Robert Boyle: An Introduction

By Michael Hunter - Birkbeck College, University of London

Life and Works

Image of a brass cast by C.R. Berch of an ivory medallion of Boyle produced by Jean Cavalier in 1690
Brass cast by C.R. Berch of an ivory medallion of Boyle produced by Jean Cavalier in 1690

ROBERT BOYLE (1627-91) was the prime exemplar of the experimental philosophy espoused by the Royal Society in its formative years. In a whole series of books in which experimental and experiential data was carefully expounded, Boyle sought to vindicate a mechanistic view of nature at the expense of rival theories, notably the worldview associated with Aristotelian scholasticism. Boyle was also a major apologist for the new science, expounding its rationale, working out its philosophical implications and reflecting at length on the mutual relations between science and religion. Recent studies have added a new dimension to our understanding of Boyle, illustrating the complexity of his view of the world and the extent of his debt to such intellectual traditions as alchemy. We also now have a better understanding than hitherto of Boyle's intellectual evolution, and it has become clear that the serene image of him that has come down to posterity belies a complex personality which makes better sense of his intellectual career.

Image of Lismore Castle, Co. Waterford
Lismore Castle, Co. Waterford, Boyle's birthplace. Although the castle was greatly altered in the Nineteenth Century, this view shows the gatehouse leading into the main courtyard of the castle, built by the first Earl of Cork in about 1610 and modified in 1622

Boyle was born at Lismore Castle on 25 January 1627, the youngest son of Richard Boyle, first Earl of Cork, an 'adventurer' who made his fortune in Ireland and who, as Lord High Treasurer of that country, was one of the richest and most influential men in Britain. Boyle's background was thus a wealthy, aristocratic one, and he undoubtedly carried the marks of this for the rest of his life, displaying an patrician demeanour to which his contemporaries almost automatically deferred. Indeed, one recent author, Steven Shapin, has argued that it was primarily to this that the extreme trustworthiness that contemporaries imputed to his science should be attributed. Boyle's upbringing was fairly conventional. He was educated partly at home and partly at Eton College, completing his education by travelling to France, Italy and Switzerland, where he spent several months and where he received further instruction. It was during these continental travels that Boyle had a conversion experience, occasioned by an awe-inspiring thunderstorm, which he recounted in his autobiography. This had a formative influence on his entire subsequent life; his profound religiosity, the subject of much comment by contemporaries, is equally, if not more, important in understanding his later intellectual personality than his aristocratic background. Not only did Boyle's deep theism inform his outloook in natural philosophy, as in life in general; in addition, it may be argued that the obsessiveness which he showed in his pursuit of his goals grew directly out of the religious imperatives which dominated his life.

Image of the title-page of the 3rd edition of Seraphic Love (1663)
The title-page of the 6th edition of Seraphic Love (1678) (Edward Worth Library, Dublin)

Boyle returned to England in 1644, settling on the estate left to him by his father at Stalbridge in Dorset; here, he spent much of the next decade. From the outset, Boyle self-consciously embarked on a career as a writer, but, contrary to what might be expected from his later publications, his efforts were not initially devoted to science. His first project (in 1645-6) was his Aretology, a somewhat stilted treatise on 'Ethicall Elements' intended to lay down the rudiments of morality as a basis for the pursuit of virtue. Subsequently, Boyle experimented with other literary genres, including pious reflections, imaginary lives, speeches and letters presenting moralistic prescriptions to fictional addressees: one of the latter was ultimately to appear in modified form as Some Motives and Incentives to the Love of God (1659), usually referred to by its running title, Seraphic Love, and this is typical of the pious and moralistic tone of Boyle's writings of this period.

Image of the entrance gateway to Stalbridge House.
Stalbridge House was demolished in the early nineteenth century. However, the imposing entrance gateway survives.

In 1649-50, however, a major change in Boyle's preoccupations occurred. In 1649 he successfully set up a laboratory at his house in Stalbridge, and the experiments that this enabled him to carry out seem immediately to have fascinated him to an extent that transformed his career. Writings that he composed from the summer of 1649 onwards show an enthusiasm for experimental knowledge that had earlier been missing and which was to remain with him for the rest of his life. His empirical investigations at this point clearly concerned a range of chemical (and alchemical) trials; he also refers to his use of a microscope to observe the minute structure of living things; while he showed a preoccupation with collecting data about 'effluvia' and other natural phenomena that again foreshadows his later interests.


A view on Catte Street, Oxford
Oxford, where Boyle spent most of his time in the late 1650s and early 1660s. This view on Catte Street shows the Bodleian Library in the background.

Intellectually, his mentors at this stage in his career were such sixteenth-century and early seventeenth-century authors as Paracelsus, Bernardino Telesio, Francis Bacon, Tommaso Campanella and J.B. van Helmont. He also expressed his sense of solidarity with 'the chymists', and it was evidently in a chemical context that he first encountered atomist ideas to which he gave expression in his treatise 'Of the Atomicall Philosophy' of c. 1652-4. On the other hand, Boyle also wrote 'a short essay concerning chemistry, by way of a judicium de chemia & chemicis', which apparently contained the germ of his critique of 'vulgar chymists' in his famous Sceptical Chymist (1661), in which he sought to educate the 'chymists' in the need for a more philosophical approach in their study of nature. It was at this stage in his career that Boyle was most closely associated with the social reformer and 'intelligencer', Samuel Hartlib, whose ideals he shared to a significant extent, though Boyle's intellectual evolution was more independent of the Hartlib circle than has sometimes been allowed.


Boyle's commitment to experiment was strengthened, and his philosophical outlook updated, by his move to Oxford late in 1655 or early in 1656 to join the lively group of natural philosophers then established there under the aegis of John Wilkins. This group has often been seen as foreshadowing the Royal Society, founded in 1660, and it clearly had a major impact on Boyle. It was in this setting that he seriously confronted the writings of the major continental natural philosophers, notably Gassendi and Descartes, refining and modernising the ideas that he had acquired from the essentially Renaissance authors whom he had encountered earlier in the decade. In the case of Descartes, though Boyle had been aware of his writings earlier, he claimed that the figure who 'made him understand Des Cartes' Philosophy' was Robert Hooke, who entered Boyle's employ at this time and helped him in some of his crucial experiments. Indeed, it is clear that during these years, Boyle's experimental activity burgeoned, and it was with Hooke's assistance that he devised the most famous piece of experimental equipment associated with him, the vacuum chamber or air-pump in which he was able to carry out a variety of trials aimed to elucidate the nature of air.

Title-page of the second edition of Boyle's New Experiments Physico-Mechanical, Touching the Spring of the Air, and its Effects (1662).
Title-page of the second edition of Boyle's New Experiments Physico-Mechanical, Touching the Spring of the Air, and its Effects (1662). This copy was presented by Boyle to the virtuoso and diariest, John Evelyn, and bears Evelyn's ownership inscription.

The years that Boyle spent at Oxford, prior to his move to London in 1668, also saw an extraordinarily intense programme of writing on his part. It was at this time that he began or completed the numerous books on different aspects of natural philosophy which set the pattern for his subsequent intellectual career, and on which, when he began to publish on a sustained scale from 1660 onwards, his later fame was based. These included his New Experiments Physico-Mechanical, Touching the Spring of Air and its Effects (1660), Certain Physiological Essays (1661), The Sceptical Chymist (1661), Some Considerations touching the Usefulness of Experimental Natural Philosophy (1663, 1671), Experiments and Considerations touching Colours (1664), New Experiments and Observations touching Cold (1665), Hydrostatical Paradoxes (1666) and The Origin of Forms and Qualities (1666).

These works were taken up and championed by the newly-founded Royal Society, both in the Philosophical Transactions which its first secretary, Henry Oldenburg, began in 1665, and in such promotional works as Joseph Glanvill's Plus Ultra (1668); the latter gave a glowing account of each of these books, acclaiming Boyle as a man 'who alone hath done enough to oblige all Mankind, and to erect an eternal Monument to his Memory'. Indeed, in many respects, Boyle's methods became exemplary of the empirical method that the Society espoused, while the image of him initially promoted by these acolytes has dominated views of him ever since. Nor were Boyle's writings published only in English. He also made careful arrangements to have them published in Latin translations which were widely read in the international scholarly community. Indeed, it is not surprising that one of his publishers later claimed that he had become known throughout Europe as 'the English philosopher'. It was a tribute to the new-found celebrity that Boyle enjoyed in the 1660s that he was the subject at this time of various published attacks, particularly on his first scientific book, New Experiments... Touching the Spring of the Air. Works criticising this were brought out by philosopher, Thomas Hobbes, by the Jesuit, Francis Linus, and by the Dutch scholar, Anthony Deusing, and Boyle replied at length to Hobbes and Linus, disposing of Deusing in briefer comments in the preface to the Latin edition of his defence of himself against Linus.

Boyle's profuse experimental work continued throughout the rest of his life. It was represented perhaps most notably by his Experiments, Notes, &, about the Mechanical Origin or Production of Divers Particular Qualities (1675), while he also brought out various sequels to his New Experiments... Touching the Spring of the Air in which experiments using a vacuum pump were expounded, together with more miscellaneous works such as his Experiments and Considerations about the Porosity of Bodies (1684) and his Experimenta & Observationes Physicae (1691). In addition, in the 1670s, Boyle published a variety of shorter, more controversial treatises, including such more speculative writings as his Of the Systematical or Cosmical Qualities of Things (1671), while the 1680s saw the publication of a number of medical works by him, including his Memoirs for the Natural History of Human Blood (1684), his Of the Reconcileableness of Specifick Medicines to the Corpuscular Philosophy (1685) and his Medicina Hydrostatica (1690); these drew to a significant extent on work that he had done earlier, some of it while still at Oxford.

Image of the title-page of one of Richard Bentley's 1692 Boyle Lectures.
Title-page of one of Richard Bentley's 1692 Boyle Lectures.

Equally important were Boyle's publications in the last two decades of his life on philosophical and theological topics. Some of these were works which he had compiled in the 1660s but had put to one side at that time, such as his Excellency of Theology, Compar'd with Natural Philosophy (1674) -- to which was appended a key shorter work, Boyle's 'Considerations About the Excellency and Grounds of the Mechanical Hypothesis' -- and his important Free Enquiry into the Vulgarly Receiv'd Notion of Nature (1686). The latter was one of a number of works published in the final decade of his life in which Boyle presented his mature reflections on major theological and philosophical issues, notably his Discourse of Things above Reason (1681), his Disquisition about the Final Causes of Natural Things (1688) and The Christian Virtuoso (1690). In these, Boyle made a profound contribution to an understanding of what he saw as the proper relationship between God and the natural world, and man's potential for comprehending this. It was appropriate that one of the numerous codicils to Boyle's will, enacted after his death on 31 December 1691, provided for the setting up of a series of lectures for the defence of the Christian religion against atheists and others, the so-called Boyle Lectures. The first series of these was delivered by the scholar and divine, Richard Bentley, in 1692.

Thought and Significance

Boyle was an experimenter par excellence, both in theory and practice. Though Francis Bacon may have laid down guidelines for the pursuit of inductive science by controlled experiment, it was Boyle who worked out such ideas in full, eclectically building on precedents provided not only by Bacon, but also by other traditions, including that of the practical 'chymists'. In part, he did so through the consideration that he gave to the method and rationale of experiments, particularly in his Certain Physiological Essays (1661). This seminal work comprised a series of essays presenting a very subtle view of experiment, including two key essays on the significance of unsuccessful experiments, together with others in which he illustrated the way in which such trials could be deployed to provide an empirical foundation for his version of the mechanical philosophy, to which he gave the name 'corpuscularianism' to avoid the irreligious overtones that atomism had inherited from classical antiquity.

Image of the title-page of the first edition of Boyle's Certain Physiological Essays (1661)
Title-page of the first edition of Boyle's Certain Physiological Essays (1661). This copy, now in the University Library at Gottingen, is a presentation copy from Boyle.

Perhaps most crucial was Boyle's 'Physico-Chymicall Essay, Containing an Experiment with some Considerations touching the differing Parts and Redintegration of Salt-Peter' (often referred to as his 'Essay of Nitre'), in which he experimentally demonstrated how the changes that could be brought about in saltpetre by chemical means could be explained entirely in terms of the size and motion of corpuscles, without the need for any of the explanations in terms of 'forms' and 'qualities' associated with scholastic science. Similar ideas were pursued in various sequels, the most notable of which was his The Origin of Forms and Qualities (1666), a frontal attack on the predominant scholasticism of the period, in which Boyle tried to wean his contemporaries away from the essentially qualitative modes of thinking associated with Aristotelian ideas, and to indicate the superior intelligibility of mechanical explanations of phenomena.


An image of the air-pump designed by Robert Hooke
The air-pump designed by Robert Hooke and used for the experiments described in New Experiments... Touching the Spring of the Air, and its Effects(1660).

If Boyle was important for his theoretical exposition of experimentation, and his use of it to champion mechanical explanations against scholastic ones, he was no less notable for his experimental practice. Throughout his life, he displayed an extraordinary ingenuity in devising trials which would reveal significant information about the phenomena he studied, combined with an unprecedented precision in observing their outcome. This is well illustrated by Boyle's first scientific book, New Experiments... touching the Spring of the Air, which showed that, contrary to the scholastic notion that nature could not tolerate a vacuum, it was perfectly possible to produce one using the vacuum chamber or air pump that he had devised with the help of Hooke. In it, Boyle was able to carry out a whole series of experiments which illustrated the characteristics and functions of the air, for instance by studying the effects of its withdrawal on flame, light and living creatures.

New Experiments also illustrates Boyle's characteristic methods as a writer on natural philosophy. In this book -- and in his subsequent publications on experimental topics -- he went to great pains to provide a detailed account of his trials so that others could follow as closely as possible the procedures that he had followed in reaching the results that he reported. He made a positive virtue of the verisimilitude of such accounts, providing a model for others which was widely followed. His hope was that others might accept the 'matters of fact' that he had established, whatever rival interpretations might be based on them.

In other works, though he included a similarly detailed record of his own trials, he made more use of accounts of phenomena that he had been told of by others or had read about in books, a practice for which he explicitly cited the example of Bacon. Such books as his Experiments and Considerations touching Colours (1664) or his New Experiments and Observations touching Cold (1665), of his later Experimenta et Observationes Physicae (1691), are made up of a patchwork of such material, which Boyle saw as offering the basis on which a science of nature would ultumately be constructed.

When it came to the conclusions that might be derived from such data, Boyle was a little more ambivalent. He was hostile to the premature systematisation that he saw as having blighted much science prior to his time, and the result was that he showed a reluctance to draw conclusions that was criticised by some more rationalistic thinkers of his day, such as Christiaan Huygens and Gottfried Wilhelm Leibniz. On the other hand, Boyle's empirical activity was underwritten by clear explanatory goals. In particular, from the 1650s to the end of his life he never swerved from his conviction that the universe was best understood according to mechanical principles, and he ceaselessly urged the superiority of these to the Aristotelian and other alternatives that flourished in his day. Such principles appealed to him not least because he saw them as supremely compatible with God's active role in the world.

Though Boyle took it for granted that explanations should be formulated in primarily mechanical terms, however, he acknowledged that there might be intellectual differences within this basic framework, and his own views were quite flexible. Thus his interpretation of chemical phenomena took it for granted that corpuscles were endowed with chemical, as against strictly mechanical, principles, while various of the explanations that he adduced invoked 'intermediate causes', such as the concepts of the weight and elasticity in the air. His corpuscularianism was itself eclectic, drawing on a range of sources and including concepts such as 'dregs' or 'denseness' which might be seen as at odds with a strict interpretation of the mechanical philosophy.

Boyle had no illusions about the complexity of the world -- it was partly for this reason that he was so insatiable in collecting information about it -- and this was reflected by the interpretations of it that he formulated. Indeed, he ranged perhaps surprisingly far in the phenomena that he took seriously, with a truly Baconian sense that primacy should be given to establishing whether phenomena actually existed rather than dismissing them according to a priori criteria. Thus he toyed with the notion that there were 'cosmical qualities' transcending purely mechanistic laws in the universe, and he was also fascinated by authenticated reports of supernatural phenomena, on the grounds that these vindicated the reality of God's power in the world. It is in a similar context that one should see his interest in alchemy, which, though in evidence from the 1650s onwards, apparently reached a peak in the late 1670s, when he published an article in Philosophical Transactions and a tract on this subject; this evidently reflected an unusual intensity in his contact with alchemists at this time. Boyle was perfectly prepared to believe that unexpected phenomena of the kind that alchemy revealed were real: if matters were complicated by his ethical qualms as to whether such knowledge might be illicit and hence to be avoided on moral grounds, against this was the consideration that alchemy appeared to offer an empirical bridge between the natural and the supernatural realms which might provide irrefutable evidence of God's existence.

Image of the title-page and opening page of Boyle's paper on the incalescence of mercury
The title-page and opening page of Boyle's paper on the incalescence of mercury,
published in both Latin and English in the Philosophical Transactions in 1676.

Boyle's major preoccupation was the relationship between God's power, the created realm, and man's perception of it, a topic on which he wrote extensively, in books mainly published in the 1680s, though the views that they expressed may be traced in embryonic form in his earlier writings. In them, Boyle laid stress on the extent to which God's omniscience transcended the limited bounds of human reason, taking up a position that contrasted with the rather complacent rationalism of contemporary divines such as Joseph Glanvill. He also reflected at length on the proper understanding of final causes, and in conjunction with this provided one of the most sophisticated expositions of the design argument in his poeriod. Indeed, Boyle's significance for the history of science depends almost as much on the profound views on difficult issues put forward in these philosophical writings as it does on his experimental treatises.

In all his writings, Boyle was fiercely hostile to views of nature that he saw as detracting from a proper appreciation of God's power in his creation. His principal target in this respect was the Aristotelian worldview which was prevalent in his day. Boyle's intense hostility to this, and his conviction that experimental data provided the best means of undermining it, goes back to his earliest writings on natural philosophy in the early 1650s. But it continued thereafter for the remainder of his life, and scholastic views which reified nature formed his principal target in his Free Enquiry intio the Vulgarly Receiv'd Notion of Nature, published in 1686. Boyle was equally hostile to other intellectual traditions which he saw as pernicious, such as the materialism associated with Hobbes, which contemporaries frequently saw as indistinguishable from atheism. Boyle made it clear that it was because of the dangers that he perceived in Hobbes' religious principles that he devoted as much time as he did to attacking his scientific views, not only attacking him in works of the 1660s but also returning to the fray in the 1670s, despite his professed disinclination to involve himself in philosophical disputes.

Though various recent accounts of Boyle have attempted to place him in an overt ideological context, seeing him as concerned with threats to social and political stability and as framing his natural philosophy to offset these, in fact Boyle's direct concern with such issues can easily be exaggerated. The idea that his early natural philosophy was predicated on a 'dialogue with the sects' in the aftermath of the Civil War has now been discredited, and various recent authors have also been at fault in depicting him as more straightforwardly aligned with the status quo in his later years than was really the case. In fact, Boyle was independent and eclectic in his relations with the contemporary establishment, and ill at ease with certain aspects of the society of his day, particularly what he saw as the improper predominance of private interest. His own ideals were more similar to those of his Interregnum friend, Samuel Hartlib, with whom he shared the hope that the amelioration of life might somehow transcend sectarian politics if only men could be persuaded to live truly Christian lives.

Boyle's ideals for the broader role of science are perhaps best exemplified by his Some Considerations touching the Usefulness of Experimental Natural Philosophy (1663, 1671). Perhaps not surprisingly, the first part of this work celebrates the religious value of study of the natural world, but the breadth of Boyle's conception of the potential of the new science is illustrated by the subsequent sections. Thus the first section of the second part -- which constituted Boyle's most extensive single medical publication -- argued for the value to medicine of scientific findings and techniques such as chemical distillation or the theory of corpuscularianism; Boyle's conviction of science's proper role in this sphere is also in evidence in his later medical writings. The second section of the second part was devoted to broader epistemological considerations about the perfectibility of scientific knowledge and its potential value to human life, reiterating the conviction of the potential benefits of such knowledge which always accompanied Boyle's pursuit of improved understanding of the natural world in its own right.

All the essays in The Usefulness of Natural Philosophy show the diffuse style and endless enthusiasm for particular characteristics of Boyle's mature writings. In fact, however, not all of the sections of this work that Boyle wrote were published, and not all even survive. Immense as his printed output was, it was not the sum of his composition, and his unpublished papers include many manuscripts which he throught better of publishing, and which are only now seeing the light of day. Nevertheless, Boyle published enough to make himself a truly seminal figure in the science of his day. His profuse and carefully expounded experimentalism was to prove hugely influential, while the deep theism which formed the basis of his entire intellectual programme also formed part of his lasting legacy.

See where the works discussed appear in The Works of Robert Boyle