN ONTARIO SERIES IN PHILOSOPHY OF

A SERIES OF BOOKS

ON , METHODOLOGY,

AND

PUBLISHED IN CONNECTION WITH

THE UNIVERSITY OF WESTERN ONTARIO

PHILOSOPHY OF SCIENCE PROGRAMME

Managing Editor

J. 1. LEACH

Editorial Board

J. BUB, R. E. BUTTS, W. HARPER, J. HINTIKKA, D. J. HOCKNEY, C. A. HOOKER, 1. NICHOLAS, G. PEARCE

VOLUME 14 NEW PERSPECTIVES ON GALILEO Papers Deriving from and Related to a Workshop on Gali/eo held at Virginia Polytechnic Institute and State University, 1975

Edited by

ROBERT E. BUTTS Department of Philosophy, the University of Western Ontario, London, Canada

and

JOSEPH C. PITT Department of Philosophy and Religion, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, U.S.A.

D. REIDEL PUBLISHING COMPANY

DORDRECHT : HOLLAND / BOSTON: U.S.A. Library of Congress Cataloging in Publication Data

Main entry under title:

New perspectives on Galileo.

(The University of Western Ontario series in philosophy of science ; v. 14) Bibliography: p. Includes index. 1. S cience-Methodology -Congresses. 2. Science-Philosophy-Congresses. 3. Galilei, Galileo,1564-1642. I. Butts, Robert E. II. Pitt, JosephC. Q174.N48 509 /.2'4 77-17851 ISBN-I3: 978-90-277-0891-5 e-ISBN: 978-94-009-9799-8 DOl: 10.1007/978-94-009-9799-8

Published by D. Reidel Publishing Company, P.O. Box 17, Dordrecht, Holland

Sold and distributed in the U.S.A., Canada, and Mexico by D. Reidel Publishing Company,lnc. Lincoln Building, 160 Old Derby Street, Hingham, . 02043, U.S.A.

All Rights Reserved Copyright © 1978 by D. Reidel Publishing Company, Dordrecht, Holland Softcover reprint ofthe hardcover I st Edition 1978 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any informational storage and retrieval system, without written permission from the copyright owner TABLE OF CONTENTS

PREFACE vii

ROBERT E. BUTTS and JOSEPH C. PITT/Introduction ix

WINIFRED LOVELL WISAN/Galileo's : a Reexamina ti on

ROBER T E.BUTTS/Some Tactics in Galileo'~ Propaganda for the Mathematization of Scientific Experience 59

WILLIAM A. WALLACE/ and the Doctores Parisienses 87

WILLIAM R. SHEA!Descartes as Critic of Galileo 139

PETER MACHAMER/Galileo and the Causes 161

JOSEPH C. PITT/Galileo: Causation and the Use of Geometry 181

H. E. LE GRAND/Galileo's Matter Theory 197

ERNAN McMuLLIN/The Conception of Science in Galileo's 209

INDEX 259 PREFACE

The essays in this volume (except for the contribution of Dr. Le Grand) are extremely revised versions of papers originally delivered at a workshop on Galileo held in Blacksburg, Virginia in October, 1975. The meeting was organized by Professor Joseph Pitt and sponsored by the Department of Philosophy and Religion, The College of Arts and , and the Division of Research of Virginia Polytechnic Institute and State University. The papers that follow deal with problems OIf Galileo's philosophy of science, specific and general problems connected with his methodology, and with historical and conceptual questions concerning the relationship of his work to that of contemporaries and both earlier and later . New perspectives take many forms. In this book the 'newness' has, for the most part, two forms. First, in the papers by Wisan, Shea, Le Grand and Wallace (the concerns also appear in some of the other contributions), greatly enriched historical discoveries of how Galileo's science and its method• ology developed are provided. It should be stressed that these papers are attempts to recapture a deep sense of the kind of science Galileo was creating. Other papers in the volume, for example, those by McMullin, Machamer, Butts and Pitt, underscore the importance of this historical venture by discussing various aspects of the philosophical background of Galileo's thought. The historical and philosophical evaluations and analyses compliment one another. We think it important that they should - Galileo's thOUght was much too complex, much too original and much too dependent upon earlier modes of enquiry to make the task of reconstructing his philosophy of science easy. No catalogue of historical details will do that task; nor will a systematic presenta• tion by philosophers of the '' of his methodology. The authors of the following essays remain faithful to the ambiguity that was characteristic of Galileo's work as a productive . In this way they manage to instruct us best in the many dimensions of one of the seminal persons involved in creating modern science. All too frequently philosophers and historians are inclined to go their separate ways. It is our hope that the present volume will vii viii PREFACE be seen as a good example of what can be done in the difficult job of building a crossroad. This volume would not have been possible without the extraordinary cooperation of the authors of the papers, many of whom commented on and criticized portions of the papers of others involved in the workshop. The workshop itself was only possible because of the considerable support offered by Virginia Polytechnic Institute and State University through the good offices of Associate Dean of Research for Arts and Sciences Thomas Gilmer, Dean of the Research Division Randal M. Robertson, and Dean of the College of Arts and Sciences William C. Havard. We thank them for that support.

May, 1977 THE EDITORS INTRODUCTION

The now classical works of Koyre and Crombie, works different in philosoph• ical and historiographical approaches, provoked new scholarly interest in Galileo's science. The motivations of their work were, however, very similar. Both wanted a more detailed lq10wledge of Galileo's actual achievements in positive science, both sought to understand the contribution to scientific methodology generated by this major figure participating in 'the ,' and both, by means of novel insights and conceptual combina• tions of historical and philosophical materials in ways undreamed of by earlier scholars, introduced a whole new dimension to thought about science that can be called the ' of science.' Students of the scientific revolution and the work of Galileo fully realize the importance of the contributions made by these two men. The point is that no one could have forecast the impact that their work - and that of others - would have on our attempt to understand the beginnings of modern ~cience. At the present writing, there is probably no issue that receives greater attention in thought about science than the attempt to understand scientific change, scientific progress, and like concepts. That attention, moreover, is beginning completely to overshadow interests that were once dominant, for example, problems of confirmation in science, the status of hypothetico-deductive explanation, or the 'meaning' of hypothetical constructs having to do with the empirically unobservable. We can of course mention others whose keen historical or philosophical sense has led us to think new thoughts and envision new possibilities: Kuhn and Burtt are only two. But this 'Introduction' is not the place to rehearse, even in a summary, the major eontributions that have been and are now changing the character of and philosophy of science. How• ever, it does suit the purposes of this volume to indicate that the present scholarly forms of interest in the science of Galileo exist in an enriched con• text of a fairly widespread exploration of just those dimensions of Calileo's career exposed in an exciting way by Koyre and Crombie. In this connection it does seem appropriate to name some names (with apologies to those

ix x INTRODUCTION neglected for reasons of or because of simple oversight). There are three groups of contributors to mention. No one will deny that many of the most important studies of Galileo's positive scientific discoveries have been made by Stillman Drake. Equally important work has been done by William Shea, E. J. Aiton, A. Rupert Hall, Thomas B. Settle, and others. For many of these scholars the question of why Galileo accepted the conclusions he did transforms a reporting of what he actually says he did into an attempt to comprehend the methodology he is reputedly so famous for having developed. One important aspect of this methodological concern has to do with and what Galileo thought they accomplished. It is one thing to ask whether or not he dropped the steel ball from the Tower of ; it is quite another to ask why he would have thought it important to do so just in case he ever did. Drake has made meticu• lous studies of the materials which appear to show that Galileo actually did perform experiments, others, for example, Settle, have tried to reproduce what they think must have been Galileo's experiments. Galileo's 'experimental method' is obviously an important feature of his science. Important as this method is, however, discussions of what experi• ments he attempted and how he apparently construed the reputed results, do not rule out what are probably deeper considerations of method - considera• tions we are quite prepared to call 'philosophical.' Just as questions of what actually was discovered blend into questions about what the discoveries mean, so questions about what the discoveries might mean blend into questions about how the discoverer conceived the in the very construction of his questions. This very complex blend of methodological and 'metaphysical' questions constitutes the third dimension of contemporary interest in the accomplishments of GalileD'. Indeed, it would be our contention that more important work has been offered in this area than in any other. We have mentioned the classical 20th-century thinkers who have contributed memoirs on the frontier of methodology-metaphysics. Others of major importance are Winifrid Wisan, William Wallace, William Shea, and a philosopher who keeps coming back to haunt us with his challenge that science, methodology and metaphysics are all bright meadows that will turn into swamps, all hopes that will become utter disappointments - . We have suggested that three areas of Galileo's work have come into prominent focus during this century: (I) the novelty of his positive scientific INTRODUCTION xi discoveries (if any); (2) the natun: of his way of doing science - his method• ology; (3) his 'metaphysics'; the conditions, if you will, under which he would have found any science acceptable. The three categories must of course be seen in the larger context of what others were attempting in science during his lifetime, and in the framework of the kind of revolution in thought about that we now take as an obvious feature of his concerns. We shall turn away from these more general considerations in order to show respects in which the contributions to the present volume continue the vigorous activity that has been going on in Galileo scholarship during the last few decades. For the most part the papers in this volume deal broadly with the philo• sophical background of Galileo's thought and with questions concerning Galileo's methodology. Two papers, those of Shea and Wallace, appear to be more or less standard historical studies, Wallace concerned with dating Galileo's so-called Juvenalia, Shea investigating the question whether Galileo and Descartes independently both discovered the -squared law. In this case appearance is not reality; the two papers also show implications for understanding Galileo's methodology and metaphysics. It is striking that the array of papers exhibits a coincidence of similar insights and interpretations and an overlap of attention to common themes. We propose to look briefly at three such themes: Galileo's method, his views on , and his treat• ment of the nature of . As we shall see, the three themes are themselves interrelated and cannot neatly be compartmentalized. In her perceptive study of the development of Galileo's method over a 50-year period, Wisan outlines the basic points. The model for Galileo's methodology is mathematics, not logic. Unlike most of his contemporaries operating in a quasi-Aristotelian methodological tradition, he thought that knowledge came through the application of mathematics to experience - knowledge is the result of calculation or of experimental results, it is not the grasping of essences. (The profound association between this form of essentialism and the subject-predicate logic of is attested to by the large variety of metaphysical systems based on this logic leading from Aristotle to Bradley. That the logic is already to be found in is a historical commonplace.) Wisan goes on to spell out in detail how Galileo wanted rational principles to be rendered immediately evident through reason and experience, and how discovering true causes means discovering which known rational principles provide grounds for the events to be explained. xii INTRODUCTION

Shea shows that there was little contact between the younger Descartes and the work of Galileo. One wonders why? If Wisan is right and the point of Galileo's science was to render results immediately evident, is this not much like the Cartesian methodological insight that mathematical knowledge is gained through intuition? Leaving our readers to ponder this speculation, we return to Wisan's account. It follows from her account of the desiderata of Galileo's method that that method is not comparable to later formulations of what we now call the hypothetico-deductive model. Rather, the method of making basic prinCiples evident derives from Galileo's conviction that in mathematics we can proceed to evident conclusions on the basis of moving through small and necessary steps from defined terms and explicit assump• tions. Her novel conclusion is that Galileo in effect transfers this kind of mathematical model to physical science, so that inferring causes from observed effects takes the same structural form. Wi san's characterization of Galileo's methodological motives is confirmed, although obviously for different, even sometimes conflicting, reasons by a of other authors of papers in this work. In the context of his elabor• ate historico-philosophical argument that Galileo's main intellectual impulses are derived eclectically from scholastic Aristotelianism and not from the 14th-century Doctores Parisienses (a conclusion of not inconsiderable philo• sophical importance in its own right), Wallace reintroduces a point for which he has argued on earlier occasions, namely that for Galileo reasoning ex suppositione (a form of reasoning classically regarded as being only tentative logically) is demonstrative. (One should note that McMullin disputes this conclusion, arguing at some length and with persuasive logic that for Galileo ex suppositione reasoning was, as it was for many of his contemporaries, not demonstrative, but hypothetical.) Machamer suggests that for Galileo what Aristotle called 'knowledge of the reasoned ' is equivalent to mathematical demonstration_ Shea points out that Descartes' failure to find a way to manage the times-squared law mathematically contrasts with Galileo's mathe• matically more rigorous treatment. Butts, in his detailed of Galileo's argument for the applicability of mathematics to , presents a good example of the point made by both Wisan and McMullin that for Galileo the job is to render basic principles immediately evident. For the most part, the authors included in this volume agree with Wisan's reconstruction of Galileo's methodology. There are of course differences in INTRODUCTION xiii emphasis. For example, both McMullin and Wallace lay more on the Aristotelian background of Galileo's methodological style. Everyone agrees that Galileo's greatest strength lay in a gifted application of geometry to physical problems. But the nature of that application - indeed, the nature of that geometry - is disputed. Of great importance is the rich study by McMullin of what he calls Galileo's 'two conceptions of science.' On McMullin's reading Galileo's methodological career was dominated by the Greek ideal of a demonstrative science. However, faced with explaining phenomena that are physically remote, invisible, or enigmatic (the of the earth), Galileo introduced a second method similar to Peirce's 'retroduc• tion.' A much enlarged understanding of Galileo's science emerges from a close comparative study of the papers by Wisan and McMullin. For many years textbook accounts of Galileo's philosophy of science attributed to him the expurgation of fmal causes from the : from now on science will deal only with efficient causes, nature will no longer be understood teleologically. From whatever source this old chestnut comes, and whatever are its apparent merits, it contains some philosophical worms. If it is true that Galileo's model for both methodology and the nature of reality is mathematics, is it not clear that the central focus of his thought about causes would have been on formal ones? When philosophical concentration upon efficient causes becomes prominent in the Seventeenth Century, it is because attempt to reduce all forms of physical phenomena to cases of impact or collision. It is not at all clear that Galileo adopted this view of a privileged physical model, especially since - as leGrand points out in his paper - for Galileo the material atoms are transposed into atoms regarded as infinitely small, that is, as mathematical points. On such a theory it would be difficult to endorse collision as the basic explanatory model, and hence difficult to champion efficient causality as philosophically central. However one deals with these (apparent) difficulties, one will also have to deal with Stillman Drake's attempt to dispel the entire of the textbook account in his argument that Galileo was not concerned with any form of causality at all. Three of the papers in this volume address themselves directly to the question of Galileo's philosophical attitude to causes. Machamer, citing earlier work by Wallace, presents evidence that Galileo was indeed interested in causal explanation in science. Machamer's interesting point is that given Galileo's identification of mathematics and experience, the important causes xiv INTR OD UCTION are the fonnal ones: efficient causality plays no important role at all in this scenario. McMullin gives general support to Machamer's contention that Galileo did not abandon causal explanation. He provides an elaborate analysis of Galileo's use of retroductive causal explanation, claiming that this method is one of the two prominent aspects of Galileo's approach to science. Pitt suggests that Galileo's revolutionary change in ways of doing science involved the abandonment of final causes, replacing explanations in such tenns with 'mathematical descriptions' of the phenomena. There is much to consider with regard to questions about the role causality plays in scientific explana• tion. Pitt suggests that perhaps the key ingredient in a scientific revolution - a massive change from one way of doing science to an altogether different one - is a change in ways of thinking about what causes are (or ought to be regarded as being). If Wisan and Shea are right about Galileo's mathematically modelled methodology, and if Butts is correct in his portrayal of Galileo as being willing to reject the world - rather than mathematics - if the world tells us something that is false in mathematics, then surely one can make out a good case for the positions of both Machamer and Pitt: for Galileo, thought about causality can no longer be captured in Aristotelian terms. Mathematical - a science which for Aristotle and most medieval Aristotelians had a merely descriptive status with no ontological force - becomes the science for Galileo; and with the establishment of this paradigm final causes become irrelevant along with efficient causes. Indeed, if one enjoys precedent hunting, he might want to say that Galileo, along with , concluded that causal talk is really eliminable from mature science. (Galileo had not advanced to this point; taking into account Wallace's point that Galileo remained throughout his career in the grips of a mixed Aristotelian genetic inheritance, the different but reinforcing approaches to causality in Galileo in the papers by Machamer, McMullin, and Pitt reveal metaphysical postures not to be neglected in attempts to understand Galileo's metaphysical 'location' in early modern science.) Much of what has already been said about the papers in the volume points to a very generally accepted view of the science of Galileo: he was one of the first major scientists to insist that science is thoroughly mathematical. Mathe• matics must be used in the detennination of experimental limits, it must be used in calculating the implications of experimental results, and it must be INTRODUCTION xv used for the very specification of what counts as an 'object of reality.' Nearly all of the present collection of essays has something to say to this point. The essay by Butts concentrates on this issue, attempting to show in detail how Galileo argued for the applicability of mathematics to the observed world (given that the world does not contain any objects like circles, spheres, and other 'mathematical objects'), and also made the more contentious claim that reality - the reality knowable by man - is essentially mathematical. Shea reinforces this interpretation by contrasting what he calls Galileo's 'mathe• matical platonism' with Descartes' failure to commit himself to mathematical realism. We have already discussed Wisan's contention that Galileo's entire methodological development involved an essential recognition of the centra• lity of mathematical methods. Pitt claims that acceptance of mathematical descriptions of experimental results in the science of Galileo (descriptions given in the geometry of his day) eliminated altogether any appeal to tele• ological considerations. Machamer rejects the problem Butts worries about - the applicability of mathematics to the world - resting content with Galileo's identification of mathematics and experience. Also impressive is the position of leGrand, whose argument is entirely devoted to defending the thesis that Galileo introduced a novel theory of matter. In attempting to show that Galileo's confidence in mathematics is partly expressed in his acceptance of one form of the primary-secondary quality distinction, Butts puts emphasis upon what are perhaps incidental passages in . leGrand, moving from more substantial passages in Galileo's mature work, argues tmlt he was not an atomist after the fashion of Democritus (whose position does seem to depend crucially on the distinction between types of qualities), but that his theory of matter is unique in suggest• ing a new metaphysical construal of atoms as infinitely small, that is, as mathematical points. We can only comment that the distinction between primary and secondary qualities (or whatever you want to call them) in Galileo shades off into insignifigance when the total ensemble of his thoughts about the primacy of mathematics is seriously entertained. If matter is decomposible into mathematical points, if both mathematical theory and mathematically designed experiments are to be preferred methods of science, and if the Book of Nature is written in mathematical terms, then there can be no doubt that one of the leading tenets of Galileo's philosophy of science proclaims both the methodological and metaphysical advantage of xvi INTRODUCTION regarding 'saving the appearances' as 'confirming the realities.'

During the period when he was regarded as the 'father of modern science' Galileo was a much neglected figure in the history of science, a fate not unfamiliar to fathers of anything at all. It is a good thing that Galileo can now be thought of as someone who did a bit of good science in his day, and that the way in which he did it was sufficiently different to make it important. Contributors to this volume do not polish Galildo's tombstone, they seek to understand what he was trying to do. Perhaps the best compliment one can pay to a departed father is to laugh at him; the laughter of the good historian and the good philosopher is to be heard in the of the : Why did he think that? What motivated him to try that? Where was he when? Who did what to him where? Could he really have believed that? and on and on. Kant was right: understanding unique properties of an individual is an art, not a science. The papers which follow are exercises of that art. We think they are important instantiations of that art.

ROBER T E. BUTTS JOSEPH C. PITT