The Philosophy of Robert Boyle

Peter Anstey

• Publisher: Routledge
• Year: 2002
• eBook ISBN:
  9781134592029
• Topic: Philosophy
• Subtopic: Philosophy History & Theory

First Published in 2004. This book presents the first integrated treatment of the mechanical or corpuscular philosophy of Robert Boyle, one of the leading English natural philosophers of the Scientific Revolution. It focuses on the concepts central to Boyle's philosophy, including the theory of matter and its qualities, causation, laws of nature, motion and the incorporeal. The book is divided into two parts—the first examining the manner in which Boyle distinguished between various types of qualities, his view on the perception of these qualities and the ontological status of the sensible qualities. The second part examines Boyle's mechanism in general. Through detailed examination of Boyle's conceptions of motion, laws and space, it is argued that Boyle upholds a unique view of the causal interaction of natural bodies.

Part I

The theory of qualities

1 Distinctions among the qualities

Robert Boyle is the philosopher of the qualities par excellence. Of all the British natural philosophers of the mid-seventeenth century, it is he who carried out the most detailed experimental work on the qualities and produced the most sustained theoretical expositions of the corporeal qualities according to the mechanical philosophy. His researches covered an extremely wide range of qualities and continued throughout his career as a natural philosopher. And it was Boyle, of all the mid-seventeenth mechanists, who was most influential in his theoretical expositions of the nature of the qualities of bodies.¹ His impact on Newton and Locke’s understanding of the qualities of bodies is widely known.² And a measure of the impact of his work on the continent can be seen in Jean Baptiste Du Hamel’s De Corporum Affectionibus tum Manifestos tum Occultis. Published in 1670, just four years after Boyle’s Forms and Qualities, this book by the first secretary of the French Royal Academy of Sciences draws heavily on Boyle’s work on the qualities in both its content and structure.³ But why did Boyle place such an emphasis on corporeal qualities in his work? And why is it appropriate to begin a study of his corpuscular philosophy with an exposition of his theory of qualities? In short, what is it that accounts for the importance of the qualities in Boyle?

1 The importance of the qualities

There are at least three ways in which the subject of the qualities of bodies is of central importance in the natural philosophy of Robert Boyle. First, there is the simple fact of its significance in quantitative terms. Boyle wrote many works on the qualities of bodies. Second, there is the intimate relation between the theory of qualities and the corpuscular hypothesis itself. It is one of the central tenets of that hypothesis. Moreover, the theory of qualities was perhaps the key doctrine that featured in Boyle’s polemics against rival philosophies. And third, when it comes to an assessment of the significance of Boyle’s thought for the history of philosophy and for the history of science, it is the theory of qualities that motivated much of his most important experimental work and where he made his most significant contributions to human knowledge.

The quantitative significance of Boyle’s theory of qualities is primarily a result of his Baconian heritage. His overall aim for his writings on this subject was to compile a history of the qualities, in the Baconian sense, that would provide a firm basis for an adequate theory of the qualities.⁴ To that end he wrote extensively on the qualities and performed hundreds of experiments to determine their nature. His published works include a number of treatises or histories on particular qualities.⁵ And he augmented these histories with three theoretical treatises that where intended as introductions to the theory of qualities according to the corpuscular hypothesis. These works were philosophical in style and were viewed by Boyle as integral parts of the broader project. By far the longest and most important is the Forms and Qualities. Boyle tells us in his ‘Proëmial Discourse to the Reader’ that he conceived this work as ‘a general preface to the History of Qualities’ (Works, III, p. 4, S. p. 2).⁶ The other theoretical treatments of the qualities are the ‘History of Particular Qualities’ and the ‘Chemists’ Doctrine of Qualities’, both of which were published along with various histories of particular qualities. The project was never completed, but it appears that Boyle continued to conceive of his researches into the qualities in Baconian terms, for the last work he published before his death, Experimenta et observationes Physicae (1691), while written many years before, was penned as a contribution to a Baconian-style natural history.⁷ From the fact that he approved its publication we can infer that the overarching Baconian agenda of his researches into the qualities remained with him until the end of his life.⁸

However, it is too simplistic to see Boyle as single-mindedly following the Baconian agenda throughout this period and even in these publications. For his work on the qualities sprang from other motives as well. In addition to furnishing his readers with natural histories, Boyle used both his theoretical and experimental excursions into the doctrine of the qualities for polemical purposes in order to bolster the corpuscular hypothesis. Thus works such as the Forms and Qualities and the ‘Chemists’ Doctrine of Qualities’ cannot be considered exclusively as theoretical expositions of the corpuscularian conception of the qualities, for they are also polemical works, aimed at diminishing the credibility of the peripatetic and Paracelsian views of qualities.⁹ Of course this is evident from the very title ‘Of the Imperfection of the Chemists’ Doctrine of Qualities’. This work is a concise and more lucid treatment of the key polemical issues raised in Boyle’s earlier Sceptical Chymist (1661).¹⁰ But what is not often appreciated is that the Forms and Qualities aims to make the mechanical production of ‘almost all sorts of qualities’ more probable by the reporting of experiments. Thus, it contains an extended section listing experiments that allegedly render mechanical explanations of the qualities more tenable than their rivals.¹¹

Another very important motivation for Boyle’s experimental work on the nature of the qualities was his interest in physiology. As Robert Frank has ably documented, Boyle’s experimental work on the spring and weight of the air was intimately linked with his researches into the nature of respiration (Frank 1980, chapters 5 and 6).¹² Likewise his researches into the nature of nitre were not simply motivated by its usefulness in providing empirical grounds for a belief in the corpuscular hypothesis, but also for chemical reasons—it was ‘an indispensable reagent’; and even economic reasons—the need to maintain the supply of saltpetre for the production of gunpowder (Frank 1980, pp. 121–122).

Thus it can be seen that both theoretical and experimental work on the qualities of bodies are of critical importance to Boyle’s natural philosophy. In quantitative terms, the doctrine of qualities is the dominant theme in both Boyle’s scientific works and his expositions of the corpuscular philosophy. Of his forty-two published works, twenty-seven of them deal with the qualities of bodies, as do many of his contributions to the Philosophical Transactions. And there is much important material in the Boyle Papers that treats of the doctrine of the qualities, not least his tract on occult qualities.¹³

Yet of more importance for the ensuing study is the integral role that the theory of qualities plays in the corpuscular philosophy itself. Boyle is most explicit about this in the Forms and Qualities. He begins his ‘Preface’ to that work by saying,

The origin…and nature of the qualities of bodies is a subject that I have long looked upon as one of the most important and useful that the naturalist can pitch upon for his contemplation. For the knowledge we have of the bodies without us being, for the most part, fetched from the informations the mind receives by the senses, we scarce know anything else in bodies, upon whose account they can work upon our senses, save their qualities…And as it is by their qualities that bodies act immediately upon our senses, so it is by virtue of those attributes likewise that they act upon other bodies, and by that action produce in them, and oftentimes in themselves, those changes that sometimes we call alterations, and sometimes generation or corruption.

(Works, III, p. 11, S. p. 13)

According to Boyle o ne cannot speak of causes and effects in nature without referring to qualities of some kind, for it is by their qualities that bodies interact causally with both percipients and their environment. Thus Boyle claims that the natural philosopher’s ‘business is to enquire into the production and causes’ of the qualities (‘History of Particular Qualities’, Works, III, p. 293, S. p. 99). This is especially true of the mechanical philosophy which attempts to explicate all natural phenomena by appeal only to the two grand principles of matter and motion. According to the corpuscular hypothesis, motion itself is a mode of matter even though it is also the chief among secondary causes.¹⁴ Moreover, if an alternative account of nature is to appear credible at all, it will only be made so by its proponent

giving us clear and particular explications at least of the grand phenomena of qualities: which if he shall do, he will find me very ready to acquiesce in a truth that comes ushered in and endeared by so acceptable and useful a thing as a philosophical theory of qualities.

(‘Chemists’ Doctrine of Qualities’, Works, IV, p. 284, S. p. 137)

It is the theory of qualities that is the point of departure for Boyle from the peripatetics’ and chemists’ accounts of nature.

A final point on the centrality of the qualities for the corpuscular hypothesis, and this is not a point that Boyle makes, is that one cannot speak of laws of nature without reference to qualities. Law statements always contain terms that refer to qualities of some sort. In fact, the qualities of bodies seem to have some sort of priority when it comes to the epistemology of laws. We gain knowledge of laws in virtue of our knowledge of the qualities of bodies. So it is essential, if we are to get clear on Boyle’s views on causes and laws, to address the issue of the nature qualities about which he writes so much.

The third reason why the doctrine of the qualities in the corpuscular philosophy of Boyle is important has to do with Boyle’s legacy. In any assessment of his place in the history of ideas and of his contributions to scientific knowledge, it is to his reflections and experiments on the qualities that we turn. Virtually all of Boyle’s lasting contributions to science arise from his work on the qualities. One need only instance his role in the discovery of the indicator tests for acids and alkalies; his work on the qualities of air and its implications for theories of respiration; and the eventual discovery of Boyle’s Law.¹⁵ And in the history of ideas it is Boyle’s transitional role in the emergence of the distinction between primary and secondary qualities that is perhaps his most significant philosophical legacy.

So an explication of Boyle’s doctrine of the qualities is a fitting place to begin a systematic study of his corpuscular philosophy. To that end we need first to clarify the historical context of Boyle’s discussions of the qualities. This will enable us to understand the conceptual framework from which Boyle approached the subject of the qualities and will enable us to steer our way through the various distinctions between the qualities that were important, in his philosophy and the philosophical issues to which they gave rise. It is to that historical context that we now turn.

2 The historical context of Boyle’s theory

The historical context of Boyle’s discussions of the qualities is best understood by tracing the emergence and significance of three of the salient distinctions among the qualities of bodies. These are the Aristotelian distinction between first and second qualities, the scholastic distinction between occult and manifest qualities and the Lockean distinction between primary and secondary qualities. The first two of these distinctions were entrenched in philosophical reflection on the qualities of matter before Boyle, whereas the third, the Lockean distinction, only emerged in the latter half of the seventeenth century and acquired its philosophical importance after Boyle. What follows in this section is not an exhaustive study of these three distinctions, but a summary treatment that aims to put Boyle’s own views on the distinctions between the qualities into sharper focus. Moreover, these three distinctions are not the only ones that have a bearing on Boyle’s natural philosophy. For instance, there is the distinction between modes and accidents which is taken up later in chapter 4, §6.

2.1 Aristotle’s first and second qualities

The first distinction among the qualities that is relevant to understanding Boyle’s theory of qualities has its roots in Aristotle’s theory of matter. The Stagirite adopted a modified version of Empedocles’ four element theory of matter, claiming that matter consists of earth, air, water and fire.¹⁶ This was supp...

Table of contents

• Cover Page
• Half Title page
• Title Page
• Copyright Page
• Dedication
• Contents
• Preface
• Abbreviations
• Introduction
• Part I The theory of qualities
• Part II Matter in motion
• Conclusion
• Appendices
• Bibliography
• Index