The Chemical Philosophy of Robert Boyle: Mechanicism, Chymical Atoms, and Emergence [1 ed.] 9780197502501

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The Chemical Philosophy of Robert Boyle

The Chemical Philosophy of Robert Boyle Mechanicism, Chymical Atoms, and Emergence M A R I NA PAO L A BA N C H E T T I - R ​ OBINO

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3 Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and certain other countries. Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016, United States of America. © Oxford University Press 2020 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by license, or under terms agreed with the appropriate reproduction rights organization. Inquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above. You must not circulate this work in any other form and you must impose this same condition on any acquirer. Library of Congress Cataloging-in-Publication Data Names: Banchetti-Robino, Marina Paola, author. Title: The chemical philosophy of Robert Boyle : mechanicism, chymical atoms, and emergence / Marina Paola Banchetti-Robino. Description: New York, NY : Oxford University Press, [2020] | Includes bibliographical references and index. Identifiers: LCCN 2020008358 (print) | LCCN 2020008359 (ebook) | ISBN 9780197502501 (hardback) | ISBN 9780197502525 (epub) Subjects: LCSH: Boyle, Robert, 1627–1691. | Chemistry—History—17th century. | Chemistry—Philosophy—History—17th century. Classification: LCC QD22.B 76 B36 2020 (print) | LCC QD22.B 76 (ebook) | DDC 540.1—dc23 LC record available at https://lccn.loc.gov/2020008358 LC ebook record available at https://lccn.loc.gov/2020008359 1 3 5 7 9 8 6 4 2 Printed by Integrated Books International, United States of America

For my dear Ariel and my beloved parents

Contents Preface

ix

Introduction 

1

1. Chemical Philosophy in the 16th and 17th Centuries: Vitalism, Paracelsian Alchemy, and Aristotelian Hylomorphism 1.1 The Vitalistic Character of Renaissance Alchemy 1.2 The Scholastic Theory of Substantial Form 1.3 Paracelsian Spagyria and the Tria Prima 1.4 Semina Rerum, Minima Naturalia, and Vitalistic Corpuscularianism 1.5 Daniel Sennert’s Structural Hylomorphism and Atomicity as a Negative-​Empirical Concept 1.6 Jan Baptista van Helmont and the Chemical Interpretation of Spirit and Ferment 2. Chemical Philosophy vs. Rationalistic Mechanicism: The Heuristic Limits of Cartesianism for Chemistry 2.1 The Cartesian Rejection of Substantial Forms 2.2 Pierre Gassendi and the Reformation of Epicurean Atomism 2.3 The Limitations of the Cartesian Project for Chemistry and Chemical Philosophy 2.4 Mechanistic Corpuscularianism and Experimental Natural Philosophy 2.5 Boyle’s Relation to the Cartesian Project in Natural Philosophy 2.6 The Negative and Positive Heuristic Functions of the Mechanical Philosophy in Boyle’s Scientific Research Programme 3. The Ontological Complexity of Boyle’s Corpuscularian Theory: Microstructure, Natural Kinds, and Essential Form 3.1 The Sceptical Chymist: Against Scholastics and Spagyrists 3.2 Boyle’s Corpuscularian Theory of Matter 3.3 Composition vs. Microstructure 3.4 Taxonomical Classification, Natural Kinds, and Essential Form 3.5 The Empirical Nature of Essential Form: The Reduction to the Pristine State

8

11 13 16 20 26 34

45 45 47 51 60 69 73

79 79 84 90 99 104

viii Contents

4. Boyle’s View of Chemical Properties as Dispositional, Relational, and Emergent Properties 4.1 The Hierarchy of Properties in Boyle’s Chemical Ontology 4.2 Sensible Properties as Dispositional and Relational 4.3 Chemical Properties as Dispositional and Relational 4.4 Chemical Properties as Emergent and Supervenient 4.5 Supervenience, Non-​Summative Difference, and Underdetermination 4.6 Cosmical Qualities as Dispositional and Relational Properties 5. The Relation between Parts and Wholes: The Complex Mereology of Chymical Atoms 5.1 Boylean Chemistry as Mereological 5.2 Continuous vs. Contiguous Integral Wholes 5.3 Integral Parts and Essential Parts 5.4 Aquinas, Abelard, and Boyle on Substantial Unity 5.5 The Mereology of Boyle’s Chymical Atoms as Chemically Elementary Entities 5.6 A Brief Excursion into the Mereology of Epicurean Semantics

109 110 113 121 130 138 139

146 147 151 153 154 156 163

Conclusion 

168

Bibliography Index

173 191

Preface Writing this book was both more challenging than I ever anticipated and more rewarding than I ever imagined. Yet, although only one author’s name appears on its cover, this book is a product not only of my own work but is indirectly also a product of the people who have stood by me and my choices throughout the years. First and foremost, this project would not have come to fruition without the unconditional love and support of my husband and philosophical soul mate, Clevis Headley, whose constant encouragement was invaluable to the progress of my work. I am also grateful for the warm friendship and generous guidance of Hasok Chang, Jean-​Pierre Llored, Eric Scerri, Brigitte van Tiggelen, and the late Rom Harré. Their pioneering work in the history and philosophy of chemistry has been truly inspiring and has served as the standard of excellence that I have sought to emulate in my own work. I am indebted to my institution, Florida Atlantic University, for generously supporting the writing of this book with a sabbatical semester in spring 2015, and I also want to express my appreciation to my former student Ms. Cameron Black for her detailed and meticulous proofreading of the final draft of the manuscript. I want to thank Jeremy Lewis at Oxford University Press and his editorial assistant, Bronwyn Geyer, for their unwavering support of this project. They are both truly a pleasure to work with. Finally, I am also heavily indebted to the two anonymous reviewers of my original book proposal for their close and careful reading, their constructive criticisms, and their many thoughtful comments and suggestions, which helped to greatly improve the final version of this work. I benefited considerably from presenting papers on the various topics of this book at numerous conferences, which included those of the International Society for the Philosophy of Chemistry, the Philosophy of Science Association, the History of Science Society, the Science History Institute (formerly the Chemical Heritage Foundation), and the Seminar on the History and Philosophy of Chemistry at the University of Paris. Some sections of this book draw upon and revise material previously published in the following articles and chapters:  “Ontological Tensions in Sixteenth and Seventeenth Century Chemistry:  Between Mechanism and Vitalism,” Foundations of Chemistry 13 (2011), 173–​ 186; “The Ontological Function of First-​ Order and Second-​ Order Corpuscles in the Chemical Philosophy of Robert Boyle:  The Redintegration of Potassium Nitrate,” Foundations of Chemistry 14 (2012), 221–​234; “The Relevance of Boyle’s Chemical Philosophy

x Preface for Contemporary Philosophy of Chemistry,” in Jean-​ Pierre Llored (ed.), Philosophy of Chemistry: Practices, Methodologies, and Concepts (Newcastle upon Tyne:  Cambridge Scholars Publishing, 2013), 240–​265; “From Corpuscles to Elements: Chemical Ontologies from Van Helmont to Lavoisier,” in Lee McIntyre and Eric Scerri (eds.), Philosophy of Chemistry:  Growth of a New Discipline (Dordrecht: Springer, 2014), 141–​154; “Van Helmont’s Hybrid Ontology and Its Influence on the Chemical Interpretation of Spirit and Ferment,” Foundations of Chemistry 18 (2015), 103–​112; “Reality without Reification:  Philosophy of Chemistry’s Contribution to the Philosophy of Mind,” in Grant Fisher and Eric Scerri (eds.), Essays in the Philosophy of Chemistry (Oxford: Oxford University Press, 2016), 83–​110; and “The Function of Microstructure in Boyle’s Chemical Philosophy:  ‘Chymical Atoms’ and Structural Explanation,” Foundations of Chemistry 21 (2019), 51–​59. Although the writing of this book would not have been possible without the patience, advice, and constant support of my husband Clevis, I am also eternally grateful to my lifelong friend, Rebekah Guerra, for standing by me through all my struggles and successes and to my aunts, Vittoria and Giuseppina Robino, for their continued love, generosity, and support. I wish to dedicate this book to the memory of my beloved parents, Paris Edoardo Banchetti and Fortunata Robino di Banchetti. My mother, Fortunata, passed away in 1996 as I  was beginning my teaching and scholarly career at Florida Atlantic University. My father, Paris, passed away in March 2019, only one week prior to my receiving final word from Oxford University Press that my book had been accepted for publication. I believe that they would have been proud. Throughout their lives, my parents served as models of dedication, perseverance, and integrity and their influence made me who I am today. Their unconditional love and support will continue to sustain me for the rest of my life. Finally, I also dedicate this book to one of my sweet and beautiful cats, Ariel Mahogany, who was diagnosed with cancer in January 2015 as I began my sabbatical semester. The months following her diagnosis were spent taking regular breaks from the writing of this book to feed and medicate Ariel, in a desperate attempt to keep her cancer in remission. Each and every day, I wrote incessantly as she held on to life, sleeping next to me as I worked and at first even showing signs of improvement. After six months, the time that it took for me to finish the manuscript, her little body succumbed to the disease and she passed away one week after I wrote the final words of the conclusion. Ariel lived just long enough to see me finish this book and her soul lies deep within its pages. I will always feel grateful and honored that this beautiful creature chose us as her family. Although she was here only for a moment, her unconditional love will live in my heart forever.

Introduction In the introduction to his book The Aspiring Adept:  Robert Boyle and His Alchemical Quest, Lawrence Principe states that “The work I  have done on Robert Boyle since 1998 has actually been an extended digression.”1 Following this seemingly surprising statement, Principe goes on to recount how, in the process of researching the work of the mysterious 15th century alchemist Basil Valentine, he came across a 19th-​century text referencing Boyle’s experiments on the volatility of gold. Surprised by the similarity between Boyle’s experiments and those described by Valentine, Principe decided to investigate Boyle’s writings further, particularly regarding what these revealed about Boyle’s interest in chrysopoeia. The discovery of Boyle’s significant involvement with alchemy thus pulled Principe away from his researches on Valentine and resulted in the groundbreaking book cited above. I open this introduction with Principe’s account precisely because, as I read his words, they struck a familiar chord with me. My own work on Boyle for the past 10 years, and its culmination in this book, are also the result of an extended digression. In 2008, while working on a different project, I  researched early modern theories of matter and, in particular, the transition between the vitalistic theories of the alchemical tradition and the mechanistic theories that came to define early modern science. To this end, I came across two books that altered my perspective on early modern chemistry and, in the process, also altered the path of my research. These books were Antonio Clericuzio’s Elements, Principles, and Corpuscles: A Study of Atomism and Chemistry in the Seventeenth Century and Hiro Hirai’s incredibly erudite Le concept de semence dans les theories de la matière à la Renaissance: de Marsile Ficin à Pierre Gassendi. Since I was only beginning to research this topic at the time, I was surprised to discover by reading these fascinating texts that vitalism and alchemical concepts had continued to influence theories of matter well into the 17th century. I thus decided to further research these ideas and was inevitably led to the work of Robert Boyle, whose



1 Principe, The Aspiring Adept, 5.

The Chemical Philosophy of Robert Boyle. Marina Paola Banchetti-Robino, Oxford University Press (2020). © Oxford University Press. DOI: 10.1093/oso/9780197502501.001.0001

2 Introduction relationship to alchemy and to the mechanistic theory of matter have been the subject of much discussion and revaluation for the past 25 years. This revaluation has certainly been justified since, as Michael Hunter points out in his important collection Robert Boyle Reconsidered, Boyle is “a figure of undeniable significance.”2 This significance is not limited to his scientific contributions but is also philosophical, particularly with regard to Boyle’s reconciliation of the mechanistic conception of fundamental particles with his complex and nuanced ontology of chemical properties and substances. In fact, Hunter identifies a need to “abandon simplistic preconceptions about the mechanical philosophy in the seventeenth century”3 as they relate to Boyle’s chemical work, pointing out that Boyle was a sophisticated thinker who understood that “the principles of Cartesian mechanism were too limited, and that ultimately, a true new philosophy would emerge that would do justice to considerations of this kind.”4 Boyle is a much more important philosophical figure than had been previously realized and his philosophical contributions are crucial to our understanding of the creation of modern chemistry and physics. This is the case because they help to define the transition between the physics of the mechanical philosophy and the modern conception of chemistry. Boyle’s writings reveal that the mechanical philosophy was just one prominent feature of a very distinctive and well-​developed chemical philosophy. As Peter Anstey’s important book The Philosophy of Robert Boyle shows, Boyle made important and significant contributions to early modern philosophical discussions regarding the theory of qualities, of matter in motion, and of mind/​body interaction. I have taken much inspiration from Anstey’s work, especially from his excellent argument that Boyle regarded sensible qualities as dispositional and relational properties. However, although Anstey suggests that Boyle also regarded chemical properties as dispositional and relational, he never pursues this argument and restricts himself to the discussion of sensible qualities. I have therefore taken it upon myself to extend Anstey’s arguments to Boyle’s conception of chemical properties, while going a step further and also arguing that Boyle regarded such properties as emergent and supervenient. Furthermore, since the philosophy of chemistry recognizes the intimate connection between the emergence and supervenience of chemical properties and the relation between chemical wholes and their parts, I considered it imperative also to examine the kind of mereology of chymical atoms that is most consistent with Boyle’s emergentist conception of chemical qualities. Therefore, the two main goals of this book are,

2 Hunter, Robert Boyle Reconsidered, 5. 3

Ibid., 8.

4 Ibid.

Introduction  3 first, to demonstrate that Boyle regarded chemical properties as properties that emerge from and supervene upon the mechanical and structural properties of chymical atoms and, second, to demonstrate that such an emergentist position entails a non-​extensional and non-​summative mereology of chymical atoms. The emergentist reading of Boyle and the mereological theory of chymical atoms that I am proposing are both novel contributions to the scholarship on Boyle, and I am convinced that a sustained analysis of these ideas can significantly enrich our understanding of Boyle’s chemical philosophy. To explain the structure of this book, I  must first say that I  agree with Michael Hunter’s view that, although contextual considerations must always be addressed, Boyle studies should also remain sensitive to “the power and complexity of intellectual traditions in their own right.”5 Consequently, I  follow Hunter’s admonition to balance the contextual historiographical approach with a critical analysis of “the content of his ideas and the extent to which the intellectual developments with which he was associated had an internal momentum of their own.”6 Therefore, I not only situate Boyle’s ideas within the intellectual context of the early modern period and in relation to the intellectual traditions that helped shape that context, but I also thoroughly examine the internal content and logic of Boyle’s ideas regarding chymical atoms and chemical properties. Additionally, I consider the textual evidence that supports the emergentist position and non-​extensional mereology that I am proposing. To this end, the book begins by setting the historical context within which to situate Boyle’s ideas. I pursue this task by examining the dominant paradigms of 16th-​and 17th-​century chemical philosophy. More particularly, Chapter  1 focuses on three of these important paradigms, the doctrine of vitalism to which Cartesian mechanicism was responding, the theory of substantial form that had dominated Scholastic science, and the Paracelsian tria prima that functioned as the theory of principles for Renaissance and early modern alchemists. This first chapter also discusses other important concepts that are relevant throughout the book, such as the notions of semina rerum and minima naturalia and the idea that corpuscularianism was compatible with both vitalistic and mechanistic theories of matter. The chapter concludes with detailed discussions of the vitalistic corpuscularian chemical ontologies of Daniel Sennert and Jan Baptista van Helmont. These respective ontologies both served as important antecedents to the chemical philosophy of Robert Boyle and also influenced some of his more important chemical experiments. Chapter  2 contextualizes Boyle’s distinctive mechanistic corpuscularianism within the larger framework of the mechanical philosophy by, first, providing

5

Ibid., 5.

6 Ibid.

4 Introduction a detailed account of the relationship between Cartesian mechanicism and early modern chemistry. This discussion establishes that an intrinsic tension existed between Cartesian mechanicism and chemical philosophy, particularly regarding the heuristic value and scientific autonomy of chemistry. The chapter then discusses the revival of Epicurean atomism in early modern Europe and contrasts Gassendi’s mechanistic atomism with Descartes’ mechanistic corpuscularianism to show why the former view was more compatible with chemical experimental practice. The chapter also examines the competing explanations of Boyle and Spinoza regarding the redintegration of potassium nitrate to establish why Boyle rejected Spinoza’s attempt to explain experimental results strictly in terms of the positions and motions of fundamental particles. The chapter concludes with a discussion of the role played by the mechanistic philosophy in Boyle’s overall experimental program. Here, Boyle’s experimental work in chemistry, pneumatics, and hydrostatics is considered as a type of Lakatosian research programme within which the mechanical philosophy functions as the “metaphysical hard core.” As such, the mechanical philosophy serves as a negative heuristic, that is, as a limiting principle that forbids explanatory appeal to principles that are incompatible with it. As the “metaphysical hard core” of the Boylean research programme, the mechanical philosophy also serves as a positive heuristic by providing an explanatory model based on empirical clockwork mechanisms and simple machines. Following the historical and philosophical context provided by the first two chapters, Chapter 3 engages in a thorough and detailed account of Boyle’s chemical ontology. This chapter begins by discussing Boyle’s rejection of two key principles of Scholastic and Renaissance chemical ontology, that is, the theory of substantial forms and the Paracelsian theory of the tria prima. The chapter then examines Boyle’s mechanistic corpuscularian theory of matter, focusing particularly on the role played by microstructure in determining chemical properties. Boyle’s corpuscularian chemistry presupposes stable concretions of fundamental particles and I  follow William Newman in referring to these stable concretions as “chymical atoms.” Boyle’s chymical atoms are structures resulting from combinations of fundamental particles possessing only shape, size, and motion. However, Boyle accounts for the chemical properties of substances in terms of the microstructure of such chymical atoms, rather than by appealing to the shapes, sizes, and motions of their constituent fundamental particles. Boyle refers to the microstructure of chymical atoms as their texture or essential form, and he regards essential form as a mechanical property of chymical atoms, thereby accounting for stability in mechanistic terms rather than by appealing to mysterious entities such as substantial forms. Because microstructure is what accounts for a substance’s essential chemical properties, it is that which makes a particular substance the kind of substance that it is and that which allows for

Introduction  5 the taxonomical classification of material species. Here, the book compares and contrasts Boyle’s views on taxonomical classification with those of Locke, with whom Boyle engaged in numerous debates. Finally, the chapter concludes with a close examination of the experiment of reduction to the pristine state, an experiment that Boyle inherits from Sennert but which he uses to argue against the concept of substantial form and in favor of microstructure as the source of the stability of chymical atoms, even when these are combined, separated, and transposed through chemical reactions. Boyle purports to demonstrate that, since chemical substances are composed of such stable concretions, they preserve their identity through various chemical processes. The ability to recover such substances from heterogeneous mixts thus lends confirmation to the concept of essential form or structure as the source of chemical stability. Following upon this discussion of Boyle’s chemical ontology, Chapter 4 argues that Boyle holds an emergentist conception of chemical qualities, also regarding them as dispositional and relational properties. This discussion is relevant to more recent debates in the philosophy of chemistry on the emergence of chemical properties and on the reducibility of chemistry to physics. In this chapter, I  build upon Anstey’s very thorough arguments for the dispositionality and relationality of sensible qualities and I extend his analysis to chemical properties. I then argue that, in addition to considering such properties to be dispositional and relational, Boyle also considers them to be emergent and supervenient properties. I then conclude the chapter by discussing Boyle’s conception of cosmical qualities such as gravity and magnetism to demonstrate that, although he regards them as properties of corpuscular effluvia, he also regards these qualities as dispositional and relational properties. To the extent that mereological questions regarding chemical wholes and their parts are intimately connected to emergentist accounts of chemical properties, the final chapter focuses on the mereology that is implied by Boyle’s conception of chymical atoms. A lot of recent work in the philosophy of chemistry, particularly the collaborative work of Jean-​Pierre Llored and Rom Harré, has focused on the need to develop a non-​extensional, non-​summative mereology for quantum chemical wholes to account for the emergence of chemical properties from such wholes. What I propose, in Chapter 5, is that the mereology of Boylean chymical atoms must also be a non-​extensional mereology for the following two reasons. First, chymical atoms are more than simply the summation of their mechanistic fundamental parts and, second, novel properties are generated by the structural arrangement of their parts. In order to develop this argument, the chapter first examines in detail the leading mereological theories of Boyle’s time, particularly those theories that had been developed by medieval logicians and metaphysicians. The purpose of this discussion is to determine which of these theories is most consistent with the Boylean conception of

6 Introduction chymical atoms, that is, with a conception of chemical wholes from which emerge novel properties that are not properties of their parts. Based on this mereological analysis, the chapter then proposes that Boyle regarded chymical atoms as chemically elementary entities, despite their ontological reducibility to fundamental mechanistic particles, thereby anticipating the conception of elementarity later proposed by John Dalton. The chapter ends by discussing Boyle’s explicit analogy between Lucretius’ conception of the relation between individual letters and linguistic expressions and his own conception of the relation between fundamental particles and chymical atoms. Once this analogy is unpacked, it reveals a great deal regarding the manner in which Boyle conceptualizes the mereological relation between chemical wholes and their parts. In fact, the chapter extends Boyle’s analogy to help support the claim that his conception of chymical atoms, as wholes from whose microstructure emerge chemical properties, is most consistent with a non-​extensional and non-​summative mereology of wholes and parts. The conclusion recapitulates many of the book’s arguments and establishes the relevance of Boyle’s chemical philosophy for contemporary debates in the philosophy of chemistry. More specifically, the book reviews Boyle’s position regarding the microstructure of chymical atoms, the relational and dispositional nature of chemical properties, as well as their emergence and supervenience, and the autonomy of chemical explanations, and it compares these views to similar positions in contemporary philosophy of chemistry. The conclusion establishes that Boyle’s position on these matters was prescient and, in many regards, also ahead of its time, thereby justifying the current interest in Boyle’s significant philosophical contributions. It is my hope that this book will not simply contribute to our understanding of Boyle’s nuanced and sophisticated chemical philosophy but, more important, that it will situate the relevance of Boyle’s ideas in relation to the contemporary philosophy of chemistry. The philosophy of chemistry is the youngest subfield within the philosophy of science, and it is still in the process of defining its relation to the history of chemistry. Among other things, this book contributes to this process by highlighting the relevance of historical considerations for contemporary issues in the philosophy of chemistry. Some of the more important of these issues pertain to reduction, emergence, and supervenience, and there is great historical and philosophical significance in establishing that these concerns also informed the theoretical and experimental work of Boyle. This book also establishes that Boyle was deeply engaged with the philosophical implications of the practice of chemistry, particularly as it related to the mechanistic theory of matter. Furthermore, Boyle’s theories were not only associated with the mechanistic corpuscularianism of his time but were also intimately linked to themes in medieval and Renaissance philosophy.

Introduction  7 Although the study of such an important historical figure as Boyle is valuable in its own right, this study also has great significance for our understanding of early modern science to the extent that Boyle made important contributions to discussions on scientific taxonomies, the nature of chemical elements and chemical properties, natural kinds, and the debates over atomism vs. corpuscularianism. His important philosophical contributions are crucial for our understanding of the creation of modern chemistry and physics. Accordingly, this book takes a careful and critical look at how Boyle helps to define the transition from the physics of the mechanical philosophy to a modern conception of chemistry.

1

Chemical Philosophy in  the 16th and 17th Centuries Vitalism, Paracelsian Alchemy, and Aristotelian Hylomorphism

Vitalism is generally regarded as the view that “vital forces” or “vital spirits” exist and function as causal agents in nature, and that the presence of vital force or spirit marks the difference between organic and inorganic matter. Vitalistic descriptions of natural phenomena tend to be qualitative, and vitalistic processes are generally described as holistic and teleological. Most important for our purposes, vitalism views the causes of motion as inherent in matter and treats all of nature as if it were intrinsically self-​organizing.1 Throughout the history of both speculative and natural philosophy, vitalistic theories have been overlaid with theological overtones of one sort or another, and the vitalistic theories discussed herein are no exception. Medieval and Renaissance metaphysicians and natural philosophers believed themselves to be living in an enchanted universe, in which matter was not inert but either was itself animate (i.e., it contained a “world soul” or anima mundi) or was inhabited by vital forces and spirits that played a causal role in the occurrence of natural phenomena. Depending on the theological proclivities of these philosophers, the presence of a world soul or of vital forces and spirits was to be ultimately attributed either to divine emanation or to divine action. Another characteristic of Renaissance vitalism was its affirmation of a fundamental correspondence between what is above and what is below. This microcosm/​macrocosm analogy “was at the center of a group of ideas derived from the [. . .] mystical-​alchemical tradition crossed with themes common to Neoplatonic mysticism. The vital substances of objects [were] made up of invisible spirits or forces of nature.”2 Natural philosophers, or natural magicians as they were called in the Renaissance, were individuals who not only studied these vital forces and correspondences but also learned how to deploy them for controlling or altering natural phenomena. Vitalism dominated natural philosophy during the 15th

1

Bloor, “Durkheim and Mauss Revisited,” 78–​80.

2 Rossi, The Birth of Modern Science, 141.

The Chemical Philosophy of Robert Boyle. Marina Paola Banchetti-Robino, Oxford University Press (2020). © Oxford University Press. DOI: 10.1093/oso/9780197502501.001.0001

Chemical Philosophy in the 16th and 17th Centuries  9 and 16th centuries due to the Renaissance revival of Neoplatonism and hermeticism. These ideas infused the work of such dominant thinkers as Marsilio Ficino, Tommaso Campanella, Cornelius Agrippa, and Giordano Bruno and they continued to influence natural philosophy well into the 17th century. The late 16th to 17th centuries, however, witnessed a significant transition from the vitalistic ontology that had dominated medieval and Renaissance natural philosophy to the early modern mechanistic paradigm endorsed by Cartesian and Epicurean natural philosophers, who rejected the presence of vital forces in nature and regarded matter as inert rather than as inherently active. This transition was most strongly felt in the context of early modern chymistry, which gradually severed its ties to Scholastic and spagyric alchemy, thereby opening the way for mechanistic approaches to chemical philosophy.3 It is pointless to speculate about what chemistry might have become had this ontological shift never occurred, but one cannot deny that the change from a vitalistic to a mechanistic ontology significantly shaped the evolution of early modern chemical philosophy. The transition from vitalism to mechanicism was not abrupt, however, and close examination reveals that 16th-​and 17th-​century chemical philosophies involved very complex and nuanced ontologies that often straddled the line between vitalism and mechanicism. I will argue that some of these hybrid ontologies helped to shape early modern chemical philosophy and, more specifically, the chemical ontology of Robert Boyle. The ontological shift from vitalism to mechanicism occurred concurrently with the revival and reappraisal of Epicurean atomism, which in its ancient form had been strictly materialistic and deterministic. However, although Epicurean atomism was revived in the 17th century, corpuscularian theories of matter had coexisted quite comfortably with vitalism throughout the Middle Ages and the Renaissance. It would, therefore, be erroneous to claim that particulate or 3 I wish to clarify some of the terminology that I will be using in the rest of this book. The terms “chymist,” “chymical,” and “chymistry” are employed in this book, as in recent historiography of science, to indicate the transitional phase between the alchemy of the 15th, 16th, and early 17th centuries, an empirical practice with obvious magico-​theological characteristics, and the modern chemistry that emerged out of the 18th-​century Chemical Revolution. In the early 17th century, chymists tended to hybridize the magico-​theological elements of alchemy with the naturalism characteristic of modern chemistry. Although the mid-​17th century saw chymists slowly shedding the mythopoetic conception of nature, their work is still considered transitional because it retained many strongly speculative elements that were later rejected by Lavoisier. On the other hand, the modern terms “chemist,” “chemical,” and “chemistry” are employed to refer to chemical practice more generally or to refer to those practitioners who embraced the mechanistic philosophy that rejected the vitalistic or magico-​theological perspective embraced by alchemists and chymists. The terms “chymist,” “chymical,” and “chymistry” are also employed when quoting directly from early modern sources, since these were the terms commonly used in the 16th and 17th centuries with regard to chemical practice. The terms “corpuscularian” and “corpuscularianist” will be employed to refer to the corpuscular philosophy and its adherents, while the terms “mechanicism” and “mechanicist” will be employed to refer to the mechanical philosophy and its adherents, except of course when quoting directly from other sources that employ different terms, such as “corpuscularism” or “mechanism.”

10  The Chemical Philosophy of Robert Boyle corpuscularian theories of matter imply a mechanistic hypothesis. More will be said in the next chapter about the revival of Epicurean atomism, particularly as it affected chemical philosophy. However, at this point, it will suffice to say that, as late as the early 17th century, many of the most significant chemical philosophies were those that reconciled a corpuscularian theory of matter with a vitalistic ontology. As already mentioned, the shift from a vitalistic to a mechanistic chemical ontology was not sudden and radical but, rather, followed a subtle, nuanced, and gradual path from the 16th to the 17th century. In fact, aspects of vitalism and mechanicism coexisted in interesting ways in the chemical ontologies of the early modern period, with corpuscularianism as an important commonality shared by these competing perspectives. Ultimately, the gradual demise of vitalism in the context of chemical philosophy resulted not from the victory of mechanistic reductionism but from a physicalistic and naturalistic rationalization of chemical qualities. In other words, the dominant chemical paradigm shifted from a dualistic ontology of matter and spirit to an ontology in which the only causal agents in nature were entirely material principles. In this shift, vital spirit itself was eventually regarded as having a physical ontological status since it was ultimately identified with aerial niter or potassium nitrate. However, this physicalistic and naturalistic approach to the articulation of vital spirit and of other formerly immaterial concepts did not entail a commitment to an entirely reductionist mechanicism. In fact, one finds that residues of vitalism such as the concept of “seminal reasons” linger within early modern chemical ontologies, even in Robert Boyle’s own work. One also finds that Boyle’s chemical ontology is naturalistic and physicalistic but remains, to a large extent, non-​ reductionist regarding chemical qualities. Thus, I would argue that it is not the victory of mechanicism over vitalism that ushers in modern chemistry. Rather, it is the gradual naturalization of chemical qualities and processes and of concepts such as ferment and spirit that leads ultimately to the modernization of chemical practice and to the quantification of chemical theory. In this chapter, I will examine many of these ideas in detail by focusing on the more significant elements of vitalism that influenced 16th-​and 17th-​century chymistry, as well as some of the key concepts of Scholastic and spagyric alchemy that would be later rejected by the mechanistic chemical philosophy. I will also focus on some of the key figures in this transition, whose hybrid ontologies paved the way for the work of early modern chemists such as Boyle. These figures are Paracelsus, Daniel Sennert, and Jan Baptista van Helmont, whose alchemical ideas and experiments provided the concepts and methods that would have the greatest impact on Boyle’s work. In addressing the chemical ontologies of these predecessors, I will focus on the key notions that served to inform Boyle’s chemical practice. I will, however, also discuss the Scholastic and spagyric ideas

Chemical Philosophy in the 16th and 17th Centuries  11 the rejection of which helped to define Boyle’s commitment to the mechanical hypothesis, these being Scholastic hylomorphism and the Paracelsian notion of the tria prima. This chapter will, thus, provide the background for the discussion of Boyle’s complex corpuscularian ontology that is discussed in Chapter 3. I will first begin by examining vitalism to set the context for the discussions later in this chapter.

1.1  The Vitalistic Character of Renaissance Alchemy One discipline within the Renaissance tradition of natural magic that was especially receptive to vitalistic ontology was alchemy and, even during the transition from alchemy to chymistry, lingering elements of the vitalistic standpoint continued to resonate within chemical philosophy. As well, to the extent that alchemical ontology impacted developments in iatrochemistry and medicine, vitalism continued to influence these disciplines throughout the 16th and into the 17th century. However, one of the misconceptions informing much of the literature on this subject is that vitalism ended with the advent of corpuscularian and atomistic theories of matter. At the heart of this misconception is the idea that particulate theories of matter imply mechanicism. This is indeed a misconception. The historical process whereby ancient atomism was revived in the 17th century was in fact quite complex and, although “most historians [and philosophers] of science have considered early seventeenth-​century atomism as preparatory to the mechanical theory of matter,”4 there is strong evidence that for much of the 17th century many chymists adhered to a particulate theory of matter while also embracing a vitalistic ontology. Two chemically important concepts within this ontology were the notions of “spirit” and of “ferment” conceived vitalistically. As Antonio Clericuzio explains, “the doctrine of spirit played a substantial part in seventeenth-​century natural philosophy and medicine. The Neoplatonic spirit of the world was widely adopted by chemical philosophers as a principle of motion and life [. . .] This notion became central to chemistry and medicine thanks to Ficino’s De vita Philosophicae (1571).”5 To understand the complex ontologies that informed the chemical philosophies of the 16th and 17th centuries, one must realize that chemical philosophy had been involved in a process of self-​definition and development since it was first articulated as such in the work of the alchemist Paracelsus. Chemistry, as a scientific discipline, did not enjoy the long and venerable historical tradition that was enjoyed by astronomy, mechanics, mathematics, and physics. In fact, up to

4 Clericuzio, Elements, Principles, and Corpuscles, 37. 5 Ibid.

12  The Chemical Philosophy of Robert Boyle the 16th century, chemistry “had no organized structure whatsoever, no theories of change and reactions, and no clearly defined tradition. Like geology and magnetism, chemistry became a science between the seventeenth and eighteenth centuries. Unlike mathematics, mechanics, and astronomy, it was itself a product of the Scientific Revolution.”6 As Paolo Rossi explains, “there is no figure like a Euclid, Archimedes, or Ptolemy in the history of chemistry. Instead, modern chemists find themselves in the somewhat disconcerting company of alchemists, druggists, iatrochemists, sorcerers, astrologers, and other sundry figures.”7 In fact, one of the reasons for which chemistry was long considered the redheaded stepchild in the family of science is that, for much of its history up to the 17th century, it was primarily a practical enterprise that did not seem to be anchored upon a solid theoretical and philosophical foundation. As My Giyung Kim recently noted, the discourse of chemical philosophy did exist in the 16th and 17th centuries.8 However, 16th-​century chemical philosophy was grounded primarily in a vitalistic worldview heavily tinged with mystical and theological overtones. Therefore, as Kim points out, 16th-​century “alchemical and Paracelsian linguistic heritage came under increasing attack from natural philosophers seeking to domesticate this rich empirical field in order to refurbish their systems of philosophical knowledge [. . .] The institutionalization of philosophical chemistry required a social evolution of chemists from the ‘sooty empirics’ who prepared medicaments in the basement into learned savants who could converse on equal terms with the scholarly world.”9 By the 18th century, what was lacking was a philosophical chemistry, that is, an organized and systematized field of knowledge that would qualify chemistry as an independent and autonomous natural philosophy.10 Thus, the transition from practical art to institutionalized natural philosophy required the successful development of “a new philosophical language, one less hermetical and more in tune with natural philosophy, rather than a disciplined practice.”11 In fact, the 17th century represents that crucial period in chemical history during which this transition played itself out, and Robert Boyle stands out as one of the more notable figures in this process since his aim was precisely to promote “chemistry as the ‘key’ to ‘true’ natural philosophy. [He] endeavored to dissociate the laboratory practice of chemistry from the discourse of [Paracelsian] Chemical Philosophy and to forge a philosophical chemistry [chemia philosophica] that would translate the laboratory culture of chemistry for a learned audience.”12

6 Rossi, The Birth of Modern Science, 137. 7

Ibid., 139.

8 Kim, Affinity, That Elusive Dream, 3. 9 Ibid.

10

Ibid.,  3–​4. Ibid., 4. 12 Ibid., 3. 11

Chemical Philosophy in the 16th and 17th Centuries  13 Given these considerations regarding the scientific status of early modern chymistry and its close historical ties to vitalism and to alchemy, it would behoove us to examine closely the context in which early modern chymistry evolved, both by examining the ideas of 16th-​and 17th-​century alchemists and the ontological framework that informed 17th-​century chemical philosophy, particularly regarding the relationship between vitalism and corpuscularian theories of matter. In terms of ontology, it is important to realize that many 16th-​ century chymists still found themselves somewhat shackled to certain aspects of Aristotelian science as it had been revised by the Scholastics. One of the most problematic concepts with which they had to contend was the theory of substantial form, and much of Boyle’s own chemical work is invested in providing evidence against the existence of substantial form.

1.2  The Scholastic Theory of Substantial Form The Scholastic theory of substantial form has its roots in Aristotle’s theory of four causes, the two external causes being efficient (or first) cause and final cause and the two internal causes being material cause and formal cause. Though Aristotle ultimately concludes that form is substance, the substantial conception of form was developed by the Scholastics in ways that Aristotle could not have anticipated. It is thus important to examine the role played by form within Aristotelian metaphysics. I will frame my discussion of Aristotelian forms in mereological terms, both because form is a mereological concept for Aristotle and also to link this discussion with that of Boylean mereology in Chapter 5. For Aristotle, forms are organizing principles that account for the unity, identity, order, and properties of things, whether simple wholes or composite wholes. Mereologically speaking, Aristotle is concerned with what makes composite wholes distinct from mere heaps. In other words, what is the something “over and above” the parts or “elements,” to use Aristotle’s term, that is present in the whole but not in the heap.13 That “something” is form or essence, and it accounts for the unity that is present in wholes but that is absent in heaps. One of the issues that Aristotle addresses in Metaphysics Z.17 is mereological hylomorphism, that is, the idea that the form is itself a part of the whole that it unifies. Aristotle rejects mereological hylomorphism because it would ensue in an unacceptable regress. Referring to the form of composite wholes, Aristotle says, “And this is the substance [ουσια] of each thing; for this is the primary cause of its being; and since, while some things are not substances, as many as are substances are 13 For a detailed and fascinating discussion of this topic, see:  Kathrin Koslicki, “Aristotle’s Mereology and the Status of Form,” 715–​736.

14  The Chemical Philosophy of Robert Boyle formed naturally and by nature, their substance would seem to be this nature [φυσιζ], which is not an element but a principle [αρχη]. An element is that into which a thing is divided and which is present in it as matter [υλη].”14 To maintain mereological consistency, however, Aristotle also states that “both the form and the matter are proper parts of a matter/​form-​compound.”15 So, to resolve the problem of potential regress, Aristotle takes the form of a composite whole to be ontologically distinct from the material parts or elements of that whole. Aristotle’s concept of form is, therefore, distinctly metaphysical to the extent that “the unity of a substance is a product not just of its elements, but of some further unifying principle, the form, that is not itself an element.”16 Thus, the theory of forms is a “top-​down” theory of organization within Aristotelian metaphysics, in that forms are of a distinct ontological kind from the wholes that they unify. The elements that are part of the unified whole belong to the ontological category of matter, while the form belongs to the ontological category of immaterial principle, so that unified wholes are both mereologically and ontologically complex.17 However, as Kathrin Koslicki points out, “the mere recognition of a particular kind of ontological complexity within a genuinely unified whole by itself does not yet solve the mystery of why it is that these entities of distinct ontological types (in Aristotle’s case, form and matter, or principle and element) can come together to produce a single genuinely unified thing.”18 Scholastic philosophers undertook to clarify the question of what a form is exactly, and 12th-​century metaphysicians proposed several answers to this question. In part, the Scholastics were interested in spelling out the distinction between substantial forms and accidental forms, and a lot of their theorizing revolved around solving this question. By the 13th century, no consensus had been reached regarding this issue and, as John Duns Scotus pointed out, there was only one universally accepted conclusion regarding substantial forms, that is, “that the substantial form plays a part in the essence of a thing.”19 This was a universally accepted idea primarily because of a statement made by Aristotle in Physics 2.3 194b27, in which he claims that the formal cause of a thing constitutes its essence. There was, indeed, a great deal of debate among the Scholastics regarding exactly what it means to say this, though an account of these debates would take us beyond the scope of this chapter.20 However, it must be noted that, to the extent that form is an internal cause of being, it would seem to play a role 14 Aristotle, The Complete Works of Aristotle, Z.17, 1041b32–​33. 15 Koslicki, “Aristotle’s Mereology and the Status of Form,” 727. 16 Pasnau, “Form, Substance, and Mechanism,” 33. 17 Koslicki, “Aristotle’s Mereology and the Status of Form,” 723. 18 Ibid., 727. 19 Pasnau, “Form, Substance, and Mechanism,” 40. 20 Robert Pasnau provides a very detailed and meticulous discussion of these debates in his “Form, Substance, and Mechanism.”

Chemical Philosophy in the 16th and 17th Centuries  15 “very much like the role of internal efficient cause, sustaining and regulating the existence of that which the efficient cause originally produced.”21 As Robert Pasnau affirms, by the middle of the 13th century, Scholastic metaphysicians conceived of substantial form in a much more concrete way than as a merely metaphysical principle. In fact, for these Scholastics, substantial form is that which accounts for the stability of material things, that is, it is that which sustains a thing’s essential properties or the “constant set of properties that are characteristic of that thing.”22 Thus, in De mineralibus 3.1.7, Albert the Great states that “there is no reason why the matter in any natural thing should be stable in its nature, if it is not completed by a substantial form. But we see that silver is stable, and tin, and likewise other metals. Therefore, they will seem to be perfected by substantial forms.”23 Therefore, the substantial form is not to be identified with the properties or the set of properties but, rather, it is the “something further that explains their enduring presence.”24 These points will become particularly significant in my discussions of Boyle’s theory of essential form and essential properties in Chapter 3 and of Boylean mereology in Chapter 5. Despite the turn toward a concrete conception of substantial form, one does find some Scholastics affirming the more metaphysical understanding of form. Aquinas, for example, claims that substantial form is that which accounts for the individuation of a substance. Thus, in Summa contra gentiles, he states that “this is clear from the fact that both the whole and the parts take their species from it, and so when it leaves, neither the whole nor the parts remain the same species.”25 However, this metaphysical understanding of substantial form, which clearly seems more faithful to the Aristotelian account, was not dominant among the Scholastics. Pasnau explains that it is one of Aristotle’s most cherished ideas that material and efficient explanations must be supplemented by a further level of formal analysis. Scholastic authors seemed to be sliding ever farther back toward the materialism Aristotle sought to refute, as if they could not resist the temptation to ground formal explanation on material and efficient causes at a deeper level. In turn, as the Scholastic conception of form grew increasingly remote from its metaphysical roots in Aristotle, it became at the same time increasingly naturalistic.26 21 Pasnau, “Form, Substance, and Mechanism,” 35. 22 Ibid. 23 Albert the Great, Book of Minerals, 173. 24 Pasnau, “Form, Substance, and Mechanism,” 35. 25 Aquinas, Liber de veritate Catholicae fidei contra errores infidelium, seu Summa contra Gentiles, 2.72.1484. “Quod autem sit forma substantialis totius et partium, patet per hoc quod ab ea sortitur speciem et totum et partes. Unde, ea abscedente, neque totum neque partes remanent eiusdem speciei.” 26 Pasnau, “Form, Substance, and Mechanism,” 45.

16  The Chemical Philosophy of Robert Boyle We find that it is this increasingly naturalistic and wholly concrete conception of substantial forms that is handed down to Renaissance metaphysicians and to 16th-​and 17th-​century natural philosophers, and it is this conception that comes under virulent attack from mechanistic thinkers, whether they be of a Cartesian or an empiricist mindset.27 A detailed account of these critiques is given in Chapters 2 and 3. Therefore, I now turn to another important concept that informed the natural philosophical ontologies of the 16th and 17th centuries, that is, the Paracelsian concept of the tria prima.

1.3  Paracelsian Spagyria and the Tria Prima Theophrastus von Hohenheim, a.k.a. Paracelsus (ca. 1493–​1531), is a seminal figure for both early modern spagyrists and chymists. Most important, Paracelsus helps to transform 16th-​century alchemy by giving it an essentially medical identity, and he makes this the basis for the development of an alchemical epistemology.28 Paracelsus makes significant advances in medicine by arguing against the Galenic and Scholastic view that disease is caused by an imbalance of the four bodily humors, which might be cured by bleeding or herbal remedies. Anticipating the modern bacteriological and viral conceptions of disease, Paracelsus claims that the cause of disease is the presence of external agents attacking the body and that this condition can be cured through “chemical” remedies. He identifies the characteristics of many illnesses, such as goiter and syphilis, and treats them with sulfur and mercury compounds. He is, therefore, “the first to introduce the medicinal use of mineral substances to the practice of medicine. Alchemy, or ‘the spagyric art’ as Paracelsus called it, became the cornerstone of medicine.”29 By all accounts, however, the popular characterization of Paracelsus as a mystic is accurate. He fits very comfortably within the Renaissance tradition of natural magic, to the extent that the theoretical framework upon which his work relies is staunchly theological and vitalistic. Walter Pagel, Allen Debus, and other scholars30 suggest that Paracelsus is influenced in these regards by Rabbinic and Kabbalistic sources, particularly the Shemoth Rabba, that provide “a religious background for the homeopathic principle”31 that he employs in his iatrochemical preparations. Paracelsus not only posits the existence of vital forces and spirits, but he also fully affirms the theory of correspondence between

27

See Ibid.

28 See Alchemy and Chemistry in the 16th and 17th Centuries. 29 Rossi, The Birth of Modern Science, 142.

30

See Pagel, Paracelsus; Forshaw, “Cabala Chymica or Chemia Cabalistica.”

31 Pagel, Paracelsus, 217.

Chemical Philosophy in the 16th and 17th Centuries  17 microcosm and macrocosm and, in this affirmation, he is once again inspired by his intention “to unravel the occult—​‘kabbalistic’ and symbolical—​meaning of phenomena by visualising concordances everywhere.”32 Not surprisingly, this mingling of theology and mysticism with chemical philosophy shapes his interpretation of Genesis in chemical terms as the separation of the elements by God. For Paracelsus, “since the divine creation [is] best understood as a chemical process, then nature must continue to operate in chemical terms. Chemistry [is] the key to nature—​all created nature.”33 Paracelsus’ chemical philosophy is based upon three fundamental principles:  his theory of prime matter, his theory of elements, and his theory of principles. His theory of water as prime matter is based upon his chemical interpretation of Genesis in which God is a divine alchemist who spontaneously creates the world ex nihilo with water as the first element.34 His theory of the elements includes prime matter (i.e., water), fire, earth, and air, all of which he also considers to be matrices. “Plants, minerals, metals, and animals were the fruit of the four elements.”35 Although Paracelsus inherits his theories of prime matter and of the elements from ancient sources, it is with his theory of principles that he makes truly original contributions to Renaissance alchemy and to later chymistry. According to Paracelsus, the principles of chemical reaction, which he calls the tria prima, are salt, sulfur, and mercury. “This tria prima also consist[s]‌of spiritual substances and correspond[s] to the Body, Soul, and the Spirit. Salt makes bodies solid, Mercury makes them fluid, and Sulfur makes them inflammable.”36 Although the theory of the tria prima is a modification of earlier sulfur-​mercury theories of metals, it has a special significance in the rise of modern science because it represents a broadening of these theories “to provide an explanation for all of nature.”37 In addition to these fundamental principles, Paracelsus and later Paracelsians also believe that vital spirit is essential for both the organic and the inorganic worlds. “Spirits were conceived as the active agents, upon which all the principal operations in nature and in the human body depended.”38 In his De natura rerum (1537), Paracelsus states that “the life of things is none other than a spiritual essence, an invisible and impalpable thing, a spirit and a spiritual thing. On this account there is nothing corporeal, but has latent within himself a spirit and a life, which, as just now said, is none other than a spiritual thing.”39

32 Ibid.

33 Debus, The Chemical Philosophy, 86.

34 Rossi, The Birth of Modern Science, 141.

35 Ibid. 36 Ibid.

37 Debus, The Chemical Philosophy,  78–​79. 38 39

Clericuzio, “The Internal Laboratory,” 52. Paracelsus, as cited in Ibid.

18  The Chemical Philosophy of Robert Boyle Paracelsus’ chemical philosophy is, however, not merely mystical but also contains the fundamental elements of what would later become early modern chymistry and modern scientific method. For example, Paracelsus contributes to the later chemical interpretation of spirit by identifying the celestial vital substance or anima mundi, which he believes to be contained in the air, with the aerial niter (also called saltpeter, i.e., potassium nitrate). This choice is not arbitrary. His reason for identifying the vital spirit with aerial niter is that potassium nitrate gives off life-​sustaining oxygen when heated. Paracelsus reflects on what he considers to be the unique properties of potassium nitrate and claims that “no other salt in the world is like [saltpeter] [. . .] The part played by Saltpeter in gunpowder is one reason why it is different from all other salts, and Paracelsus repeatedly explains thunder and lightning in terms of an aerial, windy, or aetherial nitre and sulphur.”40 Later Paracelsians contend that, in addition to salt, there are two volatile parts in saltpeter, these being sulfur and mercury, which represent for them the soul and the spirit of the aerial niter. Based upon Paracelsus’ own investigations into the nature of the aerial niter and upon the Neoplatonic belief in the microcosm-​macrocosm analogy, Paracelsians develop the theory that the vital spirit originates in the celestial sphere and is carried in the air. It is then inhaled by human beings and reaches the heart, from which it is “carried through the body in a circular motion, imitating the divine circularity [of the celestial bodies]. This motion impressed on the blood relates not only to the spirit of the blood in the heart but to all of the spirit of the blood in the body.”41 It is interesting to note that the interest in the properties of potassium nitrate and speculation regarding its identity as the vital spirit of the world continued well into the 17th century, during which time a powerful stream of speculation wondered whether saltpeter contained the sal nitrum or spiritus mundi, the “nitrous universal spirit,” that would unlock the secrets of nature. If so, as Robert Boyle observed, the subject “may well deserve our serious enquiries” . . . Francis Bacon himself, Lord Chancellor and Privy under James I, dismissed “crude and ignorant speculations” about gunpowder and its “spirit,” yet continued to identify saltpeter as the energizing “spirit of the earth.”42

Paracelsus and the later Paracelsians also hold a persistent interest in the blood and its relation to the vital spirit. Like Helmont’s identification of vital spirit with volatile alkaline salt, which will be discussed later in this chapter, the

40

Debus, “The Paracelsian Aerial Niter,” 47.

41 Debus, The Chemical Philosophy, 235. 42 Cressy, Saltpeter,  13–​14.

Chemical Philosophy in the 16th and 17th Centuries  19 Paracelsian identification of anima mundi with saltpeter and the theory that this aerial niter penetrates the body through the blood are important first steps toward the late-​17th century naturalization of vital spirit and the reinterpretation of this notion in physicalistic terms. For 17th-​century Paracelsians, “the doctrine of the world soul, in its most theoretical formulations, was rooted in an interpretation of chemical operations. Far from being merely a recovery of a notion inherited from Neoplatonic Renaissance philosophy, this doctrine was justified by its formulation in chemical terms, which show that what is being referred to is material, albeit a very tenuous conception of matter that is called spirit.”43 Another aspect of Paracelsus’ work that contributes to the later development of early modern chymistry is his solidly empirical approach to medicine and spagyria. According to him, “to attain true knowledge one must abandon the surface of bodies, penetrate their inner nature and break them up into their constituent parts until each of these is accessible to sight and touch.”44 To make the constituent parts of bodies empirically accessible, Paracelsus emphasizes analysis, although he and later Paracelsians “[lay] the foundation for viewing analysis as only half of the equation—​as a necessary preliminary to resynthesis”45 or redintegration, as later chemists such as Boyle would call it. Paracelsus and his followers thus [change] the practice of alchemy by emphasizing the twin processes of analysis and synthesis (spagyria), to penetrate the true inner nature of bodies. When discussing this inner nature, Paracelsus is heavily influenced by Ficino and “place[s]‌special emphasis on semina, which he [also] consider[s] as invisible spiritual forces and as archetypes.”46 There are clearly echoes of the Augustinian doctrine of seminal reasons in Paracelsus’ conception of semina. For him, “Semina, which originate in the Word [or Logos] are contained in the Yliaster [the universal matrix of the cosmos] and are prior to chemical principles and to elements. For Paracelsus, nature as a whole is a panspermia,”47 meaning that seeds imbue the entire universe with life. In this regard, Paracelsus is deeply influenced by the ancient Aristotelian doctrine of semina rerum, which contributes invaluably to the persistence of vitalism in the 16th and even into the 17th century. To the extent that the concept of seminal reasons and that of minima naturalia 43 Joly, “Les alchimistes étaient-​ils des matérialistes? Quelques remarques sur le psychisme humain et l’esprit du monde,” 61: “On voit alors à quel point la doctrine de l’esprit du monde, dans ce qu’elle pourrait avoir de plus théorique, s’enracine dans une interprétation des opérations chimiques. Loin de n’être que la reprise conceptuelle d’une notion héritée de la philosophie néoplatonicienne de la Renaissance, cette doctrine se justifie par sa formulation en des termes chimiques qui montre bien que ce dont il est question relève de la matière, même s’il s’agit de cette matière extrêmement tenue que l’on nomme esprit.” 44 Bianchi, “The Visible and the Invisible: From Alchemy to Paracelsus,” 18. 45 Newman and Principe, “Alchemy and the Changing Significance of Analysis,” 79. 46 Clericuzio, Elements, Principles, and Corpuscles, 18. 47 Ibid.

20  The Chemical Philosophy of Robert Boyle play such an important role in 17th-​century chymistry, I will now discuss these concepts in greater detail. Together these notions occupy an invaluable place in the development of vitalistic corpuscularianism and continue to impact particulate theories of matter well into the 17th century.

1.4  Semina Rerum, Minima Naturalia, and Vitalistic Corpuscularianism The doctrine of semina rerum has a long and complex history and received conflicting interpretations as it was adopted by different philosophical traditions.48 Lucretius and other Epicureans conceive of semina rerum, or the “seeds of things,” in entirely physical terms as atoms, while the Stoics conceive of semina as immaterial active and formative principles having nothing to do with atoms. Inspired by the Stoic interpretation of semina, Neoplatonic philosophers argue that the ordering principle of the universe, or Logos, contains within itself active constituents that they likened to “seeds.” Hence, Neoplatonists refer to these active constituents as logoi spermatikoi (λόγοι σπερματικοὶ), a term later Latinized as rationes seminales, that is, “seminal reasons.” For Neoplatonists, seminal reasons contain a rational “program” that specifies the creative power that is immanent in nature. In its Neoplatonic iteration, this idea plays a central function in Augustinian ontology and Augustine uses it to reconcile apparent exegetical tensions between the account of creation in Genesis 1 and that in Ecclesiasticus 18:1 (Book of Sirach).49 The notion of semina rerum interpreted in Stoic terms ultimately occupies a prominent role in the natural philosophies of the 15th and 16th centuries, which are heavily influenced by the Renaissance revival of Platonism and Neoplatonism. In particular, as already pointed out in the previous section, Paracelsus makes considerable use of the notion of seminal reasons, which he interprets as the forces and active powers in any object, and this idea resonates in the work of later Paracelsians. However, the writings of the French Paracelsian Pierre-​Jean Fabre (1588–​1658) indicate that, by 1629, the notion of semina acquires clearly 48 Hiro Hirai provides an extensive, detailed, and definitive history of this concept as it evolved from the Renaissance to the early modern period, and I am heavily indebted to his work and to the work of Antonio Clericuzio for my discussion here. See Hirai, Le concept de semence dans les théories de la matière à la Renaissance, and Clericuzio, Elements, Principles, and Corpuscles. 49 Augustine identifies a tension between the account found in Genesis 1, according to which God created the universe in stages, and the account found in the Book of Sirach (also called Ecclesiasticus), according to which God created everything at once. Augustine reconciles this apparent conflict by arguing that, although God did not create all species of things at once, he implanted in nature the seminal reasons or “seeds” of all things that will ever exist, even though each of these species of things is materially realized at different points in time.

Chemical Philosophy in the 16th and 17th Centuries  21 physicalistic connotations, albeit still within the context of a generally vitalistic conception of nature. In his Traicté de la peste, Fabre states that “seeds are in the heavens and descend into the inferior elements, as if within their matrix, in order to become elementary mixts and material bodies. God wanted it and disposed it thus through his mighty power and wisdom.”50 As already mentioned, for Paracelsus semina are the causal agents responsible for the generation of natural bodies, including metals in the bowels of the earth, and this idea continues to influence Paracelsians throughout the 16th and 17th centuries. Paracelsus’ contemporary Girolamo Fracastoro takes this Neoplatonic interpretation of semina rerum a step further by combining it with Lucretian atomism, reinterpreting it “in terms of invisible units of matter”51 and arguing that semina are also the causes of communicable diseases when they propagate through the atmosphere and penetrate a host organism. In this way, both Paracelsus and Fracastoro greatly advance the medical theory of diseases by moving away from the strictly Galenic theory of humoral imbalance and toward the ontological theory of pathology and contagion. However, influenced by the revival of Epicurean atomism, 17th-​century chemists would eventually both incorporate the concept of semina rerum into their chemical ontologies and interpret this concept in much more naturalistic and physicalist terms than the Paracelsians ever did. Semina rerum become particularly relevant for 17th-​century mineralogy, with many chymists and metallurgists attributing the birth and growth of metals in the bowels of the earth to specific “seeds” that endow these metals with an internal vegetative principle. For metallurgists and chymists, it is this internal principle that permits the transmutation of a base metal into a noble metal. “The relation between the doctrine of metallic seeds and that of transmutation resides in the theory of one type of seed for all metals, rather than specific seeds for different metals, which means that the seed can produce different metals according to the degrees of maturation that it has reached.”52 Among the chymists who sustain this seminal conception of the generation of metals are many corpuscularians such as John Webster, Daniel Sennert, Jan Baptista van Helmont, Pierre Gassendi, Walter Charleton, and the young Robert Boyle.53 50 Fabre, Traicté de la peste, selon la doctrine des médecins spagyriques, 19–​20: “Les semences de toutes les choses sont dans les Cieux, & descendent ça bas dans les éléments inférieurs, comme dans leur matrice, pour y estre faictes mixtes élémentaires, & corps matériels. Dieu la voulu & la disposé ainsi par sa toute puissance & sagesse.” 51 Clericuzio, Elements, Principles, and Corpuscles, 17. 52 Clericuzio, “Alchimie, philosophie corpusculaire, et minéralogie dans la Metallographia de John Webster,” 298. “Le rapport entre la doctrine de la semence des métaux et celle de la transmutation réside dans la théorie d’une seule semence pour tous les métaux, mais pas de semences spécifiques, ce qui signifie que la semence peut produire différents métaux selon les degrés de maturation auxquels elle parvient.” 53 Ibid., 297–​298.

22  The Chemical Philosophy of Robert Boyle In addition to the concept of semina rerum, the notion of minima naturalia also plays a significant role in the 16th-​century revival of atomism and in the development of 17th-​century corpuscularianism. Although the modern revival of Epicurean atomism dates to Poggio Bracciolini’s 1417 rediscovery of Lucretius’ De rerum natura,54 what makes it possible for Epicurean atomism to be resurrected in its modern version is the survival of non-​Epicurean corpuscularian theories of matter through late antiquity and into the Middle Ages. The notion of minima naturalia can be traced at least as far back as Aristotle, for whom minima are the minimum amount of matter necessary to instantiate a specific substantial form.55 However, by interpreting minima naturalia as the smallest possible and irreducible particles of reagents, many medieval and Renaissance alchemists develop their own type of corpuscularianism or particulate matter theory. This “alchemical atomism” functions as a qualitative version of Epicurean atomism, and the concept of minima thus interpreted allows Scholastic and Renaissance chymists to embrace a corpuscularianism in which the fundamental particles are endowed with substantial form and in which the properties of said particles are chemical and not strictly mechanical.56 Thus, although the atomism of Democritus, Epicurus, and Lucretius had been materialistic, mechanistic, and deterministic, the many advocates of atomism during the Renaissance seek to reconcile Epicurean atomism with a non-​mechanistic conception of the universe and employ a qualitative conception of minima for the purpose of developing a vitalistic atomism. One of these Renaissance philosophers is Giordano Bruno who, in his De triplici minimo et mensura, cleverly combines the medieval concept of minima with the Neoplatonic doctrine of anima mundi to develop a notion of atoms as enlivened by soul. For Bruno, “the atom itself is to be understood as one aspect only of [. . .] a triple minimum. The primary minimum is the monad: the first principle of quantity and as such the basis of metaphysics. The next type of minimum [. . .] is the mathematical point: the first principle of extension and the basis of geometry. The atom is the minimum of body, or three-​dimensional minimum: and as such the basis of physics.”57 In a manner that seems to provide an anticipatory reply to 17th-​century debates regarding the incompatibility of the mathematical and physical conceptions of atoms, Bruno argues that there is no incompatibility in considering the minimum both as geometrical point and as three-​dimensional body or corpuscle.58 For Bruno, the physical atom is an indivisible and weightless sphere 54 Gatti, “Giordano Bruno’s Soul-​Powered Atoms,” 163. 55 Murdoch, “The Medieval and Renaissance Tradition of Minima Naturalia,” 91–​97. 56 Clericuzio, “Alchimie, philosophie corpusculaire, et minéralogie dans la Metallographia de John Webster,” 300. 57 Gatti, “Giordano Bruno’s Soul-​Powered Atoms,” 166. 58 Ibid.

Chemical Philosophy in the 16th and 17th Centuries  23 that has no substantial form but whose principle of form and motion is the soul, that is, “a spiritual substance hidden deep within all atomic minimi.”59 The soul of atoms functions much like seminal reasons in that it directs, structures, and coordinates atomic concretions, thereby “transforming them into live, moving and organic bodies.”60 Thus, the soul of atomic minima performs the function of “bonding” physical atoms to each other, in accordance with rational structures. For Bruno, “the minimum was clearly a relational notion that referred to the process of composing and decomposing, an idea that allowed him to distinguish mathematical and physical minima, at the price, however, of a somewhat bizarre mathematics.”61 As will be pointed out in later chapters, one of the weaknesses of the mechanical philosophy, a weakness that also infuses the work of Boyle, is that it does not recognize the concept of force and, thus, cannot account for how physical atoms or corpuscles are held together to form stable corpuscular concretions and macroscopic bodies. As well, the mechanical philosophy can only account for the mobility of particles by attributing this to the action or will of God. Bruno’s vitalistic atomism, on the other hand, “[avoids] a number of the difficulties which would beset the mechanical philosophy of the following century by introducing an element of soul or energy into his atoms, thereby proposing a vitalistic concept of self-​moving and self-​coordinating matter.”62 Bruno’s specific conception of atoms as ensouled illustrates the compatibility of the particulate or corpuscularian theory of matter with vitalistic ontology and serves as one example of what may be called “vitalistic corpuscularianism,” a theory of matter that would later be embraced by the influential 17th-​century Paracelsians Daniel Sennert and Jan Baptista van Helmont. Despite the continued influence of vitalistic corpuscularianism, the interpretation of minima gradually begins to change, as early as the 1650s, by taking on more materialistic connotations. For example, Giulio della Scala (a.k.a. Scaliger) interprets minima as particles and Daniel Sennert unequivocally interprets minima as atoms, thus paving the way for the materialistic corpuscularianism of many early modern chemists and of Robert Boyle. It is also interesting to note that corpuscularian chymists often couple the seminal conception of metals discussed earlier with a mechanistic conception of minima naturalia, to explain how seeds affect the birth, growth, and transmutation of metals. John Webster, for example, explains the properties of gold by appeal to the compacting of its minimal particles: “Gold is more dense and compacted then [sic] any other of the



59

Ibid., 173. Ibid., 174. 61 Meinel, “Early Seventeenth-​Century Atomism,” 75. 62 Gatti, “Giordano Bruno’s Soul-​Powered Atoms,” 180. 60

24  The Chemical Philosophy of Robert Boyle Metals, that is, it is less porous then [sic] any of the rest being so closely joyned per minima, that little or none of the air, or globuli aetherei (as Cartesius calls them) can lodge within its particles. And this is the cause of two other of its properties: to wit its heaviness, and power of extension, both of which are far beyond either of those qualities in other Metals.”63 According to Webster, this close compaction of minima is also responsible for the transmutation of less noble metals into gold. He states: there is a radical Solution and Penetration of all the small parts of atoms of the metal to be changed, by the subtile penetrability and ingression of their so much purified and exalted Tincture, and thereby all things in it whatsoever that are of an Heterogeneous nature, are separated and extruded, and the Homogeneous Particles joined together per minima as much as Nature can admit of and so must needs be of less bulk, and possesses less room or place, which is manifest in Gold.64

Paracelsians in the 17th century, however, continue to consider vitalism to be compatible with the corpuscularian theory of matter, and one of the Paracelsians whose work is particularly intriguing in this regard is Sebastien Basso (a.k.a. Basson or Bassonus), whose Philosophia naturalis (1621) “stands out as one of the earliest and most articulate expositions of the corpuscular theory of matter.”65 In fact, along with Isaac Beeckman, Basso is considered one of the early inventors of molecular theory. Basso strongly affirms that all natural phenomena are caused by the motions and rearrangements of atoms and, in this regard, he has much in common with later mechanistic atomists. Yet, Basso’s work also stands out as a prime example of Neoplatonic vitalism, since he understands motion in terms of sympathy and antipathy, that is, in terms of internal forces of attraction and repulsion with which atoms are endowed by the actions of the world soul and, ultimately, of God. Although Basso’s endorsement of a corpuscularian theory of matter significantly contributes to the eventual development of early modern chymistry, other Paracelsians take even further steps toward the development of a theory of vital spirits that would, eventually, lead to the 17th-​century reinterpretation of these spirits in chemical and naturalistic terms. “From the 1650s the notions of spirit (and of fermentation) became central issues [.  .  .] [Many English chymists and physiologists] shared the view that matter was endowed 63 Webster, Metallographia, or an History of Metals, as cited in Clericuzio, “Alchimie, philosophie corpusculaire, et minéralogie dans la Metallographia de John Webster,” 299–​300. 64 Clericuzio, “Alchimie, philosophie corpusculaire, et minéralogie dans la Metallographia de John Webster,” 301. 65 Clericuzio, Elements, Principles, and Corpuscles, 30.

Chemical Philosophy in the 16th and 17th Centuries  25 with an internal principle of organization, life and sensibility, namely, the spirit which they described in terms of particles having specific chemical properties.”66 This explains why “the distillation of spirits became an important component of seventeenth-​century chemistry and medicine [.  .  .] [for the purpose of] identifying and manipulating the spiritual essences extracted from natural bodies by means of distillation [.  .  .] [and for] ‘capturing’ the spirit of the world, which Paracelsians conceived as the celestial vital substance contained in the air.”67 We see this same preoccupation with conceiving spirit in chemical terms among the French Paracelsians. The work of Duschesne and Croll, for example, develops the view “that medical spirits and spirits extracted by chemists [have] the same source, namely, the spirit of the world. On this basis they stated that the only active remedies [are] those prepared by using spirits extracted by distillation.”68 Additionally, although the 17th-​century French Paracelsians continue to appeal to God as the creator of matter and compare the lapis philosophorum to the Trinity in its expression of divine unity, their chemical philosophy is materialistic and naturalistic, and their central focus on corporeal substances is founded upon the operations and manipulations of the chemical laboratory. Thus, in spite of the symbols and analogies employed, the principles invoked, including that of the world soul, are always conceived as being material.69 Such unambiguously chemical interpretations of vital spirit and world soul are even more evident in the chemical philosophy of Jan Baptista van Helmont, for whom vital spirit (archeus) is conceived as an alkaline salt that moves through the body. As we shall see presently, there is a strong relationship between Helmont’s theory of vital spirits and his corpuscularian theory of matter. At this point, therefore, I will proceed to examine the work of the iatrochemist Daniel Sennert and, after this, of the alchemical atomist Jan Baptista van Helmont, both of whom serve as transitional figures between the vitalistic corpuscularians and the early modern Epicurean atomists and as influential predecessors of Robert Boyle.

66 Clericuzio, “The Internal Laboratory,” 59. 67 Ibid.,  53–​54. 68 Ibid., 53. 69 Joly, “Les alchimistes étaient-​ils des matérialistes? Quelques remarques sure le psychisme humain et l’esprit du monde,” 62: “Les principes qu’elle invoque, y comprit l’Esprit du Monde, sont toujours matériels [. . .] au-​delà des symboles et des analogies qu’elle déploie dans ses discours [. . .] elle forge sa doctrine au contact des opérations de laboratoire et de la manipulation des diverses substances corporelles qui font de la matière, vivante ou minérale, l’objet central de sa réflexion.”

26  The Chemical Philosophy of Robert Boyle

1.5  Daniel Sennert’s Structural Hylomorphism and Atomicity as a Negative-​Empirical Concept There are many reasons to be grateful for the work of 20th-​century historians and historiographers of science in reappraising the contributions of the alchemical tradition to the development of early modern chemistry. One of the figures who has benefited from such reappraisal is the renowned Wittenberg iatrochemist Daniel Sennert (1572–​1637), whose work was once regarded as insignificant at best and regressive at worst. Marie Boas, for example, was quite censorious in her assessment that “Sennert contributed nothing new to the development of a mechanical philosophy based upon a theory of atoms.”70 What recent historiography shows, however, is that, far from being tangential, Sennert’s theories and experimental methods significantly impacted the development of later atomism. Although Sennert’s theories are transitional between Scholastic ontology and mechanistic atomism, he has been characterized as an archetypal transitional figure precisely because his work is significant in several ways. As of 1619, Sennert embraced a conception of matter that hybridized the Scholastic theory of substantial forms with classical atomism. He also rejected the Scholastic conception of homogeneous mixts and endorsed an early version of chemical structuralism. Thus, his work marks an early attempt at conceptualizing atomism in the context of post-​Paracelsian alchemy. Secondly, his work anticipates the important role that structuralism would later play in modern chemistry. Finally, Sennert’s negative-​empirical conception of “atomicity” influences Boyle’s conception of “chymical atoms” and anticipates Antoine-​Laurent de Lavoisier’s understanding of elementarity as determined by the limits of chemical analysis. Sennert uses a variety of experiments to support his commitment to atomism, the most notable of which is his “reduction to the pristine state,” which eventually becomes an important experimental procedure for later chemists such as Boyle. In this experiment, the limits reached by chemical analysis play a notable role in determining what constitutes “atomicity.” In fact, the aspect of Sennert’s empirical work that most impacts later chemistry is his conception of “atomicity” as grounded in the limits attained by the analytical method of the laboratory. This notion of atomicity focuses on what cannot be achieved in the context of experimental practice and with the available methods of analysis. This way of understanding “atomicity” is, therefore, considered to be a negative-​empirical concept. The term “negative-​empirical concept” first appeared in the work of David Knight71 in 1967, in his book on 19th-​century English matter theories. The term was then appropriated by Arnold Thackray72 in his 1970 work on 18th-​century

70

Boas, “The Establishment of the Mechanical Philosophy,” 429.

71 Knight, Atoms and Elements.

72 Thackray, Atoms and Powers.

Chemical Philosophy in the 16th and 17th Centuries  27 Newtonian matter theory, and it was later resurrected in Bernadette Bensaude-​ Vincent and Isabelle Stengers’s 1993 book on the history of chemistry73 to describe Boyle’s concept of element. Bensaude-​Vincent and Stengers explain that “the idea of a negative-​empirical concept is  .  .  .  a purely epistemological notion. It represents a new type of argument that locates the authority of proof not within reason but within experimental practice.”74 However, although the term “negative-​empirical concept” may have been coined in the late 1960s, the practice of defining either atomicity or elementarity operationally as the limits of experimental analysis can be traced at least as far back as the 13th century, where it played an important role in Scholastic alchemy. As William Newman has emphasized: already in the High Middle Ages (if not earlier) alchemists were employing this approach . . . According to this analytical ideal, a substance is viewed as elementary if it cannot be decomposed by the tools of the alchemist. In fact, an atomism based on the resistance of materials to laboratory operations such as sublimation and calcination can already be found the Summa perfectionis of Geber. As strikingly powerful analytical agents were [later] discovered, these provided chymists with the means to identify “atoms” that could withstand dissolution into [their] components.75

Negative-​empirical principles that defined the temporary limits of analysis were, therefore, used from the Middle Ages to the 18th century to provide operational definitions of chemical elements or substances. Sennert’s use of negative-​empirical concepts is particularly important because these form a part of a larger theoretical program, in which his compositional theory of matter serves to provide an account of substances and mixts that he considers superior to the Scholastic accounts. More specifically, Sennert rejects the Scholastic idea that genuine mixts are endowed with distinctive substantial forms. The Scholastics inherit their conception of mixts from Aristotle, but they modify the Aristotelian view in significant ways. Regarding the formation of new compounds, Aristotle believes that “the form of the product appear[s]‌out of nothing, ex nihilo, whereas the forms of the original bodies [disappear] into nothing, in nihilum.”76 A true mixt, then, is one in which “the ingredients act to change each other so that they cease actually to exist.”77 However, Aristotle qualifies this position by adding that the ingredients within the mixt “continue to

73

Bensaude-​Vincent and Stengers, A History of Chemistry. Ibid.,  51–​52. Newman, “What Have We Learned from the Recent Historiography of Alchemy?,” 320. 76 Meinel, “Early Seventeenth-​Century Atomism,” 71. 77 Wood and Weisberg, “Interpreting Aristotle on Mixture,” 682. 74

75

28  The Chemical Philosophy of Robert Boyle exist potentially, and [so] they can be separated out again.”78 Thus, for Aristotle, synkrisis (synthesis) does not preclude the possibility of diakrisis (analysis). Unlike Aristotle, the medieval Scholastics do not consider the four elements to be fundamental but instead posit an undifferentiated prime matter (the πρϖτον δεκτικόν or proton dektikon) that is endowed with qualities by immaterial substantial forms. Each of the four elements is generated and determined in its essential properties by the presence of a distinctive substantial form. This view hylomorphism impacts on the Scholastic theory of mixts. According to Scholastics such as Aquinas, when two substances are mixed, the substantial forms of the individual ingredients are destroyed and replaced by the substantial form of the mixt, which determines its distinctive properties as well as its homogeneity and uniformity. This view implies that the ingredients of a genuine mixt cannot be recovered, since their substantial forms no longer exist. Therefore, according to Scholastics such as Aquinas, true synthesis precludes the possibility of analysis. Sennert realizes that this conclusion presents a problem for the Scholastic theory and thus rejects the idea that homogeneous mixts are endowed with their own distinctive substantial forms. However, given the lack of viable alternatives to the Scholastic theory, Sennert is reluctant to give it up entirely, preferring to salvage some of its important features. He does so by developing a hylomorphic corpuscularianism that rejects undifferentiated prime matter and, instead, posits fundamental, indivisible, and immutable particles called atoms, each endowed with a distinctive substantial form.79 Sennert’s ontology is hierarchical and pluralistic since “there are various grades of atoms and each higher grade of atom is composed of an organization (or structure) of the lowest grade of atoms.”80 The simplest atoms are the minima naturalia and the first composed atoms (or corpuscles) immediately above the minima are the prima mixta. The prima mixta themselves can compose higher orders of compounded corpuscles.81 Thus, in Sennert’s account, it is not chemical substances but, rather, their atoms that are endowed with form. According to him, the distinctive substantial forms of a material body’s atoms, coupled with the unique microstructure according to which the corpuscles are arranged, account for the chemical properties that are peculiar to that material body. In his view, when two or more substances are synthesized, their respective corpuscles are rearranged spatially to form a new microstructure so that the new compound has properties that differ from those of its ingredients. For Sennert, the components of the mixt can be recovered and



78 Ibid. 79

Michael, “Daniel Sennert on Matter and Form,” 286.

80 Ibid. 81 Ibid.

Chemical Philosophy in the 16th and 17th Centuries  29 returned to their pristine state when the original microstructural configuration of their respective corpuscles is restored via analysis with aqua fortis, aqua regia, or fire. Sennert believes that this type of atomism provides a better theory of mixture and one that can be supported by experimental evidence. Sennert’s atomism, however, diverges significantly from classical atomism. Classical atomism endorses the view that atoms are substantially uniform and are distinguished only by the mechanistic properties of shape, size, and spatial orientation. In Sennert’s hylomorphic atomism, the different types of atoms are endowed with distinctive immaterial substantial forms that define their essence and determine their distinctive properties. I would venture here to say that Sennert’s hylomorphic atomism constitutes an attempt at explaining the existence of natural kinds from within an atomistic perspective, albeit one that is not mechanistic. In this regard, I would also add that, although his theory retains elements of the Scholastic theory of substantial forms, Sennert’s rejection of undifferentiated prime matter in favor of hylomorphic atomism represents an early attempt at articulating a distinction later made by Diderot and the French materialists between “la matière” and “les matières,” that is, between theoretical and abstract prime matter and the diverse and concrete substances of the chemist’s laboratory.82 Sennert’s theory is also an early version of a type of chemical structuralism and there is an interesting interplay between essence and structure in his theory. Although he considers simple atoms to be elementary particles, Sennert also believes that the observable properties of different substances are determined by the structure according to which their atoms are arranged, along with the substantial forms of the atoms. Sennert regards such corpuscular aggregations as non-​elementary atomic species that have specific chemical properties observable at the macro-​level. The chemical synthesis of substances simply involves altering the structural arrangement of the elementary corpuscles of those substances in order to form a new structural composition. When such microstructures are altered, the new structural aggregation of the mixt constitutes a different material species with different observable chemical properties. Sennert’s structural explanation of mixture is that it involves a rearrangement of the elementary “atoms” of the components so that the chemical properties of the mixt are distinct from the chemical properties of the components. Therefore, while the atoms of Substance A  and of Substance B retain their substantial forms when A is mixed with B, the resulting Substance C will have properties that are distinct from A and B precisely because the structural arrangement of 82 For a fascinating discussion of the distinction between “la matière” and “les matières” in 18th-​ century French materialist thought, see Pépin, La philosophie expérimentale de Diderot et la chimie, and Pépin, “Quelques perspectives chimiques pour le matérialisme?”

30  The Chemical Philosophy of Robert Boyle the constituent atoms has been altered. For Sennert, although the structural arrangement of corpuscles is altered during synthesis, the substantial forms of the elementary particles remain unchanged, making it possible to recover the original substances through analysis. The importance of these ideas for Sennert is that they invalidate the Thomistic conception of mixts, particularly the claims that the forms of the components are destroyed in the synthesis, that the mixed substance has a distinctive form of its own, and that the components are not recoverable from the uniformity and homogeneity of the mixt. As an experimental chymist with little sympathy for pure speculative philosophy, however, Sennert recognizes the difficulty of positing any sort of immaterial substantial form to explain the essential properties of a material substance, whether that substantial form is posited as belonging to the material substance as a whole or to each of its elementary particles. The difficulty, of course, arises from the fact that substantial form is regarded as being immaterial, that is, “completely insensible, it is considered to be a causal terminus post quem [a causal limit] from which perceptible qualities arise without revealing the nature of their source. Substantial form, therefore, is a sort of ‘black box’, that is, a device or system that can be viewed only in terms of its inputs and outputs or transfer characteristics. from which qualities emerge. The unknowable nature of Sennert’s substantial form is an Aristotelian empiricist’s statement of nescience.”83 In spite of these problems, Sennert believes that he can experimentally corroborate his hylomorphic atomism by demonstrating, against the Scholastic view of true synthesis, that substances are recoverable from mixts via chemical analysis. Once this has been experimentally demonstrated, it will prove both that the particles of the component substances are “atomic” and that these particles retain their substantial forms in the mixt. Sennert uses several variations of the “reduction to the pristine state” to establish that substances are recoverable from homogeneous mixts. Although earlier alchemists and iatrochemists had used the reduction to the pristine state for strictly pragmatic purposes, Sennert uses this analytical procedure for primarily theoretical purposes, to provide empirical support for the idea that the atomic ingredients of a mixt are recoverable and that these atoms retain their distinctive substantial forms within the mixt. For Sennert, “the validity of chymical analysis is borne out by the Scholastic axiom ‘The things into which composites can be dissolved are the things out of which they are made’—​based on Aristotle’s De caelo 3 302a 15–​18.”84 It is interesting to note that Boyle would later appropriate this same experimental procedure but he would use it for the



83 Newman, Atoms and Alchemy, 138–​139. 84

Ibid., 97.

Chemical Philosophy in the 16th and 17th Centuries  31 exact opposite theoretical purpose, that is, to undermine the idea of substantial form in favor of the notion of mechanistic form. Although Sennert performed reductions to the pristine state using various mixtures, I will discuss only one of these, which is considered the most influential of his reductions, in which he dissolves silver in aqua fortis (nitric acid), resulting in a clear blue liquid. The resulting liquid is filtered to show that no solid residue remains and that the mix is homogeneous. Sennert then precipitates the silver from the liquid by pouring salt of tartar (potassium carbonate) into the solution. After cleaning, drying, and heating the precipitate, he observes that a satisfactory quantity of the silver has been recovered from the solution, thereby invalidating the Scholastic claim that the components of a homogeneous mixt are not recoverable. Sennert describes the results of this experiment as follows: “If aqua fortis is poured on, the silver is so thoroughly dissolved that no metal can be detected in the water by sight. But since it is really present, it can emerge thence in segregated form, and certainly in such a way that . . . the silver retains its own nature.”85 He explains that, although the liquid into which the silver is dissolved may seem to be completely clear so that it can be filtered with no residue, nonetheless the silver preserves its own nature in it . . . thus also if a single mass be made by fusion of gold and silver together . . . the gold and other metals retain their own nature in aqua fortis and can be precipitated again in the form of a powder, sometimes dark, sometimes yellow, sometimes of another color.86

Sennert believes that the atomistic implications of this experiment are clear. Despite having been completely dissolved in the acid, the silver can be recovered to a great degree of quantitative precision. For Sennert, this means that the corpuscles of the silver have retained their essential identity and their distinctive substantial forms in the liquid, although these corpuscles have been clearly restructured so that the qualities of the original silver are no longer observable in the liquid. The action of the salt of tartar works to restore the original structural composition of the silver atoms, which is made manifest when the original silver precipitates out of the solution. Sennert, therefore, interprets this experiment as confirmation of hylomorphic atomism.

85 Sennert, De chymicorum cum Aristotelicis et Galenicis consensu ac dissensu, 213: “Si vero possea aqua fortis affundatur, ita solvitur argentum, ut ullum metallum in ea aqua deprehendi visu non possit: cum tamen revera insit & hinc segretatum emergat . . . & argentum suam naturam retineat.” 86 Ibid.: “Argentum suam naturam retineat . . . quae in aurum & argentum purissimum fusione iterum reducitur . . . Aurum, ut & alia metalla, retinent suam naturam in aquis fortibus in forma pulveris, nunc atri, nunc flavi, nunc alterius.”

32  The Chemical Philosophy of Robert Boyle The fact that the silver can be recovered by precipitation confirms that its corpuscles are atomic since the acid is able to break down their structural composition but not the corpuscles themselves. “Sennert’s explanation of the apparent disappearance of silver in aqua fortis involves the necessary assumption that the particles into which it was divided were extremely small”87 and this assumption is reinforced when the minuteness of the silver atoms is confirmed by passing them through filter paper before their precipitation from the acid-​silver solution. From the perspective of the “negative-​empirical” principle, the corpuscles of the silver are therefore operationally a-​tomos—​ indivisible—​ since they have resisted all efforts at laboratory decomposition into [their] components . . . the precipitated silver particles are also so small that they satisfy another canonic criterion of atomism—​the requirement of minute size.88

Following this and similar experiments, including ones in which gold and silver are alloyed and then recovered via analysis and precipitation, Sennert concludes that 1) the analytical tools have not succeeded in breaking down the particles of the metal, therefore these particles are operationally “atomic” and 2) the recovery of the metal to its original state and with great quantitative precision proves that the atoms of the component retain their substantial forms in the mixt. Following these experiments, Sennert believes that he has ample empirical evidence “for the two theses that he had wanted to prove—​that a metal seemingly mixed with an acid or with another metal retains its own nature intact, and that it is composed of extremely tiny corpuscles. In doing this, he has simultaneously shown the inadequacy of the . . . Scholastic theories of mixture while also providing a convincing demonstration of the reality of semi-​permanent atoms that experience no substantial modification.”89 It is important to emphasize that Sennert is not using the term “atom” in its literal sense, that is, to mean an ontologically indivisible particle. Rather, by “atom,” Sennert means “a particle of matter that cannot easily be divided or decomposed into other substances.”90 Thus, for Sennert, the term “atom” simply means “operationally indivisible,” thereby rendering atomicity as a negative-​empirical concept. Sennert also believes that there are different genera of atoms that reflect different stages of corpuscular composition or structure. Those atoms of silver and gold that Sennert claims to observe as the products of the “reduction to the



87 Newman, Atoms and Alchemy, 122. 88

Ibid., 99–​100. Ibid., 123. 90 Newman, “What Have We Learned from the Recent Historiography of Alchemy?,” 319. 89

Chemical Philosophy in the 16th and 17th Centuries  33 pristine state” are “what he takes to be atoms of higher compositional stage, not the tiny elemental corpuscles out of which the former are composed.”91 However, although the visible atoms of silver that result from the reduction are at a higher compositional stage, they are not further reducible via analysis and are, therefore, considered as operationally elementary. “In the context of his complex atomism, the analytical agents of the chymist are used by Sennert to define the constitution of ‘indivisibility’.”92 From a historical and philosophical standpoint, Sennert’s work is interesting for several reasons. First, although the reduction to the pristine state cannot ultimately prove Sennert’s compositional theory of matter, Bensaude-​Vincent and Stengers point out that “the operations that brought reversibility to the fore inspired a new classification of chemical procedures that theoretically favored purification processes.”93 Second, Sennert’s hylomorphic atomism serves as an important transitional hypothesis from the Scholastic theory of substantial form to mechanistic corpuscularianism, and he develops an innovative compositional theory whose structural focus anticipates not only the work of later chemists such as Boyle but also the eventual structural focus of modern chemistry. Third, Sennert’s experimental work involves “both a synthetic and an analytic stage . . . [this] paired cycle of synthesis and analysis used in a demonstrative proof ”94 would have great repercussions in the early modern period, such as, for example, when Boyle and Spinoza use experiments such as the redintegration of potassium nitrate to provide empirical support for mechanistic corpuscularianism. Finally, Sennert’s negative-​empirical approach and operational understanding of atomicity would be important for future chemists “in considering the limits of technical analysis to provide the natural philosopher with a working ‘atom,’ namely, any substance that was resistant to dissolution in the laboratory.”95 The negative-​empirical approach to elementarity “resurfaces most importantly in the work of Lavoisier, who claims that the term ‘element’ should be restricted to the ‘last point which analysis is capable of reaching’.”96 As Newman points out, Sennert’s work shows “the interplay between the two types of qualitative explanation [. . .] the structural and the substantial [. . .] Sennert uses a generalized microstructural explanation in combination with chymical properties originating in the substantial form to explain the origin of a

91 Newman, Atoms and Alchemy, 128. 92

Ibid., 97. Bensaude-​Vincent and Stengers, A History of Chemistry, 33. Newman, “What Have We Learned from the Recent Historiography of Alchemy,” 317–​318. 95 Newman, Atoms and Alchemy, 127. 96 Antoine-​Laurent de Lavoisier, Traité élémentaire de chimie, xvii. 93 94

34  The Chemical Philosophy of Robert Boyle macrolevel effect.”97 It must certainly be recognized that Sennert is a man of his time and that, despite the prescience of his atomism, of his analytical methods, and of his theory of microstructure, his conception of matter is hylomorphic and thus still firmly grounded in the Aristotelian and Scholastic notions of substance that would later be supplanted by the mechanistic philosophy. In addition to this, Sennert’s theory of matter retains significant elements of vitalism that ground it in the traditions of Paracelsian alchemy. For example, Sennert believes that sympathy or affinity and, very rarely, antipathy play an important role in the dissolution and precipitation of substances. Finally, although he turns to experiment to support his hylomorphic atomism, Sennert fails to sustain the notion of corpuscular substantial form within chemical explanations. This is because, as Bensaude-​Vincent and Stengers have pointed out, Sennert’s reduction to the pristine state is “not sufficient to support his atomism, since the Scholastic idea of the mixt would be perfectly capable of explaining reversibility.”98 For example, a Scholastic alchemist could argue that the clear blue solution that results from pouring aqua fortis on silver is not a genuine mixt precisely because the silver is recoverable by analysis, so Sennert’s experiment does not prove his atomistic theory. In fact, this problem is an instance of the underdetermination of theory by evidence, since the recovery of silver from the nitric acid solution in which it has been dissolved can be explained by several incompatible theories such as, in this case, Sennert’s hylomorphic atomism as well as the Scholastic theory of mixts. As we shall see in Chapter 3, Boyle’s theory of mechanistic form represents yet another attempt at explaining the result of this same experiment, using an entirely different paradigm and one that provides a much more satisfactory heuristic alternative to the theory of substantial form in any of its iterations. It is indeed ironic that Sennert’s emphasis on microstructure as the source of chemical qualities and chemical stability would later be used by Boyle to significantly reinforce his arguments against the very concept of substantial form. I will now turn to Jan Baptista van Helmont (1579–​ 1644), another important Paracelsian whose reconceptualization of the notions of semina, minima, spirit, and ferment had great impact on the ideas of Boyle.

1.6  Jan Baptista van Helmont and the Chemical Interpretation of Spirit and Ferment The bulk of Helmont’s chemical and medical philosophies are concerned with the activity of vital spirit in nature. He believes that all things in nature arise

97 Newman, Atoms and Alchemy, 136. 98

Bensaude-​Vincent and Stengers, A History of Chemistry,  32–​33.

Chemical Philosophy in the 16th and 17th Centuries  35 from spiritual seeds, that is, from semina that possess the life force of all animals, vegetables, and minerals. By means of a ferment, semina mingle with water to become individual entities. These ideas are interdependent with what Newman calls Helmont’s “vitalistic corpuscularianism.” Helmont’s complex chemical ontology integrates the non-​vitalistic corpuscularianism that he inherits from Geber with Paracelsian vitalism. He, then, also applies the Scholastic theory of minima naturalia to his idea of chemical combination. Pre-​Helmontian natural philosophers had tended to embrace either the concept of minima naturalia or the concept of semina rerum, depending on their own tendencies either toward materialism or toward vitalism, since minima were associated with materialistic ontologies while semina were associated with vitalistic conceptions of the universe. Unlike his predecessors, however, Helmont does not consider these concepts as incompatible and, instead, embraces both since each plays a distinct role in his hybridized chemical ontology. Helmont follows Paracelsus in interpreting semina as “the main agents in nature [and as] spiritual non-​corporeal entities,”99 while minima remain for him strictly physical corpuscles. In fact, “Helmontian atoms are identical with the minima naturalia, i.e., the smallest particles into which a substance may be divided. There is little doubt that for van Helmont minima naturalia are actual physical units. [However,] it is also apparent that they have qualitative determinations, not mechanical properties.”100 These qualitative and non-​mechanical properties are accounted for by semina, which work together with minima to bring about changes in nature by providing the spiritual force of action that brings about qualitative chemical alterations. Helmont modifies the Geberian and Scholastic theories by postulating that spiritual semina serve as the center for the actualization of forms. Like Severinus before him, Helmont rejects the Aristotelian theory of elemental qualities and maintains that it is semina rerum that function as the causes of all generation. He considers semina to be the link between the visible and the invisible realms, that is, between the material and the spiritual domains.101 Following Paracelsus in favoring the Stoic over the Epicurean interpretation of semina, Helmont believes that these are not corporeal or visible seeds. Rather, they are spiritual substances “whose active ordering principle is an architectonic spirit, endowed with scientia”102 or knowledge. Helmont calls this vital spirit the archeus, and it is safe to say that the archeus fulfills the same function in Helmontian ontology as the Logos had fulfilled in Neoplatonic ontology.



99 Clericuzio, Elements, Principles and Corpuscles, 56.

100 Ibid. 101

Clericuzio, “From van Helmont to Boyle,” 307.

102 Ibid.

36  The Chemical Philosophy of Robert Boyle According to Helmont, if natural substances did not contain a vital and seminal principle, they would be “dead and inert.”103 For Helmont, semina contain “information” that regulates the way a material substance will develop, in a process that he regards as analogous to fermentation. The development of semina occurs by way of an “idea” that is impressed upon the seed and that originates in the divine mind. God’s agent in this process is the archeus, which transmits ideas to semina.104 The efficient agency of the archeus is reminiscent of the role played by the agent intellect in medieval Aristotelian hylomorphism. However, the difference is that for Helmont the archeus is an internal efficient cause, rather than an external principle as the agent intellect was for the Scholastics.105 Helmont explains that all semina have their own archei, by which they are directed to specific goals. The archeus that governs each semen is a spiritual substance directing the course of generation or, in the case of disease, that of corruption. Like Paracelsus, Helmont regards all organic processes as based upon chemical events that are always presided over by the archeus, the vital spiritual force that is the embodiment of energy. As well, like Paracelsus, Helmont rejects the humoral conception of disease in favor of a pathogenic conception. So, for him, a body is healthy when all of the different chemical processes are governed correctly by the archeus. Disease, then, is understood as the failure of the archeus to govern correctly, and this occurs as a result of germs entering the body and bringing about chemical changes that the archeus cannot master. Finally, death results when the archeus or vital spirit is lost, and natural chemical changes are left entirely to themselves without any restraining influence,106 thereby resulting in the decomposition of the body. The ontological status occupied by the archeus is that of an interface between the corporeal and the incorporeal. Though it is not essentially material, it does exercise a profound effect on material processes. For example, in the human body, the archeus directs morphogenesis and the generation of specific individual organs. Given his belief in the universality of the archeus, therefore, it is not surprising that Helmont would claim that all things arise from the action of the internal archeus, the semina, and the resultant ferments.107 Thus, Helmont’s comprehensive and influential worldview is clearly an attempt to unify chymical, medical, and theological ideas. According to Helmont, semina and archeus are the real internal principles directing both animate and inanimate things in their generation and 103 Hirai, Le concept de semence dans les théories de la matière à la Renaissance, 451. 104 Oldroyd, “Some Neo-​Platonic and Stoic Influences on Mineralogy in the Sixteenth and Seventeenth Centuries,” 140–​141. 105 Hirai, Le concept de semence dans les théories de la matière à la Renaissance, 451. 106 Moon, “Van Helmont, Chemist, Physician, Philosopher and Mystic,” 25. 107 Debus, The Chemical Philosophy, 340–​343.

Chemical Philosophy in the 16th and 17th Centuries  37 development. In a 1631 letter to Marin Mersenne, he accuses Aristotle of having simple-​mindedly overlooked the important principle of the archeus in favor of the very crude and mechanical notion of external efficient causes.108 Thus, Aristotelian natural philosophy, in its ignorance of semina and archeus, reduces much of nature to an artifact that is devoid of internal principles of motion or change. For Helmont, semina are indispensable self-​ moving principles and the archeus, or vital spirit, functions as the “internal efficient cause” of all substances. Helmont goes so far as to identify the archeus with “gas” and, thus, believes to have made it empirically accessible. Semina are immaterial principles that are hidden deep within bodies and, unlike material substances, “semina operate by means of a ‘radial activity’ that need not involve physical, bodily contact.”109 Because semina are the origin of all genuine and real change, that is, of all chemical change, their “deep internal workings . . . constitute the ultimate object of practical laboratory studies”110 in Helmontian chymistry. One important point to keep in mind is that one of Helmont’s major goals, which underlies much of his chymistry, is the attempt to distinguish superficial physical changes from the intimate chemical interactions that result in substantial change, that is, in transmutation. Helmont makes a significant effort in trying to distinguish superficial from substantial change and, to do so, he grafts his vitalistic interpretation of semina, archeus, and ferment onto the materialist and corpuscular notion of minima naturalia.111 Helmontian chymistry distinguishes the mere mechanical division and spatial displacement of minima, conceived as corpuscles or “atoms,” from the “deep connection” and alteration of substances that results from seminal interactions. As will be stressed, for Helmont, superficial changes are merely physical and due to mechanical operations, such as the division and spatial rearrangement of minima, while genuinely substantial change is chemical and, therefore, involves the transformation of the original corpuscles of a substance into corpuscles of a different type through the action of ferments guided by semina. Therefore, although the aspects of Helmontian chymistry dealing with changes of state can be correctly associated with “mechanical corpuscularianism,” those aspects of his chymistry that deal with reactions, mixtures, and transmutations are more correctly associated with “vitalistic corpuscularianism.”112 108 van Helmont, “Lettre à Marin Mersenne,” 13:  “Archeus sive causa efficiens interna (quam Aristoteles ignoravit; omnem causam efficientem externam indigetans, rustico ac plane mechanico intellectu).” 109 Newman and Principe, Alchemy Tried in the Fire: Starkey, Boyle, and the Fate of Helmontian Chemistry, 62. 110 Ibid., 295. 111 Ibid., 64. 112 Newman, Gehennical Fire: The Lives of George Starkey, an American Alchemist in the Scientific Revolution, 148–​149.

38  The Chemical Philosophy of Robert Boyle Helmont appeals to the distinction between merely physical superficial changes and truly chemical substantial changes to account for the various alterations undergone by water, since water plays a central role in his chymical philosophy. Ontologically, Helmont rejects the four elements of Aristotelian cosmology and embraces, instead, an elementary monism. Inspired in part by Thales, he believes that water is the universal element that, through transmutation, transforms into the various substances that exist in the world. Some of the changes undergone by water are merely mechanical and superficial alterations. These include the changes of state from liquid to solid, vapor, and gas (a term coined by Helmont from the word “chaos”). These superficial changes do not involve the action of semina but simply the spatial rearrangement of minima. Thus, when explaining the superficial transformation of water into vapor, Helmont relies on his theory that the corpuscles of water are composed of shells that correspond to the three Paracelsian principles or tria prima, that is, the three principles of mercury, sulfur, and salt. The mercury and salt are found in the two outer shells, while the sulfur inhabits the core. He claims that these three principles cannot be separated in water, but they can exchange places. This is what Helmont refers to as the “extraversion,” or the “turning inside out,” of parts. Based on these assumptions, Helmont argues that the normal vaporization, or sublimation, of water takes place as follows: Upon heating, the three principles of water undergo “extraversion.” This exchange of place results in the extenuation,113 or “thinning out,” of the particles of water into “atoms.” Since they are so small and light, these “atomic” corpuscles are “driven up by the heat,”114 resulting in a change of state from liquid to vapor. Helmont also explains the process of freezing (or solidification) by employing a similar, albeit reversed, account of the internal spatial rearrangement of the minima or corpuscles. His chief purpose in both cases is precisely to explain, in purely physical and mechanical terms, the striking changes observed when water vaporizes or freezes. The main point, in Helmont’s own words, is that “It is not a new substantial generation when vapor is elevated from water, since it is only an extenuation, due to the extraversion of the parts. No mutation of essence occurs where there is only local division and extraversion of parts.”115 Since these are not genuine chemical changes, they cannot be accounted for by chemical explanations. As mentioned earlier, however, Helmont considers water to be the fundamental element from which all other substances are formed. Thus, it can undergo changes other than merely superficial changes of state, that is, it can undergo true 113 From the Latin extenuare, “to make thin” (based on tenuat, “it thins”). 114 Newman and Principe, Alchemy Tried in the Fire, 65. 115 van Helmont, Gas aquae, 75: “Non est itaque nova, ac substantialis generatio, dum ex aqua vapor elevatur, cum sit tantum extenuatio, propter partium extraversionem. Non intercedit enim essentiae mutatio, ubi sola est localis divisio & partium extraversio.”

Chemical Philosophy in the 16th and 17th Centuries  39 “mutation of essence.” Such “mutation of essence” or transmutation of water into different substances is a chemical change that is governed by the active ordering principles of archeus and semina. These active principles radically convert water into all the various substances that exist in the world.116 The complex process by which the semina induce the passive material of water to take on the qualities of other substances is fermentation. For Helmont, then, archeus, semina, and ferment are closely related principles upon which all natural phenomena ultimately depend. He also believes that most of these substances can eventually be transformed back into primordial water by using heat and cold, thereby establishing a continuous cycle of creation and destruction. Helmont tells us that “nothing doth arise anew in Nature, without a seed. In the next place, Every seed operates by dispositions . . . which it propagates in the matter for its intended [purpose].”117 Helmontian chymistry, however, is not the only context in which the notion of semina is important for explaining generation and transmutation. To the extent that his chymistry is closely tied to his medical ideas, Helmont also attempts to create medicines based on his conception of transmutation via semina. He argues that any substance heated with the alkahest118 will be first decomposed into its proximate ingredients (that is, salt, sulfur, and mercury) and, by being further heated, will be reduced to water. If this process is stopped at the correct point and the alkahest is distilled off, the “first essence” (ens primum) of the dissolved substances would be left behind as a crystalline salt. This essence was said to contain the concentrated medicinal powers of the dissolved substance, free from any noxious properties, much like a spagyric preparation but, according to Helmont, far easier to prepare. In these chemical and iatrochemical processes, Helmont tells us that “the mediating Instruments, by which the semina dispose materials, [are] Ferments” (Van Helmont 1662, 859). In De lithiasi, Helmont states that “ferments . . . are instruments by which the indwelling seeds of all things, or semina, go about their business . . . it is the ferments that allow these seeds to work.”119 For example, if we examine Helmont’s explanation of the development of metals and minerals, he claims that water interacts with a ferment (in a manner that he does not specify) to generate the physical seeds that, in time, develop to produce a metal or a mineral. “The ferment prepares, arouses and produces the seeds of corporeal substances.”120 Thus, ferments serve as the mediating agents between the semina

116 Newman, “The Corpuscular Transmutational Theory of Eirenaeus Philalethes,” 65–​66. 117 van Helmont, De lithiasi, in Oriatrike Or, Physick Refined (1662), 859. 118 In Paracelsian alchemy, the alkahest is a hypothetical universal solvent with the power to dissolve every substance, including gold. 119 van Helmont, De lithiasi, 29. 120 van Helmont, as quoted in Hirai, Le concept de semence dans les théories de la matière à la Renaissance, 455: “Le ferment prépare, suscite et produit les semences des choses corporelles.”

40  The Chemical Philosophy of Robert Boyle rerum, as immaterial principles, and the physical seeds that produce the specific substances in nature. In his Imago fermenti, Helmont further explains that “fermentation is the predecessor wholly necessary to every transmutation”121 and to every real chemical and substantial change. Helmont believes that, when a body is reduced into smaller atoms than its substance can stand, the body will be transmuted. He explains that this reduction to smaller particles is carried out by ferments: “The imbibed ferment, seizing the foresaid atoms, imbues them with its own alien character, during the reception of which there occur divisions of particles. The resolution of the matter follows these heterogeneities and divisions of particles  .  .  .  into minima.”122 Therefore, a ferment is a substance with the ability to divide matter into its most minimal particles. Such division is the key to any genuine chemical reaction. Thus, for Helmont, true mixture of substances must also be explained in these same terms. After two substances have been divided into minimal particles, their respective semina are free to act on one another. Only in this fashion can two substances be truly mixed into a new, third substance. Once again, the central agent in all these chemical processes is the archeus, which Helmont calls the Archeus faber, the “Master-​workman” and “Governor of generation.” He explains that “any and all material bodies in the world require a beginning to their movements, something that ‘excites and internally directs generation’ ”123 and his is the archeus. Helmont’s complex chemical ontology is, therefore, the hybridization of the “mechanistic” conception of corpuscles capable of undergoing spatial inversion with the “vitalistic” conception of substantial chemical transformation via ferments governed by the active principles of archei and semina rerum. Helmont’s corpuscularianism, unlike the materialist atomism of antiquity, denies that substances can genuinely form compounds by a mere juxtaposition of their minute particles. As established earlier, Helmont distinguishes between “mere apposition” of particles and true “wedlock.” The first of these is a “bare commingling,” which Helmont contrasts to the genuine “marriage” that occurs when substances are deeply connected. As in modern chemistry, Helmont asserts that what we would call today a “mechanical mixture,” in which particles are merely juxtaposed, is not a compound at all. Helmont considers this another example of 121 van Helmont, Imago fermenti, in Ortus medicinae, 69. 122 Ibid.: “Quaternus haustum fermentum, arripiens praefatos atomos, eos alieno sui charactere imbuit, in cuius susceptione fiunt divisiones partium, quas partium heterogeneitates & divisiones, resolutio materiae consequitur. Hactenus nimirum Chymia digerit, ac putrefactiones praemittit, ut accepto fermento partes dehiscant in minima.” 123 Hirai, Le concept de semence dans les théories de la matière à la Renaissance, 457: “Van Helmont explique ensuite que n’importe quel corps dans le monde a besoin d’un commencement de ses mouvements, ‘excitateur et directeur interne de la génération’.”

Chemical Philosophy in the 16th and 17th Centuries  41 a mere superficial change, not real or substantial and, therefore, not genuinely chemical. But here, the similarity between Helmontian chymistry and modern chemistry obviously ends. Where modern chemistry speaks of compounds, in which recoverable elements are held together by chemical bonds, Helmont speaks of “indissoluble marriages.” As Newman and Principe explain, Helmont’s idea of a “chemical change” is “considerably more restricted than our own analogous division between physical and chemical change . . . [This is because Helmont views] all processes in which the initial ingredients are recoverable as examples of superficial, rather than of genuine substantial change. Only when the change is so radical that the original substances cannot be recovered”124 does Helmont consider that a true chemical reaction has taken place. Such radical and irreversible transformations occur only when substances are irrecoverably altered by the intervention of new semina or the mortification of old semina. For example, Helmont does not consider the dissolution of gold in aqua regia to yield a transparent yellow liquid to be a genuine chemical change, “because the original gold may be recovered unchanged from the solution by precipitating it with salt of tartar (or potassium carbonate).”125 In his Progymnasma meteori, Helmont explain that only substances that can “indissolubly marry,” and only in a very restricted way, are volatile substances or “spirits.” If one tries to mix grosser matter, one will not achieve a permanent coalescence (coalitus) but merely a juxtaposition of particles. Therefore, according to Helmont, substances must be volatilized or subtilized before a true compound can be formed or even before a transmutation can occur. Helmont, however, does not believe that a mere mixture of spirits constitutes proper and indissoluble chemical “marriage.” For such a “marriage” to occur, the substances must be subtilized “to the point that they cannot be further [reduced].”126 If the subtilizing continues beyond that point, the substances will irreversibly coalesce and “will finally pass into another substance.”127 In Imago fermenti, it becomes clear that Helmont’s concept of transmutation is based upon the fundamental Scholastic principle, regarding minima naturalia, that “there is a natural limit to divisibility, beyond which a substance, qua substance, cannot pass.”128 Thus, he affirms that, if a substance should pass this limit, then it will become another substance. Helmont expresses this idea once again, this time using the language of atomism, by saying that: “I have found that so often as a body is divided into

124

Newman and Principe, Alchemy Tried in the Fire, 66.

126

van Helmont, Progymnasma meterori, 42.

125 Ibid. 127 Ibid.

128 Newman, Gehennical Fire, 142

42  The Chemical Philosophy of Robert Boyle smaller atoms than the necessity of its substance can stand, a transmutation of that body will immediately follow, except in the case of an element.”129 There is therefore, in Helmont’s theory, no intermediate state between mechanical mixture and transmutation. Although his theory of chemical change radically differs from our own modern understanding, Helmont’s claim that non-​substantial changes of state are due to the spatial rearrangement of corpuscles ultimately had the interesting consequence of facilitating the corpuscularian explanations for many of the alterations observed in the 17th-​century chemist’s laboratory. To elaborate further, since Helmont considers all laboratory processes in which the initial ingredients are recoverable as examples of superficial changes rather than genuine substantial mutation, it follows that chemistry actually leaves considerable room for explanations in terms of the spatial rearrangement of particles and, thus, in terms of “mechanistic” corpuscularianism. By Helmont’s own standard, short of genuine irreversible mixtures or of genuine transmutations, very few laboratory processes would actually require explanations in terms of archeus, semina, and ferments. Thus, although mere juxtaposition of parts, spatial rearrangement, and mechanical processes are relegated, by Helmont, to the realm of the not genuinely chemical, they are nonetheless of key importance in his own experimental work.130 As with Sennert, when we study Helmont, we must keep in mind that he is a transitional figure and that his language and metaphors are imbued with vitalism and anthropomorphism, using such terms such as “marry,” “conceive,” and “impregnate” to describe chemical processes. For example, he describes the process of mixture very poetically as two substances losing their own being to one another and, through the action of semina, giving rise to a third but different substance. In effect, the use of such metaphors illustrates the manner in which Helmont has grafted the Geberian theory of minima naturalia with the hylozoism of Paracelsus to arrive at a unique type of vitalistic corpuscularianism that blurs the distinction of matter and spirit, thereby allowing him to attribute to ferments guided by immaterial principles the power to carry out chemical transformations. Helmont’s spiritualistic characterization of the fermentation process contrasts sharply with the more materialist conceptions of fermentation of his time, such as that of Thomas Willis. However, in its various forms, the fermentational program found powerful followers in the second half of the 17th century. Although interesting, Helmont’s theory of genuine transmutation as an irreversible change of substance is in tension with his account of water as the

129 130

van Helmont, Progymnasma meterori, 72. Newman and Principe, Alchemy Tried in the Fire,  66–​67.

Chemical Philosophy in the 16th and 17th Centuries  43 universal element from which all other substances are formed. He explains that, in order to form all of the substances that exist, water undergoes a true “mutation of essence” or transmutation, involving the active guidance of archeus and semina. He adds that most substances can be transformed back into primordial water, thereby establishing a continuous cycle of creation and destruction. However, this latter claim conflicts with Helmont’s own claims about genuine transmutation, since this process is supposedly irreversible. Nowhere in Helmont’s writings does he either acknowledge or resolve this conflict between his elementary monism and his theory of chemical transmutation. Furthermore, although Helmont’s chemical interpretation of spirit and ferment affirms that genuine chemical transformation requires the action of non-​ corporeal semina rerum, guided by the spiritual archeus and acting by means of fermentation, the great majority of his laboratory observations do not conform to his definition of genuine transformation or “true mixtures.” Most of his experimental work involves substances that are ultimately recoverable following analysis and synthesis. Although for Helmont only the immaterial archeus, semina rerum, and ferments have genuine chemical functions and are the true object of chemical study, he concedes that the majority of changes that he observed in his own experimental work requires mechanical explanations in terms of the extenuation of parts. However, despite its close ties to medieval and Paracelsian alchemy, Helmont’s work goes far beyond that of Paracelsus and his other predecessors, insofar as he takes one of the first steps toward the naturalization of chemical explanations by employing the notion of a physical particle as the object of chemical change. Though his explanations continue to be steeped in the vitalistic ontology that dominated both medieval and Renaissance natural philosophy, Helmont significantly contributes to the naturalization of chemical ontology and of chemical philosophy and, thus, to its modernization. After Helmont’s efforts to provide a chemical interpretation of spirits and ferments, it would not be long before other chemists completed the naturalization of these two notions. Eventually, the mechanical philosophy championed by Descartes, Spinoza, and Boyle would dominate the discourse regarding chemical transformations and would explain the chemical activities of spirits and ferments in terms of the mechanistic properties of fundamental particles. Thus, although Sennertian and Helmontian chymistry made contributions that would influence the chemical philosophy of Robert Boyle, the vitalism that lingered in their chemical philosophies was a liability in an age that was quickly being overtaken by the mechanistic philosophy. For many chemists, mechanicism provided the only viable alternative to the theory of substantial form, and much more will be said about this in the next chapter. However, that chapter will also show that the Cartesian attempt to resolve the problem of substantial form by appealing

44  The Chemical Philosophy of Robert Boyle to a strict mechanicism entailed sacrificing the status of chemistry as systematic natural philosophy. It would be up to Robert Boyle to find a way to reconcile the mechanistic philosophy with experimental chemistry and he would do this, in part, by embracing some of the key notions of Sennertian and Helmontian thought.

2

Chemical Philosophy vs. Rationalistic Mechanicism The Heuristic Limits of Cartesianism for Chemistry

“Mechanicism,” or the mechanical philosophy, is the view “according to which matter is inert and all interactions in nature are produced by the impact of particles.”1 The mechanical philosophy, whether in its Cartesian or in its empiricist iteration, became quite critical of the Scholastic theory of substantial form which, by the 17th century, had acquired a wholly concrete interpretation as a power or cause “over and above” the material constitution of bodies from which all their properties flow. Robert Pasnau mentions that the two chief 17th-​ century criticisms against the notion of substantial form were that it was an obscure notion and that forms should not be treated as substances.2 Despite their many other disagreements, one thing about which both Cartesian and empiricist mechanicists could agree was that the concept of substantial form, understood as “something” over and above the material constitution of bodies that served as the source of their phenomenal properties, had absolutely no heuristic or explanatory value. One of the questions that this book addresses in detail, in this and in the following chapters, is whether the mechanical corpuscularian hypothesis could provide some other explanatory alternative to account for the properties of material bodies or whether it could simply re-​conceptualize the notion of form to give it a mechanistic and corpuscularian interpretation. Here, I will show that Cartesian mechanicists preferred the former option while, in the next chapter, I will establish that Boyle chose the latter option.

2.1  The Cartesian Rejection of Substantial Forms Descartes’ interpretation of substantial forms is that they are meant to be something subsistent in material bodies and, in a letter to the Dutch philosopher and

1 Clericuzio, Elements, Principles, and Corpuscles, 7. 2

Pasnau, “Form, Substance, and Mechanism,” 45.

The Chemical Philosophy of Robert Boyle. Marina Paola Banchetti-Robino, Oxford University Press (2020). © Oxford University Press. DOI: 10.1093/oso/9780197502501.001.0001

46  The Chemical Philosophy of Robert Boyle physician Henricus Regius, Descartes states that “to prevent any ambiguity of expression, it must be observed that when we deny substantial forms, we mean by the expression a certain substance joined to matter, composing with it a merely corporeal whole, and which no less than or even more than matter, is a true substance or a thing subsisting per se, since it is said to be an actuality, and matter only a potentiality.”3 According to Pasnau, Descartes’ criticism is based on a misunderstanding of the Scholastic view of substantial forms, perhaps due to a conflation of the Scholastic view with some of Aristotle’s own pronouncements in De anima. This being said, Descartes finds the notion of substantial forms to be incompatible with a truly mechanistic corpuscularian view of inanimate material bodies and believes that the mechanical philosophy can dispose of this idea, since there is only one res extensa that is shared by all material bodies and its mechanical affections fully account for the phenomenal qualities that we observe. Because he believes that the qualities and behaviors both of natural bodies and of artifacts are fully accounted for by their mechanical affections, Descartes rejects the Scholastic distinction between natural and artificial bodies according to which the former are endowed with substantial forms while the latter lack substantial forms. Although Descartes believes that the mechanistic hypothesis can fully explain both the properties and the behavior of all material bodies without recourse to any notion of form, substantial or otherwise, his formless mechanicism does not help him resolve the mereological question with which Aristotle was clearly concerned in his Metaphysics. That is, how does one account for both the synchronic and the diachronic unity that distinguishes composite (i.e., divisible) wholes from mere collections or heaps. I specify composite wholes here because Descartes has no trouble accounting for the synchronic and diachronic unity of simple (i.e., indivisible) wholes such as res cogitans since, in this unique case, he willingly appeals to substantial form, as did his Scholastic predecessors. The difficulty for composite wholes, however, also translates into a difficulty for realism about natural kinds and for the notion that extended bodies can legitimately and non-​arbitrarily be classified as belonging to distinctive material species. Because Descartes, like Hume, denies the presence of any sort of metaphysical “glue” that holds material bodies together, in space and time, he must find some other way of explaining unity. His mechanistic commitments preclude endorsing any sort of force or occult quality that holds particles together to account for a body’s 3 Descartes, The Correspondence between Descartes and Henricus Regius /​De briefwisseling tussen Descartes en Henricus Regius, 106: “Ne enim aliqua sit ambiguitas in verbo, hic est notandum, nomine formae substantialis, cum illam negamus, intelligi substantiam quondam materiae adiunctam, et cum ipsa totum aliquod mere corporeum componentem, quaeque non minus, aut etiam magis quam materia, sit vera substantia, sive res per se subsistens, quia nempe dicitur esse Actus, illa vero tantum Potentia.”

Chemical Philosophy vs. Rationalistic Mechanicism  47 unity, nor does he wish to re-​conceptualize the notion of form in mechanistic terms. Thus, the mereological question of what accounts for the unity of composite wholes remains unanswered.4 In his Principles of Philosophy, Descartes argues that particles are separated by their motions and are joined together by their state of rest. His argument suggests that appealing to another substance beyond that of the particles to explain unity would lead us into a regress when we try to explain how this other substance holds the particles together. On the other hand, appealing to a mode other than rest to explain unity would violate the principles of mechanicism by invoking a non-​mechanistic principle. Yet, the idea that composite wholes are unified simply because their particles are at rest is an unsatisfactory explanation, if for no other reason than that it cannot account for the stability of material bodies. Thus, as already stated, the mereological question remains unanswered as does the question of what accounts for the stability of material bodies that warrants their classification into natural kinds or material species. The inability to accommodate any notion of form or to re-​conceptualize this notion in mechanistic terms is one of the weaknesses of this ontology. For this, among other reasons, Boyle finds it difficult to fully reject the notion of form and, instead, tries to reconceptualize it in mechanistic terms. As we shall see in the next chapter, Boyle’s chemical philosophy represents one of several attempts to develop a conception of form that resolves the questions of unity and identity, while remaining completely committed to the mechanistic corpuscularian hypothesis.

2.2  Pierre Gassendi and the Reformation of Epicurean Atomism Pierre Gassendi (1592–​1655) was arguably the strongest proponent of mechanistic Epicurean atomism in early 17th-​century France although we now know that, far from simply being a “rationalistic mechanicist,” Gassendi was also influenced by Paracelsians such as Peter Severinus and Jan Baptista van Helmont.5 From the point of view of chemical philosophy, his Philosophia Epicuri syntagma (1649) is significant because it marks the shift from the vitalistic corpuscularianism of Sennert and Helmont to the mechanistic corpuscularianism of the sort later defended by Walter Charleton, Robert Boyle, and Isaac Newton. Gassendi contributes to the acceptance of Epicurean atomism by making this view compatible with Christian theism, and he does this by revising classical atomism in significant ways. Before discussing these

4 5

For a detailed discussion, see Pasnau, “Form, Substance, and Mechanism.” Hirai and Yoshimoto, “Anatomie du chymiste sceptique,” 93.

48  The Chemical Philosophy of Robert Boyle revisions, however, it is important to point out that atomism is one among several corpuscularian theories, not all of which accept the existence of atoms as indivisible particles. One such non-​atomistic view is Cartesian corpuscularianism, and it is important to examine this in some detail to understand where and why Gassendi chooses to break with Cartesianism in this regard. Descartes rejects atomism because he believes matter to be infinitely divisible due to its essential property of extension. Thus, although the minutest detectable particles may be called “atoms” for brevity’s sake, these particles are not truly a-​ tomos, that is, not truly indivisible. According to Descartes, even if God wished for some particles to be indivisible in nature, it does not follow that these particles are indivisible in principle and that God could not divide them if he wished to do so. In Principles of Philosophy (Principia philosophiae), he states “even if we suppose that God wished to reduce some part of matter to a minuteness so extreme that it could not be divided into smaller parts, we could not conclude from this that it is indivisible. For if God rendered this part so small that no creature could divide it, he certainly could not deprive himself of the power to divide it: because it cannot be that he could diminish his own power.”6 Thus, Descartes reaches the conclusion that “there cannot be any atoms or particles of bodies that are indivisible, as some philosophers have imagined. No matter how small we imagine particles to be, since they must be extended, we cannot conceive that there is not one among these that cannot be further divided in two or more even smaller particles [. . .] We shall say then that the smallest possible extended particle that can exist can always be divided.”7 Gassendi, however, rejects the Cartesian claim that the essential property of matter is extension and that this makes the notion of indivisible material particles incoherent. Instead, in the Syntagma philosophicum (1658), Gassendi claims that matter is that which has dimensions and is capable of resistance, which means that prime matter is constituted of solid and indivisible particles. Because Gassendi wishes to attribute both empirical reality and causal power to material atoms, he also rejects the Cartesian view that only geometrical points can be considered indivisible and atomic, since these have no empirical reality or causal power. 6 Descartes, Principia philosophiae, 51:  “Quin etiam, si fingamus, Deum efficere voluisse, ut aliqua materiae particula in alias minores dividi non possit, non tamen illa prioprie indivisibilis erit dicenda. Ut etenim effecerit eam a nullis creaturis dividi posse, non certe sibi ipsi ejusdem dividendae facultatem potuit adimere: quia fieri plane non potest, ut propriam suam potentiam imminuat.” 7 Descartes, Les principes de la philosophie, 74: “il ne peut y avoir des atomes, ou des parties de corps qui [. . .] soient indivisibles, ainsi que quelques Philosophes ont imaginé. D’autant que, si petites qu’on suppose ces parties, néantmoins, parce qu’il faut qu’elles soient estenduës, nous concevons qu’il n’y en a pas une entr’elles qui ne puisse estre encore divisée en deux ou plus grand nombre d’autres plus petites [. . .] nous dirons que la plus petite partie estenduë qui puisse estre au monde, peut tous-​ jours estre divisée.”

Chemical Philosophy vs. Rationalistic Mechanicism  49 Gassendi also disagrees with Descartes’ complete denial of form, since this is equivalent to denying substantial identity. Gassendi points out that, when material bodies undergo changes, there is something that undergoes those changes but also that endures in time. This, however, does not mean that he endorses the Scholastic notion of substantial form, an idea that all mechanistic corpuscularians rejected. In fact, Gassendi does not purport to answer the question of what the subject of change is. He simply limits himself to pointing out that Descartes’ ontology is incomplete in this regard. Although we may never be able to answer the question of what the subject of change is and although our ontology may always be incomplete, Gassendi claims that we should at least admit this and not pretend that there is no problem, as Descartes seems inclined to do. I wish to pause here and point out that Boyle attempts to pick up precisely where Gassendi leaves off by attempting to resolve the question of the enduring subject of change in mechanistic terms. Much more will be said about Boyle’s proposed solution in the next chapter. Returning to Gassendi, another disconcerting problem that he detects in Cartesian corpuscularianism is its failure to explain an important mereological “element in all natural development, for completed wholes [attain] to natures that their parts [do] not possess.”8 Like Sennert before him and Boyle after him, Gassendi opts for the hypothesis that “the primordial atoms combine with one another to form compound corpuscles,”9 which he calls “molecules” (moleculae). These molecules are mereologically distinct from atoms in that they are composite and stable wholes that possess qualities not possessed by their constituent atoms. To properly address the issue of whether wholes acquire properties that are “over and above” those of their discrete parts, one must engage in a detailed discussion of mereology and, in particular, of chemical mereology. I will engage in such a discussion in Chapter 5 but, for now, suffice it to say that, although Gassendi offers no mereological explanation for the stability of molecules or for the relation between molecules and their constituent particles, he finds such an explanation to be the only satisfying alternative to the reduction of all higher-​ level properties to the mechanistic properties of fundamental particles. Although, as an atomist, Gassendi believes in the ontological dependence of the higher-​level properties of molecules upon the lower-​level mechanistic properties of atoms, he also recognizes that this ontological dependence does not entail explanatory reductionism. In fact, explanatory reductionism has little heuristic value for Gassendi, at least when one is confronted with the task of explaining the stability and chemical properties of substances. For him, because molecules are produced by chemical resolution, they are in a certain sense

8

Gregory, “The Animate and Mechanical Models of Reality,” 311.

9 Newman, Atoms and Alchemy, 191–​192.

50  The Chemical Philosophy of Robert Boyle “elementary,” although they are not simple or fundamental particles as such. Though Gassendi does not speculate about what it is that makes molecules stable, that is, what “holds” them together, he does hypothesize that molecules are compound corpuscles that cannot be further analyzed and that serve as the intermediaries between indivisible atoms and tangible perceptible bodies. In this sense, Gassendi’s “molecule” is very close to Sennert’s “chymical atom” minus the hylomorphism. Although it must be stressed that, for Gassendi, the only true elements are atoms since they are the only particles that are completely indivisible, he also believes that there are several intermediary levels of compounded corpuscles between fundamental atoms and concrete bodies, and it is these molecules that compose the traditional chemical “elements” (sulfur, mercury, salt, earth, water). Clearly anticipating the work of Boyle, Gassendi believes that textural alterations to molecules produce new qualities in substances, and that such changes in qualities can be induced by chemical operations. He suggests that the molecules of chemical principles characterize the various species of bodies, depending on their proportion and composition. He finds it difficult, however, to distinguish homogeneous bodies with identical molecules from mixed bodies, especially when determining the nature of metals.10 As mentioned at the beginning of this section, Gassendi contributes to the acceptance of Epicurean atomism by revising classical atomism in important ways to make it compatible with Christian theism. Significantly, Gassendi argues against Epicurus that motion is not inherent in matter and that, therefore, an external cause is required to impress motion upon atoms. This external cause is God as the prime mover. Gassendi’s arguments in this regard were crucial to the success of mechanistic atomism in Europe and had a great influence on the work of Walter Charleton (1619–​1707). Charleton’s work was, in turn, the primary vehicle for the acceptance of mechanistic atomism in England and for the influence of Gassendi’s ideas on Robert Boyle. In fact, Boyle is one of the first English scientists to embrace “purified” Epicurean atomism as advocated by Gassendi and Charleton, though he adjusts Epicurean theory to make it compatible with the Cartesian view of matter. As we shall see in Chapter 3, Boyle attempts to bring the atomic and mechanical philosophies within the compass of experiment. In fact, one of the main reasons for Boyle’s influence on the Royal Society’s acceptance of mechanical atomism was that his experiments were indeed qualitatively and quantitatively superior to those that had been previously performed by other chemists. However, it will be shown that Boyle did not endorse a reductionistic chemical ontology



10

See Pinet, “La philosophie de la matière de Galilée à Newton,” 67–​82.

Chemical Philosophy vs. Rationalistic Mechanicism  51 and that much of his chemical work consisted precisely in rendering his mechanistic and corpuscularian theory of matter compatible with the need for chemical explanations that did not simplistically reduce higher-​level properties to the lower-​level mechanical properties of corpuscles. In part, this may have been due to the recognition that the sort of explanation championed by Spinoza and other Cartesian mechanicists suffered from a lack of heuristic power and could, theoretically, be hostile both to the autonomy of chemistry and to chemical ontology.

2.3  The Limitations of the Cartesian Project for Chemistry and Chemical Philosophy Although not all mechanistic philosophers were Cartesians, mechanicism lent itself well to the Cartesian project of building scientific theories in a deductive manner, since “deduction allowed finding general principles under which elements of knowledge were to be structured.”11 Thus, when applied to chemistry, the Cartesian project required that general deductive principles be assumed and then employed to interpret the result of chemical experiments. It is not surprising, therefore, that 17th-​century chemistry textbooks typically endorsed a theory of matter that was grounded in mechanicism but “very often defined chemistry as an art, not as a purely deductive science in the manner of the Cartesian project,”12 precisely because chemistry did not lend itself to the sort of deductive derivation favored by Cartesians.13 In fact, Alexis Smets identifies a tension, in the 17th century, “between chemical and physical theories, and between practice and theory.”14 The controversies that erupted due to this tension, such as that between Leibniz and Stahl, raised “the crucial questions of the status and role of theories . . . as well as that of the relations that chemistry should or should not keep with other disciplines, and notably with mechanics and medicine.”15 Smets emphasizes, however, that “in spite of the eventual difficulty of erecting chemistry on its own principles, there existed a real need, internal to chemistry itself, for a theory that gave a solid account of practice.”16 In the chapters to follow, I will demonstrate how Boyle attempted to develop a chemical philosophy that could give such a solid account of practice within the context of a mechanistic theory of matter and that, in spite of his



11

Smets, “The Controversy between Leibniz and Stahl on the Theory of Chemistry,” 291.

12 Ibid. 13 Ibid. 14 Ibid. 15 Ibid. 16 Ibid.

52  The Chemical Philosophy of Robert Boyle failure in this regard, he laid the groundwork for Lavoisier’s later contributions to the modernization of chemistry. Returning to the Cartesian project, this project attempted to ultimately explain all qualities in terms of the quantitative mechanical affections of size, shape, and mobility of fundamental particles and to formulate explanations of all material phenomena, including chemical phenomena, in such mechanistic terms. For Cartesians, all higher-​level phenomena, properties, and processes were deducible from mechanistic lower-​level properties. In this view, “the physical world is represented by particles of matter in motion and can be interpreted by the laws of motion determined by statistics [. . .] dynamics [and] mechanics [. . .] Natural phenomena such as air resistance, friction, the different behaviors of individual bodies, the qualitative features of the physical world were now considered irrelevant to the discourse of natural philosophy or viewed as disturbing circumstances which were not [. . .] to be taken into account in an explanation of the physical world.”17 For Descartes and his followers, “any explanation of natural events requires the building of a mechanical model as a ‘substitute’ for the actual phenomena being studied.”18 Mechanical philosophy is, therefore, anti-​vitalistic and anti-​teleological, since it assumes that “nature is not the manifestation of a living principle but is a system of matter in motion that follows [mathematically precise] laws [. . .] the explanation of natural phenomena excludes all reference to vital forces or final causes.”19 In addition to accounting for all the properties of matter in terms of the quantitative and mechanical affections of particles, Cartesian mechanicism accounts for all changes in inorganic and organic material bodies through deterministic and mechanistic laws of motion that are external to matter itself. According to this view, “all interactions in nature are produced by the impact of particles”20 in accordance with mechanical principles. As mentioned in the earlier discussion of Gassendi, Cartesians sought to ensure that their affirmation of mechanistic principles would be compatible with Christian doctrine by arguing that matter is not intrinsically active or self-​organizing and that its motions are not self-​ determined. Instead, the motions and impact of particles are entirely determined by mechanistic causal chains and external laws of motion determined by God. Additionally, Descartes proposes to explain the variety of material bodies in the universe, as well all qualities and phenomena, via the mechanical affections of particles of universal matter.



17

Paolo Rossi, The Birth of Modern Science, 122. Ibid., 125. 19 Ibid. 20 Clericuzio, Elements, Principles, and Corpuscles, 7. 18

Chemical Philosophy vs. Rationalistic Mechanicism  53 This discussion explains why the ultimate goal of the Cartesian project was to erect all natural philosophical theories from a priori first principles, while using deduction to structure those theories. As already suggested, this approach engendered a certain hostility, on the part of Cartesians, toward the conception of chemistry as a theory of chemical qualities and substances and toward the idea that chemical explanations were autonomous from mechanistic physical explanations. I will argue, in the chapters to follow, that this is precisely why Boyle felt the need to develop a complex chemical philosophy and ontology that, while grounded in the mechanistic theory of matter, could retain its explanatory autonomy. As Mi Gyung Kim has recently pointed out and as I will elaborate in greater detail in Chapter 3, “it is entirely possible that Boyle designed his ‘corpuscular’ philosophy as a hybrid of the alchemical particulate theories and the mechanical philosophy. The two different orders of particles, linked by elaborate yet fragile connections, could meet the demands of chemical practice and systematic philosophy simultaneously,”21 thereby beginning to forge the link between laboratory practice and philosophical chemistry that was eventually completed via the 18th-​century Chemical Revolution. To understand the reason for which many 17th-​century chemical philosophies rejected strictly mechanistic explanations of chemical phenomena and processes, one must closely examine the implications of Cartesian mechanicism for chemical theory and practice. It must first be clarified that Descartes did take an interest in the experimental sciences and believed that much practical knowledge could be acquired from them. In fact, Descartes was deeply interested in the subject matter of the sciences and he offered explanations for many different kinds of empirical phenomena, from the motions of the planets to the passage of light from the sun to the earth and other phenomena. However, as Chalmers explains, Descartes ultimately hoped to subsume these sciences under “his mechanical account of the universe involving nothing other than portions of matter/​extension in motion . . . Insofar as basic processes . . . came to be regarded as physical processes subject to mathematical laws, the characterization of physical causes came to be seen as intrinsically mathematical . . . A term that had come into use in the early seventeenth century to accommodate these trends was ‘physico-​mathematics’.”22 In the second part of his Principles of Philosophy (Les principes de la philosophie, 1647), Descartes posits that “there is only one material substance in the entire universe, and we know it only because of its extension; and all the properties that we distinctly experience in this substance are due to its divisibility into parts and it receives the various dispositions that we experience by the movement of said

21 Kim, Affinity, That Elusive Dream, 42.

22 Chalmers, One Hundred Years of Pressure, 60.

54  The Chemical Philosophy of Robert Boyle parts.”23 In the fourth part of this massive work, Descartes attempts to apply the principles of the mechanistic hypothesis to the objects of chemistry. However, as Bernard Joly points out, in spite of addressing himself to the subject matter of chemistry, Descartes has no intention of developing a specifically chemical discourse.24 Rather, Descartes’ aim is to provide mechanistic accounts for all properties of matter, including properties such as magnetism. For example, he explains the phenomenon of magnetic attraction by appealing to differently shaped particles that fit and lock into each other, very much like the pieces of a jigsaw puzzle. Although Descartes’ explanations are not all as simplistically mechanistic as the example of magnetic attraction might imply, he does ultimately attempt to explain even seemingly non-​mechanical properties, such as fluidity and solidity, in terms of the motion of corpuscles relative to each other. Liquid substances like the universal ether are thought to be composed of corpuscles that are in constant motion in relation to each other, while solid substances are composed of corpuscles that are at rest with respect to each other. Even the “cosmical quality” of light, which is a seemingly non-​mechanistic phenomenon, is explained in terms of the linear movement of ether corpuscles away from the sun. Furthermore, although he believes that such corpuscles are stable, Descartes explains this stability by once again appealing to the relative rest of the parts of each corpuscle in relation to each other. Even when the young Descartes briefly wrote on hydrostatics, his interest in the topic was ultimately absorbed within his “ambitious plan to construct an outline of the ultimate corpuscular structure of the universe in its entirety.”25 As Chalmers explains, “The corpuscular system of the world outlined in Descartes’ Principles of Philosophy treated pressure in liquids and the transmission of light in analogous ways. Both were seen as resulting from the transmission of pushes from corpuscle to corpuscle. This had the result that the linear transmission of hydrostatic forces in liquids was as fundamental as the linear transmission of light.”26 Besides hydrostatics, Descartes also demonstrated an interest in chemistry and anatomy, which he began studying in 1630 and from which he believed much could be learned, as he admitted in a letter to Marin Mersenne dated April

23 Descartes, Oeuvres philosophiques de Descartes, 311: “Il n’y a donc qu’une même matière en tout l’univers, et nous ne la connoissons que par cela seul qu’elle est étendue; et toutes les propriétés que nous apercevons distinctement en elle se rapportent à cela seul qu’elle peut être divisée et mue selon ses parties, et partant qu’elle peut recevoir toutes les diverses dispositions que nous remarquons pouvoir arriver part le mouvement de ses parties.” 24 Joly, Descartes et la chimie, 106:  “si Descartes aborde ici l’examen des objets de la chimie, il n’entend pourtant pas développer un discours spécifiquement chimique.” 25 Chalmers, One Hundred Years of Pressure, 59. 26 Ibid.

Chemical Philosophy vs. Rationalistic Mechanicism  55 15 of that year.27 However, the problem for Descartes consisted in whether chemistry could qualify as a systematic natural philosophy or, as we would say today, a theoretically autonomous science. This problem, in turn, related to the question of whether chemistry could provide explanations that appealed primarily to mechanistic causes. In his Principles of Philosophy, Descartes certainly attempts to formulate what could be regarded as a mechanistic approach to chemical explanations that “proposes to explain the properties of chemical substances by invoking the configuration of the ‘small particles’ of which they are formed; with regard to chemical operations, one can hypothesize that they result from the manner in which those small particles come into contact with one another through the incessant movement in which they have been agitated by the flux of subtle matter.”28 For example, his account of how different metals form in the earth is given exclusively in terms of the shapes and sizes of the particles that compose the different metals: “According to the different sizes and shapes of these particles of matter [.  .  .] they compose the different kinds of metals, which I  would have here explained in greater detail had I  the convenience to conduct all of the experiments that would be required to verify my reasoning on this subject.”29 In this work, Descartes also presents mechanistic accounts of chemical operations such as distillation, which he explains as the forced escape of small particles by means of an alembic. In his view, “the particles that can be easily chased out of terrestrial bodies by the action of fire are of different types, as one can experience quite easily through chemistry [. . .] there are those [. . .] that escape quite easily from those bodies; that is to say, those that, being collected and joined together through the means of an alembic, compose the aqua vitae, such as we are accustomed in extracting from wine, from wheat and from numerous other materials.”30 The caustic nature of acids is attributed to the pointy or spiky

27 Descartes, Letter to Mersenne (April 15, 1630), 21: “I am now studying chemistry and anatomy simultaneously; every day I learn something that I cannot find in any book.” 28 Joly, “Chimie et mécanisme dans la nouvelle Académie royale des sciences:  les débats entre Louis Lémery et Etienne-​François Geoffroy”: “Descartes propose de rendre compte des propriétés des substances chimiques en invoquant la configuration des ‘petites parties’ dont elles sont formées; quant aux opérations de la chimie, on peut faire l’hypothèse qu’elles résultent de la manière dont ces petites parties entrent en contact avec les autres dans le mouvement incessant dont elles sont agitées par les flux de la matière subtile.” 29 Descartes, Oeuvres philosophiques de Descartes, 380:  “Selon les diverses grandeurs et figures qu’ont ces parties du corps [. . .] elles composent diverses espèces de métaux, lesquelles j’aurait peut-​ être ici plus particulièrement expliquées si j’avais eu la commodité de faire toutes les expériences qui sont requises pour vérifier les raisonnements que j’ai faits sur ce sujet.” 30 Ibid., 393: “Les parties qui peuvent être chassées hors des corps terrestres par l’action du feu sont de divers genres, comme on expérimente fort clairement par la chimie [. . .] il y en a [. . .] qui sortent fort aisément hors de ces corps; à savoir celles qui, étant ramassées et jointes ensemble par le moyen d’un alambic, composent des eaux-​de-​vie, telles qu’on a coutume de les tirer du vin, du blé et de quantité d’autres matières.”

56  The Chemical Philosophy of Robert Boyle particles of acidic substances, and the neutralization of acids is explained as the spiky particles fitting into the pores of the alkaline particles, thereby locking them together and hiding the acidic particles’ points. The Cartesian account does not suggest that chemical qualities are higher-​level properties that have any causal power in chemical processes, because causal efficacy is attributed only to mechanistic properties and to primary causes. In the preface to The Principle of Philosophy, Descartes faults the chemists of his time for basing their conclusions on principles that are not primary and self-​ evident by stating that “all conclusions that are deduced from a principle that is not evident cannot themselves be evident [. . .] when one begins with flawed principles, inasmuch as one cultivates them and applies them carefully to extract diverse consequences from these, thereby thinking that one philosophizes well, then one will just as much distance oneself from the knowledge of truth and from wisdom.”31 It is ironic that Descartes should say this, however, since the veracity of the mechanistic corpuscularian hypothesis is simply assumed by him and never proven, which would be an impossible task since these principles are themselves neither self-​evident nor empirically confirmable. The French Cartesian Jacques Rohauld (1618–​1672) admits that Cartesian natural philosophy is just as guilty of postulating hidden causes for observed phenomena as Paracelsian chymistry, though in the case of Cartesian mechanicism these causes are corpuscles so small that they resist any possible detection. Thus, Rohault poses the rhetorical question, “What good do those long and nice Disputes do, about the Divisibility of Matter? For though it could not be accurately determined, whether it be infinitely divisible or no; it would be sufficient to know that it can be divided into Parts small enough to serve for all Purposes that can be.”32 Yet, to fully understand the limitations of Cartesian mechanicism with regard to chemical philosophy, one must fully grasp the rigidity of its position concerning explanation in natural philosophy. All of the French Cartesians shared the view that “phenomena have to be explained by the motion, figure, and size of particles of a universal matter—​even if one can distinguish different sorts of particles. Secondly, the only admissible explanatory causes are the motion, size, and figure of particles, because only these fit the nature of bodies [. . .] and are able to explain their production. To explain a phenomenon is to explain this mechanical genesis.”33 For example, Géraud de Cordemoy is almost dogmatic in 31 Descartes, Les principes de la philosophie, 17–​18: “toutes les conclusions que l’on déduit d’un principe qui n’est point évident ne peuvent pas être évidentes [. . .] lorsqu’on a de mauvais principes, d’autant qu’on les cultive davantage et qu’on s’applique avec plus de soin à en tirer diverses conséquences, pensant que ce soit bien philosopher, d’autant s’éloigne-​ t-​ on davantage de la connoissance de la vérité et de la sagesse.” 32 Rohault, System of Natural Philosophy, preface. 33 Peterschmitt, “The Cartesians and Chemistry,” 194–​195.

Chemical Philosophy vs. Rationalistic Mechanicism  57 his appeal to strictly mechanistic explanations. In Le discernement du corps et de l’âme en six discours (1666), he states, “I have made a little reflection upon the notions that are held regarding bodies and matter, and I have seen that bodies can be conceived only as indivisible substances and that matter can be conceived only as a heap of these same substances.”34 As Luc Peterschmitt notes, there is no place for chemistry in this rigidly mechanistic atomism, claiming that “chemistry presents a problem for mechanism; indeed, chemistry turned mechanism into a problem, because chemistry is a limit for mechanism [. . .] chemistry reveals that mechanism is a scientific ideology, extending concepts and models of explanation outside of their realm.”35 Peterschmitt illustrates this point by showing that the most strictly Cartesian mechanicists of the 17th century either completely ignored chemical phenomena in their explanations of processes such as dissolution and digestion and attempted to explain these processes via strictly mechanical means or they attempted to actually provide a critique and refutation of chemistry as a legitimate experimental practice. Cordemoy favored the first approach, while Rohault favored the second. The basis of Rohault’s critique is the fact that, since analysis could not yield fundamental particles, even mechanistic chemists had to treat the final products of analysis as operationally “elementary” for heuristic purposes. Rohault disapproves of this method used by chemists and claims it to be defective because it succeeds only in isolating “the sensible parts of which a body is composed”36 while the fundamental principles escape it. “In his view, if experiment and observation seem to lead to some states of matter (principles or elements), what chymists present as their principles cannot be properly described as such. A principle is not an empirical fact, but part of the theory.”37 As an aside, it is interesting to note that the methodological practice that Rohault finds most objectionable, that is, the appeal to operational elementarity rather than to fundamental principles, is precisely the method that was later advocated by Antoine Lavoisier as a way of modernizing chemical practice and of quantifying chemical explanations, thereby distancing chemistry from its former more speculative and metaphysical concerns regarding the ultimate 34 de Cordemoy, Le discernement du corps et de l’âme en six discours, pour servir d’éclaircissement à la physique, 15: “J’ay seulement fait un peu de reflection sur les notions que l’on a des corps, & de la matière, & j’ay reconnu que l’on ne sauroit concevoir les corps que comme des substances indivisibles, & que l’on ne sauroit concevoir la matière que comme un amas de ces mesmes substances.” 35 Peterschmitt, “The Cartesians and Chemistry,” 201. 36 Rohault, Traité de physique, 153:  “Ce qui faite donc que je n’approuve pas la méthode des Chymistes, c’est premièrement parce qu’elle est défectueuse; d’autant qu’il est certain qu’en travaillant le plus exactement qu’il est possible, ils ne sauroient recueillir & ramasser que les parties sensibles dont un corps est composé.” 37 Dobre, “Cartesianism and Chymistry,” 129.

58  The Chemical Philosophy of Robert Boyle nature of matter. Nonetheless, since Rohault favors a hypothetico-​deductive approach to science, the methods employed by chemists are unsatisfactory and “their so-​called principles are not well founded.”38 Thus, to the extent that chemists’ access to true principles is operationally and empirically restricted, “the whole of their knowledge amounts to being able to give names to things that they do not know at all; thus it is impossible to predict what would result when they are mixed, which is however one of the main conditions demanded of the elements.”39 Consequently, by denying to chemical theory its predictive power, Rohault is denying to chemistry the status of a legitimate empirical science. It is important to note that, although Cordemoy, Rohault, and other strict Cartesian mechanicists deny the scientific status of chemistry, they still consider the activities of chemists to be useful for the progress of science. For example, though Nicolas Lémery and Pierre-​Sylvain Régis argue that the foundational principles of chemistry must always be limited to negative-​empirical concepts and that only mechanistic physics can achieve a complete knowledge of fundamental principles, they also recognize the albeit limited heuristic value of chemistry for understanding the nature and properties of composed and mixed substances. In his Cours de chymie (1683), Lémery claims that in chymistry, the term “principle” is not to be taken in an exact sense; because the substances which are so named are principles only with respect to us, and insofar as we cannot go further in the division of bodies; but one understands that these principles are still divisible into an infinity of parts which may be more justly termed principles [. . .] But if one wants to approach as near as possible to the true principles of nature, there is no more assured way than that of chymistry [. . .] This art [. . .] will give a very great idea of the nature and figure of the first little bodies that enter into the composition of mixed bodies.40

In his Cours entier de philosophie (1691), Régis states, in a very similar vein to Lémery, that 38 Ibid. 39 Rohault, Traité de physique, 155: “Si bien que toute leur science se borne à savoir donner des noms à des choses qu’ils ne connoissent point du tout, & du mélange desquelles il est part conséquent impossible de prévoir ce qui en pourra résulter; que est cependant une des conditions principales que l’on demande dans les Élemens.” 40 Lémery, Cours de chymie, 5: “Le nom de Principe en Chymie, ne doit pas être pris dans une signification tout à fait exacte; car les substances qu’on appelle ainsi, ne sont principes qu’à nôtre égard, & qu’en tant que nous ne pouvons point aller plus avant dans la division des corps: mais on comprend bien que ces principes sont encore divisibles en une infinité de parties qui pourroient, à plus juste titre, estre appellées Principes [. . .] mais si l’on veut approcher autant qu’il se pourra des véritable principes de la nature, on ne peut prendre une voye plus assurée que celle de la Chymie: cet Art [. . .] donnera une fort grande idée de la nature & de la figure des premier petits corps qui ont entré dans la composition des mixtes.”

Chemical Philosophy vs. Rationalistic Mechanicism  59 among the chymists, the term principle is not to be taken in an exact sense; because the substances to which they give this name are principles only with respect to us, and insofar as art cannot go any further in the division of bodies, although one can be sure that these principles are themselves composed of an infinity of parts of the first element, which may be more justly termed principles. One must however grant that if one wants to approach as near as possible to the true principles of nature, there is no more assured way than chymistry; because [. . .] it gives nevertheless a very great idea of the nature and figure of the insensible particles that enter into the composition of mixed, gross, and palpable bodies.41

Peterschmitt convincingly argues that, for these Cartesian mechanicists, “chemists did not develop a science, but they have worked diligently and have provided the materials for a science. Chemistry is at best an experimental art which displays the phenomena that are to be explained [. . .] Without the chemists, it is not possible to be a good and productive mechanist.”42 Ultimately, however, the only genuinely scientific explanation is the one provided by the mechanicists, that is, an explanation in terms of the mechanical affections of particles and of the mechanistic principles that govern their motions. Unfortunately for the Cartesians, however, they were unable to demonstrate the truth of their hypothesis that chemical principles are equivalent with mechanistic affections of fundamental particles. In a sense, such reasoning (i.e., proving an identity of properties) is not strictly possible from a logical point of view. It would require showing that all the properties are the same, which is absurd in a practical sense, since it would require an exhaustive enumeration of all properties [.  .  .] the question that remains is whether it is really possible to give a mechanical explanation of chemical matters of fact.43

Ultimately, in the mid-​18th century, Lavoisier would circumvent these questions entirely by forsaking all metaphysical speculations about the nature of ultimate 41 Régis, Cours entier de philosophie ou Système général selon les principes de M. Descartes, 333–​ 334: “Il est vray que le nom de Principe ne doit pas être pris chez les Chymistes dans une signification tout à fait exacte; car les substances qu’ils appellent de ce nom, ne sont Principes qu’à nôtre égard & en tant que l’Art ne peut pas aller plus avant dans la division des Corps, bien que nous soyons assurés que ces Principes soient eux-​mêmes composés d’une infinité de parties du premier Élément qui pourroient à plus juste titre estre appellés Principes. Il faut avoüer pourtant que si l’on veut approcher autant qu’il se pourra des véritables Principes de la Nature, on ne peut prendre une voye plus assûrée que celle de la Chymie; car [. . .] elle donne néanmoins une fort grande idée de la Nature & de la figure des particules insensibles qui entrent dans la composition des Corps Mixtes, grossiers & palpables.” 42 Peterschmitt, “The Cartesians and Chemistry,” 198. 43 Ibid., 200–​201.

60  The Chemical Philosophy of Robert Boyle matter and by restricting his chemical theorizing to that which could be empirically observed, measured, and classified. In his Essays de chimie (1702), the chemist Wilhelm Homberg anticipates Lavoisier’s rejection of metaphysics when he claims agnosticism regarding the nature of fundamental principles and states that “we have not yet been able to establish anything incontestable as to the figure, order and motion of the primary matters”44 and by concluding that chemistry must restrict itself to material and sensible principles. Thus, as already noted, it is precisely by embracing the negative-​empirical conception of elementarity and rejecting the appeal to fundamental principles that Lavoisier was ultimately able to modernize chemistry as a purely empirical and quantitative science. Due to its inability to account for chemical qualities and phenomena, Cartesian mechanicism, as well as Descartes’ insistence that matter is inherently inert, met with some degree of resistance in the context of 17th-​century chemistry, physiology, and medicine. In fact, as was discussed in Chapter 1, for many chymists and physiologists, organization and spirit were inherent in matter although, in this transitional period, spirit was conceived in chemical terms rather than as an immaterial substance. However, even for those chemists who embraced the mechanistic corpuscularian philosophy as a theory of ultimate matter, mechanicism had to be made compatible with the existence and causal efficacy of chemical properties, as well as for the existence of stable chemical substances. “In spite of the eventual difficulty of erecting chemistry on its own principles, there existed a real need, internal to chemistry, for a theory that gave a solid account of practice.”45 It is, therefore, in this context that we must understand Robert Boyle’s chemical philosophy as an attempt to reconcile the mechanistic hypothesis of fundamental particles with the empirical reality of causally efficacious chemical properties, substances, and reactions.

2.4  Mechanistic Corpuscularianism and Experimental Natural Philosophy Although early modern particulate matter theorists clearly believed that atoms and corpuscles have empirical reality, actual empirical support for atomism and corpuscularianism was lacking in the early 17th century. As Christoph Meinel aptly points out, “in atomism [. . .] there was no experimental proof possible, although most corpuscular theories of the seventeenth-​century explicitly claimed to be based upon experience.”46 The (mostly unconvincing) arguments that were 44 Homberg, “Essays de chimie,” 33: “Nous n’avons pas encore pû déterminer rien d’incontestable sur la figure, sur l’arrangement & sur le mouvement des premieres matières.” 45 Smets, “The Controversy between Leibniz and Stahl on the Theory of Chemistry,” 291. 46 Meinel, “Early Seventeenth-​Century Atomism,” 68.

Chemical Philosophy vs. Rationalistic Mechanicism  61 presented in support for atomism fell into five general categories. The first group of arguments, which can also be found in the writings of ancient Epicurean atomists, involved analogically extrapolating the existence of atoms, as well as their minute dimension, from macroscopic phenomena. Daniel Sennert, in fact, performed an experiment in 1636 in which he “described a distillation in which a stream of alcohol vapor passed through a sheet of paper, the density of which was supposed to give an idea of how small the atoms really were [. . .] However, it is clear that there was no quantitative methodology behind these indications. Sennert used the language of the laboratory in a merely figurative and persuasive manner, appealing to the imagination of the reader.”47 The second type of argument in favor of atomism was based on microscopic observations. Since the invention of the compound microscope in the 1590s, early modern scientists had been fascinated with “the worlds to be found in a drop of water,”48 although it wasn’t until the publication of Giambattista Odierna’s L’occhio della mosca (The Fly’s Eye) in 1644 that the first detailed account of microscopic observations became available to the larger scientific community. It was also not until the 1660s that the microscope became widely used for scientific research. Gassendi was one of the first natural philosophers to realize the potential of this instrument for research, although this “was presented as an empirical fact by Henry Power a few years later.”49 However, as Power’s own attempts demonstrated, the potential of the 17th-​century microscope as a research tool was more likely to be fulfilled in areas such as biology than in the theory of matter. The best one could do, once again, was to extrapolate the existence and dimension of atoms from what was observed via the microscope. Since [atoms] are so small that they could be inferred only rationally, methodological difficulties [. . .] arose if one attempted to model the real after the visible.”50 The third type of argument in favor of atomism and corpuscularianism concerned “transport phenomena in which material substances appear or disappear invisibly [. . .] [For example,] [t]‌he drying of bread or the slow evaporation of liquids are material processes, although the flux of material cannot be observed. In all these cases, quantitative change can be recorded, and from this the existence of invisible parts of matter could be inferred.51 However, although this type of naively inductive argument rendered plausible the existence of atoms or corpuscles, it could neither prove their existence nor establish the material identity of these particles.



47

48

Ibid.,  78–​79. Ibid., 80.

49 Ibid. 50 51

Ibid., 84. Ibid., 81.

62  The Chemical Philosophy of Robert Boyle The fourth type of argument, based on physical experiments involving changes such as condensation and rarefaction, attempted to provide more convincing empirical evidence for the existence and behavior of atoms. These experiments remained inconclusive, however, because their results were open to interpretation regarding the existence or non-​existence of the vacuum. The ancient atomists had posited a vacuum, to explain the mobility of hard and impenetrable atoms and, thus, the possibility of change. This vacuum could be either a continuous void or an interparticulate void. However, the existence of the vacuum was extremely controversial in the 17th century. Even after the first vacuum was produced by Torricelli in 1643, in a column of mercury and under controlled experimental conditions, it was not clear what the implications of this experiment were for atomist and corpuscularian matter theories. In fact, no clear consensus could be reached on this issue, with some philosophers arguing for the continuous universal vacuum, others arguing for interparticulate vacua, and others still arguing against the existence of any vacuum at all and in favor of a substance, such as the ether, that both filled the spaces between atoms and held the particles of bodies together.52 However, as Meinel points out, “the re-​introduction of an active spirit or ether into atomism, aimed at explaining how the atoms interact and how their actions are transmitted, undermined the theoretical consistency of the mechanical corpuscularianism. [. . .] Plenist corpuscular theories such as Basso’s and Descartes’ exemplify that it was entirely acceptable to assume corpuscles without admitting the void.”53 Still, the physical experiments themselves could not settle this question, since the very results of these experiments could be interpreted to support any of the competing hypotheses regarding the vacuum. It is no wonder, then, that Cartesian mechanical philosophers such as Spinoza were suspicious of the usefulness of experiment for confirming the mechanical hypothesis and ultimately sought to replace the uncertainty of laboratory practice with the rigorously mathematized discourse of physics.54 It seems then that the fifth type of argument, based upon chemical processes such as the reduction and redintegration of substances, had the greatest potential for providing empirical support to atomistic and corpuscularian theories of matter. As will be discussed in more detail in the next chapter, one of the important experiments that Robert Boyle appropriates in this regard is Daniel Sennert’s reduction to the pristine state. There is, however, another important experiment that Boyle uses for lending empirical support to mechanistic corpuscularianism, 52 Ibid., 82. 53 Ibid., 83. 54 Joly, “Le cartésianisme de Boyle,” 155: “Les pratiques incertaines du laboratoire doivent [. . .] laisser place à la rigueur d’une physique rationnelle qui se justifie dans la mathématisation de son discours.”

Chemical Philosophy vs. Rationalistic Mechanicism  63 that experiment being the redintegration of potassium nitrate. To the extent that Spinoza disagreed with Boyle’s interpretation of this experiment, it became the focus of a very lively epistolary debate between Boyle and Spinoza, a debate that was mediated by their mutual friend Henry Oldenburg who was responsible both for translating and for transporting the letters between the two philosophers from England to the Netherlands and back. The historical significance of this experiment is that it illustrates the distinction between those natural philosophers who were committed to the value of experiment for confirming or disconfirming hypotheses regarding the nature of matter and those philosophers for whom experiment had little heuristic power and who relied instead on a priori arguments to support their theory of matter. Before I discuss the Boyle-​Spinoza controversy over the interpretation of the redintegration of potassium nitrate, however, I will describe Boyle’s experiment and its results. Boyle’s reasons for choosing to work with potassium nitrate are worth mentioning. Seemingly in agreement with Paracelsus that “no other salt in the world is like [saltpeter],”55 Boyle may have chosen saltpeter for his experiment because he believes it to be “ ‘the most catholic of salts,’ a most puzzling concrete, ‘vegetable, animal, and even mineral,’ both acid and alkaline, ‘partly fixed and partly volatile.’ The knowledge of it, Boyle opined, ‘may be very conducive to the discovery of the nature of several other bodies, and to the improvement of divers parts of natural philosophy.’ ”56 It is, perhaps, because of these properties of potassium nitrate that Boyle believes he can analyze it into “fixed nitre” and “spirit of nitre,” which have seemingly contradictory properties. He, thus, sets out to analyze a sample of potassium nitrate and then to resynthesize the products of analysis to yield the original saltpeter. The experiment proceeds as follows:  during the process of analysis, Boyle throws hot coal into a measured sample of potassium nitrate (KNO3), also called niter or saltpeter, thereby decomposing the saltpeter and yielding “fixed nitre” or potash (K2CO3 or potassium carbonate) and nitrogen dioxide gas (NO2). The nitrogen dioxide gas is then condensed on the glass and mixed with water to produce “spirit of nitre” (HNO3, aqua fortis or nitric acid). The analysis complete, Boyle proceeds to redintegrate the saltpeter by synthesizing the “fixed nitre” or potash with “spirit of nitre” that has been sourced separately, thereby obtaining a good amount of potassium nitrate of negligibly lesser weight than the original sample.57 According to Boyle, this experiment shows that potassium nitrate or saltpeter is a chemical compound, rather than a mixture, because the properties of the saltpeter are distinct from those of fixed niter and

55

Paracelsus, as cited in Clericuzio, “Carneades and the Chemists,” 52.

57

Duffy, “The Difference between Science and Philosophy,” 126.

56 Cressy, Saltpeter: The Mother of Gunpowder, 14.

64  The Chemical Philosophy of Robert Boyle the spirit of niter, fixed niter being alkaline and spirit of niter being volatile and acidic. Boyle states that when salt-​petre is distilled, the volatile liquor and fixed salt, into which it is reduced by the fire, are endowed with properties exceedingly different both from each other, and from those of the undissipated concrete. For the spirit of nitre is (as we formerly have observed) a kind of Acetum Minerale, and possesses the common qualities to be met with in acid spirits [. . .] whereas the fixed nitre is of an alkalizate nature, and participates [in] the qualities belonging generally to lixiviate salts; and salt-​petre it self is a peculiar form of salt, discriminated by distinct properties both from those salts, that are eminently acid [. . .] and from those, that are properly alkalizate [. . .] And whereas salt-​petre it self is partly fixed, and partly volatile, the acid ingredients of it are altogether volatile, [and] the alkalizate fixed.58

Boyle concludes that the parts constituting saltpeter are of “different specific and chemical natures,” although made of the same universal matter as saltpeter itself. These constituent parts exhibit properties that are distinct from those of the potassium nitrate:  alkalinity and fixedness for the fixed niter, acidity and volatility for the spirit of niter. From this reconstitution, Boyle infers that saltpeter is a heterogeneous compound in which the fundamental corpuscles of the component parts remain unchanged, but the chemical properties are altered and transformed because of the structural change that brings about the re-​synthesis. [Boyle’s] explanation of the experiment was not grounded on the primary and mechanical affections of particles. His interpretation of the “redintegration” of nitre was based on the consideration that nitre was a compound body and that the parts into which it was analyzed were not “volatile and fixed parts of that concrete” but two distinct substances of different nature, which are obtained from nitre by altering its texture. From this alteration, it follows that corpuscles of spirit of nitre and those of fixed nitre “are enabled to disband from concrete and associate themselves with those of their own nature.”59

For the sake of accuracy, it is important to note that Boyle’s account of the analysis and redintegration of saltpeter does not correctly render what actually occurs in the experiment. The reason for this error is that Boyle was neither aware of the contributions made by the coal and the water to the reactions nor was he aware that these contributions account for the differences in properties between

58 Boyle, Certain Physiological Essays, in The Works of Robert Boyle, 105. 59 Clericuzio, Elements, Principles, and Corpuscles, 140.

Chemical Philosophy vs. Rationalistic Mechanicism  65 saltpeter and those of fixed niter and spirit of niter. To better understand the actual chemical process involved, the experiment can be illustrated as follows, with the relevant substances in the analysis and synthesis indicated in bold: 1) Analysis of potassium nitrate: 4KNO3 + 3C → CO2↑ + 2NO2↑ + N2↑ + 2K2CO3 (K2CO3 — ​alkaline and fixed)

2) Reaction with water: 2NO2 + H2O → HNO3 + HNO2 (HNO3 —​acidic and volatile)

3) Redintegration (or re-​synthesis) of potassium nitrate: K2CO3 + 2HNO3 → 2KNO3 + H2O + CO2↑

In step one of the analysis (4KNO3 + 3C → CO2↑ + 2NO2↑ + N2↑ + 2K2CO3), coal contributes carbon to form fixed niter or potassium carbonate, which is strongly alkaline due to its carbonate ion. In step two of the analysis (2NO2 + H2O → HNO3 + HNO2), water contributes hydrogen to form spirit of niter or nitric acid, which is strongly corrosive. In the process of re-​synthesis or redintegration (K2CO3 + 2HNO3 → 2KNO3 + H2O + CO2↑), the potassium and oxygen combine with the nitrogen of spirit of niter to form potassium nitrate once again, while the remaining oxygen combines with hydrogen to yield water and with carbon to yield carbon dioxide, which is released into the air. However, because he is unaware of the actual chemical reactions in this experiment, Boyle does not attribute the alkalinity of the fixed niter to the carbonate ion contributed by the coal and the acidity of the spirit of niter to the hydrogen contributed by the water. Instead, Boyle mistakenly attributes the changes in properties to changes in the textures of the corpuscular concretions and uses this experiment to support his structural corpuscularian theory of chemical substances, which will be discussed in detail in Chapter 3. Nevertheless, notwithstanding the errors in Boyle’s interpretation of the reactions, what makes his interpretation philosophically interesting is that, despite his commitment to the mechanical philosophy, Boyle does not invoke the mechanical affections of fundamental particles but appeals, instead, to the chemical properties of the substances involved in the experiment. Bernard Joly makes an important point that bears repeating: for Boyle, although mechanical explanations sustain the chemical explanations, the latter remain autonomous

66  The Chemical Philosophy of Robert Boyle and cannot be replaced or clarified by the former.60 The reasons for this will become clear once Boyle’s complex corpuscularian theory of matter is discussed in the next chapter. As mentioned earlier, Boyle’s interpretation of this experiment is at the center of a series of epistolary exchanges with Spinoza, via Henry Oldenburg’s mediation. Spinoza specifically rejects Boyle’s argument that the analysis of the saltpeter is a decomposition of a chemical compound into two different substances with distinctive chemical properties. Spinoza also rejects the claim that the re-​ composition of the two separate substances alters their texture and, thereby, their properties to transform them once again into saltpeter. Instead, Spinoza argues that the experiment is consistent with the Cartesian mechanistic view that differentiations among extended substances are always due to different quantities of motion and rest of the particles. Spinoza argues that the different properties of the fixed niter, the spirit of niter, and the potassium nitrate (or saltpeter) are due to a difference in the motion of the basic particles of universal matter, rather than to an essential difference in structure or texture as Boyle surmises. For Spinoza, the a priori approach to the theory of matter succeeds in uncovering the real nature of matter, and he does not believe that Boyle’s experiment either amplifies or improves on the Cartesian approach. As well, for Spinoza, the only criterion that accounts for the variety of material bodies and their properties is the quantifiability of the mechanical properties of fundamental particles.61 In his correspondence with Oldenburg, Spinoza declares that “Boyle infers from his experiment concerning the reconstitution of Niter that Niter [potassium nitrate] is something heterogeneous, consisting of fixed and volatile parts, whose nature (so far as the Phenomena are concerned, at least) is nonetheless very different from the nature of the parts of which it is composed, though it arises solely from the mixture of these parts.”62 Spinoza, however, rejects the view that a whole compound could possibly display novel or distinct properties from those of its parts, and this is one reason for his rejection of Boyle’s explanation. Spinoza proposes a different interpretation of the experiment that he himself reproduces several times. He tells Oldenburg that “in order [. . .] to explain 60 Joly, “Chimie et mécanisme dans la nouvelle Académie royale des sciences:  les débats entre Louis Lémery et Etienne-​François Geoffroy,” 4: “Boyle expose la suite des opérations par lesquelles il divise le salpêtre en esprit acide et sel alcali puis le recompose à partir des deux substances que la distillation avait permis de séparer, la réversibilité des opérations constituant la preuve que la composition du salpêtre, alors considéré comme une substance hétérogène, est bien connue. Or, pour rendre compte de ces opérations, Boyle n’invoque pas tant le mouvement et la forme des corpuscules que les qualités chimiques des diverses substances qui ont la propriété de dissoudre, de précipiter ou de fixer. Bref, pour Boyle, l’explication chimique garde son autonomie et ne peut être réduite à une explication mécanique qui sans doute la sous-​tend mais ne peut jamais être explicitée en tant que telle [emphasis mine].” 61 See Gabey, “Spinoza’s Natural Science and Methodology,” 177–​179. 62 Spinoza, The Collected Works of Spinoza, 173–​174.

Chemical Philosophy vs. Rationalistic Mechanicism  67 this phenomenon in the simplest possible way, I will suppose no other distinction between spirit of nitre and nitre itself than that which is sufficiently manifest: namely, that the particles of the latter are in a state of rest, while those of the former are swiftly moved with respect to one another.”63 Spinoza concludes that the spirit of niter is simply the volatile state of pure, crystallized saltpeter and he dismisses the fixed niter as an impurity that was mixed in with the original sample of potassium nitrate. Thus, the only difference between saltpeter and spirit of niter is a difference in the motion of their basic particles, whose basic shapes are the same, rather than to a structural difference in the texture of corpuscular concretions. The Boyle-​Spinoza debate regarding the redintegration of potassium nitrate is a concrete example of the fundamental disagreement over the role of experiment in adjudicating between different explanatory models. Although Boyle’s interpretation of the experimental results is no less theory-​driven than Spinoza’s, Boyle considers these results to serve the heuristic purpose of settling the question in favor of corpuscularianism over the theory of substantial form. For Boyle, the experiment clearly demonstrates that hylomorphism is mistaken because, if the substantial form of saltpeter were destroyed in the analysis, its redintegration would not have been possible. Although Spinoza agrees with Boyle’s rejection of hylomorphism, he rejects Boyle’s chemical account of the reactions and insists on imposing an a priori explanatory framework upon the experimental results. Thus, Spinoza’s interpretation of the experiment is not only theory-​driven, but it is driven by an a priori framework that nullifies the role of experiment in adjudicating between competing explanatory models. Mechanistic theoreticians such as Spinoza do not completely reject the role of experiment in establishing a theory of matter. However, Spinoza is intent on upholding the primacy of rational intuition over sensory evidence by forcing an a priori mechanistic explanation of experimental results that might otherwise suggest a different understanding of the nature of matter and its properties. Therefore, he does not consider a priori hypotheses regarding the nature of fundamental matter to be refutable by experimental evidence. In fact, he claims that experiment “cannot uncover the nature of things: sensory knowledge belongs to the imagination, the knowledge of essences and causes to the intellect alone.”64 In order to experimentally disprove a conclusion that is dictated by rational intuition, one would have to establish its logical impossibility, which is something that no experiment can do. For Spinoza, while experimental results that are consistent with an a priori theory can be taken to confirm the theory, results that are incompatible with a rationally determined theory cannot weight against that

63 Oldenburg, The Correspondence of Henry Oldenburg, 449–​459. 64

Gabey, “Spinoza’s Natural Science and Methodology,” 177–​179.

68  The Chemical Philosophy of Robert Boyle theory. Thus, since Boyle’s experiment does not establish the logical impossibility of the Spinozist account, then there is no reason to interpret this experiment in any other way than in the fashion proposed by Spinoza. Although Spinoza’s position may seem eccentric, “alleged experimental confirmations of mechanical hypotheses were far from being as conclusive as the theoreticians and experimentalists of the mechanical philosophy pretended.”65 As Thomas Kuhn points out, and as was discussed earlier in this chapter, the same mechanistic philosophy that helped Boyle to argue against the theory of substantial form “proved a sterile and occasionally adverse intellectual climate for an understanding of the processes underlying chemical change.”66 An experimental chemist such as Boyle certainly used the mechanical philosophy to buttress his understanding of the fundamental nature of matter, but he was not interested in subordinating chemical explanations to mechanistic ones. By its very nature, the chemical approach was pragmatic, realistic, and eclectic. Most chemists worked on real matter and real properties in a purposeful way [. . .] They simply could not afford to rely too closely on a rigid theory [. . .] Hence, it was not the mechanical philosophy that was to succeed in chemistry, but a noncommittal, substance-​oriented notion of the corpuscle as something closer to an elementary particle or a small amount of substance, corresponding to something real in the chemists’ vessels and furnaces and endowed with sensible properties.67

As a chemist, Boyle was strongly committed to explaining chemical phenomena in a manner that accounted for the qualitative changes that occur in chemical processes. He was, therefore, not satisfied with simply explaining all chemical reactions and transformations by appealing to the motions and other mechanical affections of fundamental particles. Boyle clearly understood that strict mechanicism held negative implications for considering chemistry as a systematic natural philosophy independent of mechanics or, to use more contemporary terminology, for considering chemistry as an autonomous science with its own distinctive explanations. He did not favor the kind of mechanistic interpretation of all phenomena that was advocated by Descartes in the Principles of Philosophy precisely because such an interpretation comes at the price of being unable to predict novel chemical properties of bodies. In fact, it is not surprising that “the most ardent defenders of Cartesian mechanism, at the end of the 17th and the beginning of the 18th centuries were [. . .] virulent adversaries

65

Ibid., 180. Kuhn, “Robert Boyle and Structural Chemistry,” 15 67 Meinel, “Early Seventeenth-​Century Atomism,” 101. 66

Chemical Philosophy vs. Rationalistic Mechanicism  69 of chemistry,”68 precisely because they understood that the requirement for ultimately mechanistic explanations leaves little room for any heuristically independent science other than physics.

2.5  Boyle’s Relation to the Cartesian Project in Natural Philosophy Despite Boyle’s resistance to the project advocated in Descartes’ Principles of Philosophy, many early modern scholars considered Boyle to be an advocate not only of the mechanical philosophy but of the very strict type of mechanistic explanation favored by Cartesians. According to Joly, this attribution can be traced at least as far back as Fontenelle who, in his History of the Royal Academy of Sciences (Histoire de l’Académie Royale des Sciences) of 1733, not only identifies corpuscularianism with Cartesian mechanicism but also attributes these undifferentiated positions to Boyle.69 Joly explains that, after having opposed the “spirit of chemistry” to the “spirit of physics,” “Fontenelle, in a manner that may seem rather abusive, effects a double operation. First, he identifies corpuscularianism with Cartesian mechanism, in other words, with the idea that the explanation of all natural phenomena must be ‘reduced’ to the invocation of mechanical relations among ‘small particles’; there are, therefore, only two variables: the configuration of these small particles (their size and shape) and their motion. Secondly, [Fontenelle] attributes this position to Boyle.”70 Gabriel François Venel and several other 18th-​century chemists went so far as to regard Boyle as more of a physicist than a chemist, precisely because of his association with what they called “the corpuscular-​mechanical philosophy.” In his article titled Chymistry or Chemistry, written for Diderot and d’Alembert’s Encyclopédie, Venel says of Boyle that he “is ordinarily counted among the chemists, and he has indeed written much on chemistry. However, he is too much of a corpuscularian-​mechanistic physicist or, strictly speaking, a physicist, so that we have contrasted him with the chemist at the beginning of this 68 Joly, “Le cartésianisme de Boyle du point de vue de la chimie,” 55:  “Une fois ses opérations expliquées, la chimie disparaît pour laisser la place à une science mécaniste qui se reconnaît sous le nom de physique. On ne s’étonnera pas, dans ces conditions, que les plus ardents défenseurs du mécanisme cartésien, à la fin du XVIIe et au début du XVIIIe siècle aient été [. . .] de farouches adversaires de la chimie.” 69 Joly, “Chimie et mécanisme dans la nouvelle Académie royale des sciences:  les débats entre Louis Lémery et Etienne-​François Geoffroy,” 3. 70 Ibid.: “Fontenelle effectue, d’une manière qui peut sembler abusive, une double opération. D’une part il identifie le corpuscularianisme au mécanisme cartésien, c’est-​à-​dire à l’idée selon laquelle l’explication de tous les phénomènes naturels doit se ‘réduire’ à l’invocation de relations mécaniques entre les ‘petits corps’; il n’y a donc que deux variables: la configuration de ces petits corps (leur taille et leur figure) et leur mouvement. D’autre part [Fontenelle] fait de cette position celle de Boyle.”

70  The Chemical Philosophy of Robert Boyle article.”71 Several of Boyle’s works do indeed contain very clear statements in favor of mechanicism, especially The Excellency and Grounds of the Corpuscular or Mechanical Philosophy, the title of which clearly conflates the notion of corpuscularianism with that of mechanicism as though these notions implied each other.72 However, as Chapter  1 extensively argued, not only does corpuscularianism not entail mechanicism but, especially in the 16th and 17th centuries, corpuscularian theories of matter were often accommodated within vitalistic ontologies. Thus, “the acceptance of a particulate theory of matter very rarely involved the idea that all natural phenomena could be accounted for by means of particles endowed only with mechanical properties.”73 Despite Boyle’s unfortunate conflation of corpuscularianism with mechanicism in the title Of The Excellency and Grounds of the Corpuscular or Mechanical Hypothesis, the evidence shows that he does not embrace the strictly Cartesian mechanicism attributed to him by Fontenelle, Venel, and some contemporary scholars and that his corpuscularianism was instead influenced by the work of Helmont, Sennert, and other vitalistic corpuscularians. As argued in this and in the following chapters, Boyle’s complex chemical ontology clearly resists any simplistically mechanistic interpretation and more recent scholarship rejects traditional readings of Boyle, supporting instead the kind of non-​reductionist interpretation of his chemical philosophy that I am defending in this book.74 Boyle does affirm the mechanical philosophy and accepts that the mechanistic properties of corpuscular concretions serve as the general causes of natural phenomena. However, this does imply for him that one must invoke such causes to explain the behavior and structure of different chemical bodies, and he finds fault with the “Epicureans and Cartesians” who attempt to establish a direct

71 Venel, Chymie ou Chimie, 299: “[Boyle] est ordinairement compté parmi les chimistes; & il a effectivement beaucoup écrit sur la chimie. Mais il est trop exactement physicien corpusculaire-​ mécanicien, ou physicien proprement dit, tel que nous l’avons mis en contraste avec le chimiste au commencement de cet article.” 72 Several other authors have argued against the conflation of corpuscularianism and mechanicism, and further argument on this topic extends beyond the scope of this chapter. For a more detailed, although not exhaustive, discussion of this topic, I refer the reader to: Rattansi, Alchemy and Chemistry in the 16th and 17th Centuries; Clericuzio, “A Redefinition of Boyle’s Chemistry and Corpuscular Philosophy” and Elements, Principles, and Corpuscles; Pagel, Joan Baptista van Helmont: Reformer of Science and Medicine; Debus, The Chemical Philosophy: Paracelsian Science and Medicine in the Sixteenth and Seventeenth Centuries. 73 Clericuzio, “A Redefinition of Boyle’s Chemistry and Corpuscular Philosophy,” 563–​564. 74 See, for example:  Principe, “Newly Discovered Boyle Documents in the Royal Society Archive” and The Aspiring Adept; Clericuzio, “A Redefinition of Boyle’s Chemistry and Corpuscular Philosophy” and Elements, Principles, and Corpuscles; Anstey, The Philosophy of Robert Boyle, “Boyle on Seminal Principles,” and “Robert Boyle and the Heuristic Value of Mechanism”; Chalmers, “The Lack of Excellency of Boyle’s Mechanical Philosophy,” “Boyle and the Origins of Modern Chemistry,” and The Scientist’s Atom and the Philosopher’s Stone; and Newman, “The Significance of ‘Chymical Atomism’,” “The Alchemical Sources of Robert Boyle’s Corpuscular Philosophy,” and Alchemy Tried in the Fire.

Chemical Philosophy vs. Rationalistic Mechanicism  71 connection between all observed phenomena and the mechanical affections of corpuscles.75 In An Essay on Various Degrees or Kinds of the Knowledge of Natural Things, Boyle states that Epicureans and Cartesians “are so charm’d with ye clearness & pleasure of Theorys & explications, yt are deriv’d immediately from metaphysical and mathematical notions & theorems; yet they oftentimes give forced and unnatural accounts of things, rather than not to be thought to have deriv’d them immediately from these highest principles. And, wch is much worse, they despise & perhaps too condemn or censure all yt knowledge of the works of nature yt Physicians, Chymists & others pretend to, because they cannot be clearly deduc’d from the Atoms, or ye Catholic Laws of motion.”76 In fact, Boyle embraces many of the ideas that informed the natural philosophies of his vitalistic predecessors, albeit interpreted in chemical terms and stripped of their explicitly vitalistic content. Thus, “although Boyle often repeated that the mechanical properties of corpuscles were to be regarded as the most general notions of natural philosophy, a closer analysis of his natural philosophy reveals a number of agents not operating according to the principles of the mechanical philosophy. These agents are seminal principles, spirits, and ferments—​ which Boyle conceived as corpuscles endowed with the power of fashioning other parts of matter [. . .] Boyle’s conclusions are explicitly anti-​reductionistic.”77 In his chemical explanations, Boyle does not appeal to any of the properties of fundamental matter precisely because the limits of chemical analysis do not permit the isolation of the most elementary corpuscles. Instead, he intends to use analytical methods to identify homogeneous chemical substances constituted by combinations of aggregate corpuscles.78 Boyle’s rejection of strictly mechanistic explanations of chemical phenomena contributed importantly to the 17th-​century debate over the status of chemistry that raged on among many natural and speculative philosophers. Boyle’s insistence on developing chemical, rather than strictly mechanical, explanations of his experimental work played a significant role in the recognition of chemistry as a science proper, independent 75 Joly, 2: “Certes, Boyle affirme que les effets que nous observons dans la nature résultent des diverses tailles, formes, mouvements et concrétions d’atomes. Ce sont là les causes générales de toutes les choses. Mais il n’en résulte pas qu’il soit possible de rendre compte de tel ou tel phénomène en invoquant la figure, la taille et le mouvement des corpuscules dont la concrétion constitue la structure des différent corps chimiques. Boyle s’en prend alors explicitement aux ‘Épicuriens et Cartésiens’ qui prétendent établir un lien direct entre les phénomènes observés et les propriétés mécaniques des atomes” 76 Boyle, An Essay of Various Degrees or Kinds of the Knowledge of Natural Things, in Royal Society Boyle Papers, Vol. 8, folio 166r. 77 Clericuzio, Elements, Principles, and Corpuscles, 103–​109. 78 Bernard Joly, “Le cartésianisme de Boyle du point de vue de la chimie,” 152: “Boyle ne prétend pas descendre jusqu’à ce niveau ultime de la structure de la matière, puisque l’analyse chimique n’isole pas réellement les corpuscules élémentaires dont l’existence est affirmée. Boyle entend plutôt s’arrêter au niveau des agrégats de corpuscules composés selon diverses combinaisons, qui sont en quelque sorte de véritables substances chimiques homogènes.”

72  The Chemical Philosophy of Robert Boyle from physics. “The specificity of chemical objects, of the operations that involve them, and of the science that studies them is thus preserved. Thus, unlike what is concluded by Descartes, mechanistic explanation does not substitute chemical explanation.”79 Yet, Boyle’s rejection of strictly mechanistic explanations is not intended as an attack against the mechanistic hypothesis. In fact, quite the opposite is true. As Joly emphasizes, mechanical explanations sustain chemical explanations “and guarantee their coherence, while at the same time preserving a certain autonomy for chemistry since both levels of explanation are maintained.”80 Therefore, Boyle hoped both to reconcile chemistry with ontological mechanicism and, through experimental means, to provide support for mechanistic corpuscularianism. In the preface of A Physico-​Chymical Essay, he explicitly expresses the hope that his experimental work may conduce to the Advancement of Natural Philosophy, if, as I  said, I  be so happy as, by any endeavours of mine, to possess both Chymists and Corpuscularians of the advantages that may redound to each Party by the Confederacy I am mediating between them, and excite them both to enquire more into one anothers Philosophy, by manifesting, that as many Chymical Experiments may be happily explicated by Corpuscularian Notions, so many of the Corpuscularian Notions may be commodiously either illustrated or confirmed by Chymical Experiments.81

Interestingly, Boyle’s conception of spirit and ferment is clearly influenced by the work of Basso, Sennert, and Helmont. As Clericuzio points out, a transformation of the notion of spirit by 17th-​century English chemical physiologists permitted them to view vitality as resulting from the chemical activity of substances rather than arising from a homogeneous spirit or soul, regarded as an immaterial substance.82 Boyle’s theory on the general nature and classification of spirits was, in part, developed during his studies of the spirit of blood. In Memoirs for the History of Blood, he “recorded that from the distillation of blood he had obtained, besides oily and phlegmatic parts, a clear liquor which, though probably it contained some phlegm, might be called spirit, because ‘it is fully satiated with saline and spirituous parts’ [. . .] Boyle’s researches on the

79 Ibid.: “La spécificité des objets chimiques, des opérations qui les concernent et de la science qui s’en occupe se trouve ainsi préservée. De ce fait, à la différence de ce qui se produit chez Descartes, l’explication mécaniste ne vient pas se substituer à l’explication chimique.” 80 Ibid., 152–​153: “elle la maintient et en garantit la cohérence, conservant ainsi à la chimie une certaine autonomie puisque les deux niveaux d’explication sont maintenus.” 81 Boyle, Certain Physiological Essays, 92. 82 See: Antonio Clericuzio, The Internal Laboratory.

Chemical Philosophy vs. Rationalistic Mechanicism  73 spirit of blood [. . .] brought about the abandonment of the belief that spirit as such—​a homogeneous and vaguely defined [non-​physical] substance—​had to be regarded as the origin of vital spirit.”83 What I will argue in the next section is that Boyle’s position on these matters is not inconsistent with his ultimate ontological commitment to the mechanical philosophy. Rather, his resistance to strict explanatory reductionism can best be explained by examining more closely the two distinct functions of the mechanical philosophy in Boyle’s scientific research programme.

2.6  The Negative and Positive Heuristic Functions of the Mechanical Philosophy in Boyle’s Scientific Research Programme In spite of the fact that Boyle’s approach to chemical explanation does not rely on primary causes at the level of fundamental particles and appeals instead to higher-​level chemical properties, his commitment to the mechanical philosophy remains an important constant in all of Boyle’s work. I argue in this section that the reason for this commitment is that the mechanical philosophy fulfills two distinct functions for Boyle, and I thus hope to resolve the apparent tension between his ontological commitment to mechanistic corpuscularianism and his resistance to mechanistically reductive explanations. In order to develop my argument, I will examine Boyle’s commitment to the mechanical philosophy from the perspective of Imre Lakatos’s distinction between the positive and negative heuristics of scientific research programmes.84 For Lakatos, a scientific research programme is constituted neither by pure theory alone nor by empirical research divorced from theory. Rather, scientific research programmes involve both components, a theoretical “hard core” and an experimental “protective belt.” The “hard core” is constituted by theories that are deemed irrefutable by methodological fiat, while the “protective belt” is constituted by auxiliary hypotheses that can be either confirmed or falsified by experimental observations, and each of these components fulfills a different function. The hard core of theoretical hypotheses grounds the research programme and defines what Lakatos calls the “negative heuristic” of the programme. The negative heuristic is a limiting principle that forbids scientists from directing “the modus tollens [of falsification] at this ‘hard core’.”85 Lakatos’s classic example of a 83 Ibid., 64. 84 Lakatos, “Falsification and the Methodology of Scientific Research Programmes”; Lakatos, The Methodology of Scientific Research Programmes; Lakatos, “Criticism and the Methodology of Scientific Research Programmes.” 85 Lakatos, “Falsification and the Methodology of Scientific Research Programmes,” 133.

74  The Chemical Philosophy of Robert Boyle “hard core” is Newton’s gravitational theory. “In Newton’s programme the negative heuristic bids us to divert the modus tollens from Newton’s three laws of dynamics and his law of gravitation. This ‘core’ is ‘irrefutable’ by the methodological decision of its protagonists: anomalies must lead to changes only in the ‘protective’ belt of auxiliary, ‘observational’ hypotheses and initial conditions.”86 On the other hand, the “protective belt” of the scientific research programme defines its positive heuristic, which “consists of a partially articulated set of suggestions or hints on how to change [and/​or] develop the ‘refutable variants’ of the research programme [and] how to modify [and/​or] sophisticate, the ‘refutable’ protective belt.”87 Lakatos explains that, in developing the protective belt, “we must use our ingenuity to articulate or even invent ‘auxiliary hypotheses,’ which form a protective belt around this core, and we must redirect the modus tollens to these. It is this protective belt of auxiliary hypotheses which has to bear the brunt of tests and get adjusted and re-​adjusted, or even completely replaced, to defend the thus-​hardened core.”88 For this reason, Lakatos maintains that the positive heuristic is “more flexible than the negative heuristic . . . Thus, the methodology of scientific research programmes accounts for the relative autonomy of theoretical science . . . Which problems scientists working in powerful research programmes rationally choose is determined by the positive heuristic of the programme.”89 Lakatos also discusses what he calls “metaphysical research programmes” and explains that the hard core of such research programmes is irrefutable because it is non-​empirical, while the auxiliary hypotheses of the protective belt are refutable, and it is towards these that experiments are directed. The “metaphysical” hard core of such research programmes forms the background to scientific theories and provides “the main guide for directing the scientists’ attention to certain problems rather than to others.”90 Thus, the negative heuristic of the “metaphysical” hard core serves as a limiting and directive principle. In a manner that is very relevant for our purposes here, Lakatos discusses Cartesian metaphysics as a classic example of a “metaphysical research programme.” He states that “Cartesian metaphysics, that is, the mechanistic theory of the universe—​ according to which the universe is a huge clockwork with push as the only cause of motion—​functions as a powerful heuristic principle: excluding, on the negative side, all scientific theories . . . which are inconsistent with it (negative heuristic) and implying, on the positive side, a ‘metaphysical’ research programme to



86 Ibid. 87

Ibid., 137. Ibid., 133. 89 Ibid., 137. 90 Lakatos, “Criticism and the Methodology of Scientific Research Programmes,” 178. 88

Chemical Philosophy vs. Rationalistic Mechanicism  75 look behind all phenomena (and theories) for explanations based on clockwork mechanisms (positive heuristic).”91 If one can conceive of Boyle’s natural philosophy and experimental work as a scientific research programme in the Lakatosian sense, then one can argue that the mechanical philosophy fulfills important functions both as a negative and as a positive heuristic. I believe that Lakatos’s comments on Cartesian metaphysics cited here provide us with a useful guide to help us unpack these ideas. When the mechanical philosophy is considered as the theoretical grounding of Boyle’s research programme, it functions as its irrefutable “metaphysical” hard core. It is a deep philosophical theory about the nature of matter that can be neither confirmed nor falsified by experiment precisely because it is non-​empirical. This is what is defended in Boyle’s theoretical writings as an alternative to the theory of substantial forms and to the spagyric principles. The term “mechanical,” when used in this context, is used in the stricter ontological sense and refers to mechanistic corpuscularianism. Following Lakatos’s remarks about the relation between the hard core and the protective belt, one can say that the “metaphysical” hard core of mechanistic corpuscularianism is relatively autonomous from Boyle’s experimental work in the sense that it neither stands nor falls on the basis of specific experimental discoveries. As the “metaphysical” hard core of Boyle’s research programme, the mechanical philosophy functions as a negative heuristic or as a limiting principle that excludes or forbids any explanations that are inconsistent or incompatible with it. Borrowing from the vocabulary of apophatic theology, Andrew Pyle considers this sense of the mechanical philosophy as a via negativa that “can be construed as the fourfold denial of (1) action at a distance, (2) spontaneity, (3) immanent or irreducible teleology, and (4) incorporeal causes.”92 Thus, according to the mechanical philosophy’s negative heuristic, a necessary condition

91 Ibid., 168. 92 Pyle, “Boyle on Science and the Mechanical Philosophy,” 181. Although recent scholarship would seem to contradict Pyle’s claim regarding the mechanical philosophy’s rejection of teleology, it is important to emphasize that Pyle is specifically referring to the rejection of immanent teleology, as distinguished from extrinsic teleology. Immanent teleology locates final causes within nature itself, so that final causes are intrinsic to natural phenomena. Extrinsic teleology, on the other hand, identifies the finality of nature with God’s purposes. What recent scholarship shows is that many adherents of the mechanical philosophy (including Boyle himself in his Disquisitions about the Final Causes of Natural Things of 1688) embraced extrinsic teleological explanations to counteract atheistic Epicureanism. But this in no way contradicts Pyle’s claim that the mechanical philosophy implied a denial of immanent teleology. For more on this topic, see Boyle, A Disquisition about the Final Causes of Natural Things; Lennox, “Robert Boyle’s Defense of Teleological Inference in Experimental Science”; Osler, “From Immanent Natures to Nature as Artifice,” “How Mechanical was the Mechanical Philosophy?,” and “Whose Ends?”; Carlin, “The Importance of Teleology to Boyle’s Natural Philosophy” and “Boyle’s Teleological Mechanism and the Myth of Immanent Teleology”; and Shanahan, “Teleological Reasoning in Boyle’s Disquisition about Final Causes.”

76  The Chemical Philosophy of Robert Boyle for an explanation to qualify as mechanical is that it must exclude all reference to substantial forms, sympathies and antipathies, vital forces, the anima mundi, or other immaterial causes. Boyle’s writings support this conception of the mechanical philosophy as a negative heuristic. In the Hydrostatical Discourse, he explains that, although he believes in the existence of an incorporeal God who created the world and the laws that govern it, what happens to inanimate bodies does not require appeal to immaterial agents and is strictly attributable to mechanical causes, even if these causes are not fully known or understood. Boyle then invokes Occam’s razor to support this claim by saying that “this, being agreeable to the generally own’d rule about Hypotheses, that Entia non sunt multiplicanda absque Necessitate, has been by almost all the modern Philosophers of different Sects thought a sufficient reason to reject the agency of Intelligences.”93 When used in his chemical writings, the mechanistic reference functions in the same way and “allows Boyle to reject the obscurities and the contradictions of traditional doctrines that were coming into question in his own time without thereby condemning chemistry to a reabsorption by physics.”94 One can argue that Boyle remains committed throughout his entire scientific career to the negative heuristic of mechanistic corpuscularianism, that is, to eschewing any explanatory principle that is incompatible with the mechanical philosophy, such as substantial forms, vital spirits, spagyric principles, action at a distance, and anima mundi. On the other hand, when considering Boyle’s research programme from the point of view of its protective belt of auxiliary empirical and refutable hypotheses regarding chemical, pneumatic, and hydrostatic phenomena, the mechanical philosophy takes on different connotations. To the extent that the positive heuristic concerns experimental work designed to test empirical hypotheses, the mechanical philosophy serves to provide a model for how all natural phenomena behave, that is, as clockwork mechanisms in which the various connected parts transmit motion to each other. Alan Chalmers points out that that the term “mechanical,” when used in Boyle’s experimental writings on hydrostatics and pneumatics, does not refer to mechanistic corpuscularianism but is used in the more common sense of this word, that is, as referring to the science of simple machines. He explains that “machines bring about their effects by virtue of the way in which pushes and pulls are transmitted through them via the connection of their parts. Boyle also made explicit the point that an understanding of machines involved taking properties such as weight and elasticity for granted,

93 Boyle, An Hydrostatical Discourse, in The Works of Robert Boyle, 159. 94 Joly, “Le cartésianisme de Boyle du point de vue de la chimie,” 154: “La référence mécaniste permet ainsi à Boyle de rejeter les obscurités et les contradictions des doctrines chimiques finissantes de son temps sans pour autant condamner la chimie à une résorption dans la physique.”

Chemical Philosophy vs. Rationalistic Mechanicism  77 without requiring that they be explained at some deeper, corpuscular or other, level.”95 It is interesting to see that Chalmers’s point here concurs with Lakatos’s claim that, in its positive heuristic, the mechanical philosophy provided the impetus “for explanations based on clockwork mechanisms.”96 It is also interesting to note that the negative and positive heuristics work hand in hand for, if physical phenomena are described as being analogous to clockwork mechanisms in which connected parts transmit motion to each other, then action at a distance is perforce rejected as an explanatory principle. In experimental writings such as An Hydrostatical Discourse, Of the Systematical or Cosmical Qualities of Things, the appendix to Final Causes, and the Workdiaries, “Boyle arrived at and utilised explanations that were innovative but which were not ultimate.”97 However, to the extent that the non-​mechanistic properties, subordinate causes, and cosmical qualities that Boyle invokes are subject to the laws of mechanics, these explanations abide by the negative heuristic of eschewing appeal to non-​material principles. Thus, although these explanations do not make explicit reference to mechanistic corpuscularianism, the limiting principle of the mechanical philosophy is built into them. Boyle’s conception of the mechanical philosophy is not one that requires replacing chemical discourse with mechanistic discourse and it is certainly not one that implies the subversion of chemistry as an autonomous science. In fact, Boyle believes that, by establishing the uselessness and lack of heuristic power of substantial forms and of the Paracelsian tria prima, the mechanical philosophy can actually serve to justify chemical practice and the explanatory appeal to chemical properties as causal agents, as well as the discovery of new homogeneous substances that enter into the composition of mixed bodies.98 As this book ultimately demonstrates, Boyle endorses a conception of chemical properties as emergent, dispositional, and relational and he takes this position to be perfectly compatible with his commitment to the mechanical philosophy. The following chapter establishes that his conception of chemical

95 Chalmers, One Hundred Years of Pressure, 111. 96 Lakatos, “Criticism and the Methodology of Scientific Research Programmes,” 168. 97 Chalmers, “The Lack of Excellency of Boyle’s Mechanical Philosophy,” 545. 98 Joly, “Le cartésianisme de Boyle du point de vue de la chimie,” 154–​155: “Il ne s’agit donc pas, comme chez Descartes, de remplacer le discours des chimistes par un discours mécaniste, mais au contraire de montrer que l’hypothèse mécaniste facilite le développement de la chimie en lui offrant de nouvelles perspectives: guidés par les principes du corpuscularianisme, les chimistes devraient pouvoir découvrir de nouvelles substances homogènes qui entrent dans la composition des corps mixtes [. . .] Alors que Descartes se livre à une réduction mécaniste de la chimie qui implique sa disparition en tant que telle et le rejet de sa tradition, Boyle veut au contraire la conserver, y compris dans sa dimension alchimique, en la justifiant par une philosophie mécaniste dont la fonction n’est pas de rendre compte par le menu détail des diverse propriétés des corps chimiques, mais de montrer l’inutilité des théories principielles traditionnelles, qui n’apportent finalement rien à la compréhension des opérations chimiques.”

78  The Chemical Philosophy of Robert Boyle properties is buttressed by a complex corpuscularian ontology that allows him to formulate autonomously chemical explanations in which structural differences account for chemical differences, chemical properties have causal power, and material bodies with different essential properties belong to different material species. Boyle’s complex ontology thus accommodates mechanicism, structural realism, and realism about natural kinds, while remaining committed to the mechanical philosophy as the best available alternative to Scholastic hylomorphism.

3

The Ontological Complexity of Boyle’s Corpuscularian Theory Microstructure, Natural Kinds, and Essential Form

One of Boyle’s principal heuristic reasons for preferring mechanistic particulate theories to the Scholastic theory of substantial form or to the Paracelsian notion of the tria prima is that neither of these theories could provide satisfactory explanations for chemical phenomena and processes. Thus, above all things, The Sceptical Chymist represents an extended critique of these two unsatisfactory theories. I propose first to review Boyle’s critique and then move on to a detailed account of his mechanistic corpuscularianism as an alternative to the notion of substantial form and to the spagyric theory of principles.

3.1  The Sceptical Chymist: Against Scholastics and Spagyrists By the mid-​17th century, it is evident to natural philosophers that most chemical reactions do not involve the active role of some form of salt, sulfur, or mercury. Eventually, therefore, the notion of the tria prima quickly loses credibility for early modern chemists such as Boyle. In the preface to The Sceptical Chymist, Boyle explains that “there are a thousand Phaenomena in Nature [. . .] which will scarcely be clearly & satisfactorily made out by them that confine themselves to deduce things from Salt, Sulphur and Mercury, and the other Notions peculiar to the Chymists, without taking much more Notice than they are wont to do, of the Motions and Figures, of the small Parts of Matter, and the other more Catholick and Fruitful affections of Bodies.”1 Boyle appeals to corpuscularian principles to argue against some of the fundamental assumptions of the Paracelsian doctrine of the tria prima or hypostatical principles. According to this doctrine, because salt, sulfur, and mercury are the principles of mixed bodies, these ingredients can always be extracted via analysis by fire. However, Boyle remarks that “it does not appear, that Three is precisely and Universally the Number of the Distinct

1 Boyle, The Sceptical Chymist, 208.

The Chemical Philosophy of Robert Boyle. Marina Paola Banchetti-Robino, Oxford University Press (2020). © Oxford University Press. DOI: 10.1093/oso/9780197502501.001.0001

80  The Chemical Philosophy of Robert Boyle Substances or Elements, whereinto mixt Bodies are resoluble by Fire; I mean that ’tis not prov’d by Chymists, that all the Compound Bodies, which are granted to be perfectly mixt, are upon their Chymical Analysis divisible each of them into just Three Distinct Substances, neither more nor less, which are wont to be lookt upon as Elementary.”2 After noting this, Boyle presents two arguments against the hypostatical principles, the first of which is speculative and relies upon the corpuscularian principles, while the second is “drawn from Experience,” to use Boyle’s own words. In the first argument, Boyle posits that those substances that are considered elements by the spagyrists may themselves be composed of numerous coalitions of minute particles. “It will not be absurd to conceive, that such primary Clusters may be of far more sorts than three or five; and consequently, that we need not suppose, that in each of the compound Bodies we are treating of there should be found just three sorts of such primitive Coalitions.”3 This argument is a priori and depends upon assuming the truth of corpuscularianism. As such, it presupposes that corpuscles are elementary and that salt, mercury, and sulfur are themselves coalitions of elementary particles. If so, it is reasonable to suppose that there may be more than merely three of such coalitions for, if we grant that the so-​called tria prima or hypostatical principles are not elementary, then we have no reason to believe that all compound bodies should be reducible to one of these three substances. Boyle is saying that, in fact, salt, mercury, and sulfur are not principles. However, because this is an a priori argument that depends upon assuming the truth of corpuscularianism, Boyle’s argument will only be acceptable to those who embrace this same assumption. The argument itself does nothing to establish the truth of corpuscularianism over that of the tria prima hypothesis. Boyle seems aware of this weakness and refrains from presenting this argument as being conclusive in favor of corpuscularianism. Instead, he limits himself to claiming that it is at least plausible to conceive that the spagyric elements may be reducible to more fundamental particles. Boyle’s second argument, on the other hand, attempts to use empirical evidence to establish that the tria prima are not elementary principles. Here, Boyle relies on several experiments in which he purports to have established, by way of analysis, that many bodies “in their Resolution Exhibite more principles than three.”4 From these considerations, he concludes that



2

Ibid., 278. Ibid., 279. 4 Ibid., 284. 3

Boyle’s Corpuscular Theory  81 the Ternary Number is not that of the Universal and Adequate Principles of Bodies. If you allow of the Discourse I lately made You, touching the primary Associations of the small Particles of matter, You will scarce think it improbable, that of such Elementary Corpuscles there may be more sorts than either three, or four, or five [. . .] confining our selves to such wayes of Analyzing mix’d Bodies [. . .] it may without Absurdity be Question’d, whether besides those grosser Elements of Bodies, which they call Salt Sulphur and Mercury, there may not be Ingredients of a more Subtile Nature, which being extreamly little, and not being themselves Visible, may escape unheeded at the Junctures of the Destillatory Vessels.5

Given these considerations, Boyle places the burden of proof on those chymists who embrace the Paracelsian theory of the tria prima and adds that they have failed to meet this burden of proof because they have not provided credible support for the existence of the hypostatic principles. First, regarding any of the purportedly empirical evidence provided by spagyrists, Boyle argues that experiments “wont to be brought, whether by the common Peripateticks, or by the vulgar Chymists, to demonstrate that all mixt bodies are made up precisely either of the four Elements, or the three hypostatical Principles, do not evince what they are alleg’d to prove.”6 He adds that if what those patriarchs of the Spagyrists, Paracelsus and Helmont, do on divers occasions positively deliver, be true; namely that the Alkahest does Resolve all mixt Bodies into other Principles than the fire, it must be decided which of the two resolutions (that made by the Alkahest, or that made by the fire) shall determine the number of the Elements, before we can be certain how many there are . . . although we should acquiesce in that resolution which is made by fire, we find not that all mixt bodies are thereby divided into the same number of Elements and Principles; some Concretes affording more of them than others do; Nay and sometimes this or that Body affording a greater number of Differing substances by one way of management, than the same yields by another . . . Nor does it appear more congruous to that variety that so much conduceth to the perfection of the Universe, that all elemented bodies be compounded of the same number of Elements, then [sic] it would be for a language, that all its words should consist of the same number of Letters.7



5

Ibid., 284–​285. Ibid., 342–​343. 7 Ibid., 343. 6

82  The Chemical Philosophy of Robert Boyle Boyle also rejects the a priori arguments in favor of spagyrist theories by saying that these arguments, which pretend to be drawn from Reason [. . .] are Commonly grounded upon such unreasonable or precarious Suppositions, that ’tis altogether as easie and as just for any man to reject them, as for those that take them for granted to assert them, being indeed all of them as indemonstrable as the conclusion to be inferr’d from them; and some of them so manifestly weak and prooflesse; that he must be a very courteous adversary that can be willing to grant them; and as unskilful a one that can be compelled to do so.8

Satisfied that he has thus dispatched the tria prima hypothesis, Boyle turns his critical attention to the theory of substantial forms. Boyle attacks the theory of substantial forms while critiquing what he considers to be a flawed conception of chemical qualities in the theories of chymists and alchemists such as William Sennert and other Paracelsians. In Of the Imperfection of the Chemists’ Doctrine of the Qualities, Boyle states that one of the main suppositions of these chemists is that this or that quality must have its πρϖτον δεκτικόν9—​as Sennertus, the learnedest champion of this opinion, calls it—​or some particular material principle, to the participation of which, as of the primary, native and genuine subject, all other bodies must owe it [. . .] I think it will be hard to show what is the πρϖτον δεκτικόν of gravity, volatility, heat, sonorousness, transparency, and opacity, which are qualities to be indifferently met with in bodies whether simple or mixed.10

To understand the role of the πρϖτον δεκτικόν within the theory of substantial forms, it is important to recall from Chapter 1 that Sennert had attempted to resolve the problems with the Scholastic theory of substantial forms by adopting corpuscularianism and by attributing such forms to the fundamental particles of substances, rather than to the substances themselves, thereby allowing for the possibility of both analysis and synthesis. However, in spite of Sennert’s persistent efforts to save the theory of substantial forms by rendering it compatible with corpuscularianism, this theory had run its course by the mid-​17th century and needed to be replaced with less problematic and more informative explanations for chemical and other physical processes and phenomena.



8 Ibid. 9

proton dektikon or “prime matter.”

10 Boyle, Of the Imperfection of the Chemists’ Doctrine of Qualities, 121–​123.

Boyle’s Corpuscular Theory  83 For Boyle, substantial form could not provide adequate explanations for the chemical transformations that occurred via analysis and synthesis, in part because such explanations either did not explain anything or explained things in a circular fashion. I elaborate further. If one simply claims that analysis destroys the form of a substance while synthesis restores it, then this by itself is not enough to tell us what this form is. On the other hand, if one claims that substantial form is something non-​physical that disappears during analysis and then reappears during synthesis, then this does not explain how a chemical procedure can causally affect a non-​material “form.” Lastly, if by “substantial form” one simply refers to the substance itself, then the explanation for what happens during analysis and synthesis is rendered circular. That is, the substance has been altered because the substance has been altered. Any of these options leaves us epistemically unsatisfied. To be fair, there is another and more interesting way of understanding substantial form that can serve as a precursor to Boyle’s structural conception. That is, substantial form can be understood as referring to the inner structure that gives a substance its essential properties. Of course, if one were to opt for this interpretation of substantial form, then one would still have to explain what this inner structure is. This, however, is clearly not what the Scholastics meant by “form.” It is also not what Sennert meant by “form” since he took “substantial form” and microstructure to be two different things, the former being the immaterial and inherent essence of distinctive corpuscles and the latter being the spatial arrangement of these to form specific material bodies. Boyle, however, latches on to the conception of form as inner structure and seeks to understand it in strictly material and corpuscularian terms, without any reference to the dubious notion of “substantial form” or any of its problematic connotations. Boyle believes that mechanistic corpuscularianism provides a more reasonable alternative to the theories of the tria prima and of substantial form and that this serves as a compelling reason for favoring it. However, an even more compelling reason for preferring mechanistic corpuscularianism is that it explains the phenomena of nature by appealing to entirely physical principles rather than to immaterial notions, although Boyle rejects the more extreme materialist tenets of ancient and modern atomism. In fact, in Of the Excellency and Grounds of the Corpuscular or Mechanical Hypothesis, he makes it clear that his intent is not to embrace all facets materialistic Epicurean atomism but [to] plead onely for such a Philosophy, as reaches but to things purely Corporeal, and distinguishes between the first original of things; and the subsequent course of Nature [. . .] the Phaenomena of the world [. . .] are Physically produc’d by the Mechanical affections of the parts of Matter, and what they operate upon one another according to Mechanical Laws. And now having shewn what kind

84  The Chemical Philosophy of Robert Boyle of Corpuscular Philosophy ’tis that I speak of I proceed to the particulars that I thought the most proper to recommend it.11

After explaining this, Boyle goes on to enumerate those aspects of corpuscularianism that, in his view, make it superior to competing hypotheses. The first aspect “is the Intelligibleness or Clearness of Mechanical Principles and Explications”12 in contrast to the unintelligibility of Peripatetic, Scholastic, and Spagyric notions such as archeus, tria prima, and so forth. Secondly, mechanical corpuscularian principles enjoy “great Comprehensiveness”13 in that they provide the foundation for explanations of all sorts of phenomena, whether these are physical, chemical, pneumatic, static, or hydrostatic in nature. He indicates that “the Mechanical Principles are so universal, and therefore applicable to so many things, they are rather fitted to include, than necessitated to exclude, any other Hypothesis that is founded on Nature, as far as it is so.”14 Thus, Boyle believes that mechanical corpuscularianism is compatible with any other explanatory hypothesis, once that hypothesis is equally naturalistic and physicalistic in its principles. This is an important point since, as we shall see both in this and in the following chapters, Boyle’s chemical ontology and his brand of mechanistic corpuscularianism are most compatible with an emergentist conception of chemical qualities.

3.2  Boyle’s Corpuscularian Theory of Matter As was discussed in detail in the previous chapter, there was considerable disagreement among speculative and natural philosophers regarding the role of chemistry in providing empirical support for the mechanical hypothesis. On the other hand, there was also considerable debate regarding whether the mechanical hypothesis could ever provide satisfactory explanations for chemical phenomena, for the causal efficacy of chemical properties, and for the stable nature of chemical substances. There is no doubt that Boyle remains firmly committed to the mechanical hypothesis as the soundest available alternative to the theory of substantial form and to the spagyrist theory of principles. But, he also believes that chemistry is able to provide empirical support for the mechanical hypothesis.



11 Boyle, Of the Excellency and Grounds of the Corpuscular or Mechanical Hypothesis, 105. 12

Ibid., 104. Ibid., 106. 14 Ibid., 109. 13

Boyle’s Corpuscular Theory  85 Peter Anstey has discussed in detail the three types of empirical arguments in favor of mechanical corpuscularianism that Boyle derived from his chemical experiments, and I rely here on his excellent discussion for my own exposition. First, Boyle uses the results from redintegration experiments, particularly from the redintegration of niter, to support the view that this chemical process is better explained in corpuscularian terms than by appealing to substantial forms. Second, he argues from the reduction to the pristine state, which I discuss later in this chapter, for the same conclusion. Third, he argues from the mechanical production and alteration of qualities for the superiority of the corpuscularian theory and, therefore, for the hypothesis itself.15 These ideas will be examined more closely in the following sections of this chapter. Suffice it to say at this point that the results of chemical experiments can, at the very least, provide empirical evidence against hylomorphism, thereby indirectly supporting the mechanical philosophy. However, to the extent that the Cartesian mechanistic hypothesis is unable to accommodate the notion of chemical properties or of stable chemical substances, the challenge for Boyle is to provide empirical chemical support for mechanistic corpuscularianism without sacrificing chemistry itself. To succeed in this task, Boyle revises the mechanical hypothesis to accommodate ontological realism about chemical properties and about their causal agency in nature. Thus, he develops a nuanced theory of matter that combines a mechanistic conception of fundamental particles with a realist ontology of chemical qualities, causes, and substances. Boyle’s clearest statement of his theory is found in The Origin of Forms and Qualities (1666). Here, he takes a position that mediates between those of Gassendi and Descartes. Although Boyle rejects classical Epicurean atomism, he does find certain aspects of Gassendian atomism to be especially compelling. One of the things that makes Gassendi’s revision of classical atomism attractive for Boyle is the insistence that nature should not be treated as an agent. Boyle agrees with Gassendi that nature as such is inanimate and devoid of purpose, volition, and sentience and that the only source of agency is God.16 Yet, against Gassendi and in agreement with Descartes, Boyle denies the presence of a God-​given internal energy or “motive virtue” within material corpuscles. He argues this point again in Of the Excellency and Grounds of the Corpuscular or Mechanical Hypothesis, in which he distances himself in this regard both from ancient atomists and from some modern atomists such as Gassendi by specifying that



15 16

Anstey, “Essences and Kinds,” 22. Shapin and Schaffer, Leviathan and the Air-​Pump, 202.

86  The Chemical Philosophy of Robert Boyle when I  speak of the Corpuscular or Mechanical Philosophy, I  am far from meaning with the Epicureans, that Atoms, meeting together by chance in an infinite Vacuum, are able of themselves to produce the World, and all its Phaenomena; nor with some Modern Philosophers, that, supposing god to have put into the whole Mass of Matter such an invariable quantity of Motion, he needed do no more to make the World, the material parts being able by their own unguided Motions, to case themselves into such a System (as we call by that name).17

Although he agrees with Descartes that all particles may be infinitely divisible by God, Boyle also believes that corpuscles are impenetrable and indivisible in nature and that they resist any attempt to penetrate or divide them by chemical means. Thus, for him, corpuscles are infinitely divisible in theory but are impenetrable and indestructible in practice. In his early manuscript Of the Atomicall Philosophy (1651–​1653), Boyle had already distanced himself from Cartesians by equating atoms with minima naturalia, although his conception of minima differs from that of the Scholastics by ruling out substantial form.18 In this work, Boyle states that “by Atoms the Assertors of them understand not indivisible Mathematical points [. . .] but minima naturalia [. . .] Because tho they may be further divided by Imagination yet they cannot by Nature.”19 Furthermore, and again disagreeing with Descartes, Boyle believes that matter conserves shape and size and cannot, therefore, be reduced to pure geometrical extension. Like visible bodies, insensible corpuscles have three essential mechanical affections: shape, size, and mobility. According to Boyle, although God did not endow corpuscles with internal “motive virtue,” God furnished corpuscles externally with various motions and directed their various movements and compositions to form the variety of inanimate and animate bodies that exist in nature. In The Origin of Forms and Qualities, Boyle describes in detail his complex theory of matter. Note that Boyle’s first point in the following list is a reiteration of what has already been said regarding minima naturalia, and it is also a statement of his agreement with Gassendi and disagreement with Descartes regarding the divisibility of fundamental particles. Boyle states: 1. That there are in the World a great store of Particles of Matter, each of which is too small to be, whilst single, Sensible: and being Entire, or Undivided, must needs both have its Determinate Shape, and be very Solid. Insomuch, that though it be mentally, and by Divine Omnipotence divisible, yet by

17 Boyle, Of the Excellency and Grounds of the Corpuscular or Mechanical Hypothesis, 104–​105. 18

See Clericuzio, Elements, Principles, and Corpuscles.

19 Boyle, Of the Atomicall Philosophy, 227.

Boyle’s Corpuscular Theory  87 reason of its Smallness, Nature doth scarce ever actually divide it; and these may in this sense be call’d Minima or Prima Naturalia. 2. That there are multitudes of Corpuscles, which are made up of the Coalition of several of the former Minima Naturalia; and whose Bulk is so small, and their Adhesion so close and strict, that each of these little Primitive Concretions or Clusters (if I may so call them) of Particles is singly below the discernment of Sense, and though not absolutely indivisible by Nature into the Prima Naturalia that compos’d it [. . .] they very rarely happen to be actually dissolv’d or broken, but remain entire in a great variety of sensible Bodies, and under forms and disguises.20 For Boyle, the mechanical philosophy is a superior hypothesis in part because it is a “bottom-​up” theory of organization in which minima occupy the lowest level and corpuscular concretions occupy progressively higher levels of complexity. Primary concretions represent a second order of complexity above fundamental mechanistic particles and form clusters of even higher degrees of complexity, such as that which occurs when different homogeneous substances are mixed together. As discussed later in this chapter, Boyle attributes the real constitution of a material body and its essential properties to the underlying corpuscular structure, in which the fundamental particles fit so closely together as to form stable chemical species that resist analysis, even by the most corrosive agents available. Microstructure creates stable entities that are of a higher order of complexity than the minima and that have non-​mechanical properties, in addition to the mechanical properties of fundamental particles. Some of these non-​mechanical properties are specifically chemical and have the power to affect other parts of matter in various ways. In some of his writings, Boyle describes chemical qualities by alluding to seminal powers, that is, to the power of generation and the power to “fashion other parts of matter.” Unlike the Scholastics, however, he regards seminal powers not as spiritual but as material and as originating from the specific structures of corpuscular concretions. Boyle’s notion of compounded corpuscles is influenced by Gassendi and, although he does not adopt the Gassendian term “molecule,” Boyle does avail himself of the concept that is attached to this term. Both in his early works and in his later writings, Boyle explains chemical reactions by means of the compounded corpuscles or corpuscular concretions that I  am here discussing, since he considers that chemical reactions take place at this higher level of corpuscular organization. Boyle refers to this first order of compounded corpuscles as the



20 Boyle, The Origin of Forms and Qualities, 325–​326.

88  The Chemical Philosophy of Robert Boyle “prima mixta,” but the prima mixta are themselves compounded to form higher and higher orders of complex particles. In The Sceptical Chymist, he explains that it does not at all appear, that all Mixtures must be of Elementary Bodies; but it seems farr more probable, that there are divers sorts of compound Bodies, even in regard of all or some of their Ingredients, consider’d Antecedently to their Mixture. For though some seem to be made up by the immediate Coalitions of the Elements, or Principles themselves, and therefore may be call’d Prima Mista or Mista Primaria, yet it seems that many other Bodies are mingl’d (if I  may so speak) at the second hand, their immediate Ingredients being not Elementary, but these primary Mixts newly spoken of; And from divers of these Secondary sort of Mixts may result, by a further Composition, a Third sort, and so onwards.21

Although the concept attached to the term “prima mixta” is the same as that attached to the term “molecule,” William Newman has suggested using the term “chymical atoms” in reference to the prima mixta. The term “chymical atom” is an appropriate name for these compounded corpuscles, more so than the term “molecule,” because the term emphasizes their operational atomicity. For Boyle, chymical atoms are not analyzable by any of the ordinary chemical means available in his time, such as nitric acid, hydrochloric acid, and fire. He, thus, considers them to be highly stable entities. To the extent that chymical atoms are stable, homogeneous regarding their essential properties, and operationally fundamental in that they cannot be further chemically analyzed, they can be legitimately considered as chemically “elementary” entities. In fact, “within the framework supplied by Boyle’s Essay of the Atomicall Philosophy, [the terms] ‘elementary’ and ‘atomic’ can be seen as coextensive terms—​both imply resistance to decomposition.”22 According to Boyle, chymical atoms endow homogeneous substances with the properties that define them as members of specific material species, that is, essential properties. Thus, although these compounded corpuscles are hierarchically secondary with respect to primary corpuscles, they are primary with respect to homogeneous substances and, when combined, they form primary mixtures that can in turn be combined to form different degrees of mixtures. In the context of chemical decomposition, “the identity between the smallest available particles and the substance as a whole provides direct evidence for such atomism, since an obvious consequence of this uniformity is that no decomposition products are present . . . homogeneity after attempted analysis is a warrant for the claim that the material at hand is atomic.”23

21 Robert, The Sceptical Chymist, 296–​297. 22 23

Newman, “The Significance of ‘Chymical Atomism’,” 254. Ibid., 254–​255.

Boyle’s Corpuscular Theory  89 It must be acknowledged at this point that, according to Boyle, prima mixta or “chymical atoms” may be reduced in the context of chrysopoetic transmutation, which is not an ordinary chemical process. Transmutation is indeed of central importance in Boyle’s work and he does believe that, unlike ordinary chemical agents, the alkahest (i.e., the universal solvent described by Paracelsus) and the Philosopher’s Stone act upon the prima mixta, either reducing them into primordial water or converting base metals into gold. Indeed, Boyle implies that his own menstruum, peracutum,24 does this as well when it transmutes gold into silver and he claims to have witnessed the Anti-​Elixir doing the same. His desire to see what such experiments can reveal about the composition of matter is undoubtedly a key reason for his fervent search for these arcana throughout his career.25 However, Boyle’s belief that the prima mixta can be analyzed by the alkahest, the Philosopher’s Stone, or the peracutum does not invalidate the claim that, in the context of ordinary chemical operations, the prima mixta is operationally elementary. Although there seems to be a paradox between Boyle’s chymical atomism and his belief in chrysopoetic transmutation, Newman explains that chymical atomism and chrysopoeia were anything but incompatible. The fact that metals stubbornly retained their own identity in the face of analytical assaults by chymists was a knowledge born of hard experience. Hierarchical theories of matter like those of Boyle, Becker, and Stahl originated out of the alchemical tradition’s attempts to circumvent the obstinate refusal of nature to yield up the secret of transmutation. Since chymical atoms were not the solid and impenetrable units of Democritus and Leucippus, but structured composites made up of smaller particles, there was every reason to imagine that a sufficient powerful solvent [such as the alkahest or Boyle’s peracutum] should be able to penetrate and break them in to their components.26

Thus, although chymical atoms cannot be reduced by ordinary analytical means, they are in principle analyzable if a powerful enough menstruum is discovered. Therefore, Boyle’s chymical atomism is precisely what allows him to explain the chemical stability of substances, while also believing in the possibility of transmutation.

24 Boyle prepares this highly corrosive solvent by distilling a mixture of nitric acid (aqua fortis) and antimony trichloride (butter of antimony). 25 Principe, The Aspiring Adept. 26 Newman, “Robert Boyle, Transmutation, and the History of Chemistry before Lavoisier,” 77.

90  The Chemical Philosophy of Robert Boyle

3.3  Composition vs. Microstructure One of several important issues that inform contemporary philosophy of chemistry is that of structural explanation, precisely because modern chemistry is primarily concerned with microstructure. The importance of structural explanations in chemistry arose in the 19th century from the discovery of isomeric molecules, that is, molecules that are composed of the same elements in the same proportions but that display different macroscopic and, more specifically, different chemical properties. In the 1860s, A. M. Butlerov explained isomerism as based on molecular structure. Thus, the compositional formulae that had been used since the 18th and early 19th centuries had to be supplemented with structural formulae. This is what distinguishes contemporary chemistry from chemistry as it was practiced and theorized prior to the early 19th century, when the focus was placed on elemental and atomic composition. However, one of the points that I argue in this section is that concern over microstructure, albeit understood in a radically different way than it is today, also informs Boyle’s chemical philosophy. Boyle’s conception of chymical atoms cannot simply be regarded as compositional, because it is not only their composition but also the structure in which the minima are arranged that account for the essential properties of chymical atoms. I sustain that the essential property of chymical atoms is their texture, which is determined by the microstructural arrangement and coordinated movements of the minima that compose them. The chemical properties of a stable substance are due to the properties of the chymical atoms that compose it but “Invisible changes made in the minute and perhaps undiscernible parts of a stable Body may suffice to produce such alterations in its Texture, as may give it new Qualities.”27 In some ways, this view is similar to Sennert’s theory of microstructure but without the appeal to “substantial forms” of corpuscles. Genuine chemical changes can alter the texture of chymical atoms in such a way as to alter the essential properties of a substance. Mere mechanical changes, however, will simply alter the spatial relations between chymical atoms without altering their texture and will, thus, only yield a change in the extra-​essential (or non-​essential) properties of a substance. From this discussion, one can conclude that the idea of microstructure fulfills two tasks for Boyle: 1) To the extent that Boyle embraces a mechanistic conception of fundamental particles, microstructure helps him reconcile the idea that minima are endowed only with mechanical affections with the idea that different species of matter exist in nature and have distinctive non-​mechanical properties that differentiate them from other species, and 2) microstructure helps to explain



27 Boyle, History of Particular Qualities, 279.

Boyle’s Corpuscular Theory  91 Boyle’s experimental observation that some properties of substances are stable and immune to merely mechanical changes, while other properties are less stable and are susceptible to alteration by such mechanical changes. Thus, and as previously mentioned, while it is generally believed that our contemporary concern over structural explanation is a function of modern chemistry’s emphasis on microstructure, Boyle’s structural realism illustrates the way in which many of our contemporary concerns have deeply historical origins. Boyle’s spatial, geometrical, and mechanistic conception of structure allows him to appeal to form to explain chemical stability while, at the same time, rejecting the Scholastic conception of substantial form. Because mechanistic form accounts for the texture of chymical atoms and the essential properties of material bodies, he refers to this deep microstructure as the essential form. It is evident that essential form fulfills, for Boyle, the role that substantial form had fulfilled for the Scholastics and for vitalistic corpuscularians such as Daniel Sennert but without any of its problematic connotations. In fact, in The Origin of Forms and Qualities, Boyle explicitly states “that which he [Sennert] ascribes to the dominion of the specific Form, I attribute to the structure and especially to the connexion of the parts of the compounded body.”28 Again, and as previously established, although the extra-​essential properties of a chemical substance may be altered by analysis, the texture of chymical atoms remains stable within the products of analysis and this explains why the original substance can then be re-​synthesized or redintegrated. Since chymical atoms are operationally irreducible, resistant to the most corrosive analytical tools available, and operationally “elementary,” Boyle refers to them as “minima of their own genus,” a term that he appropriates from Sennert. In The Origin of Forms and Qualities, Boyle explains this. That there are multitudes of Corpuscles, which are made up of the Coalition of several of the former Minima Naturalia; and whose Bulk is so small, and their Adhesion so close and strict, that each of these little Primitive Concretions or Clusters (if I may so call them) of Particles is singly below the discernment of Sense, and though not absolutely indivisible by Nature into the Prima Naturalia that compos’d it [. . .] they very rarely happen to be actually dissolv’d or broken, but remain entire in a great variety of sensible Bodies, and under forms and disguises.29

Elsewhere, Boyle states “there are divers Concretes [. . .] wherein the noblest properties [. . .] depend immediately upon the form (or if you will result from the

28 Boyle, The Origin of Forms and Qualities, 459. 29

Ibid., 325–​326.

92  The Chemical Philosophy of Robert Boyle determinate structure of)—​the Whole Concrete; and consequently they that got about the Vertues of such bodies, by exposing them to the Violence of the Fire, do exceedingly mistake.”30 The only thing that such powerful analytical tools can do is rearrange the spatial relationships between chymical atoms, via combination, separation, and transposition of these corpuscular concretions. This, however, results in a merely mechanical alteration of the relationship between chymical atoms, rather than in a genuine alteration of their microstructure, and thus only affects the extra-​essential properties of the substance, leaving the essential properties untouched. This means, therefore, that chemical mixts can be re-​synthesized after being analyzed into the homogeneous substances of which they are composed because the chymical atoms of the homogeneous substances have not themselves been texturally altered in the process of analysis. To support this hypothesis, Boyle conducts numerous experiments through which he hopes to empirically establish the stability and operational irreducibility of chymical atoms, the most notable of which is the redintegration of potassium nitrate, which will be discussed at the end of this chapter. At this point, however, I wish to address some claims that have been recently made regarding the stability of chymical atoms. In a recent article, Kleber Cecon argues that, although Boyle’s aggregates “are relatively stable entities . . . [they] can be considered only semi-​permanent, and still not enough to establish proper intermediate causes as required for the origins of modern experimental chemistry.”31 However, Cecon adds that “this semi-​permanent nature could reflect a certain stability present in chemical substances as defined in common sense terms, which would result in observable chemical behavior. In this sense, the chemical behavior of specific substances can be considered an intermediate cause.”32 Although I agree with Cecon that Boyle appeals to subordinate and intermediate causes in chemistry, I wish to take a position stronger than Cecon’s regarding the stability of chymical atoms. In this book, I defend the view that Boyle’s notion of “atomicity” is a negative-​empirical concept defined by the limits of chemical analysis. Thus, although chymical atoms are ontologically and theoretically analyzable into their constituent fundamental particles, they are operationally irreducible and thus, for all practical purposes, they can be considered as chemically elementary entities. As already established, the stability of chymical atoms derives not from any substantial form but from their microstructural form, which Boyle considers to be a form so stable that it resists corrosive analysis and, as discussed in the next section, it provides distinct substances with operationally unalterable essential

30 Boyle, The Sceptical Chymist, 340. 31

Cecon, “Robert Boyle’s Experimental Programme,” 87

32 Ibid.

Boyle’s Corpuscular Theory  93 properties that warrant their classification within given natural kinds. In fairness to Cecon’s point, it is true that Boyle ultimately fails to provide a satisfactory theory of microstructure because he cannot explain what accounts for its stability. I address this problem at the end of this chapter. However, Boyle does endorse the existence of operationally stable entities, that is, of entities that cannot be further reduced by the then available means of analysis, such as aqua regia, aqua fortis, or even fire. Certainly, one can justifiably argue that to remain a consistent mechanistic corpuscularian, Boyle cannot regard chymical atoms as theoretically indivisible. As a chemist and natural philosopher, he affirms the existence of stable natural kinds and stable chemical properties but, to the extent that he rejects substantial forms as the agents of stability and embraces a mechanistic corpuscularian theory of matter, he must reject the theoretical indivisibility of corpuscular aggregates or chymical atoms. There is no tension here, however, because it is the operational indivisibility of chymical atoms, the stability and predictability of chemical reactions, and the causal efficacy of chemical properties that have methodological functionality and true heuristic power in the context of his experimental chemistry. In this sense, one could say that Boyle is fundamentally a pragmatist who does not allow his theoretical and ontological commitment to a given theory of matter stand in the way of the heuristic power of experimental science. The Sceptical Chymist is, thus, not merely a polemic against Scholastics and spagyrists, nor is it simply a defense of a generic conception of mechanistic corpuscularianism. It is also, first and foremost, an exposition and defense of a very specific type of corpuscularian theory, that is, one that both posits fundamental mechanistic particles as the ontological terminus of material bodies and posits stable corpuscular concretions (chymical atoms) as the operational terminus of chemical analyses. Such chymical atoms retain their texture and, thus, their identity and integrity when they enter more complex compositions with other types of chymical atoms, and this can be demonstrated because the substances that are composed of such chymical atoms are recoverable through analysis. As an example, Boyle discusses how gold and quicksilver will either dissolve or precipitate, change into a variety of different colors, become malleable or hard, form a salt or an oil, and so on, depending upon the reagent used in each experiment. He explains that the Reason [.  .  .] that I  have represented these things concerning Gold and Quicksilver, is, That it may not appear absurd to conceive, that such little primary Masses or Clusters, as our Proposition mentions, may remain undissipated, notwithstanding their entering into the composition of various Concretions, since the Corpuscles of Gold and Mercury [. . .] are able to concurre plentifully

94  The Chemical Philosophy of Robert Boyle to the composition of several very differing Bodies, without loosing their own Nature or Texture, or having their cohaesion violated by the divorce of their associated parts or Ingredients.33

Earlier in the same work, Boyle defines the term “element” to mean “those primitive and simple Bodies of which the mixt ones are said to be composed, and into which they are ultimately resolved.”34 As William Newman points out, within the framework supplied by Boyle’s Essay of the Atomicall Philosophy, “elementary” and “atomic” can be seen as coextensive terms—​both imply resistance to decomposition [. . .] The identity between the smallest available particles and the substance as a whole provides direct evidence for such atomism, since an obvious consequence of this uniformity is that no decomposition products are present [. . .] homogeneity after attempted analysis is a warrant for the claim that the material is atomic.35

Thus, in the context of chymical reactions and processes, gold and quicksilver can be considered elementary although, ontologically, they are composed of fundamental particles with strictly mechanical affections. Again, there is no tension between Boyle’s mechanistic corpuscularianism and his belief in operationally irreducible concretions because, for all practical, pragmatic, methodological, explanatory, and heuristic purposes, chymical atoms are indeed stable and operationally irresolvable elementary entities. At the end of the citation given earlier, Cecon states that Boyle’s semi-​ permanent aggregates are “still not enough to establish proper intermediate causes as required for the origins of modern experimental chemistry.”36 Cecon’s tacit allusion to the Chemical Revolution here seems to suggest that Lavoisier’s successful chemical reforms were predicated upon a commitment to completely stable and irreducible elements. However, a commitment to the theoretical irreducibility of elements was not a requirement for the development of modern chemistry. Lavoisier’s proposed reform of the nomenclature of compound substances in terms of their elementary composition forces the question of what is to be regarded as an “element.” Lavoisier proposes to answer this question by restricting himself to what can be determined via experiment. He explains that, “if by the name of element, we mean the simple and indivisible molecules that



33 Boyle, The Sceptical Chymist, 231. 34

Ibid., 220. Newman, “The Significance of ‘Chymical Atomism’,” 254–​255. 36 Cecon, “Robert Boyle’s Experimental Programme,” 87. 35

Boyle’s Corpuscular Theory  95 compose bodies, it is probable that we do not know them: if, on the contrary, we attach the name of element or principle of bodies to the idea of the last point at which analysis arrives, all of the substances that we have not yet been able to decompose by any means are, for us, to be considered elements.”37 This operational definition provides an experimental criterion for deciding when a substance should be regarded as an element, but it does not tell us what the term “element” means.38 Lavoisier understands this and admits that the table of elements derived by applying this criterion is entirely open to revision. He states, “we cannot assure that the substances that we regard as simple are not themselves composed of two or perhaps a greater number of principles. However, since these principles cannot be separated or, rather, since we have no means of separating them, they behave for us in the manner of simple substances, and we must not assume them to be composed until experience and observation prove otherwise [emphasis mine].”39 As already established, however, Lavoisier’s analytical definition is not entirely original with him. In fact, according to Paul Needham, this type of definition dates even further back than Sennert or Boyle and goes as far back as the writings of Aristotle, although the latter’s conception of elements is obviously quite distinct from that of Lavoisier.40 More interesting however is the fact that, operationally, Lavoisier’s “element” is the same as Boyle’s “chymical atom.” “Lavoisier, like Boyle before him, conceptually distinguishes between ultimate particles and the undecomposed substances of the laboratory.”41 However, although Boyle accounts for his inability to analyze such substances by theorizing that their microstructure cannot be decomposed into their constituent primary corpuscles, Lavoisier refuses to theorize about what might be occurring at the micro-​level to explain why a substance cannot be further analyzed. Thus, by Lavoisier’s own admission, his list of elements is open to revision, if future methods of analysis

37 Lavoisier, Traité élémentaire de chimie, xii: “Si par le nom d’élémens, nous entendons désigner les molécules simple & indivisibles qui composent les corps, il est probable que nous ne les connoisons pas: que si au contraire nous attachons au nom d’élémens ou de principe des corps l’idée du dernier terme auquel parvient l’analyse, toutes les substances que nous n’avons encore pu décomposer par aucun moyen, sont pour nous des élémens.” 38 Hendry, “Antoine Lavoisier (1743–​1794),” 66. 39 Lavoisier, Traité élémentaire de chimie, xii–​xiii: “Non pas que nous puissions assurer que ces corps que nous regardons comme simples, ne soient pas eux-​même composes de deux ou même d’un plus grand nombre de principes, mais puisque ces principes ne se séparent jamais, ou plutôt puisque nous n’avons aucun moyen de les séparer, ils agissent à notre égard à la manière des corps simples, & nous ne devons les supposer composes qu’au moment où l’expérience & l’observation nous en auront fourni la prévue.” 40 Needham, “An Aristotelian Theory of Chemical Substance.” See also Newman, “What Have We Learned from the Recent Historiography of Alchemy?”; Newman, Atoms and Alchemy; Bensaude-​ Vincent and Stengers, A History of Chemistry. 41 Levere, Transforming Matter, 81.

96  The Chemical Philosophy of Robert Boyle reveal that these “elements” are further operationally reducible to more fundamental entities. I cannot, therefore, agree with Cecon that a fixed or stable conception of elementarity is what lies at the origins of modern experimental chemistry since, as mentioned, Lavoisier admits that what is considered elementary at one time is open to revision as analytical methods improve. Rather, Lavoisier’s reform and modernization of experimental chemistry lies in his staunch empiricism, in his emphasis on a quantitatively oriented chemical methodology, and in his rejection of philosophical theories of matter, which he faults for being metaphysically “suspect.” Another recent claim regarding Boyle’s chemical ontology with which I must disagree was made by Alan Chalmers, who has explicitly stated that “Boyle’s mechanical or corpuscular hypothesis is spelt out in most detail in The Origin of Forms and Qualities According to the Corpuscular . . . a key feature of it is its reductionist character. All the phenomena of the material world are to be reduced to the action of matter in motion.”42 Elsewhere, Chalmers reiterates again that “A key feature of Boyle’s mechanical philosophy that needs to be stressed is the extreme reductionism that it involved.”43 Although Chalmers concedes that, for Boyle, “bodies and substances will have qualities other than the primary [mechanical] ones, both those detectable by the senses and those involved in the interaction of bodies, such as elasticity and magnetic properties,”44 he adds that “for Boyle, the secondary qualities are to be reduced to, that is, explained in terms of, the primary ones. More specifically, all the phenomena of the material world are to be explained in terms of the shapes, sizes and mobility of corpuscles together with the spatial arrangement of those corpuscles amongst themselves. These fundamental explanations will involve appeal to the laws of nature that govern the motions of corpuscles.”45 I disagree with Chalmers’s conclusion that Boyle’s mechanistic corpuscularianism entails such an extremely reductionist explanatory approach. It is obvious that Boyle’s chemical explanations are not reductionist in the strict sense implied by Chalmers since, as Chalmers himself admits, Boyle does not invoke mechanistic corpuscularianism as an explanatory principle in his experimental writings. As was discussed at the end of the previous chapter, the mechanical philosophy as the “metaphysical” hard core of Boyle’s research programme implies an ontological reductionism of all phenomena to the mechanical affections of corpuscles and thus limits permissible explanations to those that



42

Chalmers, “The Lack of Excellency of Boyle’s Mechanical Philosophy,” 543. Chalmers, “Boyle and the Origins of Modern Chemistry,” 2. 44 Chalmers, “The Lack of Excellency of Boyle’s Mechanical Philosophy,” 544. 45 Ibid. 43

Boyle’s Corpuscular Theory  97 are consistent with the mechanical philosophy. However, although the mechanical philosophy provides such a limiting principle, its ontological reductionism has no heuristic value or explanatory power with regard to chemical reactions and transformations. Therefore, explanations of such phenomena must invoke higher-​level chemical causes for which a reductionist account would neither be accessible nor informative. As I will argue in the next chapter, Boyle holds a conception of higher-​level qualities as emergent, relational, and dispositional and, as the final chapter will show, the whole-​parts relation in chymical atoms cannot be captured with the kind of classical and summative mereology that would be required by a strictly reductionist mechanicism. At this point, however, I  wish to address the intimate connection between Boyle’s structural realism, his realism about natural kinds, and his ideas regarding the taxonomical classification of material species. As pointed out in the previous chapter, Boyle is fully aware of the limits of Cartesianism for chemistry and clearly prefers to formulate explanations that rely on chemical properties, cosmical qualities, and other subordinate causes, as the experiment involving the redintegration of potassium nitrate clearly illustrates. Further evidence of Boyle’s predilection for such explanations is found in most of his experimental writings. For example, in the Experiments Touching Colours (1664), Boyle describes and explains one experiment involving a common sublimate (probably mercuric chloride [HgCl2] and water),46 oil of tartar (potassium carbonate [K2CO3]), and oil of vitriol (sulfuric acid [H2SO4]) in the following manner: The Experiment is very easie, and it is thus perform’d:  Take good common Sublimate, and fully satiate with it what quantity of Water you please, Filtre the Solution carefully through clean and close Paper, that it may drop as Clear and Colourless as Fountain water. Then when you’l [sic] shew the Experiment, put of it about a Spoonfull into a small Wine-​glass, or any other convenient Vessel made of clear Glass, and droping in three or four drops of good Oyl of Tartar, per Deliquium, well Filtered that it may likewise be without Colour, these two Limpid Liquors will in the twinkling of an Eye turn into an Opacous mixture of a deep Orange Colour [. . .] And when the Spectators have a little beheld this first Change, then you must presently drop in about four or five drops of Oyl of Vitriol [. . .] the whole Colour, if you have gone Skillfully to work, will immediately disappear, and all the Liquor in the Glass will be Clear and Colourless as before, without so much as a Sediment at the Bottom.47 46 It is safe to speculate that this was the common sublimate used in this experiment since mercuric chloride with water was a common sublimate that Boyle used, with potassium hydrogen tartate and sulfuric acid, in a similar experiment described in History of Colours. This latter experiment is discussed in Clericuzio, Elements, Principles, and Corpuscles, 144–​145. 47 Boyle, Experiments and Considerations Touching Colours, in The Works of Robert Boyle, 150–​151.

98  The Chemical Philosophy of Robert Boyle Boyle explains the change of the solution from transparent to orange, then back to transparent, as being due to purely chemical processes so that the Yellowness of the Mercurial Solution and the Oyl of Tartar is produc’d by the Precipitation occasion’d by the affusion of the latter of those Liquors, and that the destruction of the Colour proceeds from the Dissipation of that Curdl’d matter, whose Texture is destroy’d, and which is dissolv’d into Minute and Invisible particles by the potently Acid Menstruum, which is the reason, why there remains no Sediment in the Bottom [. . .] this seems to be the Chymical reason of this Experiment, that is such a reason, as [. . .] may give such an account of the Phaenomena as Chymical Notions can supply us with.48

Although Boyle’s chemical explanation relies on the notion of texture, he does not renounce his commitment to the mechanistic corpuscularian ontology and reminds his readers that he is “sufficiently aware of the difference betwixt a Chymical Explication of a Phaenomenon, and one that is truly Philosophical or Mechanical.”49 Boyle’s commitment to chemical explanations that eschew any reference to the mechanical affections of minima naturalia is even more pronounced in his physiological essays, such as his Memoirs for the Natural History of Human Blood. In fact, the idea that natural phenomena must be explained by appealing to causes other than the mechanical affections of minima naturalia is consistent with Boyle’s approach in most of his experimental writings. For example, in the appendix to Final Causes, he states that there are a great many things of wch we may have some knowledge, and discourse to one another rationally & usefully, wch yet cannot with any convenience be immediately deduc’d from the First and simplest Principles; namely, Corpuscles and Motion; but must be deriv’d from subordinate Principles; such as ye Greate Systeme of ye World, Gravity, Fermentation, Springiness, Magnetism, &c.50

Boyle not only affirms the usefulness of such subordinate causes, which include chemical properties as well as cosmical qualities such as magnetism and gravity, but he also claims these to be the most useful of all explanatory principles in natural philosophy. Immediately after making the just-​cited remark, he states that



48

Ibid., 152.

49 Ibid.

50 Boyle, Title Material Relating to Appendix to “Final Causes,” Vol. 9, folio 40v.

Boyle’s Corpuscular Theory  99 the most useful Notions we have both in Physick, Mechanicks, Chymistry, and the Medicinal Art, are not deriv’d Immediately from the First Principles; but from—​Intermediate Theories, notions, and Rules:—​it being often sufficient for very useful Purposes, to terminate our researches into some settled rule or equivalent Axiome of Nature, and thence derive—​Practical conclusions by way of Inference or Application. Of the Subordinate or Intermediate—​causes or Theories of natural things—​there may be many; some more and some less remote from the First Principles, and yet each of them capable to afford a just delight & usefull Instruction to the mind. And these we may—​call for distinction sake, the Cosmographical, the Hydrostatical, the Anatomical, the Magnetical, the Chymical, and other causes or reasons of—​Phaenomena, as those wch are more Immediate (in our way of estimating things) than ye general and primordial causes of natural effects.51

These remarks, however, may seem to be at odds with some of the things explicitly stated in theoretical works, such as The Excellency of the Corpuscular or Mechanical Philosophy, to the effect that “if the Agents or active Principles resorted to, be not Immaterial, but of a Corporeal Nature, they must either in effect be the same with the Corporeal Principles above-​nam’d; or, because of the great Universality & Simplicity of ours, the new ones propos’d must be less general than they, and consequently capable of being subordinated or reduc’d to ours.”52 There seems to be a tension between what is said here and what Boyle claims in the appendix to Final Causes. However, as I argued in the previous chapter, this apparent tension may be resolved once one understands the distinction between the mechanical philosophy’s negative heuristic and its positive heuristic and the ensuing semantic shift in his use of the term “mechanical” in the experimental writings.

3.4  Taxonomical Classification, Natural Kinds, and Essential Form To situate Boyle both historically and philosophically regarding the issue of natural kinds, I will briefly examine the distinction between his views and those of John Locke, whom he influenced but with whom he was also engaged in lively debates. Both Locke and Boyle reject the Aristotelian conception of natural kinds, which was predicated on the possession of distinctive substantial forms. As discussed in Chapter 1, Aristotle considers substantial form to be “responsible

51

Ibid., folios 40v–​41r.

52 Boyle, Of the Excellency and Grounds of the Corpuscular or Mechanical Hypothesis, 117.

100  The Chemical Philosophy of Robert Boyle for making naturally occurring materials what they are.”53 One of the reasons for Locke’s and Boyle’s rejection of this Aristotelian view is that it is untenable both from an empiricist and from a mechanistic perspective, because it invokes a principle other than matter itself to account for the identity of material bodies as members of distinctive species. However, an underlying concern for both men is that of how to justify the taxonomical classification of material species, in the absence of substantial form. Locke wishes to preserve the distinction between nominal essence and real essence, that is, between the ideas that we acquire about substances based on their observable properties and the real nature of things, which cannot be known due to our intellectual and perceptual limitations. Due to these epistemic limits, our classifications are based on nominal essences rather than on real essences, since the latter are not empirically accessible to observation. Even though our taxonomical practices are clearly not completely arbitrary, since they are based on the observed properties of things, these observed properties reveal nothing about real essences. Thus, although there is debate among scholars about whether Locke was an ontological realist about natural kinds, his theory of taxonomical classification is strongly conventionalist.54 As any student of early modern British empiricism knows, the distinction between nominal essence and real essence was difficult to sustain within any kind of empiricist position unless that empiricism was imbued with elements of Cartesian rationalism, as was the philosophy of John Locke. George Berkeley and David Hume would jointly close the lid on the notion of real essences, along with that of abstract ideas and other “priestly dogmas” as Hume would call them, by arguing that one must not embrace any notion whose origin cannot be traced back to direct observation. Robert Boyle, whose natural philosophy is strongly committed to empiricism, is also concerned with avoiding any appeal to notions that cannot be supported by the evidence of observations. Thus, his approach to taxonomical classification is undoubtedly imbued with elements of conventionalism. In The Origin of Forms and Qualities, Boyle clearly displays conventionalist leanings when he states that “men having taken notice, that certain conspicuous Accidents were to be found associated in some Bodies, and other Conventions of Accidents in other Bodies, they did for conveniency, and for the more expeditious Expression of their Conceptions agree to distinguish them into several Sorts, which they call Genders or Species.”55 Boyle agrees with Locke that, in the 53 Chalmers, “Klein on the Origin of the Concept of Chemical Compound,” 45. 54 Some of the scholars who reject the view that Locke was an ontological realist about natural kinds are Margaret Atherton, Lisa Downing, and Jan-​Erik Jones. See Atherton, “Locke on Essences and Classification”; Lisa Downing, “Locke’s Ontology”; and Jones, “Lockean Real Essences and Ontology.” 55 Boyle, The Origin of Forms and Qualities, 322.

Boyle’s Corpuscular Theory  101 absence of substantial form, there must always be an element of convention in classification. He also agrees that the boundaries between material species may at times remain unclear, because taxonomical classifications are “made on the basis of phenomenal qualities [Accidents] and not on the basis of an understanding of their underlying structure.”56 However, it would be an error to conclude that such conventionalism is Boyle’s ultimate position. Robert Pasnau unfortunately errs in this direction by attributing to Locke and Boyle the same final position regarding taxonomical classification. Here, I will discuss and respond to Pasnau’s claim, and use this as a springboard for what I take to be a more accurate account of Boyle’s views. Pasnau states that for the scholastics, our classification of individuals into species tracks the essences of things. Though we may not have a direct or comprehensive grasp of what those essences are [. . .] we know enough to sort individuals into their true species. Like Boyle before him, Locke utterly rejected this optimistic view, and took our distinctions between species to be the product of haphazard and highly fallible groupings on the basis of superficial resemblance [. . .] Locke argues that without knowing the essence, we have no way of knowing which properties point toward the nature of the species and which are merely accidental. Hence, our distinctions between species can be grounded only on our haphazard conceptions of the nominal essences of things.57

Although I fully agree with Pasnau’s description of Locke’s view of classification, I believe that it is a mistake to equate this view with Boyle’s final position. As has been extensively argued already, Boyle does believe that one can distinguish between those properties of a material body that are accidental and those that are essential, that is, those properties that derive from the stable and operationally irreducible microstructure or essential form of the corpuscular concretions. He also believes, as I will show presently, that it is because of said essential properties that we can establish the species to which a material body belongs. Furthermore, to the extent that Boyle identifies an empirical basis for understanding the real essence of material bodies, his conventionalism is muted by the fact that he does not regard the process of classification as being purely arbitrary. For Boyle, there is an empirical relationship between the real essence of a material body and its observable properties. Those properties are essential that are jointly necessary and sufficient for a material body to belong to a specific natural kind or species. We can know these essential properties by observing that they are



56 57

Anstey, “Essences and Kinds,” 20. Pasnau, “Form, Substance, and Mechanism,” 66.

102  The Chemical Philosophy of Robert Boyle not mechanically alterable by ordinary chemical reagents.58 Thus, we can classify material bodies into kinds by identifying the necessary and sufficient properties that define those kinds. Boyle states that “since to every Determinate Species of Bodies, there doth belong more then [sic] One Quality, and for the most part a concurrence of Many is so Essential to That sort of Bodies, that the want of any of them is sufficient to exclude it from belonging to that Species: there needs no more to discriminate sufficiently any One kind of Bodies from all the Bodies of the World, that are not of that kind.”59 Although, in the earlier cited passage from The Origin of Forms and Qualities, Boyle refers to phenomenal qualities as “accidents,” we should not extract from this that such properties are merely contingent to a particular body’s membership within a species. In fact, Boyle does not distinguish the term “accident” from the term “essence” but, rather, distinguishes it from the term “substance.” Simply put, Boyle uses “accident” to mean “quality.” He explains that, although specific accidents are never essential to catholic matter as such, some accidents are essential to specific natural kinds. In his own words, “Nor need we think that Qualities being but Accidents, they cannot be essential to a Natural Body; for Accident, as I  formerly noted, is sometimes oppos’d to Substance [.  .  .] and though an Accident can be but accidental to [universal] Matter [. . .] yet it may be essential to this or that particular Body.”60 Thus, Boyle’s conventionalism regarding taxonomical classification is tempered by realism regarding the essential properties of natural kinds, which serve as guides for such classification. He firmly believes that “the real constitution of a body, along with its constituent properties, mind-​ independently makes it the kind of thing that it is.”61 Key passages in The Origin of Forms and Qualities indicate that Boyle’s realism about natural kinds compels him to formulate an empirically sound theory of taxonomical classification that explains the existence of natural kinds through a material principle, rather than through a substantial principle that is distinct from matter. He, therefore, replaces the notion of substantial form with one of mechanical form that is grounded in his structural realism and, as previously established, because mechanical form determines the essential properties of a substance, Boyle refers to it as “essential form.” For Boyle, essential forms are “naturally repeated material structures of bodies that determine their kind. Matter constitutes a ‘form’ [. . .] when it is ordered in specific structures.”62 Boyle clarifies that the term “form,” as he employs 58 We are excluding from our discussion those extraordinary chemical processes such as chrysopoeisis, which involve unusually powerful reagents such as the alkahest or the Philosopher’s Stone. 59 Boyle, The Origin of Forms and Qualities, 323. 60 Ibid., 324. 61 Jones, “Locke vs. Boyle,” 660. 62 Jones, “Boyle, Classification, and the Workmanship of the Understanding Thesis,” 177.

Boyle’s Corpuscular Theory  103 it in this context, does not mean a substance separate from or independent of matter. In The Origin of Forms and Qualities, he states, “though I shall for brevities sake retain the word Forme, yet I would be understood to mean by it, not a Real Substance distinct from Matter, but onely the Matter it self or of a Natural Body.”63As Peter Anstey concurs, “it is clear that, for Boyle, form can be defined in terms of phenomenal qualities or underlying micro-​structure, though the weight of textual evidence suggests that it was the qualities rather than mechanical affections which are the primary referent of the term.”64 However, I would add that, although essential qualities of a substance are the primary referent of the term, it is the microstructure that accounts for the essential qualities. Thus, essential form is microstructure. Since the qualities are observable, while the essential form is not, qualities are what reveal the form to the observer. Boyle holds that the mechanical form is the essential form of material bodies because, without it, bodies would not have the essential properties that they do in fact have. The peculiar mechanical form of a body is sufficient to denominate it as a body of a certain kind. Thus, “so long as bodies possess the right structure, they are part of that species.”65 For this reason, Boyle also disagrees with the Scholastic distinction between natural substances and artifacts, a distinction that is grounded in the theory of substantial forms. In fact, all mechanistic philosophers rejected this distinction precisely because they rejected substantial forms. For Descartes, this meant that neither artificial nor natural bodies have form of any sort. However, for Boyle, though neither natural nor artificial bodies have substantial forms, they both have essential mechanical forms that qualify them as members of particular species, thus rendering the natural/​artificial substance distinction irrelevant “for there is not always such a difference as many imagine between the one and the other.”66 As will be seen in the final chapter, the unity afforded to chymical atoms by essential form also provides mereological reasons for rejecting the natural/​artificial substance distinction. Boyle’s conception of form can do all the work for the mechanical philosophy that substantial form did for the Scholastics. That is, it can explain species membership, “account for the unity of the body as a single entity, and ground the properties of the body.”67 He also indicates his preference for structural essential form over substantial form in The Sceptical Chymist, stating that “This Aggregate or result of Accidents you may, if You please, call either Structure or Texture [. . .] Or if, retaining the Vulgar Terme, You will call it the Forme of the thing it denominates, I shall not much oppose it; Provided the word be interpreted to mean but what

63 Boyle, The Origin of Forms and Qualities, 324. 64

Anstey, “Essences and Kinds,” 20. Jones, “Boyle, Classification, and the Workmanship of the Understanding Thesis,” 179. 66 Robert Boyle, Letters and Papers of Robert Boyle, 300. 67 Jones, “Boyle, Classification, and the Workmanship of the Understanding Thesis,” 177. 65

104  The Chemical Philosophy of Robert Boyle I have express’d, and not a Scholastick Substantial Forme, which so many intelligent men profess to be to them altogether Un-​intelligible.”68 The unintelligibility of substantial form is, in no small part, due to its immateriality and empirical inaccessibility. However, although essential form is also empirically inaccessible as such, something about it is revealed by phenomenal and chemical properties. Thus, although we have no direct perceptual access to essential form or deep structure, the results of specifically designed chemical experiments give us indirect epistemic access to it and I discuss the most famous of these experiments in the following section.

3.5  The Empirical Nature of Essential Form: The Reduction to the Pristine State It is true that Boyle’s chymical atoms and their microstructure are entirely hypothetical posits, since they are not empirically accessible as such just as substantial form had not been empirically accessible. Unlike substantial form, however, chymical atoms are postulated as material entities with causal properties, which implies that experiments can be conducted to confirm hypotheses about these entities. To be more precise, because the microstructure or essential form of chymical atoms accounts for the stability of chemical substances and of chemical properties, essential form retains an empirical connection to the world that the epistemically suspect notion of substantial form did not have. Thus, a chemist can conduct experiments to demonstrate that microstructure is stable in chemical processes such as combination, separation, and transposition of chymical atoms, which are merely mechanical processes that alter only the extra-​essential properties of substances. Of the many experiments that Boyle uses for these purposes, the one that he considers most effective for establishing the stability of microstructure is “the reduction to the pristine state,” an experiment that he appropriates from Daniel Sennert. As Christoph Meinel points out, however, Sennert himself had inherited this procedure from iatrochemists and pharmacists who had used it for pragmatic and atheoretical purposes, such as describing quantitatively the formation and decomposition of metallic substances.69 Sennert had both appropriated and further developed the reduction to the pristine state for theoretical reasons, that is, to provide empirical support for vitalistic corpuscularianism and for the theory of substantial form as an immaterial principle of identity. As already explained in Chapter 1, however, Sennert regarded the minute particles

68 Boyle, The Sceptical Chymist, 356. 69

Meinel, “Empirical Support for the Corpuscular Theory in the Seventeenth Century,” 85.

Boyle’s Corpuscular Theory  105 or atoms of substances, rather than the substances themselves, as endowed with form. Thus, for Sennert, the purpose of reduction to the pristine state was to establish empirically that the corpuscles of a chemical substance retained their distinct substantial form even when that specific substance was fused with other substances. Sennert eventually developed different types of reduction to achieve different theoretical purposes, and Boyle appropriated these methods selectively to provide empirical support for his conception of mechanical form. “The first type [of reductions] were simple distillations and sublimations of substances such as alcohol, sulphuric acid, and sulphur, which he regarded to be merely mechanical operations by means of which bodies were mashed into their atoms.”70 This particular type of reduction to the pristine state was not useful for Boyle’s purposes, and he thus shunned it in favor of the second type of reduction developed by Sennert, which attempted to show that it is the actual atoms of a substance that retain their form, rather than the substance as such. For this experiment, Sennert had fused “gold and silver together to obtain an entirely homogeneous alloy. Then he poured aqua fortis or nitric acid on it. The silver was dissolved, whereas the gold particles settled to the bottom. He separated the two phases and precipitated the silver from the solution to obtain another fine sediment. Eventually, he melted both powders and obtained, quantitatively, gold in the first case, silver in the latter.”71 Boyle appropriates this type of reduction because he believes that it can establish the stability of chemical substances and can, thus, indirectly serve to establish 1) the existence of stable chymical atoms, 2) a mechanical explanation for essential properties, and 3) the empirical grounds for a non-​arbitrary taxonomic classification of natural kinds. Although Boyle carries out the experiment with various metals, the basic procedure of “reduction to the pristine state” is the same throughout. It basically involves dissolving metallic atoms in acid, inducing precipitation of those atoms by adding an alkali, and reducing the precipitate thereby restoring it to its former state. For Boyle, the conclusion to be drawn from this experiment is that the metal had “simply been hidden within the solution all along in the form of indissoluble”72 corpuscular aggregates or chymical atoms and that the metal’s essential properties had not been altered, which is what allows for their recovery via precipitation and reduction. William Newman describes one such experiment in detail. “One of Boyle’s most important reductions to the pristine state involves the dissolution of camphor in nitric or sulfuric acid. If sulfuric acid is used, the camphor forms a deep

70 Ibid. 71

72

Ibid.,  85–​86. Newman, “Newton’s Early Optical Theory and Its Debt to Chymistry,” 291–​292.

106  The Chemical Philosophy of Robert Boyle reddish solution and loses its color. Hence, the camphor becomes unrecognizable as camphor and seems to be perfectly mixed in the solution. But the mere addition of water causes the camphor to precipitate and to return to its former state, including the reacquisition of its powerful scent.”73 In The Sceptical Chymist, Boyle describes a solution to the pristine state involving gold and concludes that the metal is made up of “minute Masses or Clusters” that are aggregates of more minute particles74 and that the aggregate corpuscles are “not easily dissipable into such Particles as compos’d them.”75 Here, Boyle is “making a strong claim for the semi-​permanence of second-​order or aggregate corpuscles”76 or chymical atoms and, thus, for the existence and stability of essential form. Boyle concludes that non-​ essential phenomenal changes, such as those observed in the reduction to the pristine state, are the result of alterations in the spatial relations between aggregate corpuscles that leave the microstructure of these corpuscles untouched. Once again, he reaches this conclusion due to his inability to alter the camphor’s essential properties, which accounts for his recovery of the camphor in its original state. It is clear from this that Boyle’s conception of chymical atoms is a negative-​empirical concept, that is, it is a concept that reflects “the limits of the technique of analysis”77 and is defined by those limits. Thus, although he embraces the theoretical existence of more fundamental entities, Boyle defines atomicity and elementarity in operational terms, that is, in terms of what remains as the homogeneous final product of analysis. Newman explains how this operationally defined chymical atomism fits within the context of Boyle’s chemical philosophy: According to this analytical ideal, a substance is viewed as elementary if the tools of the chemist cannot decompose it. Hence, the concept is negative in that it defines an element solely in terms of what chemistry cannot do, and empirical in that it relies on the experience of the laboratory. For this reason, then, the ability of aggregate corpuscles [or chymical atoms] to withstand the corrosive menstrua of the seventeenth century makes it probable that they are operationally indissoluble, and hence atomic. For Boyle, the identity between the smallest available particles and the substances as a whole provides direct evidence for such atomism, since an obvious consequence of this uniformity is that no decomposition products are present. Homogeneity after attempted analysis is a warrant for the claim that the material at hand is atomic.78

73

Ibid., 292.

74 Boyle, The Sceptical Chymist, 230. 75 Ibid. 76

Newman, “The Alchemical Sources of Robert Boyle’s Corpuscular Philosophy,” 583. Bensaude-​Vincent, Bernadette, and Stengers, A History of Chemistry, 37. 78 Newman, “The Significance of ‘Chymical Atomism’,” 254. 77

Boyle’s Corpuscular Theory  107 Thus, “the irreducible constituents that function in chemical reactions, that is, ‘chymical atoms,’ are themselves concretions of an underlying homogeneous matter that retain their structural arrangement through analysis by fire or chemical corrosives. These allow Boyle to retain an essential form within matter and thus to avoid the consequences of a completely permissive mereology.”79 This last point will be examined in more detail in the final chapter of this book. The success of these experiments convinced Boyle of the truth of his hypothesis regarding the stability of chymical atoms and their deep structures. However, the burden for Boyle is that of explaining why the deep structure of chymical atoms would resist penetration by air or alteration by fire or any of the other extremely caustic analytical tools of the chymical laboratory. Let us remember that Boyle considers microstructure to result from the adhesion of minima in a very close spatial and geometrical juxtaposition, which brings these particles so close together that even air cannot traverse them. Why would such powerful analytical tools as nitric acid, sulfuric acid, or fire be unable to break through the extremely close and tight juxtaposition of minima that forms the structure of chymical atoms? Let us remember that Boyle embraces mechanicism and would, therefore, reject the possibility that the deep structures of chymical atoms are held together by the presence of bonding forces, even if such a hypothesis had been available to him as an alternative to that of geometrical structure. The failure to explain how the tight spatial juxtaposition of minima could possibly result in the stability and operational irreducibility of chymical atoms is one of the many weaknesses of Boyle’s structural hypothesis. Given Boyle’s adherence to the notion of aggregate corpuscles or chymical atoms with essential form, I would agree with recent authors who emphasize that Boyle’s mechanistic corpuscularianism incorporates a compositional theory of matter that allows for a non-​reductionist account of chemical properties within the context of a mechanistic conception of minima naturalia. However, I argue that it is not simply the composition of aggregate corpuscles that does the work. Rather, it is the composition coupled with structure or texture that accounts for the chemical properties of substances. I contend that Boyle’s notion that structure, rather than mere composition, defines chemical identity anticipated by several centuries the concept of chemical isomerism. Boyle believes that the microstructural nature of matter is not merely philosophical speculation but is supported by empirical evidence of the sort provided by the reduction to the pristine state. His chymical atomism and structural realism are operational notions, rather than purely metaphysical ones. Though these theories are grounded in the mechanistic hypothesis, they emphasize



79

Anstey, “Essences and Kinds,” 21.

108  The Chemical Philosophy of Robert Boyle aggregate corpuscles “that retain their substantial identity rather than deriving all of their macro-​level properties from [. . .] mechanical characteristics”80 of prima naturalia. For Boyle, the chymical atom is “an operationally indestructible bit of matter [.  .  .] not a putative entity merely and strictly composed of uniform catholic matter.”81 The determinate and essential properties of chemical substances, arising from the microstructure of chymical atoms, function as causal agents in the laboratory and in nature. Essential form also provides a non-​arbitrary method for classifying material species as natural kinds, leaving their substantial identity intact without the need for the dubious concept of substantial form, at least as it was altered from its original Aristotelian purpose and handed down from the medieval tradition and through the Renaissance. In the following chapter, I will argue that, although the microstructure or texture of chymical atoms determines the disposition of a chemical substance to display certain non-​mechanical properties, it is the substance’s relation to other substances in the context of specific chemical processes and procedures that allows dispositional properties to be actualized and to causally affect changes in other material bodies. As well, I will also argue that Boyle conceives of chemical qualities as emergent properties, to the extent that he regards chemical qualities as novel properties that supervene on the texture or essential form of chymical atoms.



80 81

Newman, “The Significance of ‘Chymical Atomism’,” 263. Ibid., 263–​263.

4

Boyle’s View of Chemical Properties as Dispositional, Relational, and Emergent Properties As indicated in the previous chapter, Boyle considers texture or microstructure to be a mechanical, albeit not fundamental, feature of chymical atoms. Therefore, to establish that Boyle favors a non-​reductionist conception of chemical qualities, it is not enough to show that these qualities are a function of microstructure and are, therefore, not directly reducible to the mechanical affections of fundamental particles. If we merely stop at establishing this, then we will simply have shown that Boyle’s views regarding chymical atoms are comparable to those of Gassendi regarding molecules. If all we can determine is that chemical properties are reducible to texture, then we would still have to consider Boyle’s chemical philosophy as mechanistically reductionist, although not in the strict sense. To establish that Boyle holds a non-​reductionist chemical ontology, we must go further than this and argue that he considers chemical qualities to be dispositional, relational, emergent, and supervenient properties. This is precisely what I intend to do in this chapter. To accomplish this goal, I first argue that Boyle considers chemical qualities to be dispositional and relational. Peter Anstey has already shown that, for Boyle, sensible qualities are dispositional and relational. I will examine in detail Anstey’s arguments and show that these arguments can be extended to Boyle’s conception of chemical qualities. However, although this will constitute a first step toward establishing a non-​reductionist interpretation of Boyle’s chemical ontology, we must go a step further and argue that Boyle conceives of chemical qualities as emergent properties that supervene upon microstructure. This means showing that he considers chemical qualities to be something novel, “over and above” the chymical atoms from which they emerge. I believe that there is enough textual evidence in Boyle’s chemical writings to sustain such an argument and I will, thus, refer extensively to these writings. My conclusions in this chapter will serve as a foundation for my discussion in the final chapter, in which I will continue this line of argument by fleshing out the mereological theory that is most consistent with this non-​reductionist interpretation of Boyle’s chemical ontology. The Chemical Philosophy of Robert Boyle. Marina Paola Banchetti-Robino, Oxford University Press (2020). © Oxford University Press. DOI: 10.1093/oso/9780197502501.001.0001

110  The Chemical Philosophy of Robert Boyle

4.1  The Hierarchy of Properties in Boyle’s Chemical Ontology Before I begin discussing the dispositionality and relationality of chemical qualities, I wish to delineate in detail the hierarchy of properties in Boyle’s ontology to establish exactly where chemical properties fit in relation to mechanical properties. To do this, I wish to first distinguish between Boyle’s conception of qualities and those of Galileo Galilei, who first articulated his distinction between primary and secondary qualities in Il Saggiatore (1623). Though Boyle is somewhat indebted to Galileo’s views, there are important differences between them regarding the primary/​secondary quality distinction. After this, I will provide a brief overview of Boyle’s conception of qualities1 and then proceed to a discussion of Anstey’s arguments for the dispositionality and relationality of sensible qualities. I  will then extend Anstey’s arguments to defend the notion of dispositionality and relationality of chemical qualities in Boyle’s ontology. As is well known, Galileo was the first natural philosopher to draw an explicit distinction between primary and secondary qualities. However, we shall see that there is a sharp difference between what Galileo means and what Boyle means when each of them appeals to this distinction. Although Galileo articulates the distinction between primary and secondary qualities for reasons similar to Boyle’s, that is, as an alternative to Aristotle’s unsatisfactory qualitative conception of properties, Galileo’s account is distinct from Boyle’s in that Galileo does not take secondary qualities to be qualities of the object at all but locates them in the perceiver instead. In Il Saggiatore, he states: I say that, as soon as I conceive of a material or corporeal substance, I feel myself pulled by the need to conceive that it is limited and configured by this or that shape, that it is large or small in relation to other substances, that it is in this or that place, in this or that time, that it is either in motion or at rest, that it either touches or does not touch another body, that it is one, few or many, and I cannot separate it in my imagination from these conditions; but that it must be white or red, bitter or sweet, loud or mute, sweet smelling or foul smelling, I do not feel mentally compelled to apprehend it as being necessarily accompanied by these conditions [. . .] I think, therefore, that these flavors, odors, colors, etc. [. . .] hold residence only in the sensitive body so that if the animal is removed, so will all these qualities also be removed and annihilated.2 1 I  am particularly indebted for this discussion to Peter Anstey’s very clear schematization of Boyle’s division of qualities in The Philosophy of Robert Boyle, 29. 2 Galileo Galilei, Il Saggiatore, 370: “Per tanto io dico che ben sento tirarmi dalla necessità, subito che concepisco una materia or sostanza corporea, a concepire insieme ch’ella è terminata e figurata di questa or quella figura, ch’ella in relazione ad altre è grande or piccola, ch’ella è in questo or quel luogo, in questo o quel tempo, ch’ella si muove o sta ferma, ch’ella tocca o non tocca un altro corpo, ch’ella

Boyle’s View of Chemical Properties  111 The only relationality in Galileo’s ontology is that which exists between objects and perceivers, and this is what constitutes the ontological difference between the two types of qualities. As Filip Buyse points out in a recent paper on the topic, “the difference between the two types, for Galileo, is that primary properties belong necessarily to the body in itself . . . and exist, as a consequence, independently of the observer. In short, they are mind-​independent properties. Secondary affections, on the contrary only exist . . . in the mind of an observer. Thus, they are mind-​dependent qualities.”3 It follows that, for Galileo, secondary qualities are relational, while primary qualities are non-​relational. Therefore, he finds it impossible to fit solubility, malleability, fixedness, volatility, or magnetism into his arrangement of qualities. The reason for this is that these qualities are both clearly relational (though in a different sense of relationality) but also independent of observers. Thus, these qualities seem to fit neither his description of primary qualities nor his description of secondary qualities. Yet, since many of these qualities are chemical qualities, they are precisely the types of qualities that Boyle wishes to account for. In fact, Boyle is concerned not only with “the qualities which corporeal objects possess in themselves and as they are related to percipients, but [with] the qualities which corporeal objects possess as they are related to other corporeal objects and the universe of which they are a part as well.”4 For Boyle, the distinction between primary and secondary qualities is inherently connected to his mechanistic corpuscularian ontology. As we have already established, for him, the most fundamental and truly inherent properties of corporeal objects are the mechanical qualities of fundamental particles (minima naturalia), which consist of the shape, size, and mobility of these particles. These are the qualities that Boyle considers to be primary. Texture is also considered a mechanical primary quality, but it is a quality that is inherent in corpuscular concretions, rather than in fundamental particles. The mechanical primary properties are considered inherent to corporeal objects and, as such, they are considered non-​relational. That is, even if a material body were alone in the universe, unaccompanied by any other body or any perceiver, that corporeal object would still have its inherent mechanical primary properties, that is, the

è una, poche o molte, né per veruna imaginazione posso separarla da queste condizioni; ma ch’ella debba essere bianca o rossa, amara o dolce, sonora o muta, di grato o ingrato odore, non sento farmi forza alla mente di doverla apprendere da cotali condizioni necessariamente accompagnata [. . .] Per lo che vo io pensando che questi sapori, odori, colori, etc. [. . .] tengano solamente lor residenza nel corpo sensitivo, sì che rimosso l’animale, siano levate ed annichilate tutte queste qualità.” 3 Buyse, “The Distinction between Primary Properties and Secondary Qualities in Galileo Galilei’s Natural Philosophy,” 23. 4 O’Toole, “Qualities and Powers in the Corpuscular Philosophy of Robert Boyle,” 303.

112  The Chemical Philosophy of Robert Boyle mechanical affections of its minima partes as well as the microstructure of its corpuscular concretions. The second type of quality is the non-​mechanical secondary quality, which represents those qualities that are not inherent in corporeal bodies, that derive from the texture of corpuscular concretions, and that are dispositional. These dispositional qualities are also considered relational because they are manifested only when the corporeal object that possesses these dispositions is in the presence either of another object or of a perceiver. This category of non-​mechanical secondary qualities is itself divided into three sub-​categories: manifest qualities, occult qualities, and sensible qualities. Under the sensible qualities, we find color, sound, odor, and taste. As shall be argued, these qualities are relational because the object’s disposition to affect a perceiver in particular ways is not actualized until the object is in the presence of a perceiver. Under occult qualities, we find magnetism and electricity, so-​called cosmical qualities, which will be discussed later in this chapter. For Boyle, occult qualities are real because, although they never become manifest in and of themselves, their effects upon corporeal bodies are manifested under the appropriate conditions. It will also be argued that, for Boyle, occult or cosmical qualities are not inherent to objects but, rather, affect objects to the extent that these objects are part of a universe of objects and laws of nature. Finally, under manifest qualities, we find a further subdivision between first, second, and third qualities. The first manifest non-​mechanical secondary qualities are the qualities that Aristotle related to the four elements, that is, the qualities of hot, cold, wet, and dry. The second manifest non-​mechanical secondary qualities are the chemical qualities, and the third manifest non-​ mechanical secondary qualities are the medical qualities. Here is a list of Boyle’s divisions among qualities:5





Primary qualities: (mechanical, inherent, non-​relational properties) Minima naturalia • Shape • Size • Mobility Corpuscular concretions • Texture (“essential form”) Secondary qualities: (non-​mechanical, non-​inherent, relational, dispositional properties) 1. Sensible

5 Again, I am here indebted to Anstey’s schematization, though my list may look somewhat different from the sketch that he provides on p. 29 in The Philosophy of Robert Boyle.

Boyle’s View of Chemical Properties  113

• Color • Sound • Odor • Taste 2. Occult • Magnetism • Electricity 3. Manifest: a. First • Hot • Wet • Cold • Dry b. Second • Chemical qualities c. Third • Medical qualities

Although Galileo based his primary/​ secondary quality distinction on whether the qualities in question were dependent upon the presence of an observer, Boyle bases his primary/​secondary quality distinction on whether the qualities in question are mechanical and inherent or non-​mechanical and non-​ inherent. Among the secondary, non-​mechanical, and non-​inherent properties, the sensible properties are regarded as dispositional and relational in that they are dependent upon the presence of a perceiver, while the chemical properties are regarded as dispositional and relational for different reasons. I will discuss these reasons in Section 4.3 of this chapter. At this point, however, I will present the arguments for the dispositionality and relationality of sensible qualities and what these arguments entail for reductionism.

4.2  Sensible Properties as Dispositional and Relational The most detailed account of sensible properties as dispositional and relational is found in Peter Anstey’s insightful study of Boyle’s chemical philosophy, titled The Philosophy of Robert Boyle. However, Anstey does not extend his very well developed and tightly argued discussion to chemical qualities. I propose to do precisely this in this chapter, that is, extend Anstey’s arguments for the dispositionality and relationality of sensible qualities to chemical qualities. Following this, I will propose that, for Boyle, chemical qualities are “novel” properties that emerge from and supervene upon the relation between chemical

114  The Chemical Philosophy of Robert Boyle substances and their microstructures. The discussion in this chapter will then serve to buttress the discussion in the final chapter regarding the complex mereology of chymical atoms. As he begins his thorough and detailed discussion of the dispositionality and relationality of sensible properties, Peter Anstey points out that the term “dispositional” can be understood in two different manners. It can refer to the way in which the parts of “x” are disposed or arranged to form “x,” or it can refer to the disposition or inclination of “x” as a whole to affect or be affected by other bodies in particular ways. Anstey clarifies that, for Boyle, these two distinct meanings are related since the power of “x” to affect or be affected by other bodies is a function of the texture or structure of the corpuscular concretions of “x.” This is the reason why, as previously stated, arguing for the dispositionality of properties may not suffice to establish that Boyle held a non-​reductionist view of such properties. Before specifically addressing sensible qualities, Anstey acknowledges that Boyle considers all non-​mechanical qualities, including chemical qualities, to be dispositional and relational. Anstey explains that, for Boyle, “most if not all non-​mechanical qualities are powers. If this is so, they are powers to bring about certain effects in other bodies and, in the case of the sensibles, in percipients.”6 Briefly addressing chemical qualities, Anstey states that “it is not unusual to find [Boyle] saying such things as quicksilver ‘has a quality or power [. . .] to dissolve gold and silver, and a capacity or disposition to be dissolved by aqua fortis’ [. . .] it is in virtue of the ‘disposition’ [i.e., texture] of its parts that snow has the ‘disposition’ [i.e., power] to reflect light.”7 After stating this, however, Anstey gives no further elaboration regarding chemical qualities and turns his full attention to the dispositionality and relationality of sensible qualities such as color, sound, taste, and odor. One of Anstey’s concerns is to use the argument for dispositionality and relationality to dispel the view that, for Boyle, sensible qualities are entirely reducible to the mechanical affections of minima naturalia. Although Anstey is correct in this claim, a reductionist could still argue that dispositional qualities are reducible to texture, which is itself a mechanical property, albeit of corpuscular concretions. This is the reason why I  believe that the argument for emergence must also be made, in order both to sustain and to strengthen the non-​reductionist interpretation of Boyle’s chemical ontology. Anstey begins his discussion by first arguing against Peter Alexander’s reductionist interpretation of Boyle. Alexander bases his interpretation on an

6 Anstey, The Philosophy of Robert Boyle, 87. 7 Ibid. Anstey is here citing from Boyle’s Cosmical Qualities, in The Works of the Honourable Robert Boyle, 306; italics added by Anstey.

Boyle’s View of Chemical Properties  115 often-​cited passage from The Origin of Forms and Qualities.8 The passage reads as follows: We may consider then, that when Tubal-​Cain, or whoever else were the Smith that Invented Locks and Keyes, had made his first Lock [. . .] That was onely a Piece of Iron, contriv’d into such a Shape, and when afterwards he made a Key to that Lock, That also in it self Consider’d, was nothing but a Piece of Iron of such a Determinate Figure; but in Regard that these two Pieces of Iron might now be Applied to one another after a Certain manner, and that there was a Congruitie betwixt the Wards of the Lock and those of the Key, the Lock and the Key did each of them now Obtain a new Capacity and it became a Main part of the Notion and Description of a Lock, that it was made to Lock or Unlok by that other Piece of Iron we call a Key, that it was Fitted to Open and Shut the Lock, and yet by these new Attributes there was not added any Real or Physical Entity, either to the Lock, or to the Key, each of them remaining indeed nothing, but the same Piece of Iron, just so Shap’d as it was before.9

In this passage, Boyle analogizes the relationship between sensible qualities and perceivers to the relationship between a lock and key. In this passage, Boyle states that the lock and the key each have the disposition to obtain a new capacity that they did not previously have, when one object is brought together with the other. When these two objects are brought together, the key obtains the capacity of opening the lock and the lock obtains the capacity of being opened by the key. These dispositions have nothing to do with any peculiar power residing in each of these objects independently but are due, instead, to the respective shapes of the objects in question. In the same way, sensible qualities are not ontologically distinct entities in material bodies but simply endow material bodies with the power to affect other bodies in particular ways, when they are brought together with those bodies under the right conditions.10 Alexander reads the passage as implying that the respective capacities acquired by the lock and key are nothing “over and above” their distinctive shapes and, thus, are entirely reducible to these shapes. Although these capacities are not manifest until the lock and key are brought together, he considers it wrong “to claim that this is any ontological addition.”11 Anstey not only disagrees with Alexander’s interpretation of this passage, but he also wonders why Alexander does not cite other passages that



8

For Peter Alexander’s discussion see his Ideas, Qualities, and Corpuscles.

9 Boyle, The Origin of Forms and Qualities, 309–​310.

10

See Ibid., 310.

11 Anstey, The Philosophy of Robert Boyle, 98.

116  The Chemical Philosophy of Robert Boyle suggest a non-​reductionist interpretation of sensible qualities. For example, in the An Introduction to the History of Particular Qualities, Boyle says the following: “Especially considering [. . .] that the qualities commonly called sensible, and many others too, being according to our opinion but relative attributes, one of these now mentioned alterations, though but mechanical, may endow the body it happens to with new relations both to the organs of sense, and also to some other bodies, and consequently may endow it with additional qualities [emphasis mine].”12 As is clear from this passage, Boyle does believe that there is ontological addition when the dispositional qualities of one body affect another body that is disposed to be thusly affected. In other words, the affected body will be endowed with additional qualities that it did not previously possess. For example, a body is said to have a particular sensible quality, say redness, when that body is disposed to affect the visual organs of a perceiver in such a way that, under the right conditions, the perceiver will experience the sensation of red. The presence of an idea of redness in the mind of the perceiver is an ontological addition, since this idea was not present prior to the interaction with the red object.13 Clearly, for the perception of color to occur, the perceiver must be disposed toward such a perception. Thus, if the material object is in the presence of a specific organism whose sense organs are not disposed to perceive color, color will not manifest in the material body with relation to that specific organism. So, color is both a dispositional and a relational quality, according to Boyle. Boyle’s belief that all sensible qualities are both dispositional and relational is grounded in his mechanistic corpuscularian ontology. To explain this, Anstey refers to the hierarchy of qualities, discussed in the first section of this chapter: First, there are mechanical properties of matter, then there are the relations between bodies and finally there are the sensible (and other non-​mechanical) qualities or powers. Now, Boyle constantly says things to the effect that the sensible qualities or powers are “derived from” or “deduced from” the mechanical affections. Thus, the mechanical affections seem to have some sort of ontological priority over the sensibles. Further, the sensible qualities or powers seem somehow to be dependent upon or identical to relations. So, relations seem to have some ontological priority over the sensibles. Finally, since it appears that relations cannot exist in the absence of relata, their relata seem to have some sort of ontological priority over the relations.14 12 Boyle, An Introduction to the History of Particular Qualities, 115. 13 As Anstey convincingly argues, Boyle accepts a dualist and representational view of perception, similar to that of Descartes and other 17th-​century philosophers. This is the reason why, in explaining the perception of redness, I have used language consistent with the dualist and representational theory. 14 Anstey, The Philosophy of Robert Boyle, 88.

Boyle’s View of Chemical Properties  117 For Boyle, then, the ontological base of qualities consists of the mechanical affections of fundamental particles. When such particles are structurally arranged to form corpuscular concretions, they endow the material body with the disposition to affect and/​or to be affected by other material bodies in specific ways. Thus, when the material body in question (agent) comes into relation with another body that is appropriately disposed (patient), the sensible qualities of either one or both material bodies will be altered according to the respective dispositions of these material bodies. I agree with Anstey that this account accurately reflects Boyle’s view on the origin of qualities. However, this account does not settle the question of reductionism/​non-​reductionism, because it happens to be compatible with both interpretations of non-​mechanical qualities. To settle the question in favor either of reductionism or of non-​reductionism, Anstey must answer the following queries: “Are sensible qualities or powers either reducible to or distinct from relations? And are relations either reducible to or distinct from the mechanical properties of their terms?”15 To answer these questions, one must examine whether Boyle regards non-​mechanical properties as ontologically distinct from their mechanistic base. It is in this regard that both Anstey and I would disagree with Alexander’s reductionist reading, according to which there is no distinctness between the non-​mechanical properties and their mechanistic base. Anstey, in fact, presents a very convincing argument in favor of a distinction, and I will now examine his argument in detail. Anstey begins by listing four logical possibilities regarding the ontological status of relations and of sensible qualities or powers, where R represents the reduction relation and D represents the distinctness relation. These four possibilities are:

1. R (Quality, Relation) and R (Relation, Relata) 2. R (Quality, Relation) and D (Relation, Relata) 3. D (Quality, Relation) and R (Relation, Relata) 4. D (Quality, Relation) and D (Relation, Relata)16

Keeping in mind that we are operating within a Boylean ontological framework, there are two ways to interpret this list of logical possibilities. The first way is to read the list as describing the various possibilities of reduction and distinctness with respect to a given material body and its dispositional qualities. Thus,

15 Ibid. 16 Ibid., 90. In my rendition of this list of possibilities, I differ from Anstey by using the term “quality” instead of “power,” though this is simply a preference and makes no difference to the argument itself, since both Boyle and Anstey use these terms interchangeably.

118  The Chemical Philosophy of Robert Boyle to the extent that the disposition to manifest a particular quality is a function of the microstructure or texture of corpuscular concretions and that this microstructure represents a particular relation between fundamental particles, the terms used must be read in the following manner: “Relata” refers to the fundamental corpuscles endowed only with mechanical affections, “relation” refers to the microstructure or texture in which the fundamental corpuscles are arranged to form corpuscular concretions, and “quality” refers to the particular non-​ mechanical quality that a given material body is disposed to manifest. Read in this way, possibility (1) tells us that there is nothing distinct from the mechanical affections at the ontological base and, thus, that qualities are reducible to relations and relations are reducible to relata. Since reduction is a transitive property, this would make qualities reducible to relata, in this case to the mechanical affections of fundamental particles. This is the reductionist account favored by Alexander, since it “collapses powers into relations which in turn collapse into their relata.”17 Possibility (2) tells us that since relations and relata are distinct, there is a “two-​tiered ontology,” to use Anstey’s term, in which qualities are reducible to relations but relations are distinct and not reducible to relata. Possibility (3) tells us that, since qualities are distinct from relations, there is a “two-​tiered ontology” in which qualities are not reducible to relations but relations are reducible to their relata. Finally, possibility (4) tells us that, since qualities are distinct from relations and relations are distinct from relata, there is a “three-​tiered ontology” in which qualities are not reducible to relations and relations are not reducible to relata. The only possibility that is fully reductionist is (1) and the only possibility that is fully non-​reductionist is (4), while (2) and (3) each involve some combination of reduction and non-​reduction. A second way to read this list is as describing the various logical possibilities of reduction and distinctness with respect to one body or material substance (agent) as it affects another body or material substance (patient). Read this way, the list deals with a higher ontological level of relata and relations and the terms must be read in the following way: “Relata” refers to the agent and the patient, “relation” refers to the contact between them, and “quality” refers to the manifest properties of the agent that affects the patient. After arguing that Boyle endorses neither possibilities (1), (2), or (3), Anstey defends possibility (4) as being the most representative of Boyle’s position, and he employs the notion of qualities as relational as a key element of his argument.18 Read as describing this higher ontological and relational level, possibility (4) tells us that the relation itself is 17 Ibid. 18 Ibid., 90–​108. Explaining Anstey’s arguments against possibilities (1), (2), and (3) would take me far beyond the scope of this chapter. However, once we accept the relationality of qualities in Boyle, this suffices to lend the bulk of the support to Anstey’s argument in favor of possibility (4), thereby making it unnecessary to discuss the arguments against the other possibilities.

Boyle’s View of Chemical Properties  119 “over and above the agent and the patient [which serve] as grounds of the relation [. . .] it is the distinctness relation (D) between the power and the relation that resists reduction [emphasis mine],”19 even if one were to concede that the relation is multilaterally reducible to its relata. With regard to this second reading, Anstey points out that the relationality of qualities is not “simply dyadic [. . .] but often involves many more relata than simply the agent and patient.”20 Following this discussion, Anstey cites passages from several works as textual evidence that Boyle supports this view of relationality. These include The Origin of Forms and Qualities, the History of Particular Qualities, and the Cosmical Qualities. In these passages, Boyle stresses repeatedly the point that bodies should not be considered in isolation but always as parts of the universe, if one is to understand the origin of sensible qualities. He claims that “every distinct portion of matter, whether it be a corpuscle of a primary concretion, or a body of the first, or of any other order of mixts, is to be considered not as if it were placed in vacuo, nor as if it had relation only to the neighbouring bodies, but as being placed in the universe, constituted as it is, amongst an innumerable company of other bodies.”21 He adds that “in reference to the Production of Qualities, a Body is not to be considered barely in it selfe, but as ’tis placed in, and is a portion of the Universe.”22 As Anstey points out, however, although this may make Boyle one of the first proponents of the relational conception of qualities, the question of the ontological status of relations is still open. Did Boyle consider relations to be reducible to relata? We do know that Boyle considered that all the relevant relata must be present for the relational quality to manifest. He states, “so most of those powers and attributes, that we call qualities in bodies, depend so much upon the structure or constitution of other bodies, that are disposed or indisposed to be acted on by them, that if there were no such objects in the world, those qualities in the bodies, that are said to be endowed with them, would be but aptitudes to work such effects.”23 Regarding sensible qualities, the presence of a perceiver is required in order for the disposition of an object to be manifested:  “if there were no Sensitive Beings, those Bodies that are now the Objects of our Senses, would be but dispositively, if I may so speak, endow’d with Colours, Tasts, and the like; and actually but onely with those more Catholick Affections of Bodies, Figure, Motion, Texture, &c.”24 Thus, the power of a material body to cause a percipient

19

Ibid., 105. Ibid., 108. 21 Boyle, History of Particular Qualities, 298. 22 Ibid. 23 Boyle, Of Mens’ Great Ignorance of the Uses of Natural Things, 479–​480. 24 Boyle, The Origin of Forms and Qualities, 319. 20

120  The Chemical Philosophy of Robert Boyle to experience a particular sensible quality is dependent upon the presence of a percipient, implying that “the sensible qualities are explicated by a relation to our senses.”25 Therefore, it is not only the existence of the relata, but also their presence in some proximity and in some type of relation to one another, that are required for the manifestation of sensible qualities. As Frederic O’Toole stresses, for Boyle “the possession of certain primary qualities, although a necessary condition for the possession of a power or capacity, is not, by itself, a sufficient condition for the possession of a power or capacity.”26 Thus, regarding sensible qualities, the presence of a perceiver appropriately disposed to be affected by the powers or qualities of a given object is necessary for that power or quality to be manifested. As mentioned earlier in this chapter, however, Boyle is not simply concerned with relations between objects and perceivers and with the qualities that manifest when such relations are actualized. As a chemist, Boyle is primarily concerned with relations between substances and with how the properties of such substances affect and are affected by one another. Thus, the question of whether chemical properties are dispositional and relational is an extremely relevant one. Although Boyle does regard chemical qualities as ontologically dependent upon mechanical properties, he does not believe that chemical reactions occur at the fundamental level of particles but that they take place between corpuscular concretions that are differentiated by virtue of the chemical properties to which they give rise.27 Additionally, Boyle’s many remarks regarding the producibility of chemical properties in compounds from ingredients that do not bear the properties in question suggests that Boyle possibly endorses a notion of chemical qualities as emergent properties, ontologically dependent upon but not deducible from or reducible to the mechanistic affections of shape, size, and mobility. Because Boyle refrains “from establishing a direct relationship between a given quality and a set of mechanical properties of the simplest corpuscles”28 and is openly critical of Epicureans and Cartesians who “pretend to explicate every particular Phaenomenon by deducing it from the Mechanicall affections of Atomes or insensible particles,”29 it is very likely that he also considered chemical properties to be dispositional and relational.



25 Anstey, The Philosophy of Robert Boyle, 104.

26

O’Toole, “Qualities and Powers in the Corpuscular Philosophy of Robert Boyle,” 312. See Newman, “The Alchemical Sources of Robert Boyle’s Corpuscular Philosophy,” 567–​585. 28 Clericuzio, Elements, Principles, and Corpuscles, 108. 29 Boyle, An Essay of Various Degrees or Kinds of the Knowledge of Natural Things, Vol. 8, folio 166r. 27

Boyle’s View of Chemical Properties  121

4.3  Chemical Properties as Dispositional and Relational As already stressed, the arguments that Anstey presents in favor of the dispositionality and relationality of sensible qualities can be used to argue for the dispositionality and relationality of chemical properties, as well as for the claim that chemical properties are not entirely reducible to the mechanical affections of primary particles or to texture tout court. As I will argue in this section, chemical qualities are just as relational as sensible qualities, since they are actualized only when two or more substances with the appropriate dispositions find themselves in each other’s presence and under the right conditions. For example, the water solubility of sugar is a dispositional property because it is only manifested when sugar is actually placed in unsaturated water. As is being stressed throughout this book, although Boyle endorses a mechanistic conception of fundamental matter, he is also a realist about chemical and other non-​mechanical properties and is strongly committed to the development of chemical explanations for chemical reactions and processes. Therefore, he is not satisfied with the idea of reducing all qualities and processes to the mechanical affections of fundamental particles. As was discussed in Chapter 2, strictly mechanistic explanations simply could not satisfactorily account for chemical phenomena, and early modern chemists, regardless of their commitment or lack of commitment to the mechanistic hypothesis, recognized the limitations of a strictly mechanistic philosophy. Thus, Boyle concurs with Paracelsians and other critics of strict mechanicism that chemical qualities and operations cannot be explained simply by invoking the mechanical properties of shape, size, and mobility. Therefore, although he was critical of the Paracelsian doctrine of principles and qualities, Boyle’s criticism “did not entail that all chemical properties were reducible to [. . .] mechanical attributes [. . .] [He presented] the idea that a quality had relative character, namely, that it was generated from the constant interaction of different corpuscles, which themselves might not bear the quality in question [and] he himself developed new and more sophisticated ways of detecting the chemical qualities of bodies.”30 For example, in his essay Of the Producibleness of Chymicall Principles, Boyle examines the various chemical properties of salts. Regarding solubility, he states that “a disposition to be dissoluble in this or that liquor may be acquired by mixture, and the new texture of parts.”31

30 Joly, “Chimie et mécanisme dans la nouvelle Académie royale des sciences:  les débats entre Louis Lémery et Etienne-​François Geoffroy,” 4: “Boyle n’invoque pas tant le mouvement et la forme des corpuscules que les qualités chimiques des diverses substances qui on la propriété de dissoudre, de précipiter ou de fixer. Bref, pour Boyle, l’explication chimique garde son autonomie et ne peut être explicitée en tant que telle.” 31 Boyle, Of the Producibleness of Chymicall Principles, 35.

122  The Chemical Philosophy of Robert Boyle One way in which non-​ mechanical secondary qualities, such as chemical properties, are dispositional is that they result from the way the primary particles are structured to form chymical atoms. If the disposition of particles is altered in any way, different chymical atoms will be produced and this will result in different chemical properties. Experiments involving analysis, synthesis, and redintegration all involve the restructuring of chymical atoms, that is, altering the dispositions of the minima naturalia. The redintegration of potassium nitrate, discussed in Chapter 2, can be examined from this perspective. The experiment illustrates, among other things, that the structural disposition or texture of concretions accounts for the chemical properties of a body and when these textures are altered either by breaking down the body into its component substances or by compounding the body with another body, the interaction of the different chymical atoms will produce different chemical qualities. Thus, redintegration requires a reassociation of the fixed and volatile parts according to their original dispositions. Another way in which Boyle considers non-​mechanical secondary qualities to be dispositional is that he regards them as powers to affect other bodies in specific ways. As Clericuzio explains, “Boyle maintained that chemical qualities depended [. . .] on the way in which the corpuscles that composed a given body were disposed to act upon, or to be acted on by, those of other bodies [. . .] [and that they] emerged from the constant interactions of corpuscles passing from one body to the other [. . .] [thus] he denied that they directly originated from the mechanical properties of their primary particles.”32 In an important passage from The Origin of Forms and Qualities, Boyle explains that neither sensible nor chemical properties have any ontological being of their own apart from the microstructure of the material body in which they subsist. However, he also adds that they cannot be said to subsist as such in the microstructure of the material body. Instead, the specific microstructure or texture endows the material body with the ability or disposition to affect or to be affected by other material bodies in specific ways. Boyle states: Whereas one Body doth often seem to produce in another divers such Qualities, as we call Sensible, which Qualities therefore seem not to need any reference to our Senses, I consider, that when one Inanimate Body works upon another, there is nothing really produc’d by the Agent in the Patient, save some Local Motion of its Parts, or some Change of Texture consequent upon that Motion; and so, if the Patient come to have any sensible Quality, that it had not before, it acquires it upon the same account, upon which other Bodies have it, and it



32

Clericuzio, “A Redefinition of Boyle’s Chemistry and Corpuscular Philosophy,” 588.

Boyle’s View of Chemical Properties  123 is but a consequent to this Mechanical Change of Texture, that by means of its Effects upon our Organs of Sense, we are induc’d to attribute this or that sensible Quality to it.33

Boyle reiterates this point later by saying that “Bodies of very differing Natures, being put together, like the Wheels, and other peices [sic] of a Watch, and by their connection acquiring a new Texture, and so new Qualities, may, without having recourse to a substantial Form, compose such a new Concrete, as may as well deserve to have a substantial Form attributed to it, by virtue of that new Disposition of its parts, as other Bodies that are said to be endow’d therewith.”34 The dispositions to affect and/​or to be affected in specific ways are due to the microstructures or textures of both the substances in question. However, such dispositions are manifested when the requisite material bodies come into contact with one another, under the requisite conditions. In this sense, the dispositionality of properties is intimately connected to their relationality. For example, Boyle tells us, some bodies have the disposition to be cathartic or purgative only when mixed with gold. Boyle accounts for the purgative power of the resulting mixture by appealing to the microstructures of the substances that have been mixed, which means substance A has the disposition to become purgative when mixed with gold, and that gold has the disposition to make substance A purgative. Applying the same analysis that Anstey gives for dispositional sensible properties, we can say that there is a “three-​tiered ontology” here, in which the purgative quality is distinct from the relation between substance A and gold, and in which the relation between substance A and gold is itself distinct from the individual relata. Clearly, there is no reducibility here, because neither substance A nor gold has the purgative quality apart from the relation in which the two substances are mixed. Furthermore, the mixed purgative substance has the disposition to purge the digestive system of an organism and the digestive system has the disposition to be purged by the mixture. The phenomenon of purging, however, is manifested only when the mixed substance and the digestive system of the organism come into contact with one another, under the right conditions. Thus, the same “three-​tiered ontology” analysis can be applied to the relation between the mixed purgative substance and the digestive system being purged. One problem with the kind of reductionist interpretation favored by Alexander and criticized by Anstey is that it would entail collapsing the distinction that Boyle clearly wants to affirm between primary mechanical qualities and secondary non-​mechanical qualities. We can illustrate this with an example that

33 Boyle, The Origin of Forms and Qualities, 320. 34

Ibid., 355.

124  The Chemical Philosophy of Robert Boyle Boyle discusses in The Origin of Forms and Qualities. This is the example of gold, which has a disposition to be soluble in aqua regia, a mixture of hydrochloric acid (HCl) and nitric acid (HNO3), and a disposition to be insoluble in aqua fortis, or concentrated nitric acid. Regarding these dispositions, Boyle states the following: I do not see, why we may not conceive, That as to those Qualities, (for Instance) which we call Sensible, though by virtue of a certain Congruity or Incongruity in point of Figure or Texture, (or other Mechanical Attributes,) to our Sensories, the Portions of Matter they Modifie are enabled to produce various Effects, upon whose account we make Bodies to be Endow’d with Qualities; yet They are not in the Bodies that are Endow’d with them any Real or Distinct Entities, or differing from the Matter it self. Thus though the modern Gold-​Smiths and Refiners reckon amongst the most distinguishing Qualities of Gold [. . .] that it is easily dissoluble in Aqua Regis, and that Aqua Fortis will not work upon it; yet these Attributes are not in the Gold any thing distinct from its peculiar Texture [. . .] There are some Bodies not Cathartick, nor Sudorifick, with some of which Gold being joyn’d acquires a Purgative Vertue, and with others a power to procure Sweat [. . .] Nature her self doth [. . .] produce so many things, that have new Relations unto others; And Art, especially assisted by Chymistry, may, by variously dissipating Natural Bodies, or Compounding either them, or their Constituent Parts with one another, make such an Innumerable Company of new Productions, that will each of them have new operations, either immediately upon our Sensories, or upon other Bodies, whose changes we are able to perceive.35

As O’Toole points out, “to identify the powers and capacities of corporeal objects with certain of their primary qualities is to collapse the distinction between what an object will do or will have done to it and what is in itself. That is, it is to assert that what a thing can do or have done to it is nothing distinct from what it is in itself.”36 This would entail collapsing the distinction between objects and dispositions, and an absurd conclusion would ensue from this. Since the texture constitutes what an object is in itself, collapsing the distinction between an object and its dispositions would mean collapsing the distinction between its texture and its dispositions. Since identity is a reflexive and transitive relation, if we interpret Boyle’s words in reductive terms and argue that qualities collapse with texture, this would lead to the conclusion that:



35

36

Ibid., 310–​311. O’Toole, “Qualities and Powers in the Corpuscular Philosophy of Robert Boyle,” 311.

Boyle’s View of Chemical Properties  125 1. Texture of gold (T) = Disposition to be soluble (S) 2. Texture of gold (T) = Disposition to be insoluble (−S) /​ ∴ 3. T = S and T = −S The conclusion that texture is equal to two opposite dispositions is clearly absurd. Further, if we attempt to avoid this conclusion by saying that there is no distinction between disposition to be soluble and the disposition to be insoluble (S = −S), then we fall into another absurdity. These problematic conclusions clearly result from the fact that one is ignoring the relationality of these dispositions and that new relations lead substances to acquire novel dispositional properties. Once relationality is introduced, the contradiction is avoided thus: 1. Texture of gold (T) = Disposition to be soluble in relation to aqua regia (Sar) 2. Texture of gold (T)  =  Disposition to be insoluble in relation to aqua fortis (−Saf ) /​ ∴ 3. T = Sar and T = −Saf Gold has the disposition to be soluble in relation to aqua regia, and it has the disposition to be insoluble in relation to aqua fortis. Clearly, it is the texture of gold that brings about these dispositions. However, the texture of gold must be brought into relation with the texture of aqua regia in order to be disposed to solubility. This means that the texture of gold reacts with that of aqua regia in such a manner that the gold is dissolved. As well, the texture of gold must be brought into relation to aqua fortis in order to be disposed to insolubility. Again, this means that, when the texture of gold is brought into such a relation, no reaction occurs and the gold is not dissolved. Though Boyle might explain this in mechanical terms by speculating that the texture of the chymical atoms fits differently with that of aqua regia than it does with that of aqua fortis, it is still the case that neither disposition exists apart from the relation that permits its manifestation, since it is within the world as a whole that a body has its secondary qualities. Besides leading to absurd conclusions, however, collapsing the distinction between objects and dispositions would, in turn, also mean collapsing the distinction between inherent qualities and non-​inherent qualities, which is something that Boyle does not wish to do. If he wished to collapse all qualities thusly, Boyle would not have bothered drawing distinctions between different types of qualities in the first place. Instead, as O’Toole suggests, Boyle identifies “certain of the primary qualities of an object [i.e., texture] as the properties in virtue of which the object can do or have done to it what it does.”37 Thus, the texture of gold is

37 Ibid.

126  The Chemical Philosophy of Robert Boyle the property in virtue of which gold is disposed to be soluble in aqua regia and to be insoluble in aqua fortis. Put differently, gold’s disposition to be soluble in aqua regia and insoluble in aqua fortis is not ontologically the same thing as the texture of gold but, rather, is a function of this texture. As I will argue later in this chapter, the disposition to be soluble or insoluble should also be considered as an emergent property that supervenes upon the texture. It would also follow from the reductionist collapse of non-​mechanical properties with texture that all non-​mechanical properties, including chemical properties, would simply be epiphenomal and would have no causal power. However, chemical properties obviously have causal power and must, therefore, not be simply epiphenomenal. In fact, Boyle stresses the validity and autonomy of chemistry as natural philosophy precisely because chemical properties not only have causal power but also have a greater heuristic and explanatory power than do the mechanical affections of minima naturalia. This is precisely why Boyle invokes non-​mechanical properties almost exclusively in his chemical, hydrostatic, and pneumatic experimental accounts. As already stated, Boyle stresses that chemical dispositions are actualized when substances are brought into the appropriate relations with one another. He illustrates this with an experiment in which sulfur and salt of tartar are mixed together, thereby acquiring the property of being soluble in spirit of wine, a property that neither substance manifests prior to the mixture, although Boyle attributes the acquisition of solubility to an alteration in the structure of the compound corpuscles or chymical atoms of both the sulfur and the salt of tartar that results from these substances being mixed together. This example shows that solubility is indeed a novel property that would not be manifested in the absence of the appropriate chemical relations. This establishes that, for Boyle, chemical properties such as solubility, fixedness, and others are both dispositional and relational, since they arise from the relation between appropriately disposed chemical substances. In other words, the disposition to manifest a specific quality or property is a function of the relation of substance A to substance B. In the absence of this relation, the property does not manifest. However, we may be tempted at this point to accuse Boyle of the same circularity of which Aristotle is guilty when discussing dispositional properties. In the context of Aristotelian science, a body A is said to affect a body B in specific ways, because A is disposed to affect B and B is disposed to be affected by A precisely in those ways. Such circularity made Aristotelian science completely ineffective for explaining causal relationships. It might be tempting to say that Boylean explanations are as circular and vacuous as the Aristotelian explanations. However, I would argue that Boyle is not guilty of circularity because, although Aristotle offers no further explanation regarding why bodies are disposed to affect and be affected by other bodies in specific ways, Boyle does

Boyle’s View of Chemical Properties  127 offer such an explanation beyond merely saying that the dispositions are there. His explanation, as has already been stated, is that the various dispositions of bodies to manifest qualities and to either affect or be affected by other bodies derive or emerge from the microstructure or texture of their corpuscular concretions and from the way those structures are altered or are affected when those bodies come into contact. I grant that it is precisely the causal powers of the corpuscular concretions that are unknown or perhaps even unintelligible. However, Boyle’s postulation of unobservable theoretical entities and causal powers in order to explain observed dispositional properties is, in principle, no more vacuous than any other scientific postulation of theoretical entities to explain observed phenomena. Returning to the discussion of relationality, there is another and more complex way in which chemical properties can be said to be relational. The relationality of chemical properties is not only a feature of the relation between chemical substances but is also a feature of the relation between the chemical substances, the experimental environment in which those substances are placed in relation with each other, and the actions of the chemist in relation to the goals of the experiment. To examine this aspect of relationality, let us consider Steven Shapin’s discussion of the generation of “matters-​of-​fact” in the context of Boyle’s experimental programme. Though Shapin’s discussion focuses on the production of pneumatic “matters-​of-​fact” via experiments with the air-​pump, the same analysis can be applied to the generation of chemical “matters-​of-​fact.” As Shapin insightfully notes, Boyle and his colleagues at the Royal Society were profoundly aware that the phenomena and processes that they witnessed via their experimental work were very much “artifacts” of the experiments. To elevate these “artifacts” to the status of “matters-​of-​fact,” experimenters needed to use various strategies that would present their experimental results in a manner that decontextualized them from the experimental conditions within which they were generated. Specifically focusing on Boyle’s experiments with the air-​ pump, Shapin explains that “Boyle’s experimental programme had as its end-​ product the generation of indisputable matters of fact [. . .] in the setting of early Restoration England there was no one solution to the problem of knowledge that commanded universal assent [. . .] Boyle sought to secure universal assent by way of the experimental matter of fact [. . .] [However,] Boyle’s matters of fact were machine-​made.”38 As Shapin points out, however, “what makes a fact different from an artifact is that the former is not perceived to be man-​made [. . .] a matter of fact is taken to be the very mirror of nature. To identify the role of human agency in the making 38 Shapin, “Pump and Circumstance:  Robert Boyle’s Literary Technology,” 481–​ 520. See also: Shapin and Schaffer, Leviathan and the Air-​Pump.

128  The Chemical Philosophy of Robert Boyle of an item of knowledge is to identify the possibility of its being otherwise. To shift agency on to natural reality is to stipulate the grounds for universal assent.”39 Shapin then goes on to discuss the various material, literary, and social technologies employed by Boyle and his assistants to ensure that the man-​made artifacts of the experiment would be perceived as natural matters-​of-​fact. A discussion of these various technologies would take us beyond the scope of this chapter. However, one can extend Shapin’s general analysis of Boyle’s pneumatic experiments to the generation of matters-​of-​fact in the chemical laboratory. Doing this will allow us to understand better the complex layers of relationality of chemical properties. Applying Shapin’s analysis to the generation of chemical “matters-​of-​fact,” the solubility of the mixture of sulfur and salt of tartar in spirit of wine is an “artifact” of the actions of the chemist and of the experimental conditions. It is not likely that such conditions would ever be reproduced in nature, as it is highly improbable that such substances would ever be mixed outside of the context of a scientific experiment in which the sole purpose is precisely to render them soluble in spirit of wine. Thus, the solubility of this mixture in spirit of wine is an artifact of the experiment and is, therefore, relational in an even more complex manner than described so far. The quality of being soluble, in this experiment, results not only from the relation in which the complex corpuscles find themselves but also from the relation with the actions of the chemist and with the very specific experimental conditions. It is only when the results of this experiment are presented as matters-​of-​fact that the chemist’s actions and the experimental conditions in which these artifacts were generated are “written out” of the account and the mixture’s solubility is presented as though it were a simple “matter-​of-​fact” discovered by Boyle. One of the most interesting concepts used to discuss the relationality of properties in the contemporary philosophy of chemistry is the concept of affordance.40 The concept of affordance was introduced in contemporary scholarship by psychologist James J. Gibson, who defines it as what an environment offers to an animal as a possibility for action.41 Affordances are, therefore, dispositional and relational and characterize the suitability of an environment for a particular observer, although Gibson emphasizes that affordances are observer-​independent and not subjective. Gibson theorizes that human beings and other animals alter

39 Shapin, “Pump and Circumstance,” 507–​508. 40 See, for example, Harré, “New Tools for Philosophy of Chemistry”; Earley, “Why There Is No Salt in the Sea”; Llored, “Emergence and Quantum Chemistry,” “Whole-​Parts Strategies in Quantum Chemistry,” and “Relations, caractérisations, et ‘affordances’ ”; Bensaude-​Vincent, “Philosophy of Chemistry or Philosophy with Chemistry?”; and van Brakel, “Philosophy of Science and Philosophy of Chemistry.” 41 Gibson, “The Theory of Affordances.”

Boyle’s View of Chemical Properties  129 and modify their environments to increase the action possibilities that the environment affords to them. Rom Harré, who has also written extensively in the philosophy of psychology, appropriates the notion of affordance as a conceptual tool for the philosophy of chemistry. According to Harré, “adopting the concept of ‘affordance’ to analyze the nature of chemical studies, it becomes clear that chemical ‘facts’ are attributes not of an independent world revealed by the use of an apparatus, but are dispositional properties of a hybrid entity—​an indissoluble union of apparatus, experimenter, and world . . . when the apparatus is being put to use by a chemist it is related to the world in such a way that the phenomena it displays can exist only as the apparatus in integrated materially into the world.”42 What is interesting about this, however, is that the notion of affordance as a useful conceptual tool for chemistry does not seem all that new. In fact, Boyle avails himself quite extensively of the notion of “affordance” in his chemical writings, as far back as The Sceptical Chymist. Since the concept of affordance is inherently relational and dispositional, it can be argued that, even in his earlier works, Boyle appeals to a relational and dispositional notion of chemical qualities. In fact, in The Sceptical Chymist, the relational and dispositional concept of affordance is used precisely to critique the notion of substantial forms and spagyric principles. For example, as part of this critique of the Paracelsian notion of the Alkahest, as the substance that is able to “resolve all mixt Bodies into other Principles than the fire,”43 Boyle states “although we should acquiesce in that resolution which is made by fire, we find not that all mixt bodies are thereby divided into the same number of Elements and Principles; some Concretes affording more of them than others do; Nay and sometimes this or that Body affording a greater number of Differing substances by one way of management, than the same yields by another [emphasis mine].”44 Elsewhere in the same work, Boyle states that “sometimes by corrosive Liquors . . . and sometimes by the operation of common Sulphur (especially well open’d and associated with fit Salts) Silver has afforded some grains of very pure Gold [emphasis mine].”45 In another of his chemical writings, while describing an experiment with saltpeter, Boyle states, “we dissolv’d in fair water as much fix’d Nitre as we could, and filtrating the Solution through Cap-​paper we satiated with Spirit of Nitre, after the manner above describ’d, and then setting it to evaporate very slowly, and afterwards suffering it to cool, we obtain’d within some hours after the first mixture of the Liquors, store of fine little Crystalls of Petre, which shot in the Liquor; the remaining part of which being evaporated afforded more of them.”46 There 42 Harré, “New Tools for Philosophy of Chemistry,” 79. 43 Boyle, The Sceptical Chymist, 343. 44 Ibid. 45 Ibid., 58. 46 Boyle, “Some Specimens of an Attempt to Make Chymical Experiments Useful to Illustrate the Notion of the Corpuscular Philosophy,” 97.

130  The Chemical Philosophy of Robert Boyle are countless more example in The Sceptical Chymist and other works that are too many to cite here. The fact that Boyle relies so often on the concept of affordance, which many contemporary philosophers of chemistry consider to be an invaluable tool for conceptualizing relationality and dispositionality, is evidence that his work is still relevant today for philosophy of chemistry. It is, indeed, important also to point out that Boyle is one of the first natural philosophers to recognize the relationality of chemical properties. However, because many readers of Boyle have limited themselves to The Origin of Forms and Qualities, they conclude mistakenly that the mechanistic lock-​and-​key analogy provided by Boyle in this essay exhausts his account of the relationality of qualities. However, a more accurate understanding of relationality requires examining other texts, in which Boyle stresses the role played by the surrounding environmental conditions in determining the dispositions of both agent and patient. I will explain this in the next section, in which I propose that Boyle regards chemical qualities as emergent and supervenient properties.

4.4  Chemical Properties as Emergent and Supervenient As mentioned earlier in this chapter, to establish Boyle as a non-​reductionist, one must also establish that he regards chemical properties as being emergent, and this is what I hope to demonstrate in this section. It should be emphasized that the issues of emergence and reducibility are themselves closely related to the more general issues of the autonomy of chemical explanations and of chemistry as a science. The reducibility of chemical laws to physical laws would necessitate that physical laws be universal and fundamental, and that all laws in the special sciences be non-​ fundamental instantiations of these more general and universal physical laws. Given what has been said so far regarding Boyle’s view of the nature of chymical atoms, it seems that Boyle would side against the view that chemical laws are reducible to the laws of mechanics and, thus, in favor of the idea that at least some chemical laws can be considered operationally fundamental and irreducible. While the strict mechanistic philosopher posits a single fundamental law, or few such laws, the emergentist allows that there could be a great many laws that are operative in nature. A strict mechanistic approach to chemistry would conclude that just a few laws suffice to determine the behavior of all chemical substances and chemical compositions. Accordingly, it should be possible to deduce the behavior of all chemical substances simply by turning to the few laws of mechanics that govern fundamental particles. An emergentist, however, will favor the view that at least some fundamental laws that describe the behavior of chemical substances

Boyle’s View of Chemical Properties  131 are not merely instances of the more general and fundamental laws of mechanics.47 With regard to this issue, I firmly believe that Boyle would side with the emergentist position and I will base my discussion on what has already been stated regarding his chemical ontology and on his views of qualities as dispositional and relational. What I hope to show is that his notion of chemical properties allows Boyle (1) to more clearly conceptualize the result obtained from his own chemical experiments, (2) to assert the autonomy of chemical explanations from mechanical explanations, and, therefore, (3) to assert the legitimate status of chemistry as an autonomous science that is operationally and epistemologically, if not ontologically, independent from mechanics. To strengthen the argument that Boyle considers chemical properties to be emergent, we must examine what the concept of emergence entails and whether Boyle’s conception of chemical properties conforms to the concept of emergence. Stated in general terms for our purposes here, the central tenets of emergentism are the following:

1. Emergence of novel higher-​level properties 2. Non-​deducibility of emergent properties 3. Irreducibility of emergent properties 4. Causal efficacy of emergent properties

The concept of emergence also entails several interdependent features, which are related to the general features described earlier. The first of these features is novelty, that is, the component parts of a substance do not display the emergent property of that substance. The second feature of emergence is unpredictability, which is related to the notion of non-​summative difference between the supervenient properties and the “subvenient” properties of the submergent base. In other words, the supervenient properties are not those of the submergent base nor can they be additively derived from the properties of the base. The third feature of emergence is the metaphysical relation of supervenience, that is, “a relation of determination and dependence of one set of properties on another.”48 The first question for us, then, is whether Boyle regards chemical properties to be novel features of chymical atoms that are not displayed by the component particles. In Of the Imperfection of the Chemists’ Doctrine of Qualities, Boyle openly critiques the conception of qualities embraced by “chemists,” that is, by Peripatetics and Paracelsian alchemists and spagyrists. Here, Boyle argues against the idea that the properties of material bodies, including chemical 47 See Hendry, “Is there downward causation in chemistry?,” 179. I am here referring to Hendry’s point about downward causation in chemistry to set the context for my discussion of Boyle’s position. 48 Newman, “Chemical Supervenience,” 49.

132  The Chemical Philosophy of Robert Boyle properties, can be simply deduced from the ingredients of which those bodies consist. He states: I shall venture to add that the way employed by the chemists, as well as the Peripatetics, of accounting for things by the ingredients—​whether elements, principles, or other bodies—​that they suppose them to consist of, will often frustrate the naturalist’s expectation of events, which may frequently prove differing from what he promised himself upon the consideration of the qualities of each ingredient. For the ensuing notes contain divers instances, wherein there emerges a new quality differing from, or even contrary to, any that is conspicuous in the ingredients: as two transparent bodies may make an opacous mixture; a yellow body and a blue, one that is green; two malleable bodies, a brittle one; two actually cold bodies, a hot one; two fluid bodies, a consistent one, &c. [emphasis mine].”49

I call the reader’s attention, here, to Boyle’s explicit use of the term “emerges” in reference to qualities or properties. We should also take note of the examples he uses, of both sensible and chemical qualities, to illustrate the point that something new is indeed produced when two distinct substances are mixed together, that is, a new quality is produced that was not possessed by either of the two substances individually. What accounts for the new quality, as Boyle explains in the following passage, is the alteration of the corpuscular concretions upon mixing the two distinct substances: divers qualities may be changed even in such constant bodies as metals, without the addition of any considerable proportion of the simple ingredients to which they [spagyrists] are wont to ascribe those qualities, provided the agent (as an efficient rather than material cause) be able to make a great change in the mechanical affections of the parts whereof the metal it acts on is made up [. . .] changes it produces in the constituent texture of it [. . .] the chemists’ salt, sulphur and mercury themselves are not the first and most simple principles of bodies, but rather primary concretions of corpuscles or particles more simple than they, as being endowed only with the first or most radical (if I may so speak) and most catholic affections of simple bodies, namely bulk, shape, and motion or rest, by the different conventions or coalitions of which minutest portions of matter are made those differing concretions that chemists name salt, sulphur, and mercury.50



49 Boyle, Of the Imperfection of the Chemists’ Doctrine of Qualities, 129. 50

Ibid., 131–​132.

Boyle’s View of Chemical Properties  133 There is plenty of textual evidence to demonstrate that, in fact, Boyle does consider both sensible and chemical qualities to be novel properties that are not displayed by minima naturalia. Let me add that this view of chemical and other non-​mechanical qualities as “novel” properties has significant mereological implications that will be discussed in more detail in the final chapter. Now, however, let us examine whether chemical properties do indeed display novelty. In the Mechanical Origin and Production of Volatility and Fixedness, Boyle claims that “the same material parts of a corporeal substance, which, when associated and interwoven after a determinate manner, constituted a solid and fixed body [. . .] may by having their texture dissolved, and by being freed from their former implications or cohesions, become the parts of a fluid body, totally volatile.”51 Elsewhere, he states that “whatever be the number or qualities of the chemical principles, if they be really existent in nature, it may very possibly be shewn, that they may be made up of insensible corpuscles of determinate bulks and shapes; and by the various coalitions and contextures of such corpuscles [. . .] the very qualities of this, or that ingredient, flow from its peculiar texture [emphasis mine].”52 Although Boyle clearly affirms the ontological dependence of chemical properties on mechanical affections, he “also maintains that chemical qualities depended more on the way in which the corpuscles that composed a body were disposed to act on, or to be acted on by, those of other bodies [. . .] He believes that chemical qualities emerge from the constant interaction of corpuscles by passing from one body to the other.”53 As he states, in The Origin of Forms and Qualities: the Colour, Odour, Tast, and other qualities of that Body are to be deriv’d, it will be easie for us to recollect, That such Changes cannot happen in a portion of Matter, without so much varying the Nature of it, that we need not deride the ancient Atomists, for attempting to deduce the Generation and Corruption of bodies from [. . .] the transposition of their (suppos’d) Atoms [. . .] according to us, the various manner of the Coalition of several Corpuscles into one visible Body is enough to give the a peculiar Texture, and thereby fit them to exhibit diverse sensible Qualities, and to become a Body, sometimes of one Denomination, and sometimes of another.54

Boyle offers further examples of the novel and emergent character of chemical qualities when, in discussing salinity, he proposes that:



51 Boyle, The Mechanical Origin and Production of Volatility and Fixedness, 373.

52 Boyle, About the Excellency and Grounds of the Mechanical Hypothesis, 454–​455. 53

Clericuzio, “A Redefinition of Boyle’s Chemistry and Corpuscular Philosophy,” 588.

54 Boyle, The Origin of Forms and Qualities, 328–​332.

134  The Chemical Philosophy of Robert Boyle whether we allow the Epicurean Hypothesis or the Cartesian; the first Saline Concretions that were produc’d by Nature must be confess’d to have been made of Atomes, or of Particles, that before their conjunction, were not Saline [. . .] small portions of matter may be so broken into minute, and these fragments may be so shap’d and connected, as, when they are duely associated, to compose a Body capable of being dissolved in water, and of affecting the organs of Taste.55

Like other chemical properties, the property of salinity cannot simply be accounted for mechanistically but clearly emerges from the texture of specific corpuscular concretions. In fact, Boyle’s “aim was to reject the notion that sensible qualities were reducible to this or that ingredient of a mixed body. He clearly put forward the idea that a quality had relative character, namely, that it was generated from the constant interaction of different corpuscles, which themselves might not bear the quality in question.”56 As has been argued extensively, for Boyle, chemical properties are indeed novel properties that are distinct from the mechanical affections of the submergent base, and these emergent properties are not merely epiphenomenal since they have causal power. Furthermore, such properties have an explanatory power in chemical reactions that the mechanical affections do not have, which is why Boyle never directly appeals to the mechanical affections of prima naturalia in his chemical explanations. Thus, “Boyle maintained chemical qualities depended more on the way in which the corpuscles that composed a given body were disposed to act on, or to be acted on by, those of other bodies  .  .  .  He thought that chemical qualities emerged from the constant interactions of corpuscles passing from one body to another. Accordingly  .  .  .  he denied that they directly originated from the mechanical properties of their primary particles.”57 In his essay on The Origin of Forms and Qualities, Boyle explains that, because fundamental matter “being in its own nature but one, the diversity we see in bodies must necessarily arise from somewhat else, than the matter they consist of.”58 The diversity in chemical and sensible qualities arises from the specific way the first-​order corpuscles coalesce to form primary concretions or second-​order corpuscles. He, in fact, “refrained from establishing a direct relationship between a given quality and a set of mechanical properties of the simplest corpuscles.”59 Additionally, his many remarks regarding the producibility of chemical principles in compounds from ingredients that do not bear

55 Boyle, The Producibleness of Chemical Principles, 34.

56

Clericuzio, “A Redefinition of Boyle’s Chemistry and Corpuscular Philosophy,” 564. Ibid., 588. 58 Boyle, The Origin and Forms of Qualities, 460. 59 Clericuzio, Elements, Principles, and Corpuscles, 108. 57

Boyle’s View of Chemical Properties  135 the qualities in question further supports the view that he endorses a notion of chemical properties as emergent, that is, as ontologically dependent upon but not reducible to the submergent base. Boyle clearly states that “things may acquire by mixture very differing qualities from those of any of the ingredients.”60 However, although we have established that Boyle regards chemical properties to be novel features of chymical atoms that are not displayed by the component particles, this is not enough to establish that he regards chemical properties to be emergent properties. To do so, we must answer a second question, that is, whether Boyle regards chemical properties as supervenient, that is, whether chemical properties are determined by and dependent upon the mechanistic properties of the lower-​level mechanistic base. To the extent that, for Boyle, any change in chemical qualities requires a change in the mechanical property of texture or structure of chymical atoms, it would seem that chemical properties display this crucial feature of emergence, that is, supervenience. In The Mechanical Origin and Production of Volatility and Fixedness, Boyle claims that “the same material parts of corporeal substance, which, when they were associated and contexed [. . .] after such a determinate manner, constituted a solid and fixt body, as a Flint or a lump of Gold; by having their Texture dissolved, and (perhaps after being subtilized) by being freed from their former implications or firm cohesions, may become the parts of a fluid body totally Volatile.”61 For Boyle, chemical qualities clearly supervene on mechanical qualities, that is, any change in chemical qualities requires a change in the mechanical properties of the submergent base, namely, a change in the secondary mechanical property of texture or structure. Thus, if we wish to say that Boyle regards chemical properties as emergent, we must also establish that he considers chemical properties to be novel and causally efficacious properties that cannot be deduced from or reduced to the submergent base of mechanistic particles. The third question we must answer is whether, for Boyle, chemical properties display non-​summative difference from the properties of the subvenient base. To establish that Boyle believes this, we must argue that for him chemical properties are not properties of minima naturalia nor can they be additively derived from the mechanistic properties of minima. As established in Chapter 3 and in Section 4.2 of this chapter, to the extent that the same fundamental corpuscles can, in principle, be compounded into differently structured chymical atoms whose chemical properties will vary according to these structures, it follows that the chemical properties of a body cannot simply be deduced from the fundamental mechanistic particles that compose it but are a function of the structure of chymical

60 Boyle, Letters and Papers of Robert Boyle, 270.

61 Boyle, The Mechanical Origin and Production of Volatility and Fixedness, 373.

136  The Chemical Philosophy of Robert Boyle atoms. Thus, it is the structural disposition or texture of the particles that accounts for the emergence of chemical properties in compounded corpuscles that are not attributable to the mechanical affections of minima naturalia. Boyle makes this plainly clear when he states that “we can little better give an account of the phaenomena of many bodies, by knowing what ingredients composed them, than we can explain the operations of a watch, by knowing how many, and of what metals the balance, the wheels, the chain, and other parts are made of,”62 making it also clear that a facile reductionism is not entailed by an adherence to the mechanical philosophy. One of Boyle’s reasons for preferring the mechanical hypothesis to the spagyrist notion of the tria prima is that the mechanical hypothesis provides a superior explanation for the great variety of material bodies and their qualities than the idea that there are only three unvarying fundamental principles. Boyle clarifies this by pointing out that, although shape, size, and mobility refer to only three principles, each of these can take many distinct forms, thereby giving rise to a numerous variety of mechanical affections of primary particles. Thus, the shapes of primary particles are varied, as is their size and the speed of their motions. When prima naturalia of various sizes and shapes are brought together into corpuscular concretions, their textures or microstructures will be as numerous and diversified as the possibilities of combinations are numerous. These varying structures give rise to the great variety of material bodies with their respective variety of sensible, chemical, and other non-​mechanical qualities. This variety of properties, however, would not be possible if the properties of the whole were simply summatively equal to the properties of the parts. Boyle states, “if it be said that these ingredients, by the texture resulting from their mixtures, may acquire qualities that neither of them had before, I shall answer that to allege this is in effect to confess that they must take in the Mechanical principles (for to them belongs the texture or structure of bodies) to assist the chemical ones.”63 Thus, far from believing that mechanical principles are incompatible with the notion of emergent chemical qualities, Boyle is confident that the emergence of chemical qualities is best explained via the mechanical principle of structure. This represents both Boyle’s affirmation of and commitment to mechanistic corpuscularianism and his clear departure from a strictly reductionist approach to chemical explanations. Despite some arguments made to the contrary,64 Boyle’s reliance on chemical explanations in terms of higher-​level non-​mechanical properties does not

62 Boyle, About the Excellency and Grounds of the Mechanical Hypothesis, 454. 63 Boyle, Of the Imperfection of the Chemists’ Doctrine of Qualities, 133. 64 See, e.g., Chalmers, “Boyle and the Origins of Modern Chemistry” and “The Lack of Excellency of Boyle’s Mechanical Philosophy.”

Boyle’s View of Chemical Properties  137 render him any less committed to the mechanical hypothesis as a grounding theory. Let us recall here the discussion in Chapter 2 of both the negative and the positive heuristic role of the mechanical philosophy in Boyle’s scientific research programme. Thus, his confidence in the emergent character of chemical properties is, above all else, evidence of his anti-​reductionism and commitment to providing chemical, rather than mechanical, explanations. However, as William Newman explains, “it does not follow from the fact that these explanations are not based on the catholic affections of the prima naturalia that they are not mechanical.”65 Texture is, after all, considered a “mechanical affection” to the extent that textural changes are changes in the spatial relations between particles. The interpretation of Boyle’s explanations as non-​mechanistic is based on the erroneous assumption that all mechanistic explanations must perforce be reductive. Newman also points out that If we look at the vast majority of Boyle’s experimental demonstrations of the mechanical origin of qualities, it is precisely such aggregate corpuscles that usually come into discussion [.  .  .] aggregate corpuscles distinguished by their chymical properties, not initial atoms having primary qualities alone. Nonetheless, it is the “mechanical texture” formed by the association of these finely ground particles that produces the explosiveness of gunpowder [. . .] The radical disjunction claimed by some scholars to exist between Boyle’s mechanical philosophy and chymistry is in fact illusory.66

For Boyle, a commitment to the mechanical hypothesis is perfectly compatible with a chemical philosophy grounded in chemical explanations that are not simplistically reductionist, and he defends this compatibility by stating that “the mechanical principles are so universal, and therefore applicable to so many things, they are rather fitted to include, than necessitated to exclude, any other hypothesis, that is founded in nature, as far as it is so.”67 As Joshua Gregory notes, for Boyle “a principle was required to clothe the naked corpuscles into the richness of nature. if Demokritos were right, physically real magnitudes might have no sensible qualities [. . .] if fresh corpuscular dispositions were not connected with new qualities, the originally naked corpuscular mechanism was an utterly incompetent conception.”68 What is interesting about Boyle’s conception of chemical qualities, specifically as it relates to his chemical experiments, is that he does not seem to embrace a simplistic



65 Newman, Atoms and Alchemy, 188–​189. 66 Ibid.

67 Boyle, About the Excellency and Grounds of the Mechanical Hypothesis, 453. 68

Gregory, “The Animate and Mechanical Models of Reality,” 310–​311.

138  The Chemical Philosophy of Robert Boyle dichotomy of reduction/​emergence but, rather, is able to adapt the mechanistic hypothesis to his practical chemical endeavors by working out a hybrid ontology of fundamental particles with strictly mechanistic properties and corpuscular concretions from which emerge causally efficacious chemical properties. As William Newman has so aptly stated, “it is clear that we can no longer accept the view that Boyle’s corpuscularism was simply a ‘physicist’s theory’ grafted by him onto a purely qualitative chemistry.”69

4.5  Supervenience, Non-​Summative Difference, and Underdetermination Because we are arguing that supervenience is a feature of emergence and because emergence is conceived as an ontological feature of the world, whereas unpredictability and derivability are epistemic notions, it is best to speak of supervenience in terms of ontological underdetermination. Following Achim Stephan, Robert Francescotti advocates replacing “the unpredictability constraint with the following underdetermination thesis:  the emergent properties of the whole are underdetermined by the properties of its proper parts [. . .] The crucial question [therefore] is whether the properties of the parts at one time underdetermine the properties of the whole at that same time.”70 This underdetermination is accounted for precisely through the notion of relationality. In fact, emergence and supervenience, understood in terms of relationality, are keys to answering the questions of the reducibility of higher-​level properties to lower-​ level structures. Although the phenomena, reactions, and processes studied by chemists “are thought to be ontologically dependent upon relationships at the primary level [. . .] supervenience allows us the virtue of ontological dependence, without the vice of explanatory reduction.”71 To the extent that chemical species, understood as wholes, display properties that are underdetermined by their component parts, the fundamental laws that govern the individual parts cannot, even in principle, permit us to deduce a complete account of the behavior of the chemical species. As Michel Bitbol explains, “there may exist differences between global states without any corresponding differences between the local states that are supposed to underpin them [. . .] Properties and states cannot be treated as preexistent intrinsic features. They must be construed as relational.”72 To connect this claim to our discussion of



69

Newman, “The Alchemical Sources of Robert Boyle’s Corpuscular Philosophy,” 585. Francescotti, “Emergence,” 52–​53. 71 Scerri and McIntyre, “The Case for the Philosophy of Chemistry,” 224. 72 Bitbol, “Downward Causation without Foundations,” 13. 70

Boyle’s View of Chemical Properties  139 Boyle, it is clear that the few laws supposed by the mechanical philosophy to determine the physical constitution of chemical wholes would not suffice to account completely (or, perhaps, even partially) for the behavior of such wholes. Therefore, if such fundamental physical laws do not suffice to explain the behavior of chemical species and if only uniquely chemical laws can satisfactorily provide such explanations, then Boyle is able to affirm the autonomy of chemistry from the mechanical philosophy even if chemical wholes are ontologically dependent upon mechanistic parts. As Mario Bunge has said with regard to contemporary chemistry, but which also applies to early modern chemistry even under the umbrella of the mechanical philosophy, “if it were possible to define every chemical concept in terms of physical concepts, and deduce every chemical law statement from a set of physical premises, chemistry would still keep its peculiar referents (chemical systems), methods (e.g., acidity measurement and neutralization), and goals (e.g., understanding and controlling chemical syntheses).”73 What I propose to do in the next, and final, section of this chapter is argue that Boyle regards not only chemical properties but also cosmical qualities, like magnetism and gravity, as being dispositional and relational. Although cosmical qualities are also regarded as ontologically dependent on the properties and behavior of corpuscles, the causal power of these properties emerges only when the proper environmental, relational, and dispositional conditions are in place.

4.6  Cosmical Qualities as Dispositional and Relational Properties I have been arguing that there is no tension between Boyle’s commitment to mechanistic corpuscularianism and his belief that higher-​level qualities are relational and dispositional properties. To further illustrate this point, I now turn to Boyle’s discussion of cosmical qualities, since he considers these properties both as having corpuscular origins and as being dispositional and relational properties. For Boyle, cosmical qualities such as magnetism and gravity are, in fact, powers in the aerial corpuscular effluvia that penetrate the pores of bodies disposed to be affected by these particles. Catherine Wilson explains that both vitalistic and mechanistic corpuscularians often invoked the notion of corpuscular effluvia to account for apparent action at a distance and for other otherwise unexplainable phenomena. Corpuscularians made such phenomena “intelligible by positing invisible, mobile, active particles capable of agitating within corporeal



73

Bunge, “Is Chemistry a Branch of Physics?,” 210–​211.

140  The Chemical Philosophy of Robert Boyle objects and also capable of traveling great distances—​perhaps even from celestial objects to the earth.”74 Incidentally, the notion of aerial effluvia is compatible both with the Paracelsian ontological conception of disease and with the account of illness via contagion first articulated by Fracastoro in 1546. Although many vitalistic corpuscularians accounted for the powers of these aerial particles by appealing to seminal reasons, the inner workings of aerial effluvia were also “a preoccupation of the mechanical philosophers.”75 For mechanistic philosophers, corpuscular effluvia provided explanations for phenomena that had previously seemed mysterious and unexplainable by physicalistic and naturalistic means. Boyle himself takes the theory of corpuscular effluvia to be perfectly compatible with his version of the mechanistic philosophy, arguing that a body’s disposition to be affected by the cosmical qualities of aerial particles is itself a function of the structure of the body in question. To this end, Boyle emphasizes three principles regarding cosmical qualities, the last two of which are considered the most important and all three of which he takes to be purportedly confirmed by experimental observations. These principles are: 1. That there are many Bodies, that in divers cases act not, unless they be acted on & some of them act, either solely or chiefly as they are acted on by the Catholick and unheeded Agents, we have been speaking of. 2. That there are certain subtle Bodies in the world, that are ready to insinuate themselves into the Pores of any Body disposed to admit their action, or by some other way to affect it, especially if they have the concurrence of other unobserved Causes and the establisht lawes of the Universe. 3. That a Body by a mechanicall Change of Texture may acquire or loose a fitnesse to be wrought upon by such unheeded Agents, and also to diversify their operations on it upon the score of its varying Texture.76 The first principle is Boyle’s affirmation of the existence of cosmical qualities. The second principle is Boyle’s identification of cosmical qualities with aerial corpuscular effluvia. The third principle is Boyle’s identification of mechanistic principles as governing the disposition to be affected by cosmical qualities. As previously stated, and as he explicitly affirms, Boyle considers the last two principles as most important. It seems clear to me that the reason for this is that the last two principles jointly confirm his commitment to the compatibility of cosmical qualities with the mechanical philosophy. This is the case because the second principle attributes cosmical qualities to corpuscular effluvia that penetrate the

74 Wilson, Epicureanism at the Origins of Modernity,  71–​72. 75 Ibid.

76 Boyle, Of the Systematical or Cosmical Qualities of Things, 289.

Boyle’s View of Chemical Properties  141 pores of those bodies that are disposed to be affected, while the third principle attributes such dispositions to be affected to the texture or microstructure of the bodies in question. Boyle then provides an extended defense, as well as observational evidence, to support these last two principles. This is not enough to establish compatibility, however, since the first principle requires a more extensive defense on Boyle’s part. Such a defense is not forthcoming in Of the Systematical or Cosmical Qualities of Things since, in this work, Boyle limits himself to two paragraphs in which he simply provides empirical examples of magnetism and gravity. The more extensive discussion of cosmical qualities occurs in the appendix to this same work, which is titled Cosmical Suspicions. As the title of this appendix indicates, however, Boyle’s belief in the existence of such qualities is a mere “suspicion,” and a faint one at that. Boyle states: “it may now therefore be not unreasonable to confesse to you, that I have had some faint Suspition [. . .] that there may be, as I was beginning to say, peculiar sorts of Corpuscles that have yet no distinct name, which may discover peculiar Faculties, and Ways of working, when they meet with Bodies of such a Texture as disposes them to admit, or to concur with the Efficacy of these unknown Agents.”77 He then claims that the qualities with which these unnamed corpuscles are endowed are probably governed by laws of the universe that are themselves, as yet, unknown. Although Boyle proceeds to give empirical examples that convince him that cosmical qualities indeed exist and are governed by unknown laws of the universe, he does admit at the end of this appendix that much of what he has discussed therein is conjectural. In spite of this admission, however, he continues to affirm the existence of such qualities and their degree of influence upon natural phenomena. And whereas, Pyrophilus, I have in the former Discourse taken in the Structure and establisht Lawes of the Universe as an Helpe toward the giving an Account of the Cosmical Attributes of things; I shall here also ingeniously confesse to you, that I much feare whether we have yet attentively enough taken notice either of the number, or the Kinds of those Lawes. For as I am by some Notions and Observations inclined to think, that there may be a greater number even of the more generall Lawes, then have been yet distinctly enumerated [. . .] and those may have a greater Influence on many Phaenomena of nature then we are wont to imagine.78

77 Boyle, Cosmical Suspicions (Subjoyned as an Appendix to the Discourse of the Cosmicall Qualities of Things), 303. 78 Ibid., 305.

142  The Chemical Philosophy of Robert Boyle As has already been emphatically stressed, Boyle’s reliance upon causes other than the mechanical affections of primary corpuscles does not signal a rejection of the mechanical philosophy. To the extent that cosmical qualities ultimately originate from corpuscular effluvia, his explanatory appeal to such qualities is consistent with the mechanical philosophy’s negative heuristic as discussed in Chapter 2. As Boyle states in his Relations betwixt Flame and Air (1672), his appeal to cosmical qualities is in keeping with the mechanical hypothesis because it relies on physical causes and laws, rather than on the non-​material principles prevalent in the natural philosophies of Paracelsians and spagyrists.79 When saying this, Boyle is directly responding to Henry More’s criticism of his earlier work, New Experiments Physico-​Mechanical, Touching the Spring of the Air, and Its Effects (1660), in which Boyle had attempted to explain the results of his experiments with the air-​pump, or pneumatic engine, by appealing to strictly naturalistic principles such as gravitation and elasticity of the air. More, whose piety eventually led him to recant on his former allegiance to mechanicism, reinterprets Boyle’s experiments as indicating the presence and causal activity of “spermatical” and vital principles such as a spirit of nature or anima mundi. More regards “gravity and the ascent of the piston of the air-​pump as contradictions of mechanism.”80 In the Relations Betwixt Flame and Air, Boyle directly addresses More’s interpretation by defending the notion that gravity, air elasticity, and other non-​mechanical qualities have mechanistic origins. He states that having sufficiently proved, that the Air, we live in, is not devoid of weight, and is endowed with an Elastical Power or springiness, I endeavour’d by those two Principles to explain the Phaenomena exhibited in our Engine [. . .] without recourse to a Fuga Vacui,—​or the Anima Mundi,—​or any such unphysical Principle. And since such kind of Explications have been of late generally called Mechanical, in respect of their being grounded upon the Laws of the Mechanicks; I, that do not use to contend about Names, suffer them quietly to be so: And to entitle my now examined Explication to be Mechanical, as far as I pretend, and in the usual sense of that expression.81

This passage clearly shows that Boyle considers any explanation that eschews non-​physical principles and that affirms strictly physical causes to be a mechanistic explanation or, at least, to be compatible with the mechanical philosophy, although the ultimate mechanistic principles that govern the spring of the air or

79

Boyle, “Relations betwixt Flame and Air.” Greene, “Henry More and Robert Boyle on the Spirit of Nature,” 468. 81 Boyle, Relations betwixt Flame and Air, 148. 80

Boyle’s View of Chemical Properties  143 the pressure of water are not included in these explanations and may yet be unknown. Thus, although the term “mechanical” in these experimental writings does not explicitly refer to mechanistic corpuscularianism, it remains compatible with the mechanistic theory of matter. As I’ve suggested in this chapter, the relation between agent and patient is one that is embedded in a specific environmental context that affects the relational properties that emerge so that, if both agent and patient were to be placed together in a vacuum and away from the environmental conditions in which they are embedded, they would lose many of their dispositions to affect or be affected by each other. Some of the clearest arguments for the relationality of properties are found in Boyle’s writings on cosmical qualities, thus we should note that one of Boyle’s most important discussions of the relationality of properties and their dependence on surrounding environmental conditions occurs not in The Origin of Forms and Qualities but in his essay Of the Systematical or Cosmical Qualities of Things. Here, Boyle clearly specifies that though in estimating the Qualities of Naturall Bodies we are wont to consider but the power any particular one has of acting upon, or the capacity it has of suffering from such and such particular Bodies [. . .] yet there may be some Attributes, which may belong to a particular Body [. . .] not barely upon the score of these Qualities that are presumed to be evidently inherent in it, nor of the respects it has to those other particular Bodies to which it seems manifestly related, but upon the account of a Systeme so constituted as our World is, whose Fabrick is such, that there may be divers unheeded Agents, which, by unperceived meanes, may have great Operations upon the Bodie we consider [. . .] So that although if divers Bodies that I could name were placed together in vacuo [. . .] they would retaine many of the Qualities they are now endowed with; yet they would not have them All: but by being restored to their former places in the World, would regain a new Set of Faculties (or Powers) and Dispositions, which because they depend upon some unheeded Relations and Impressions, which these Bodies owe to the determinate Fabrick of the grand Systeme or World they are parts of, I  have [.  .  .] thought fit to name their Cosmicall or Systematicall Qualities.82

It has customarily been argued that Of the Systematical or Cosmical Qualities of Things adds nothing relevant to what is already contained in the more famous essay on The Origin of Forms and Qualities. However, as John Henry has recently pointed out, there is more to Boyle’s essay on cosmical qualities than a mere



82 Boyle, Of the Systematical or Cosmical Qualities of Things, 287–​288.

144  The Chemical Philosophy of Robert Boyle reiteration of the mechanistic origins of sensible and chemical properties. Boyle himself explains the difference between his treatment of relational and dispositional properties in this essay and the account given in The Origin of Forms and Qualities. He states: I have in the Origine of Formes touched upon this subject already, but otherwise then [sic] I am now about to doe. For whereas that which I doe there principally, (and yet but Transiently,) take notice of, is That one Body being surrounded with other Bodies, is manifestly wrought on by many of those among whome ’tis placed: that which I cheifly in This Discourse consider is, the Impressions that a Body may receive, or the power it may acquire, from those vulgarly unknown, or at least unheeded Agents, by which it is thus affected, not only upon the account of its owne peculiar Texture or Disposition, but by virtue of the general Fabrick of the World.83

As John Henry has claimed, it seems that Boyle is indeed trying to articulate a notion of non-​mechanistic relational qualities that “is rather less compatible [. . .] with all standard accounts of the mechanical philosophy.”84 For Boyle, the fabric of the world is such that all bodies within it are affected by other bodies, as well as by causes of which many may yet be unknown. According to Boyle, these causes include cosmical qualities, such as gravity and magnetism. In fact, to the extent that Boyle considers the cosmical qualities of magnetism and gravity to be “unheeded agents” that work by “unperceived means,” he considers such cosmical qualities to be occult qualities that resist mechanistic explanations. Boyle is a realist about occult qualities precisely because, despite their methodological and epistemic irreducibility to mechanistic affections, their causal power is manifested as one observes their experimental effects. This is another case in which the existence of unobservable causes is transformed, via experimental activities, into a “matter-​of-​fact.” John Henry, however, mistakenly considers Boyle’s realism regarding occult and cosmical qualities as being incompatible with “strictly mechanistic precepts.” Certainly, if Boyle’s mechanicism were strictly reductionistic, then Henry would be correct in regarding it as incompatible with the belief in occult and cosmical qualities. On the other hand, if I am correct that Boyle’s mechanicism is non-​ reductionistic, then his belief in the epistemic usefulness of appealing to occult and cosmical qualities is not necessarily incompatible with his ontological position regarding fundamental matter. As I have argued extensively, there is evidence that Boyle considers higher-​level properties to be emergent, relational,

83 84

Ibid., 288. Henry, “Boyle and Cosmical Qualities,” 121.

Boyle’s View of Chemical Properties  145 and dispositional properties whose causal powers explain not only chemical, but also hydrostatic and pneumatic, phenomena without needing to appeal to mechanistic corpuscularianism. In this chapter I  have argued that, for Boyle, chemical and other higher-​ level properties are supervenient properties that emerge from the dispositions of chemical substances in relation to other substances. He clearly conceives of chemical substances as functional wholes whose properties emerge not only from the structural ordering of their parts but also from their relationship with other chemical substances in the context of experimental practice. However, as Isabelle Stengers points out, “as soon as the question of emergence is at stake, the whole and its parts must thus co-​define themselves, and mutually negotiate what an explanation of the one from the other means.”85 The attribution of non-​ summative difference to a property of a chemical whole is itself a mereological issue, because it implies that the whole possesses properties that are not simply the summation of the properties of its parts. The next chapter will, therefore, examine these issues and will argue that the kind of mereology required to make sense of the notion of supervenience must differ from the widely assumed extensional interpretation of classical mereology, in which any parts whatever automatically compose some whole, regardless of their relation to each other.86



85 86

Stengers, “La vie et l’artifice,” 207. Newman, “Chemical Supervenience,” 50.

5

The Relation between Parts and Wholes The Complex Mereology of Chymical Atoms

In the last chapter, I argued that Boyle conceived of chemical properties not only as dispositional and relational but also as emergent and supervenient upon the submergent base. I  also suggested that an accurate account of supervenience requires a kind of mereology that is distinct from standard extensional mereology in which the properties of the whole are simply a summation of the properties of the parts. When dealing with emergent and supervenient properties, there is a non-​summative difference of properties between the whole and the parts. Mereologically, the whole itself is not merely a collection of its parts haphazardly put together but, rather, it is a composite of parts in very specific relation to one another. Together, the subvenient properties of the constituent parts and the relation of those parts and properties to one another account for the supervenient properties of the whole, and this is what accounts for the transcendence (i.e., non-​reducibility) of the supervenient properties. In the context of our discussion of Boyle, this point is significant because there is an often-​unstated mereological premise lying at the heart of strict mechanicism, that is, that natural wholes are analogous to complicated machines or artifacts, composed of parts that are lacking in any intrinsic relationship to each other. Thus, the type of mereology that best describes such wholes is a standard extensional mereology in which wholes are considered as purely summative aggregates of parts, displaying no novel properties above and beyond the properties of their distinctive parts. Yet in spite of Boyle’s commitment to the mechanical philosophy, it is not clear that he would endorse a standard extensional mereology to describe chymical atoms. Although Boyle never addresses mereological questions directly in his writings, I will argue that the type of mereology that best describes Boylean chymical atoms is a non-​extensional and non-​ summative mereology that accounts for the fact that chemical wholes display novel and emergent properties that are not present in their individual parts. Such a mereology must also take into account the relationality of the parts to one another, since such relations affect what emergent properties the chemical whole will display.

The Chemical Philosophy of Robert Boyle. Marina Paola Banchetti-Robino, Oxford University Press (2020). © Oxford University Press. DOI: 10.1093/oso/9780197502501.001.0001

The Relation between Parts and Wholes  147

5.1  Boylean Chemistry as Mereological It is clear from the discussion of Boyle’s corpuscularian theory of matter that, for him, the specific particulate composition of corpuscular concretions or chymical atoms is necessary but not sufficient to determine the chemical properties of a given substance. In addition to discrete particles with their particular shapes, sizes, and motions, the specific microstructure in which those particles are coalesced is also a necessary condition for the manifestation of particular chemical properties. In fact, as Rom Harré and Jean-​Pierre Llored have recently pointed out, “since Robert Boyle’s corpuscularian philosophy, chemistry has been a mereological science. Displacing the metaphysics of ‘continuous substances’ and ‘qualities’ as the expression of ‘principles,’ chemistry has been built on a ‘part-​ whole’ metaphysics. The grammar for the use of ‘part-​whole’ concepts is mereology.”1 However, according to Joseph Earley, “an adequate theory of wholes and parts (mereology) must consider that when individuals enter combinations of interesting sorts they no longer are the very same individuals that existed prior to the composition.”2 The mereology involved in chemical supervenience is a non-​standard mereology because “the parts undergo changes when they form a whole.”3 The presence of the supervenient property affects the properties of the constituent parts, so that the properties of the parts are dependent upon the role that they play within the whole that expresses the supervenient property. In Earley’s words, “most philosophers have yet to recognize that, when components enter into chemical combination, those components do not, in general, maintain the same identity that they would have absent that combination.”4 Good examples that illustrate Earley’s point are H2O and silver chloride. While the property of being H2O or of being silver chloride “supervenes on features of the constituent atoms, the features of the atoms on which it supervenes include features that the atoms have only by virtue of being parts of that compound. The atomic interrelations that give rise to the compound would not obtain if the atoms were parts of a different molecular type.”5 Molecules themselves are defined in accordance with chemical reaction networks and not vice versa.6 Emergence itself is also a function of the relationality of the parts within the whole, since “emergent property F supervenes only given relations [that] the parts bear to one another.”7



1 2 3 4 5 6 7

Harré and Llored, “Mereologies as the Grammars of Chemical Discourse,” 63. Earley, “Why There Is No Salt in the Sea,” 85. Newman, “Chemical Supervenience,” 56. Earley, “Varieties of Properties,” 87. Francescotti, “Emergence,” 58. I am grateful to Jean-​Pierre Llored for suggesting this useful example. Francescotti, “Emergence,” 61–​62.

148  The Chemical Philosophy of Robert Boyle As discussed in Chapter 1, Aristotle had already understood the importance of these mereological questions with regard to understanding the nature of substances. To briefly recapitulate that discussion, Aristotle rejects the idea that the form of the whole is itself a material part of the whole that it unifies, since this type of mereological hylomorphism leads into regress. The form, Aristotle tells us, is not an element but a principle [αρχη].8 However, Aristotle believes that mereological consistency requires that the form of the whole be both real and ontologically distinct from the material parts. For the Scholastics, this immaterial Aristotelian principle was conceived much more concretely as “substantial form.” Yet the Scholastics could not precisely explain what substantial form is except to say that it must exist as that which sustains the constant and stable properties that identify a particular thing as a member of a particular kind or species. As explained in Chapter 3, this is one of the reasons for Boyle’s rejection of substantial form as an immaterial principle. Instead, as that chapter established, Boyle favors the notion of essential form, understood mechanistically as the texture or structure of corpuscular concretions. Although essential form is a mechanistic structure, it is, nevertheless, also the source of a thing’s identity and of its emergent and supervenient non-​mechanical properties. It was also stressed that it is not just the composition of aggregate corpuscles that does the chemical work but, rather, it is also the structure or texture in which the minima of aggregate corpuscles are tightly coalesced that accounts for the chemical properties of substances. Thus, we must ask how to understand the notion of mechanical essential form of corpuscular concretions. This understanding is necessary in order to account for the fact that such form stands mereologically “over and above” the constituent parts of corpuscular concretions without its being considered ontologically separate from its parts. Robert Pasnau’s recent comment about Boyle’s structuralism raises some doubts about where exactly Boyle stands, from a mereological perspective, with regard to composite wholes. I will give a reply to Pasnau’s concerns but, first, I wish to quote his comment in full since it is relevant for the present discussion. Pasnau states that if “texture” [. . .] refers only to the corpuscular facts taken as a whole (that is, to a conjunction of discrete facts), then [Boyle] could really hardly have appealed to texture as that which unifies a coherent body. There would be no way to distinguish between the texture possessed by a “distinct body” and the texture possessed by, say, all the books and papers on top of my desk. Now perhaps Boyle would welcome this last result, or perhaps he was in fact torn over just how



8 Aristotle, The Complete Works of Aristotle, Z.17, 1041b32–​33.

The Relation between Parts and Wholes  149 much weight to put on the texture of the whole as a unifying principle [. . .] moreover he rejected the entire scholastic conception of substantial identity and change. So, contrary to the Aristotelian view that the parts of a substance maintain their identity only as part of that substance, Boyle argues that when a body is generated, “no new substance is in generation produced, but only that which was pre-​existent obtains a new modification or manner of existence.”9

What Boyle means in the passage cited by Pasnau is that there is no substantial form produced, that is, there is no new immaterial substance that comes into existence. For him, a change of species or genus includes a real transformation of structure and qualities but not the generation of a new substantial form. But this passage does not imply that the notion of diachronic identity is meaningless for Boyle, for he clearly states at the end of the cited passage that a new manner of existence is produced. What this means, for Boyle, is that a body belonging to a different natural kind is generated because, although all of the material particles that composed the original body are still present and no new substance has been added, the structure of those material particles has been changed to produce a material body with different properties and, thus, a material body belonging to a different species from the original. Thus, the new material body has a different identity from the original body, because it has a different essential form, that is, its corpuscles are arranged according to a different texture or structure. This is true because, as Boyle claims, if the structure is altered though the composition remains the same, the chemical properties of the substance will change. That is, a change in structure, even if not accompanied by a change in composition, yields new chymical atoms and, thus, substances with different chemical properties. Thus, Boyle rejects mereological extensionality, since the same group of fundamental particles arranged according to one structure will produce an entirely different set of properties from those that it would produce if it were arranged according to a different structure. Moreover, as explained in Chapter 3 and as Kuhn has also argued,10 Boyle’s chemical philosophy is a “structural realism” that remains situated within an overall mechanistic hypothesis. What this means is that the chemical identity of a substance is not entirely reducible to its composition but is also a function of the structure in which its particles are arranged. This structural realism, which may seem at first to be at odds with the mechanical philosophy, is nevertheless mechanistic to the extent that the structure of chymical atoms is conceived geometrically as a tight juxtaposition of particles. Though I am simply clarifying the meaning of Boyle’s structural realism here,



9

10

Pasnau, “Form, Substance, and Mechanism,” 63. Kuhn, “Robert Boyle and Structural Chemistry.”

150  The Chemical Philosophy of Robert Boyle I will address the many problems associated with this geometric conception of structure at the end of this chapter. The mereological questions raised by this discussion will also be addressed in detail later. But, for now, suffice it to say that Pasnau is mistaken in his doubts regarding Boyle’s position on compositional wholes. As elaborated in Chapter 3, the texture or essential form of a material body that gives it unity and species identity is something stable and operationally irreducible. Unlike Gassendi who offers no account of what holds molecules together, Boyle attempts to explain the stability of aggregate corpuscles in a mechanistic way by appealing to their tight spatial juxtaposition. Thus, Boyle does at least offer an account of unity for compositional wholes although, as already mentioned, there are serious problems with this account that I will address more fully later. Boyle would not agree that the texture of a material body is akin to the texture of the books and papers on Pasnau’s desk. In fact, he would argue that, although the books and papers are arranged in a particular way in relation to one another, there is no “texture” or essential form as Boyle understands these terms because there is no mereological unity. The books and papers merely constitute a heap, not a compositional whole, since this pile has no internal unity or stability and can be easily dismantled. In this sense, Boyle’s notion of essential form as material structure fulfills the same mereological purpose as the notion of form fulfilled for Aristotle, without any of its problematic metaphysical commitments. Although Boyle himself does not address these mereological questions directly or explicitly, a very distinct mereology is implied by his concept of chymical atoms as producing emergent, supervenient, and non-​summative chemical properties. Had Boyle adopted a strictly reductionist mechanicism, he would have fallen prey to the reductionist potential of standard extensionalist mereology, so that the whole must summatively display only those properties that are inherent in its parts and the properties of the whole must be entirely deducible from and reducible to the properties of the parts. I believe, however, that Boyle’s chemical ontology guides him in the direction of what we would call a non-​standard mereology. It is clear from the discussions in the previous chapter that Boyle does not consider chemical properties to be deducible from the mechanical properties of the fundamental particles that constitute these wholes. Although Boyle does not explicitly articulate these ideas in mereological terms, mereological concerns are definitely implicit in his theoretical and experimental writings and, in some sense, anticipate some contemporary concerns regarding mereology as it relates to chemical wholes. Although a detailed analysis of the mereological concerns implicit in Boyle’s writings would greatly contribute to our understanding of his chemical philosophy, it is unfortunate that very little attention has been paid to these ideas. In fact, the only explicit allusion to the presence of any sort of mereological position

The Relation between Parts and Wholes  151 in Boyle’s work is found buried in the pages of Desmond Paul Henry’s Medieval Mereology. In this work, Henry very briefly alludes to Boyle while clarifying the mereological theories of Peter Abelard. Henry hopes to elucidate Abelard’s ideas by comparing them with Boyle’s position regarding the relation between parts and wholes and by concluding that Abelard’s mereology shares great similarities with that of Boyle many centuries later. What strikes me the most about Henry’s brief discussion of Boyle, however, is that his remarks presuppose that Boyle adopts a reductionist and extensional standard mereology regarding corpuscular concretions. Therefore, in the discussion to follow, I will tease out the errors in Henry’s argument and present my own account, based upon textual evidence as well as what has already been established regarding Boyle’s chemical ontology. With this, I hope to provide the kind of detailed analysis of Boyle’s mereology that has, up to this point, been absent in the literature.

5.2  Continuous vs. Contiguous Integral Wholes In order to both explain and critique Henry’s conclusions regarding Boylean mereology, I  will begin by discussing some key mereological concepts upon which his discussion is grounded. To the extent that Henry compares Boyle to Abelard, I will begin by discussing some general concepts within Scholastic mereology. Although Scholastic logicians and metaphysicians embrace classical Aristotelian mereology as foundational, they develop and contribute new concepts and distinctions to it based upon their own metaphysical and, often, theological concerns. One of these is the distinction between integral wholes, universal wholes, and potential wholes. Since only integral wholes will be relevant for this discussion, I shall not delve into the nature of universal or potential wholes. Integral wholes can be either continuous or contiguous wholes. A continuous whole is one in which the parts share a common boundary and are “so mutually admixed that they are believed to hold together, or at least to grip one another, so that they are [. . .] truly said to be one thing.”11 An example of a continuous integral whole would be a unified whole such as a stone, a tree, or a human being. Homogeneous masses, like gold or water, are also considered continuous wholes. Abelard defines it thus: “A continuous whole is one which is made up of impredicable parts, in the sense that they cannot have their whole predicated of them, such that as long as the wholes exists the parts are not susceptible of change of place, as can be seen in the case of a house.”12 In contrast to continuous 11 Desmond Paul Henry, Medieval Mereology, 124. 12 Peter Abelard, Introductiones dialecticae, in Pietro Abelardo, 193–​194: “Continuum totum est illud quod constat ex partibus impraedicabilibus, id est non recipientibus praedicationem sui totius,

152  The Chemical Philosophy of Robert Boyle wholes, the parts of non-​continuous wholes, such as a flock of birds for example, are susceptible to change of place even while the whole continues to exist. Interestingly, although Abelard uses the example of a house to illustrate the definition of a continuous integral whole, both he and Aquinas believe that, in a strict sense, no artificial construct can genuinely qualify as a continuous whole. As mentioned earlier, for Scholastics, the unity of substances that qualifies them as continuous wholes is due to the presence of immaterial substantial forms, which are only possessed by natural substances. Such things as houses can, therefore, never truly qualify as continuous integral wholes. To the extent that only natural substances are endowed with substantial form, the unity of artificial substances, artifacts, or other things lacking substantial form is considered a lesser kind of unity. More will be said about this later, since I will argue that Boyle’s rejection of substantial forms and his commitment to mechanistic corpuscularianism would force him to reject the notion of chemical substances as continuous integral wholes. Let us now continue our discussion by examining contiguous integral wholes. A contiguous integral whole is one in which the parts are discrete but spatially close together. Such parts “are by nature disjointed, but [. . .] are put into conjunction by a craft, as in the case of a cuirass or a piece of cloth. In these instances, part is put close to part and gathered together so that a whole is then effectuated.”13 Contiguous wholes do not have substantial unity in the sense of having substantial form. Hence, for the Scholastics, artifacts can only ever be considered contiguous wholes, since they have accidental form but not substantial form. Thus, strictly speaking and by Abelard’s own criteria, the house cited in the earlier passage really only qualifies as a contiguous whole. Interestingly, however, Abelard considers that any scattered mereological whole, such as a heap of pebbles, can qualify as a contiguous integral whole even if it lacks real unity of any sort. It is precisely with regard to this issue that Abelard differs most from Aquinas and other 12th-​century logicians and metaphysicians. Given his belief in substantial forms, Abelard has no trouble explaining what it is about a continuous whole that gives it its identity as a unified whole, over and above its mereological parts. With regard to contiguous wholes, however, Abelard denies that there is any ontological “increase” in the whole over and above its parts or that any real novelty ensues upon the combined parts. This position regarding contiguous wholes is consistent since, for the Scholastics, non valentibus transmutari secundum localem positionem, manente ipso toto, ut potest videri in domo.” The only exception to this requirement is in the genitive case “of-​a” or “of-​the.” 13 Clarembald, Compendium logicae Porretanum, as cited in Henry, Medieval Mereology, 214: “At totum contiguum est cuius partes naturaliter disiuncte, arte vero sunt coniuncte, ut videtur in lorica vel in tela; ibi enim pars parti contiguatur aggregatur ut totum inde efficiatur.”

The Relation between Parts and Wholes  153 the only wholes that are greater than the sum of their parts are substances, since these are endowed with substantial forms.

5.3  Integral Parts and Essential Parts Besides distinguishing between different types of wholes, Scholastic logicians and metaphysicians also distinguish between different types of parts, more specifically, between integral parts and essential parts. This will be an extremely important distinction in my later discussion of Boyle’s mereology. The Scholastic Walter Burleigh (1275–​1344) explains the distinction thus: “Part is sometimes taken as the essential part which Aristotle and Averroes [Ibn Rushd] call the ‘qualitative part’ in many contexts, and they call the integral part the ‘quantitative part.’ In a corresponding manner, whole is taken as whole in respect of form and whole in respect of matter, and contrastingly for part there is part in respect of form and part in respect of matter.”14 Thus, integral parts are associated with the “quantitative” or material parts of a whole, which are present in only one place at a time and side-​by-​side to each other. They are, one might say, the accidental parts of a whole, so that the loss of particular integral parts does not entail any loss of identity for the whole. Material parts can increase or decrease without affecting the identity of the whole as a whole. Thus, “material parts [integral parts] are those which ebb and flow while the whole remains the same.”15 Essential parts, on the other hand, are associated with the “qualitative” or formal parts of the whole, that is, those parts that are associated with substantial forms. The loss of essential parts destroys the substantial unity of the whole. “Parts in respect of form [essential parts] are those which always remain the same, as long as the whole remains the same complete object.”16 Thus, essential parts can neither decrease nor increase in the whole, without changing the identity of the whole altogether. The notion that some parts of wholes are essential parts does not imply the kind of mereological hylomorphism that Aristotle rejects, since essential parts are not regarded as material. Rather, the essential parts of a whole are essential because they are united not by a mere principle of material summation but by a principle of form or, more precisely, substantial form. In fact, unification by form is precisely that which distinguishes essential

14 Walter Burleigh, De toto et parte, as cited in Henry, “Medieval Mereology,” 407:  “Pars enim aliquando capitur pro parte essentiali quam Philosophus et Commentator multis locis vocant partem qualitativam et parem inegralem vocant partem quantitativam. Et isto modo accipitur totum pro toto secundum formam et toto secundum materiam; et per oppositum, pars, pars secundum formam et pars secundum materiam.” 15 Ibid., 408. 16 Ibid.

154  The Chemical Philosophy of Robert Boyle parts from accidental parts. Thus, the form is that which unites the essential parts and renders them essential parts. However, to repeat, Scholastic metaphysicians do not regard the substantial form of a whole as a material part of that whole. In the next section, I  will discuss how these notions function in the context of Abelard’s mereology, and I will present an explanation and brief critique of Henry’s positive comparison of Abelard and Boyle. This will set the context for the detailed discussion of Boylean mereology in the rest of the chapter.

5.4  Aquinas, Abelard, and Boyle on Substantial Unity It is important to note here that, despite some agreements between Abelard and Aquinas, on the issue of substantial unity for example, there are also important differences in their views regarding the mereological relation between wholes and parts. Aquinas, like Aristotle, stresses the non-​identity of whole and parts, saying that there is something about the whole that is over and above its parts, though he never specifies what this “something” is. As Henry explains, Aquinas is “saddled with the task of explaining how the elements of a whole change their identity upon incorporation in, or expulsion from, the whole which they compose.”17 After putting forward several arguments that fail to explain how this is possible, Aquinas settles on the conclusion that the “something over and above” is the substantial form, that is, the “formal” principle of the substance or the quiddity, to be distinguished from its material parts.18 This implies that contiguous integral wholes are not real wholes at all, in other words, they have no real integrity since they lack substantial form. For Abelard, on the other hand, as for David Lewis many centuries later, “any sort of plurality can be taken to form some whole, even if the parts are disjointed.”19 This point was already made earlier, with regard to Abelard’s claim that any scattered mereological sum constitutes a contiguous integral whole. As was also mentioned, Abelard’s contemporaries rejected this view, including those who shared his nominalist metaphysics. For the purposes of this chapter, however, it is important to note that one of the consequences of Abelard’s mereological atomism is that, in effect, “when one thing is conjoined with another [. . .] neither has more parts than it previously had. Yet neither does the whole which is composed of these [parts] appear to increase [. . .] there is also the tendency towards denying that real novelty ensues upon the combination of parts [emphasis mine].”20 It is this last implication that will be particularly relevant for our

17

Ibid., 220. Ibid., 224. 19 Ibid., 124. 20 Ibid., 123–​124. 18

The Relation between Parts and Wholes  155 discussion later in this chapter. For, although Abelard is obviously not an advocate of the mechanical philosophy, he embraces the same sort of permissive mereology that would later be embraced by strict mechanicists, with the same sort of implications regarding the question of whether any novelty ensues upon the combination of atomistic parts and, ultimately, whether the properties of wholes are entirely reducible to the properties of their individual parts. It is in discussing these issues that Henry draws his misguided analogy between Abelardian and Boylean mereologies. I attribute Henry’s mistake to his interpretation of Boyle as a strict mechanicist, and I hope to demonstrate that Henry’s claim is indeed erroneous. He states that Boyle too “would insist that the bringing together of formerly scattered parts does not really bring into being anything which, substantially speaking, was not already there previously [. . .] previously non-​assembled quasi-​componential parts are [simply] put together or appropriately relocated.”21 Henry cites a passage from The Origin of Forms and Qualities that seems, at first glance, to support the view that Boyle embraces the same permissive mereology as Abelard: “We say that a body belonging to that species [. . .] is generated or produced de novo—​not that there is really anything of substantial produced, but that those parts of matter that did indeed before pre-​exist [. . .] are now brought together and disposed after the manner requisite to entitle the body that results from them to a new denomination, and make it appertain to such a determinate species of natural bodies.”22 If Henry were correct here, it would follow that Boyle endorses mereological extensionalism, that is, the thesis that wholes with the same parts are identical to each other regardless of the arrangement of those parts. Thus, the arrangement or structure of the parts does not affect the nature of the whole, so that rearranging the parts would simply yield the same whole. I believe, however, that Henry misinterprets Boyle’s position by misconstruing the purpose of the passage that he cites from The Origin of Forms and Qualities. I hope to demonstrate, in what follows, that the true purpose of this passage, for Boyle, is not to argue against mereological “novelty” but to argue against the presence of substantial forms. As we shall see presently, to the extent that he believes that the structure or essential form of chemical wholes imparts identity and integral unity upon them, Boyle clearly does believe essential form to be a necessary condition for unity. As Harré and Llored have recently pointed out, “chemical relations are not merely formal; sums and incomplete fragments lack chemical work. The thesis that objects with the same parts are identical, say, mereological extensionality, cannot work in this context.”23 Based upon Boyle’s conception of chymical atoms

21

Ibid., 124–​125.

23

Harré and Llored, “Developing a Mereology of Chemistry,” 211.

22 Boyle, The Origin of Forms and Qualities, 328.

156  The Chemical Philosophy of Robert Boyle as stable material species that impart unique chemical properties to substances, I firmly believe that he would concur with Harré and Llored on this point. Thus, although Boyle rejects substantial forms, he would also reject the kind of permissive mereology implied by mereological extensionalism. What I will argue later is that Boyle’s rejection of both mereological extremes, that is, his rejection of substantial forms on the one hand and of mereological extensionalism on the other hand, implies a rejection also of the distinction between continuous and contiguous integral wholes. This, in turn, implies a rejection of the distinction between natural and artificial substances, to the extent that neither has substantial form but that both have the integral unity that is supplied by essential form. This ties into the discussion of taxonomy in Chapter 3, which also established Boyle’s rejection of this distinction. In what follows, I will argue that, although Boyle lacked the vocabulary of contemporary mereology, he would most likely concur with Harré and Llored’s recent call for the development of a new set of mereological rules for the logic of chemical discourses, arguing that chemical “parts and sets are relational. They are entangled with the whole and its environment and depend on the mode of access—​cognitive or instrumental.”24 Although Boyle did not develop and could not have developed the kind of relational and dynamic chemical mereology for which Harré and Llored have recently argued, Boyle would have undoubtedly sympathized with such efforts by these contemporary philosophers of chemistry.

5.5  The Mereology of Boyle’s Chymical Atoms as Chemically Elementary Entities As mentioned in the previous section, what I hope to establish with this analysis is that Boyle does not embrace the kind of permissive, atomistic, and extensionalist mereology attributed to him by Henry. In fact, the complex corpuscularian ontology discussed in Chapter  3 lends itself to a nuanced mereological analysis that reconciles the atomism implied by the mechanical hypothesis with Boyle’s quasi-​holistic and non-​reductionist conception of chymical atoms as operationally elementary wholes that endow substances with non-​mechanistic and causal chemical properties. Most scholars would agree that mereological extensionalism is incompatible with Boyle’s mechanistic structuralism, to the extent that the texture of corpuscular concretions endows these with unity. Thus, they would agree that two chymical atoms that have the same composition but different structures must



24

Ibid., 209–​210.

The Relation between Parts and Wholes  157 produce different chemical properties. However, although they would reject an mereologically extensionalist conception of Boylean ontology, many scholars will insist that for Boyle nothing “novel” is produced when the structural disposition of particles is altered and that the qualities of a substance are nothing other than the mechanistic texture of its corpuscular concretions. As Frederick O’Toole has argued, however, one cannot correctly attribute to Boyle this “reductionist interpretation of powers and capacities.”25 In fact, a reductionist interpretation of powers and qualities leads to absurd conclusions that Boyle himself would reject. Regarding the attributes of gold to be easily soluble in aqua regis and to be insoluble in aqua fortis, for example, Boyle explicitly states that “these attributes are not in the gold anything distinct from its peculiar texture.”26 A reductionist and non-​relational reading of this statement would identify the proposition “p is not in A anything distinct from q” with the proposition “p is not distinct from q,” which would amount to saying, “p is q.” Thus, under this reductionist interpretation, one would have to conclude that, for Boyle, solubility in aqua regis and insolubility in aqua fortis are texture tout court. However, as O’Toole so aptly points out, to say this would amount to collapsing the distinction between the qualities of being soluble or insoluble and texture itself. This, however, is a problem for a number of reasons. As was discussed in Chapter 3, Boyle believes that distinct natural kinds and their properties are such by virtue of having distinctively structured or textured corpuscular concretions. Thus, it would follow that the structure or texture of their chymical atoms must be distinct, even if the respective and peculiar structures of the chymical atoms of sugar and of salt render both substances water-​soluble. We must keep this in mind when we examine the implications of the reductionist interpretation of power and qualities. Let us take the example of sugar and salt, two distinct natural kinds that are both water-​soluble. Let us use w to represent the attribute of being soluble in water, A to represent sugar, ta to represent the peculiar texture of sugar, B to represent salt, and tb to represent the peculiar texture of salt. Let us now see what would follow if we adopt the reductionist interpretation discussed earlier, this time with regard to the water-​ solubility of sugar and salt: 1. If “w is not in A anything distinct from ta”  =  “w is not distinct from ta” = “w is ta” and 2. If “w is not in B anything distinct from tb”  =  “w is not distinct from tb” = “w is tb”

25

O’Toole, “Qualities and Powers in the Corpuscular Philosophy of Robert Boyle,” 311.

26 Boyle, The Origin of Forms and Qualities, 310.

158  The Chemical Philosophy of Robert Boyle then 3. Then, “w is ta” and “w is tb” 4. Thus, “ta = tb” According to this conclusion, which follows from the reductionist interpretation of powers and qualities, the fact that both sugar and salt are water-​soluble implies that their peculiar textures, ta and tb, are in fact the same since they are both equal to w, the attribute of being water-​soluble. However, if sugar and salt have the same microstructural texture then all of their properties should be the same, not just the property of water-​solubility. This is the case because the collection of properties of a substance, according to Boyle, are derived from texture. However, if we claim that glucose and sodium chloride have the same texture and the same properties, we would have to conclude that glucose is the same as sodium chloride. This absurd conclusion follows from the reductionist claim that water-​solubility and all other properties are not anything distinct from texture. Boyle would obviously not endorse such a nonsensical conclusion and, thus, would not be likely to endorse the view that powers and qualities are not anything distinct from texture or microstructure. In fact, I argued in Chapter 4 that such properties are distinct from structure to the extent that they are dispositional, relational, emergent, and “novel” properties that supervene upon the microstructure of corpuscular concretions. It is important, then, to examine the mereology of chymical atoms and how it fits within the context of Boyle’s chemical ontology. In Boyle’s ontological hierarchy of minima naturalia and corpuscular concretions, it is the corpuscular concretions or chymical atoms that endow parts of matter with the specific faculties to fashion or alter other parts of matter. Although chymical atoms or corpuscular concretions are definitely to be considered as integral wholes and, although these wholes enjoy a great degree of stability by resisting chemical analysis, these should not be considered as continuous wholes because the parts are not “fused” together, despite Boyle’s use of the term “adhaesion.” As Boyle conceives of chymical atoms, their adhaesion is not a bond. Rather, it consists of very “close and strict” spatial proximity so that even air cannot traverse the space between the particles. Though Boyle does not go into such details, one may imagine that the parts “fit together” geometrically, which is the only account that could explain such close fitting. To the extent that the parts of chymical atoms are spatially very close but not fused, there may be a temptation to argue that Boyle’s chymical atoms are contiguous integral wholes. However, as mentioned earlier and as will be argued further at the end of this section, I believe that Boyle would reject the continuous/​contiguous distinction altogether and simply refer to chymical atoms and all other material wholes as integral wholes simpliciter.

The Relation between Parts and Wholes  159 Regarding the parts of chymical atoms in relation to the whole, the constituent fundamental particles are discrete and integral parts of the chymical atom. That is, they are the material parts, present only in one place at a time and side-​ by-​side in a very close spatial proximity. The texture or structure in which these parts “adhaere,” however, is a substantial part of the chymical atom, since it is the essential form of this concretion. For medieval metaphysicians, “substantial part” is analogous to “substantial form.” However, to the extent that for Boyle essential structural form fulfills the role played by substantial form, then we can safely say that the substantial part of chymical atoms is their essential form or texture. While the loss or exchange of one fundamental mechanistic particle for another does not result in a change of substance, because these are integral parts of the whole, the loss of structure or essential form does entail a change of substance. This is because it is precisely this structure that accounts for the specific non-​mechanical essential properties that place a substance within a particular material species. To the extent that the perceptible chemical substance or compound body is made up of chymical atoms and acquires its essential properties from the structure of these atoms, we can say that the compounded body is also an integral whole made of discrete chymical atoms as its parts. These chymical atoms are integral parts of the whole substance, since subtracting some of them from the substance would not result in the loss of the essential properties that distinguish the substance. For example, if I have a gram of potassium nitrate and I take away a half a gram, each of the halves is still potassium nitrate and still displays the same chemical properties. However, if I were to alter the structure of the chymical atoms of potassium nitrate, I would give rise to a different substance with different properties. Boyle gives numerous examples of experiments in which the component parts of a substance remain the same but the structure is altered, thereby resulting in a novel set of properties. In Of the Producibleness of Chymicall Principles, Boyle gives the examples of powdered sulfur and salt of tartar, which will not dissolve in spirit of wine. He notes, however, that “if this salt [of tartar] and sulphur be mixt together, [they will] dissolve enough of this matter to be richly colourd by it, and this without the help of external heat.”27 He concludes from this experiment that the solubility of this mixture in spirit of wine, which is not a property of the component parts, is a property that emerges from the compounding of sulfur and salt of tartar. Regarding the property of salinity, he concludes that “whether we allow the Epicurean hypothesis, or the Cartesian, the first saline concretions that were produced by nature, must be confessed to have been made of atoms,



27 Boyle, Of the Producibleness of Chymicall Principles, 35.

160  The Chemical Philosophy of Robert Boyle or of particles, that before their conjunctions were not saline,” thereby implying that the property of salinity emerges from the particular texture or structure of the chymical atoms and from their interactions. It, thus, cannot simply be accounted for mechanistically. Further in the same essay, Boyle concurs with both Paracelsus and Helmont that salts are producible from ingredients that are not salts, when he states that “salt may be made of matter, that was not salt before, and consequently that salt may be de novo produced.”28 He then devotes the rest of this essay to discussing specific experiments for the production of acid, volatile, and lixiviate (or alkaline) salts. Another example of the acquisition of novel properties is discussed in Experiments and Notes about the Mechanical Origine and Production of Volatility, in which Boyle claims that “the same material parts of a portion of corporeal substance, which, when they were associated and contexed (whether by an archeus, seed, form, or what you please,) after such determinate manner, constituted a solid and fixt body, as a Flint or a lump of Gold; by having their Texture dissolved, and (perhaps after being subtilized) by being freed from their former implications or firm cohesions, may become the parts of a fluid body totally Volatile.”29 As was argued extensively in Chapter 3, although chymical atoms are chemical composites, it is not simply their composition that determines the properties and the species of a chemical substance. Rather, the structure in which the parts are composed determines the properties of the substance. If the same number and type of minima naturalia were to be arranged differently, that is, according to a different structure, the chemical and other non-​mechanical qualities of the material body would be different. The structure displays a complex mereology in which the whole is something more “over and above” its parts and gives rise to “novel” non-​mechanical properties that are no properties of its parts. The “something more,” however, is not anything itself substantial nor is it a substantial form. Instead, the “something more” is simply the essential material form of the microstructure, which is responsible for the properties of the whole (chymical atom) that are not present in its discrete parts (fundamental mechanistic corpuscles). It is, as already established, the essential parts of the whole that account for the novel properties of the whole, which are not displayed by the fundamental particles that are its integral parts. The perceptible chemical substance or compounded body, with its various sensible and chemical properties, is simply a composite of chymical atoms that has the properties it has because of these chymical atoms. If and when the structure of these atoms is altered in any way, the substantial part of the substance will have been changed, giving rise to a

28

Ibid., 378.

29 Boyle, Experiments and Notes about the Mechanical Origine and Production of Volatility, 432.

The Relation between Parts and Wholes  161 different substance. But Boyle can explain how this occurs much more satisfactorily than could medieval metaphysicians. Medieval and Paracelsian alchemists, for example, could not account for how one immaterial substantial form could “transmutate” into another. Nor could they explain how one could analyze potassium nitrate and resynthesize it, since this would imply a loss of substantial form followed by a reacquisition of the same substantial form. Boyle, on the other hand, would simply say that transmutation is simply the alteration of the geometrical structure of the chymical atoms that generates a new species of material body. Redintegration occurs because the original microstructure of a substance is restored. But these are all material, physical processes that do not depend upon appealing to empirically suspect immaterial forms or principles. Although, according to Henry, Boyle denies that any real novelty arises in wholes that is not present in their component parts, the passage cited earlier clearly conflicts with Henry’s claim. Instead, the passage cited earlier and other passages from Boyle’s works support my contention that Boyle is simply rejecting the theory of substantial form but not the idea that mereological wholes can display properties that are novel “over and above” those of their individual parts. In fact, the passage from The Origin of Forms and Qualities cited by Henry simply states, “not that there is really anything of substantial produced,” meaning that no new matter is produced that did not previously exist in the individual parts. However, there is nothing in this passage or any other to indicate that Boyle would endorse the same sort of permissive mereology for which Abelard argued. As David Armstrong points out, mereological permissiveness “appears to have no real metaphysical consequences. Mereological wholes supervene on their parts, as do the parts supervene on the whole. Given one, the other is entailed. And on the basis of this it may be concluded that the wholes are no increase of being beyond that of their parts.”30 For Boyle, however, there are definite metaphysical consequences to rearranging the same parts according to a different structure or texture. When this occurs, a new determinate species of matter is produced, albeit no new matter as such. Relevantly, this new species of matter has different chemical and other non-​mechanical properties from the original species. As Boyle very explicitly states in the passage that is misinterpreted by Henry, “those parts of matter that did indeed before pre-​exist [. . .] are now brought together and disposed after the manner requisite to entitle the body that results from them to a new denomination, and make it appertain to such a determinate species of natural bodies,” meaning that the new structural arrangement of the parts results in a new natural



30 Armstrong, A World of States of Affairs, 120.

162  The Chemical Philosophy of Robert Boyle kind or new type of material body. This results from the pre-​existing material parts having acquired a “new modification” and, thus, having become a new type of whole. Later in the same passage, in a part not cited by Henry, Boyle adds that what distinguishes one species of natural body from another are those properties that are “necessary and sufficient to constitute any one Determinate Species of things corporeal.”31 As established in Chapter 3, Boyle believes that different species of bodies are distinguished by different sets of necessary and sufficient properties. Clearly, then, if a new species of body comes into being when the same parts are structurally rearranged, then the difference in the properties must be accounted for by the new structure and clearly not by any difference in parts. This implies, however, that something de novo is indeed produced from the new structural arrangement, and what is produced de novo are the new emergent properties whose presence characterizes a different species of material body. Thus, unlike the scattered mereological sums discussed by Abelard, whose properties remain the same after being brought together so that nothing new is added, the mereological arrangements of material parts referred to as chymical atoms bring about the existence of emergent properties that were not present prior to that particular structural arrangement. All this is explained by the fact that, although Boyle’s chymical atoms lack substantial form, they are endowed with essential form by way of their texture or structure. Thus, although they do not qualify as continuous wholes for lack of substantial form, they have a unity that is not present in contiguous wholes. Chymical atoms are not simply constituted by the close adhaesion of particles but by the structure according to which those particles are arranged. It is the structure that determines the properties of chymical atoms and that determines the particular material species to which those chymical atoms belong. On the one hand, Boyle’s rejection of substantial forms implies a rejection of chymical atoms as continuous integral wholes and, on the other hand, his rejection of mereological extensionalism implies a rejection of chymical atoms as contiguous integral wholes. Thus, I wish to argue that Boyle’s chymical atoms are neither continuous integral wholes nor contiguous integral wholes but, rather, integral wholes simpliciter. In fact, Boyle’s non-​reductionist mechanical philosophy implies the rejection of the continuous/​contiguous distinction for all material substances, not just for chymical atoms. As was discussed in Chapter 3, Boyle firmly believes that specific structure or essential form is that which distinguishes one material species from another, even if the simple parts are the same in both material



31 Boyle, The Origin of Forms and Qualities, 328.

The Relation between Parts and Wholes  163 species. Furthermore, this implies a rejection of the Scholastic distinction between natural and artificial substances, since neither type of substance has substantial form and both types of substances have essential form. As well, although material substances are not endowed with substantial forms, their unity is not reducible to a mere collection of simple parts but is something “over and above” those parts. Thus, as already concluded, Boyle’s non-​reductionist mechanistic corpuscularianism implies that, at least as far as material substances are concerned, there is no distinction between continuous wholes and contiguous wholes. If a material substance is a unified whole at all, it is an integral whole simpliciter, whether that substance be natural or artificial.

5.6  A Brief Excursion into the Mereology of Epicurean Semantics In An Introduction to the History of Particular Qualities, Boyle explains the ways in which the various affections of matter produce the varieties of qualities that exist in nature. In doing so, Boyle appeals to an analogy made by the ancient atomist Lucretius, who compares the manner by which the atoms that exist in the universe come together to produce the variety of things to the manner by which the twenty-​four letters of the alphabet come together to produce the various languages of the world. Boyle prefaces the discussion of this analogy by first listing the eleven affections that govern matter in the production of qualities. The first four are “the most primary and simple affections of matter,”32 which are local motion, size, shape, and rest. The other seven affections are posture, order, texture, porousness, effluvia, mixture or composition, “and all of them governed as well by . . . the universal fabric of things, as by the laws of motion established by the Author of nature in the world.”33 Boyle then continues: And now . . . that we have enumerated 11 very general affections of matter, which with itself make up 12 principles of variation of bodies, let me on the behalf of the Corpuscularians apply to the origins of qualities a comparison of the old atomists, employed by Lucretius and others to illustrate the production of an infinite number of bodies from such simple fragments of matter as they thought their atoms to be. For since of the 24 letters of the alphabet, associated several ways as to the number and placing of the letters, all the words of the several languages in the world may be made, so, say these naturalists, by variously connecting such and such numbers of atoms, of such shapes, sizes,

32 33

Ibid., 105. Ibid., 106–​107.

164  The Chemical Philosophy of Robert Boyle and motions, into masses or concretions, an innumerable multitude of different bodies may be formed [. . .] supposing these eleven principles were but so many letters of the alphabet that could be only put together in differing numbers and in various orders, the combinations and other associations that might be made of them may be far more numerous than you yourself will expect [. . .] of so few things so many associations may be made, each of which will differ from every one of the rest, either in the number of the things associated or in the order wherein they were placed.34

It is fortuitous that Boyle should employ Lucretius’ analogy between words and things to explain the origin of qualities since, just as the associations of a finite number of letters can generate an infinity of words, the variety of qualities and phenomena originate from the combination of a finite set of affections. To the extent that Boyle uses this Lucretian analogy, it would seem that the eleven general affections of matter function very much like rules of grammar, in that these principles govern the multitude of ways in which particles of matter can associate and combine to give rise to a multitude of qualities. Although Boyle does not specifically use this analogy with reference to aggregate corpuscles or chymical atoms, the Lucretian analogy between atoms and letters is very apt for our own discussion to the extent that the mereology of chymical atoms can itself be analogized to the mereology of linguistic expressions. What characterizes linguistic expressions (words, propositions, etc.) as wholes and distinguishes them from their discrete parts (i.e., letters) is that expressions have meaning while their discrete parts do not. Clearly, a linguistic expression is endowed with something “over and above” its individual parts, that is, the meaning of the words transcends the individual letters. Yet we can also say that there is nothing materially present in the whole other than the letters of which it is made up. But, in coming together in particular configurations, meaningless parts (letters) give rise to meaningful simple wholes (words). These words, in turn, become parts of complex wholes (propositions) whose own meaning transcends the meaning of the individual words, and so on. We can say that linguistic mereology involves the combinations and recombination of meaningless parts into meaningful wholes of varying degrees of complexity. But, the meaning of linguistic expressions, whether they be singular words or complex phrases, is not simply constituted by bringing the letters together. These letters must be combined in a particular kind of order, following the specific syntactic and semantic principles that are codified in the given language. The language itself is



34 Boyle, An Introduction to the History of Particular Qualities, 107.

The Relation between Parts and Wholes  165 constituted within the context of a particular culture and is heavily dependent upon practice and tradition. While embracing an atomistic idea of linguistic expressions as collections of letters in much the same way that material bodies are collections of atoms, Lucretius and other Epicureans were also keenly aware of the contextuality of linguistic meaning. For Epicureans, although expressions are ontological composites of letters, they acquire their meanings within the context of particular linguistic and cultural practices, “a notion of context that is not fixed but at once determining of and determined by the speech act.”35 Thus, the meaning of linguistic expressions is relational in many different ways. Regarding speech act theory, Wilson Shearin explains that “of course, Epicurus and his disciples can hardly be accused of developing in every detail a theory that was not well articulated until the second half of the twentieth century, but Epicurean thinking on language anticipates [. . .] the primary contribution of speech act theory [. . .] the recognition and articulation of the performative. It may also grasp nuances about context in speech act theory.”36 Within Epicurean semantics, the role of the speech act is performative, so that Epicurus locates his theory of language within a theory of action, that is, of practice. And, for him as for Lucretius, the performative role of speech acts fulfills a central function within their therapeutic conception of philosophy. Indeed, Shearin notes that, for the Epicureans, “a therapeutic philosophy would have great interest in acting upon the world.”37 What is interesting in this analysis of Epicurean semantics in relation to the mereology of linguistic expressions is that, although Lucretius and other Epicureans believed that words and other expressions were, materially speaking, sums of letters, there is something “over and above” the letters that makes the whole into an expression rather than simply into a collection of meaningless discrete parts. This “something” is meaning. Although the meaning of the whole transcends the discrete parts, it not an ontologically independent entity in the Platonic sense. Rather, it emerges from and supervenes upon the collection of letters, making the whole something greater than the sum of its parts. Secondly, semantics clearly implies a rejection of mereological extensionalism, since the same letters arranged differently acquire a completely different meaning, for example, “end” and “den.” Thirdly, meaning does not emerge simply as a result of bringing letters together in particular ways. As Edmund Husserl pointed out, many centuries after the Epicureans, not all collections of letters are meaningful expressions. For Husserl, what is required to make a sum of letters into an



35 Shearin, The Language of Atoms, 16. 36 Ibid. 37

Ibid., 19.

166  The Chemical Philosophy of Robert Boyle expression is a meaning-​intending act.38 For the Epicureans, who clearly could not have adopted a transcendental phenomenological conception of meaning, what is required is a performative speech act, to use 20th-​century vocabulary, through which the expression both acquires meaning and acts upon the world in transformative ways. Such speech acts are meaningful when they abide by particular contexts of linguistic and cultural practice. Three ideas stand out from this brief discussion of Epicurean semantics. First, the meaning of a linguistic expression transcends the sum of the parts (letters) that constitute the whole (expression). Second, semantics implies a rejection of mereological extensionalism. Third, meaning emerges from the relation between the parts, the whole, and the context or environment, which includes linguistic and cultural practice. Thus, albeit ontologically atomistic, Epicurean semantics rejects the idea that the meaning of expressions is simply reducible to the parts or to the sum of the parts of which those expressions are made. In fact, the meaning is not even entirely reducible to the order in which those parts are structured. There is also a crucial relational and contextual element in the constitution of linguistic meaning. My brief excursion into the mereology of Epicurean semantics was spurred by Boyle’s direct reference to the Lucretian analogy between words and things in the History of Particular Qualities to explain that a finite number of principles can result in an almost infinite number of combinations of material parts, which themselves produce an almost infinite variety of qualities. Yet the analogy is also useful to elucidate how, just as linguistic meanings transcend the sum of letters, chemical properties transcend the sum of primary corpuscles of which chymical atoms are constituted. We can equally surmise that chemical properties emerge from and supervene upon the microstructural arrangement of primary corpuscles that constitute chymical atoms in an analogous manner to that in which meanings emerge from and supervene upon the sums of letters that constitute expressions. This is not to imply that meanings and properties are ontologically of the same type. Properties are perceivable through our senses and have causal power to act upon our senses and upon other material bodies. Meanings, on the other hand, are not sensible properties, although speech acts certainly have causal impact upon the world. Nevertheless, to the extent that both Lucretius the atomist and Boyle the corpuscularian both avail themselves of the analogy between words and things, we can unpack this analogy further and see that atomism, whether physical or linguistic, does not imply a simplistic extensional mereology in 38 For a detailed account of the relationship between meaning-​intending acts, meaning-​fulfilling acts, and linguistic expressions, see: Marina Paola Banchetti-​Robino, “Husserl’s Theory of Language as Calculus Ratiocinator,” 303–​321.

The Relation between Parts and Wholes  167 which the whole is nothing over and above its parts. Just as rearranging the letters in a word without changing the letters themselves alters the meaning of the word, altering the microstructure or texture of chymical atoms without altering their composition will alter the chymical atoms and their properties. Although Boyle could not possibly have understood the concept of isomerism, his notion of substance was clearly not simplistically compositional. Boyle understood quite clearly that composition by itself is not enough to determine the properties of a chemical substance, since two chymical atoms with the same composition but different structures will display different chemical properties. However, as was argued in Chapter 4, although the microstructure of chymical atoms determines the non-​mechanical properties that these atoms are disposed to display, it is the chemical substance’s relation to other substances in the context of specific chemical processes and procedures that allows dispositional properties to emerge and causally affect changes in other material bodies. For Boyle, then, chemical substances are functional wholes whose properties emerge not only from the structural ordering of their parts but also from their relationship with other chemical substances in the context of experimental practice.

Conclusion Thomas Kuhn once stated that Robert Boyle “was a man who brought to its most developed form a type of chemical conceptualization consonant with a major tendency of the scientific thought of his day. His failure to exert an important influence upon the future course of chemical theory was due, not to an inability to ‘fit’ his scientific contributions to ‘the times,’ but to specific shortcomings of his chemical doctrines themselves.”1 Although recent authors, such as William Newman, have successfully challenged Kuhn’s view that Boyle had little influence on the development of chemistry,2 this book purports to establish that Boyle was more than a historically influential chemist. He was also an important philosophical figure whose ideas were not merely consonant with the scientific and philosophical thought of his day but may have, at times, surpassed it. Boyle anticipated many of the fundamental questions to be raised by later philosophers of chemistry, questions regarding ontological and epistemological reduction, emergence, supervenience, and disciplinary autonomy, as well as questions regarding structural disposition, the relationality of properties, and the mereology of higher and lower levels of organization. Issues regarding chemistry’s scientific autonomy are themselves directly related to the reducibility of chemistry to physics. In fact, the question of reducibility has been called “one of the main areas in which philosophical interest in chemistry should be directed.”3 Since the ontological dependency of chemical properties on fundamental physical states is not at issue, the sort of reduction being considered is epistemic rather than ontological, and the question is “whether our current description of chemistry can be reduced to our most fundamental current description of physics, namely quantum mechanics—​and with its explanatory consequences.”4 The reducibility of chemical laws to physical laws would necessitate that physical laws be universal and fundamental and that

1 Kuhn, “Robert Boyle and Structural Chemistry,” 15. 2 See, for example: Newman, “Robert Boyle, Transmutation, and the History of Chemistry before Lavoisier.” 3 Scerri and McIntryre, “The Case for the Philosophy of Chemistry,” 214. 4 Ibid. The Chemical Philosophy of Robert Boyle. Marina Paola Banchetti-Robino, Oxford University Press (2020). © Oxford University Press. DOI: 10.1093/oso/9780197502501.001.0001

Conclusion  169 all laws in the special or secondary sciences be non-​fundamental instantiations of these more general physical laws. The evidence at this point seems to weigh against the reducibility of chemical laws to the extent that at least some of these laws can be considered fundamental. Although some philosophers are firmly convinced that epistemic and explanatory reduction is both desirable and possible, at least in principle, chemists and philosophers of chemistry have serious doubts about whether the ontological dependency of chemical states upon physical states undermines the epistemic and explanatory autonomy of chemistry. In this regard, Boyle’s views anticipated those of contemporary philosophers of chemistry to the extent that he did not consider chemistry to be a “derivative” science at all but an autonomous practice. He considered chemistry to be a practice both theoretically and methodologically independent from mechanics and physics. Although the mechanization of corpuscularianism in the work of Gassendi and Descartes opened the door for the naturalization of all causes and principles, at least as far as inanimate bodies were concerned, Boyle was well aware that the mechanical philosophy could not successfully provide a complete account of chemical properties and processes. As this book demonstrates, Boyle’s rejection of reductively mechanistic explanations for chemistry shows that he “did not consider chemistry as a branch of physics . . . [and] did not reduce all chemical phenomena to the geometrico-​ mechanical affections of inert matter.”5 Boyle did not believe that chemistry should be subordinated to the mechanical philosophy6 and he distanced himself from philosophers such as Spinoza, who attempted explanations of chemical reactions by appealing to the mechanistic properties of fundamental particles. Ultimately, as an experimental scientist, Boyle could not bring himself to adopting any rigid and unrelentingly reductionist approach to chemical explanations. In addition to the explanatory autonomy of chemistry, another important issue in the contemporary philosophy of chemistry is the question of the emergence of chemical properties from relationships at more fundamental physical levels. When the concept of emergence is analyzed further, it involves a number of interdependent features. These are novelty of properties, supervenience, and non-​summative difference. There is, in fact, ample support for the notion of emergence of chemical properties, since they are clearly novel properties not found at lower ontological levels. However, when discussing emergence and supervenience, it is important also to include a discussion of relationality, and these questions are themselves closely linked to the larger question of the aforementioned autonomy of chemical explanations.

5 Clericuzio, Elements, Principles, and Corpuscles, 106. 6 Ibid.

170 Conclusion Although this book admits that Boyle lacked the philosophical vocabulary necessary to speak about emergence and supervenience, his writings display a very sophisticated understanding of these underlying issues within the context of his chemical philosophy. There is, in fact, evidence in his writings that he regarded chemical properties as emergent properties that supervene on the mechanistic property of texture or structure. Boyle was able to accommodate this emergentist position within a generally mechanistic theory of matter by developing a hierarchical corpuscularian theory that distinguished between different orders of compounded corpuscles. Of these compounded corpuscles, chymical atoms were the operationally elementary and stable chemical wholes from whose structure chemical properties emerged. By developing this hybrid chemical ontology, Boyle stressed the importance of chemical microstructure long before the development of structural chemistry in the mid-​19th century. Once structure is taken into account, mereological questions inevitably arise regarding the relations between chemical wholes and their parts, which is why it was imperative to devote one of the central chapters of this book to the mereological analysis of chymical atoms. Robert Boyle understood exactly what Robert Mulliken would state three centuries later, that is, molecules have properties that their component atoms lack because a molecule is considered as “a composite in which the atoms [lose] their singularity.”7 Boyle believed that chemical reactions occurred at the level of chymical atoms, that is, higher-​order corpuscular concretions whose properties were distinct properties from those of their more fundamental parts. Given the extensive discussion in this book, it is safe to conclude that Boyle would be in agreement with Mulliken’s claim that “a molecule has properties which the atoms do not express and its decomposition gives again the separate atoms . . . This molecular composite creates new homogeneous bodies starting from heterogeneous elements . . . Thus the composite challenges the mere sum of the parts.”8 It is very likely that Boyle would have also agreed with William Newman’s claim that “the generation of supervenient properties from subvenient ones that is so characteristic of the subject of chemical studies arises as a result of an interaction of parts that arises when such parts are in a certain configuration.”9 Furthermore, Boyle seems to have regarded the relationship between mechanical and chemical properties as an asymmetric dependence and to have suggested that chemical properties emerge from and are supervenient upon mechanical properties. In this regard, Boyle seems to have anticipated contemporary explanations for the supervenience of chemical properties on subvenient physical properties. As Eric Scerri and Lee McIntyre assert, “the supervenience argument would entail that

7

Llored, “Mereology and Quantum Chemistry,” 204.

9

Newman, “Chemical Supervenience,” 54.

8 Ibid.

Conclusion  171 if two compounds share the same macroscopic property . . . we could not necessarily infer that the microscopic components from which the compounds are formed would be identical.”10 As this book explains, Boyle also believed that different concretions of primary particles with quantitatively different mechanical properties could express the same chemical properties, such as salinity, for example. Thus, Boyle refrained from “establishing a direct relationship between a given quality and a set of mechanical properties of the simplest corpuscles.”11 His position aligns with the understanding of emergent properties as defined by contemporary philosophers, who establish that a property is emergent “if it is in some way novel or unpredictable, given the behaviours of the properties displayed by the system’s elementary components.”12 Boyle’s view that chemical properties emerge from and supervene upon mechanical properties suggests that he regarded chemical explanations as irreducible to physical explanations so that chemistry must retain its autonomy from physics and mechanics. This book’s in-​depth analysis of Boyle’s chemical philosophy is, therefore, not merely historically relevant but also philosophically germane. Once again, it establishes that Boyle anticipated many of the fundamental questions raised by the modern practice of chemistry and by contemporary philosophy of chemistry. These questions regard ontological and epistemological reduction, structural disposition, the relationality of properties, and the mereology of chemical wholes. Although as a 16th-​century chemist, Boyle lacked the appropriate philosophical vocabulary to explicitly articulate many of these ideas, his writings clearly address the same concerns as those reflected in the contemporary philosophical literature on chemistry. In order to address these concerns, he postulated a complex and nuanced hybrid and hierarchical chemical ontology, whose purpose was to accommodate the emergence and supervenience of chemical properties within the framework of the mechanical philosophy. This chemical ontology also allowed him to defend the autonomy of chemical laws and chemical explanations against those who would subordinate chemistry to mechanics and physics. Although chemistry and chemical ontology have advanced quite far since the time of Boyle, his mereological conception of chymical atoms and his perspective on the relationality and emergence of chemical properties also seem very much in tune with the positions reflected in some of the most important contemporary work in the philosophy of chemistry. In this sense, Boyle’s chemical philosophy is certainly deserving of an in-​depth study as it was both prescient and, in many regards, well ahead of its time.

10

Scerri and McIntyre, “The Case for the Philosophy of Chemistry,” 225.

12

Newth and Finnigan, “Emergence and Self-​Organization in Chemistry and Biology,” 842.

11 Clericuzio, Elements, Principles, and Corpuscles, 117.

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Index For the benefit of digital users, indexed terms that span two pages (e.g., 52–​53) may, on occasion, appear on only one of those pages. Abelard, Peter, 150–​56, 161, 162 accidental properties. See properties, accidental acids, 31–​32, 34, 55–​56, 63–​64, 65, 88, 97, 98, 105–​6, 107, 123–​24, 138–​39,  159–​60 affordance, 81, 103, 128–​30 aggregate corpuscles, 32, 71–​72, 92, 93, 94, 105–​6, 107–​8, 137, 148, 150. See also Boyle, Robert: chymical atoms; chymical atomism alchemy and alchemists, 1–​2, 3, 8–​9, 10–​13, 16, 17, 19, 22, 25–​27, 30–​31, 33–​34, 43, 53, 82, 89, 131–​32, 161 Renaissance, 3, 4–​5, 6, 8–​10, 11–​13, 16–​17, 18–​19,  22 See also Paracelsus and Paracelsians; spagyria Alexander, Peter, 113, 115–​16, 117, 118,  123–​24 alkahest, 39, 81, 89, 129–​30 alkaline salts, 18–​19, 25, 160 analysis, 19, 26–​31, 32–​34, 43, 57, 63, 64–​66, 67, 71–​72, 79–​80, 82–​83, 87, 88, 91–​93, 94–​95, 106–​7, 122, 158 Anima Mundi, 8, 18–​19, 22–​23, 24, 25, 72–​73, 75–​76,  142 Anstey, Peter, 2–​3, 85, 102–​3, 109–​10, 113–​19, 121,  123–​24 aqua fortis, 28–​29, 31–​32, 34, 63–​64, 92–​93, 105, 114, 123–​24, 125–​26, 157 aqua regia, 28–​29, 41, 92–​93, 123–​24,  125–​26 Aquinas, Thomas, 15, 28, 152, 154 archeus, 25, 36–​37, 38–​39, 40, 84, 160 Aristotle and Aristotelians, 13–​15, 19–​20, 22, 27–​28, 30, 33–​34, 35–​37, 38,

45–​47, 95–​96, 99–​100, 108, 110, 112, 126–​27, 148–​49, 150, 151, 153–​54 association of particles, 81, 122, 137,  163–​64 atomism alchemical, 22 Epicurean, 3–​4, 9–​10, 20, 21, 22, 25, 35, 47–​51, 60–​61, 83, 85 mechanistic, 3–​4, 26, 47–​51 vitalistic, 22 atoms. See atomism Augustine of Hippo, 20, 20n.49    Basso, Sebastian, 10–​11, 24–​25, 62, 72–​73 Bensaude-​Vincent, Bernadette, 26–​27, 33, 34, 106 Boyle, Robert anti-​reductionism (see reductionism and anti-​reductionism) chrysopoeia, 1, 89 chymical atoms, 2–​3, 4–​6, 26, 58, 88–​93, 94, 95–​97, 103, 104, 105–​8, 109, 113–​ 14, 122, 125, 126, 130, 131–​32, 134–​36, 147, 149–​50, 155–​63, 164–​65, 166–​67, 170, 171 corpuscularianism (see corpuscularianism: Boylean) emergentism (see emergence of chemical properties) essential form, 4–​5, 15, 91, 101, 102–​4, 105–​6, 107–​8, 148, 149, 150, 155–​56, 159,  162–​63 extra-​essential properties, 90–​92, 104 ‘lock and key’ analogy, 115–​16 and Locke, 5, 99–​101 meaning of ‘mechanical philosophy’, 3–​4,  73–​78

192 Index Boyle, Robert (cont.) mechanicism (see mechanicism: Boylean) microstructure, 4–​6, 28–​29, 34, 83, 87, 90–​99, 101, 103, 104–​5, 106, 107–​8, 109, 111–​12, 113–​14, 117–​18, 122, 123, 126–​27, 136, 140–​41, 147, 158, 160–​61, 166–​67,  170 pneumatics, x, 76–​77, 84, 113, 126, 128–​29,  144–​45 scientific research programme, 4–​5, 73–​78, 96 subordinate and intermediate causes, 92–​93, 97,  98–​99 texture, 4–​5, 64, 65, 66–​67, 90, 91, 93–​94, 98, 103–​4, 107, 108, 109, 111–​12, 114, 117–​18, 119–​20, 121, 122–​23, 124–​27, 132–​33, 134, 135–​37, 140–​41, 144, 148–​49, 150, 156–​57, 158, 159–​60, 161–​62, 163, 166–​67,  170 Bruno, Giordano, 8–​9, 22–​23    Cartesian mechanism. See mechanicism: Cartesian Cecon, Kleber, 92–​93, 94, 96 Chalmers, Alan, 53, 54–​55, 76–​77, 96–​97 Charleton, Walter, 29, 47–​48, 50 chemical alterations, 35, 37–​38, 42, 50, 64, 85, 90, 91–​92, 106, 107, 115–​16, 126, 132, 161 in Boyle, 64, 85, 90, 91–​92, 106, 107, 115–​16, 126, 132, 161 chemical bond, 41, 107, 158 chemical composition, 29, 31, 32–​33, 50, 58, 59, 77, 86, 88, 89, 90, 93–​95, 104–​5, 107, 130–​31, 147, 148, 149–​ 50, 156–​57, 160, 163, 167. See also molecules in Boyle (see Robert Boyle: chymical atoms) chemical elementarity. See Boyle, Robert: chymical atoms; Gassendi, Pierre; negative-​empirical concept; Sennert, Daniel chemical properties as dispositional. See properties: dispositional

chemical properties as emergent. See properties: emergent Chemical Revolution, 53, 94–​96 chrysopoeia, 1, 89, 90, 101–​2n.58 See also alchemy chymical atomism, 2–​3, 4–​6, 26, 50, 58, 88–​93, 94, 95–​97, 103, 104, 105–​8, 109, 113–​14, 122, 125, 126, 130, 131–​32, 134–​36, 147, 149–​50, 155–​ 63, 164–​65, 166–​67, 170, 171 see also Boyle, Robert: chymical atoms chymistry, 9, 9n.3, 10–​11, 13, 16, 17, 18, 19–​20, 21–​22, 24–​25, 27, 30, 32–​33, 37, 39, 41, 43–​44, 56, 57, 58–​59, 60, 69–​71, 72, 79–​80, 81, 82, 89, 99 Clericuzio, Antonio, 1–​2, 11, 72–​73, 122 Cordemoy, Géraud de, 56–​57, 58 corpuscular concretions. See Boyle, Robert: chymical atoms corpuscular philosophy. See corpuscularianism corpuscularianism, 3–​5, 6–​7, 9–​11, 13, 60–​62, 67, 69–​70, 80 Boylean, 79–​89, 93, 94, 96, 98, 111–​12, 116, 137–​38, 139–​40, 142–​43, 144–​ 45, 147, 152, 162–​63, 166–​67, 170 Cartesian, 47–​48, 49, 54–​55, 169 mechanistic, 28, 33, 42, 45–​46, 47–​48, 49, 50–​51, 56, 60–​70, 72, 73, 75–​77, 79–​89, 93, 94, 96, 98, 111–​12, 116, 137–​38, 139–​40, 142–​43, 144–​45, 147, 152, 162–​63, 166–​67, 169 vitalistic, 19–​25, 28, 34–​35, 40–​41, 42, 47–​48, 75, 91 corpuscularism. See corpuscularianism    Democritus, 22, 89 Descartes, René and Cartesianism, 2, 3–​4, 9, 16, 43–​44, 45–​60, 62, 66, 68–​71, 74–​75, 85, 86, 97, 100, 120, 134,  159–​60 downward causation, 112, 130–​31n.47,  138–​39    effluvia, 5, 139–​40, 142, 163 elementarity, 96, 106 (see also mereology; parts and wholes)

Index  193 operational, 5–​6, 26–​27, 57 (see also Boyle, Robert: chymical atoms; Lavoisier, Antoine Laurent; negative-​empirical concept; Sennert, Daniel elements chemical, 7, 27, 41, 50, 57–​58, 79–​80, 81, 88, 90, 94, 95–​96, 129–​30, 170 theory of, 13–​14, 16–​17, 28, 38, 81, 132 emergentism. See properties: emergent Epicurus and Epicureanism, 3–​4, 9–​10, 20, 21, 22, 25, 35, 47–​51, 60–​61, 70–​71, 75–​76n.91, 83, 85–​86, 120, 134, 159–​60,  165–​66 essential form. See Boyle, Robert; essential form; microstructure; texture essential parts. See parts, essential essential properties. See properties: essential essential structure. See Robert Boyle: essential form    ferments, 10, 11, 24–​25, 34–​35, 36, 37, 38–​ 44, 71, 72–​73, 98 Ficino, Marsilio, 8–​9, 11, 19–​20 final causes. See teleology fixedness. See fixity fixity, 63–​67, 96, 111, 122, 126–​27, 129–​30, 133, 135, 160, 165 Fontenelle, Bernard le Bovier de, 69, 70 Fracastoro, Girolamo, 21, 139–​40    Galen, 16, 21 Galilei, Galileo, 110–​11, 113 gas, 37, 38, 63–​64 Gassendi, Pierre, 3–​4, 21, 47–​51, 61, 85, 86,  87–​88 Geber, 27, 34–​35, 42 generation, 21, 35, 36, 38, 40, 87, 127–​28, 133,  148–​49 gold, 1, 23–​24, 31, 32, 89, 123, 125–​26, 129–​30, 135, 151–​52, 157, 160 analysis of, 31, 32, 39n.119, 41, 93–​94, 105–​6, 114, 123–​24, 125–​26, 157, 160    Hall, Marie Boas, 26 Harré, Rom, 5–​6, 128–​29, 147, 155–​56

Helmont, Jan Baptista van, 3, 10–​11, 18–​19, 21, 23, 25, 34–​44, 47–​48, 70, 72–​73, 81, 91 Henry, Desmond Paul, 150–​51, 153–​55, 156,  161–​62 Henry, John, 143–​45 heterogeneity. See mixts heterogeneous substances. See mixts heuristic negative, 3–​4, 73–​78, 99, 142 positive, 3–​4, 73–​78, 99 Hirai, Hiro, 1–​2, 20n.48 Hohenheim, Theophrastus von. See Paracelsus and Paracelsians homogeneity. See homogeneous substances homogeneous substances, 24, 26, 28, 29–​ 30, 31, 50, 71–​73, 87, 88, 91–​92, 94, 105, 106–​7, 151–​52, 170 humoral theory, 16, 21, 36 Hunter, Michael, 2, 3 hydrostatics, 4–​5, 54, 76–​77, 84, 99,  144–​45 hylomorphism, 10–​11, 13–​14, 26–​34, 36, 49–​50, 67, 77–​78, 85, 148, 153–​54 See also Aristotle and Aristotelian; Sennert, Daniel; substantial form hypostatical principles. See tria prima    integral parts. See parts, integral integral wholes. See wholes, integral    Joly, Bernard, 53–​54, 65–​66, 69, 72    Kim, Mi Giyung, 12, 16 Kuhn, Thomas, 68, 149–​50, 168    Lakatos, Imre, 3–​4, 73–​78 See also scientific research programme Lavoisier, Antoine Laurent, 9–​10n.3, 26, 33, 51–​52, 57–​58, 59–​60,  94–​96 Lémery, Nicolas, 58 Leucippus, 89 Llored, Jean-​Pierre Noël, 5–​6, 147, 155–​56 Locke, John, 4–​5, 99–​101 logoi spermatikoi. See semina rerum Lucretius, 5–​6, 20, 22, 163–​67

194 Index manifest qualities. See qualities, manifest mechanical affections, 45–​46, 52, 59, 64, 65–​66, 68–​69, 70–​71, 83–​84, 86, 90–​ 91, 94, 96–​97, 98, 102–​3, 109, 111–​12, 114, 116–​18, 119–​21, 126, 132–​33, 134, 135–​37, 142, 144, 163, 164, 169 mechanical philosophy. See mechanicism mechanicism, 1–​2, 3–​4, 7, 9n.3, 9–​11, 16, 22, 23, 24, 26, 29, 30–​31, 33–​34, 35, 37–​38, 40–​42, 43–​44, 45, 47–​51,  60–​69 Boylean, 3–​7, 34, 69–​78, 79, 83–​89, 90–​108, 109, 110–​20, 121–​45, 146, 148, 149–​50, 152, 154–​55, 156–​57, 159–​60, 162–​63, 167, 169, 170, 171 Cartesian, 2, 3–​4, 45–​47, 51–​60, 62, 66, 68–​70,  85 mechanism. See mechanicism mechanistic qualities. See qualities, mechanistic Meinel, Christoph, 60–​61, 62, 104–​5 menstruum, 89, 98 mercury element, 62, 93–​94 principle (see tria prima) mereology, 2–​3, 5–​6, 13–​14, 15, 46–​47, 49, 96–​97, 103, 107, 109, 133, 145, 146,  147–​67 See also parts and wholes Mersenne, Marin, 37, 54–​55 microstructure. See Boyle, Robert; essential form; microstructure; texture minima naturalia, 3, 19–​25, 28, 34–​35, 37–​38, 40, 41–​42, 86–​87, 90–​91, 98, 107, 111–​12, 114, 122, 126, 133, 135–​36, 148, 158, 160 mixts, 5, 26, 27–​31, 32, 34, 79–​80, 81, 87–​89, 91–​92, 94, 119, 129–​30 mixtures, 37, 40, 41–​42, 43, 63–​64, 66, 87–​89, 91–​92, 97, 121, 123–​24, 126, 128, 132, 134–​35, 136, 159–​60, 163 molecules, 24, 49–​50, 87–​88, 90, 95, 109, 147, 150, 170    natural kinds, 7, 29, 46–​47, 77–​78, 92–​93, 97, 99–​104, 105, 107–​8, 157 negative-​empirical concept, 26–​34, 58, 59–​60, 92, 106

See also Boyle, Robert: chymical atoms; elementarity: operational; Sennert, Daniel negative heuristic. See heuristic: negative Neoplatonism, 8–​9, 11, 18–​19, 20–​21, 22, 24, 35 Newman, William, 4–​5, 26–​27, 33–​35, 41, 65, 89, 94, 105–​6, 136–​38, 168,  170–​71 niter aerial, 10, 18–​19 (see also anima mundi; potassium nitrate) fixed and volatile, 63–​64, 65, 66–​67 redintegration of niter (see potassium nitrate: redintegration of) spirit of, 63–​64, 65, 66–​45 nitric acid. See aqua fortis nominalism, 100, 101, 154–​55 non-​mechanistic qualities. See qualities, non-​mechanistic    O’Toole, Frederic, 119–​20, 124, 125–​26,  157 occult qualities. See qualities, occult Oldenburg, Henry, 63, 66–​67    Paracelsian principles. See tria prima Paracelsus and Paracelsianism, 3, 4–​5, 10–​ 11, 12, 16–​21, 23, 24–​25, 26, 33–​35, 36, 38, 42, 43, 47–​48, 56, 58, 63, 77, 79, 81, 82, 121, 129–​30, 131–​32, 139–​ 40, 142, 160, 161 See also alchemy: Renaissance; spagyria parts and wholes contiguous wholes, 151–​53, 154–​55, 158,  162–​63 continuous wholes, 151–​53, 155–​56, 158,  162–​63 essential parts, 153–​54, 160–​61 integral parts, 153–​54, 159, 160–​61 integral wholes, 151–​53, 154–​56, 158–​59,  162–​63 Pasnau, Robert, 15, 45–​46, 101, 148, 149, 150 Peterschmitt, Luc, 57, 59 positive heuristic. See heuristic: positive potassium nitrate, 10, 18, 159–​60, 161 redintegration of, 3–​4, 19, 33, 62–​64, 65, 66–​67, 91–​92, 97, 161

Index  195 precipitation, 31–​32, 33–​34, 41, 93–​94, 98,  105–​6 prima mixta, 28, 88–​89 prima naturalia, 87, 91, 107–​8, 134,  136–​37 prime matter, 17, 28, 29, 48, 82, 82n.9 Principe, Lawrence M., 1–​2, 41 properties dispositional, 2–​3, 5, 6, 39, 53–​55, 77–​78, 96–​97, 108, 109–​10, 112, 113–​20, 121–​30, 131, 135–​36, 137–​38, 139–​45, 146, 167, 168, 171 emergent, 2–​3, 5–​6, 77–​78, 84, 97, 108, 109, 114, 120, 125–​26, 130–​38, 144–​45, 146, 147–​48, 150, 166, 168, 169–​70,  171 essential, 15, 28, 30, 77–​78, 83, 87, 88, 90, 91–​93, 101–​2, 103, 104, 105, 106, 107–​8, 149, 159 higher-​level and lower-​level, 29, 49–​51, 52, 55–​56, 73, 97, 108, 131, 135, 136–​37, 138, 139–​40, 144–​45 novel, 5–​6, 66, 68–​69, 108, 109, 113–​14, 125, 126, 131, 133–​35, 146, 152–​ 53, 154–​55, 156–​57, 158, 159–​61, 169, 171 relational, 2–​3, 5, 6, 23, 77–​78, 96–​97, 109–​10, 111–​12, 113–​20, 121–​30, 131, 138, 139–​45, 146, 147, 156, 168, 169, 171 See also qualities Pyle, Andrew, 75–​76    qualities, 2–​3, 5, 23–​24, 28, 30, 31, 35, 45–​46, 49, 50, 52, 64, 85, 90, 96–​97, 100–​1, 102, 109, 110–​20, 121–​38, 156–​57, 158, 163–​64, 166 chemical, 10, 34, 53, 55–​5 6, 60, 82, 84, 108, 109, 112, 113–​2 0, 121–​3 8,  160 cosmical, 77, 97, 98, 139–​45 mechanistic, 111 non-​mechanistic, 111–​12, 113–​20, 121–​38, 139–​45,  160 occult,  111–​12 primary, 110, 111–​12 secondary, 96, 110, 111–​12, 121–​30 sensible, 113–​20, 121–​38,  139–​45 See also properties

redintegration of niter. See potassium nitrate: redintegration of reduction to the pristine state, 4–​5, 26–​27, 28–​29, 30–​31, 32–​33, 34, 62–​63, 85,  104–​8 reductionism and anti-​reductionism, 6, 10, 43–​44, 49–​51, 70, 71, 72–​73, 96–​97, 107–​8, 109, 113–​20, 121–​45, 150–​51, 156–​57, 158, 162–​63, 168, 169, 171 relational properties. See properties: relational re-​synthesis. See redintegration Rohault, Jacques, 56, 57–​58 Rossi, Paolo, 11–​12 Royal Society of London, 50–​51, 127    salts chemical, 18, 25, 27–​28, 31, 39, 41, 63, 64, 93, 121, 126, 128, 129–​30, 157, 158,  159–​60 salt-​petre or saltpeter. See potassium nitrate scientific research programme, 3–​4, 72–​78,  96–​97 secondary qualities. See qualities, secondary seminal principles. See semina rerum semina rerum, 3, 10–​11, 19–​25, 34–​43, 71, 87, 140 Sennert, Daniel, 3–​5, 10–​11, 21, 23, 25, 26–​34, 42, 43–​44, 47–​48, 49–​50, 60–​61, 62–​63, 70, 72–​73, 82, 83, 90, 91, 95–​96,  104–​5 sensible qualities. See qualities, sensible Severinus, Petrus, 35, 47–​48 Shapin, Steven, 127–​28 spagyria, 9, 10–​11, 16–​20, 39, 75, 76, 79, 80, 81–​82, 84, 93, 129–​30, 131–​32, 136, 142 See also alchemy: Renaissance; Paracelsus and Paracelsians Spinoza, Baruch, 3–​4, 33, 43–​44, 50–​51, 62–​63, 66–​68,  169 spirit of niter. See aqua fortis spirit chemical, 18–​19, 24–​25, 34–​44, 63, 64–​65, 66–​67, 72–​73, 126, 128, 129–​30,  159–​60

196 Index spirit (cont.) vital, 8, 10, 11, 16–​17, 18–​19, 24–​25, 34–​44, 60, 62, 71, 72–​73, 76–​77, 142 Stahl, Georg Ernst, 51–​52, 89 Stengers, Isabelle, 26–​27, 33, 34, 106, 145 Stoics, 20–​21, 35 structure. See structuralism: chemical structural explanation. See structuralism: chemical structuralism chemical, 2–​3, 4–​6, 23, 26–​34, 54–​55, 64, 66–​67, 70–​71, 77–​78,  166–​67 in Boyle (see Boyle, Robert; essential form; microstructure; texture) substantial form, 3–​5, 11–​12, 13–​16, 22–​23, 28–​31, 33–​34,  43–​44 Boylean rejection of, 67, 68, 79, 83, 84, 91, 92–​93, 99–​101, 102, 103–​5, 123, 148, 149, 152–​53, 154, 155–​56, 159, 160–​61,  162–​63 Cartesian rejection of, 45–​47, 49 sulfur and sulfuric compounds, 16, 17–​18, 39, 50, 97, 105–​6, 107, 126, 128,  159–​60 sulfur principle. See tria prima supervenience of chemical properties, 2–​3, 5, 6, 7, 108, 109, 113–​14, 126,

130–​38, 145, 146, 147–​48, 150, 158, 161–​62, 165–​67, 168, 169, 170–​71 synthesis, 19, 27–​28, 29–​30, 33, 43, 64–​65,  82–​83    taxonomical classification, 4–​5, 7, 97,  99–​104 teleology immanent vs. extrinsic, 75–​76, 75–​76n.91 texture. See Boyle, Robert; essential form; microstructure; texture three principles. See tria prima transmutation. See alchemy; chrysopoeia transposition of particles, 91–​92, 104, 133 tria prima, 3, 4–​5, 10–​11, 16–​20, 38–​39, 50, 77, 79–​81, 82, 83, 84, 132, 140    vacuum, 62, 86, 143 Venel, Gabriel François, 69–​70 vitalism, 1–​2, 3, 8–​13, 16–​17, 19–​25, 33–​ 35, 37, 40–​41, 42, 43–​44, 47–​48, 52, 69–​70, 71, 91, 104–​5, 139–​40 volatility, 1, 64, 82, 111, 133, 135, 159–​60    Webster, John, 21, 23–​24