Physico-Theology: The Religious Dimension of Natural Philosophy
The seventeenth century is widely regarded as marking a ‘Golden Age’ of natural philosophy in England. Its leading advocates and practitioners—particularly Francis Bacon, Robert Boyle, and Isaac Newton—propelled the field to new heights, generating considerable interest both in the study of nature itself, and how this could be represented theoretically. While this troubled century in English history witnessed growing religious tensions, as well as the rise of forms of atheism—some tentative and reluctant, others confident and assertive1—the dominant sentiment of this age was belief in a God who created an ordered universe which the human mind could grasp, however imperfectly. Natural philosophy came to be seen as enfolding both the discovery of the rational order of the natural world, and allowing this to act as a gateway to ‘a community of values that was not dependent upon any particular religious confession’.2 Yet such an understanding of the natural world was not seen as an end in itself, but as part of a process of intellectual, moral, and spiritual refinement of the natural philosopher. Like their counterparts in ancient Greece, many English natural philosophers saw a clear link between acquiring a theoretical understanding of the natural world, and improving the moral and spiritual quality of human life.3
Political stability began to return to England after the extended period of the Civil War and Puritan Commonwealth (1642–60). The restoration of the monarchy was seen by many as a sign of a new era of progress and intellectual development. One of Charles II’s first acts was to grant a royal charter to the Royal Society of London, which quickly established itself as the institutional embodiment of the new natural philosophy, and made frequent statements to the effect that it had adopted Baconianism as its working method.4 A meeting on 28 November 1660 at Gresham College, London set out ‘a design of founding a college for the promotion of physico-mathematical experimental learning’.5 Although the new Society wanted to establish its own dedicated premises, accommodation difficulties resulting partly from the Great Fire of London (1666) led it to continue its association with Gresham College until the early eighteenth century.
So what was this ‘physico-mathematical experimental learning’ that the Royal Society adopted, and which was seen by its early apologists as defining its intellectual and cultural mission?6 To find out, we shall consider the approach to natural philosophy set out by Francis Bacon, especially in his Novum Organum (1620).
To the best of our knowledge, the phrase ‘experimental science’ was first used in English in 1570 to translate the Latin term scientia experimentalis, particularly as this phrase was found in the writings of Nicolas of Cusa.7 While many earlier studies of Bacon’s natural philosophy detached his philosophical method from his wider cultural concerns,8 there is a growing appreciation that Bacon’s natural philosophy has both theological and political aspects. Bacon distinguishes his ‘philosophy of nature’ from that of the ‘Grecians’, which he considers to largely consist of debates about words, and that of the ‘Alchemists’, which he considers to rest on ‘imposture’, ‘auricular traditions and obscurity’.9
While it is difficult to capture the essence of Bacon’s distinctive approach, Stephen Gaukroger helpfully identifies one of its central themes: a concern with ‘the understanding of and reshaping of natural processes’.10 To understand nature is to be able to redirect nature for the improvement of the human condition. The idea that an attentiveness to the natural world could be a ‘propaedeutic to self-betterment’ is encountered in many writers of the late fifteenth and sixteenth centuries.11 While Bacon would not dissent from this judgement, his emphasis lay on ‘social-betterment’, achieved through an understanding of the natural world that led into the use of nature for the advancement of human ends.12 This aspect of Bacon’s natural philosophy has led some to interpret him as an apologist for the exercise of human power and dominion over nature.13
Bacon considered natural philosophy to be a means to an important end. Knowledge of nature was not something ‘barren’, but had the potential to produce outcomes that were of advantage to humanity. This goal was grounded on an experimental, natural-historical, and broadly inductive approach to the natural sciences, coupled with the institutionalization of scientific experimentation and knowledge production in a quest for objectivity. An important distinction should be drawn here between two forms of natural philosophy, ‘speculative’ and ‘experimental’, that are encountered at this time. Peter Anstey explains this distinction as follows:
Speculative natural philosophy is the development of explanations of natural phenomena without prior recourse to systematic observation and experiment. By contrast, experimental natural philosophy involves the collection and ordering of observations and experimental reports with a view to the development of explanations of natural phenomena based on these observations and experiments.14
Like many English thinkers of his time who took an interest in what would now be understood as science, Bacon held that religion and natural philosophy ‘should be kept separate’, while at the same time holding that ‘the two were complementary to one another’.15 We thus find Bacon entwining religious and scientific themes at points, even though he clearly regards them as distinct. For example, in his Novum Organum, Bacon set his basic principle of working for human improvement against an informing (though not determining) theological context:
There cannot but follow an improvement in man’s estate, and an enlargement of his power over nature. By the Fall, man fell from both his state of innocence and from his dominion over creation. But even in this life both of those losses can be made good; the former by religion and faith, the latter by arts and sciences.16
Although Bacon pressed the case for an experimental natural philosophy, like many at the time, he drew on theological accounts of the human situation in offering his solution for its improvement.
There is a clear shift here from the earlier Renaissance idea of natural knowledge as edification, something that was good in itself, to the idea of communally gained natural knowledge as a means of securing and exercising power over nature.17 For Bacon, this includes the possibility of extending the human lifespan.18 Bacon uses the language of instauratio to speak of this great change in the place and role of humanity within the world.19
The first [ambition] is of those who desire to extend their own power in their native country; which kind is vulgar and degenerate. The second is of those who labour to extend the power of their country and its dominion among men. This certainly has more dignity, though not less covetousness. But if a man endeavour to establish [instaurare] and extend the power and dominion of the human race itself over the universe, his ambition (if ambition it may be called) is without doubt both a more wholesome thing and a more noble than the other two. Now the empire of man over things depends wholly on the arts and sciences.20
It will be clear that the goals of Bacon’s natural philosophy diverge from those of earlier writers in this tradition. But what of the methods that Bacon uses in developing this philosophy? For many, Bacon represents a landmark statement of an experimental natural philosophy, which needs to be given careful consideration.
The third part of Bacon’s Novum Organum is devoted to the question of natural philosophical method.21 Bacon locates his discussion within the cultural context of increasing anxiety about the possibility of securing reliable knowledge. For Bacon, such knowledge is best acquired through ‘a Natural and Experimental History’, characterized by the investigation of nature, and the ordered presentation of what is observed. ‘We are not to imagine or suppose, but to discover, what nature does or may be made to do.’22 We cannot predetermine nature’s structures or processes, but must discover them through reflective observation and experimentation. Nature must be ‘ranged and presented to view in a suitable order’, so that an inductive method can be used to interpret these observations.23
Although some have treated Bacon as setting out a ‘naïve empiricism’, which is inattentive to the role of generating hypotheses in advancing knowledge, this judgement seems unfair. Bacon clearly indicates that some degree of speculation or hypothesis-building is necessary in order to move beyond the aggregation of observational particularities into the development of natural philosophy in a fuller sense of the term.24 For Bacon, it was possible to derive axioms ‘from the senses and particulars, rising by a gradual and unbroken ascent, so that it arrives at the most general axioms last of all’.25 The Baconian inductive process thus represents an ascent from the particularities of empirical observation to a plausible set of broader generalizations.
So how is reliable human knowledge to be acquired? Bacon’s starting point is to recognize how human thinking can be skewed and distorted by inherited patterns of thought. This idea resonated with a theological concern of the period—namely, the belief that original sin contaminated or distorted the human capacity for reasoning, thus leading to unreliable conclusions. While this concern could be restated in non-theological terms, it emerged as a significant issue in the late sixteenth century.26 Kepler, for example, followed the leading Lutheran theologian Philip Melanchthon in arguing that mathematics and geometry were not compromised in this way by sin, and could both be grasped by the ‘natural light’ of human reason and used to mirror the structures of the universe.27
Bacon claims that four internal impediments to knowledge, which he terms ‘Idols of the Mind’, can lead to significant misreadings and misunderstandings of nature. Bacon’s intention here is to highlight how we can become trapped within a web of false productions of the human imagination, which arise from the ‘crooked mirror’ of the human mind.28 ‘I call the first, Idols of the Tribe; the second, Idols of the Cave; the third, Idols of the Market Place; and the fourth, the Idols of the Theatre.’29 Each of these ‘Idols’ subverts a true understanding of the world by ‘besetting’ the mind through conventional misreadings of the world, cultural and social pressures, or ‘attachment to preconceived ideas’—such as the idea that planetary orbits are necessarily circular. A method of inquiry is necessary that is able to neutralize or overwhelm these natural cognitive deficiencies. For Bacon, ‘the proper remedy to be applied for the keeping off and clearing away of idols’ is the ‘formation of ideas and axioms by true induction’.30 A natural philosophy thus corrects the failings of human reason, when left to its own devices.
For Bacon, induction is both empirical and rational, involving the observation and interpretation of nature, coupled with an experimental method devised to resolve points of ambiguity or uncertainty. Bacon’s central concern is to be able to go beyond merely noting and documenting the surface appearances of reality, and to penetrate to the reality that lies behind them.31 After considering the possible methods of investigation of nature, he concluded that the best method is the gathering of observations or facts about nature and proceeding to the detection of patterns within nature. His overall strategy is to begin with experience of the world, and infer certain first principles on this basis, and then inferring from these first principles what experimental methods might be devised to confirm or extend this knowledge. Gaukroger summarizes Bacon’s approach as follows:
[Bacon’s] aim is a twofold one, reminiscent of the regressus theory that had dominated discussions of method in the sixteenth century: to move inferentially from experience to first principles, and then to move inferentially from these first principles to new experiments.32
To reiterate a point made earlier, Baconian induction is not to be seen as a naïve empiricism, the mere gathering of facts, followed by an attempt to develop an orderly presentation or tabulation of these observed particulars.33 This is unquestionably part of Bacon’s method; yet it is only its starting point, not its conclusion. Bacon’s fundamental concern is to explain why these patterns, and not others, are observed in nature. To answer this question, we need to explore ‘the remoter and more hidden parts of Nature’ through experimentation to understand the patterns of behaviour or organization that we observe in nature.34 It is through experiments that we are able to remove ‘the mask and veil from natural objects, which are commonly concealed and obscured under the variety of shapes and external appearances’.35 (This concern to penetrate beneath the visibilia of the natural world may well help us understand the importance attached to the invention of the microscope, and its use by Robert Hooke.36)
Bacon was thus clear that the accumulation of facts was an important and necessary prelude to their interpretation. In his Novum Organum Bacon sets out a set of aphorisms contrasting those who merely collect facts and observations and those who generate their ideas without any reference to the external world. Bacon, it must be made clear, respected those who constructed ‘histories’ (collections of experimental results and accurate observations); his criticism was that these facts required interpretation. Insisting that the human mind must generate ideas in response to what is observed in the natural world, rather than invent or inherit such ideas and force nature to conform to them, Bacon suggests that the humble bee might offer a model for a ‘true [natural] philosophy’.
Those who have handled science have been either men of experiment or men of dogmas. The men of experiment (empirici) are like the ant, they only collect and use; the reasoners (rationales) resemble spiders, who make cobwebs out of their own substance. But the bee takes the middle course: it gathers its material from the flowers of the garden and field, but transforms and digests it by a power of its own (propria facultate vertit et digerit). Not unlike this is the true business of philosophy.37
Reflection on observations of the natural world thus leads not merely to the generation of theories concerning the world, through the intellectual digestion and assimilation of what is observed, but to the correction of views that are discovered to be empirically contestable. For Bacon, an experimental natural philosophy possesses an internal capacity for self-correction without a corresponding parallel in philosophy or theology.
The forms of experimental natural philosophy which developed from Bacon’s approach held that observation and experiment, understood in general terms as activities that produced ‘facts’, had epistemic priority over hypotheses and general principles in the acquisition of knowledge.38 These ‘facts’ might arise from direct sensory observation or from the manipulation of observed objects by the use of instruments. This new approach involved an invasive ‘penetrating interrogation of nature’ through various means, rather than the ‘respectful observation’ which was characteristic of Aristotelian science.39 Yet these facts might take two different forms: experimenta lucifera (‘luciferous experiments’) aiming to discover (or cast light on) underlying causes of phenomena; and experimenta fructifera (‘fructiferous experiments’), which may yield practical or economic outcomes, but do not advance an understanding of the natural world.40 While Bacon’s agenda of human dominion over nature led him to see fruitful experiments positively, he considered them to lack the intellectual significance of illuminating experiments. Dominion over nature ultimately required an understanding of nature and its processes, in order that these might be redirected for the public good.
Bacon’s legacy is contested, both in terms of how ‘Baconism’ is to be understood, and what its significance has been, particularly in relation to the emergence of the scientific method. In his recent tendentious account of the development of the natural sciences, Steven Weinberg treats him as something of an irrelevance.41 Edward O. Wilson, however, sees Bacon as being something of an intellectual colossus, shaping the future development of western thought into the period of the Enlightenment.42 Bacon’s views on the experimental method are clearly underdeveloped; they could, however, be extended and refined. This process is probably best seen in the works of Robert Boyle, widely regarded as the epitome of a ‘natural philosopher’, who we shall consider in the next section.43
Born in south-east Ireland, Boyle made his way to Oxford in 1655, where he established himself in some rented rooms close to University College.44 While there are no good reasons for supposing that he ever held a university or college appointment during his time at Oxford, Boyle clearly found it to be an excellent base for developing his natural philosophy, of which chemistry was an important part.45
Although Boyle appears to have been well-read in the Greek and Latin classics, he was strongly critical of ‘speculative’ approaches to natural philosophy that he found in Aristotle and the classical tradition.46 Boyle is generally agreed to have played an important role in the gradual displacement of Aristotelianism by a mechanical natural philosophy, in which natural phenomena were explained on the basis of the motion of inert particles of matter.47
Boyle argued for an approach which aimed to penetrate beneath the surface of the natural world through careful and detailed observational analysis rather than being constrained by preconceived interpretations of nature, such as that of Aristotle.48 Observation of nature leads to intentional experimentation upon nature to test (Boyle regularly uses the term ‘prove’ in the sense of ‘put to the test’) the reliability of certain hypotheses. Boyle makes this point in commending the virtuosi who
consult Experience both frequently and heedfully; and, not content with the Phaenomena that Nature spontaneously affords them, they are solicitous, when they find it needful, to enlarge their Experience by Tryals purposely devis’d; and ever and anon Reflecting upon it, they are careful to Conform their Opinions to it; or, if there be just cause, Reform their Opinions by it. So that our Virtuosi have a peculiar Right to the distinguishing Title that is often given them, of Experimental Philosophers.49
Following Bacon, Boyle stressed the importance of accumulating observational and experimental data, seeing the harvesting of these facts not as an end in itself, but in order to generate understanding through the proposal and subsequent testing of hypotheses and theories.50
It was not my chief Design to establish Theories and Principles, but to devise Experiments, and to enrich the History of Nature with Observations faithfully made and deliver’d; that by these, and the like Contributions made by others, men may in time be furnish’d with a sufficient stock of Experiments, to ground Hypotheses and Theories on.51
Boyle’s forty-three air-pump experiments of 1660 indicate the scope and value of this experimental method, particularly in relation to clarifying aspects of the respiratory process.52
In an early work entitled ‘Of the Study of the Booke of Nature’, Boyle spoke of his decision to supplement this study by engaging two other ‘Books’—the Bible, and Conscience.53 Boyle does not appear to have pursued this idea of ‘Three Books’; like many writers of this age, Boyle settled on the established Renaissance metaphor of ‘God’s Two Books’ to establish a conceptual and semiotic link between his natural philosophy and the world of religion. Although the origins of this metaphor can be traced back to the early Middle Ages, it became increasingly important during the sixteenth and seventeenth centuries.
The notion of a ‘Book of God’s Works’, which expands or enacts the ‘Book of God’s Words’, offered an intellectual imaginary of particular significance in the early modern period, that held together two distinct understandings of the natural world, with the potential for convergence on the one hand, or divergence on the other—the world as God’s creation, and the world as an object of scientific study. As Thomas Burnet pointed out, truths arising from these divergent disciplines could at least be held together, if not woven together: ‘We are not to suppose that any truth concerning the natural world can be an enemy to religion.’54 Sir Thomas Browne, an important representative of early modern natural philosophy in the generation before Boyle,55 considered this image to be foundational in holding together a coherent philosophical and religious account of the world.
Thus there are two books from whence I collect my Divinity; besides that written one of God, another of his servant Nature, that universal and public Manuscript, that lies expans’d unto the eyes of all; those that never saw him in the one, have discovered him in the other.56
Boyle was one of many to deploy this metaphor. ‘The World is the great Book, not so much of Nature, as of the God of Nature, which we should find ev’n crowded with instructive Lessons, if we had but the Skill, and would take the Pains, to extract and pick them out.’57 In an early reflection, Boyle remarked that he would spend his Sundays studying the ‘Booke of the Creatures’, and occasionally ‘trying those Experiments that may improve my Acquaintance with her’.58 Yet Boyle is clear that these Books are different, requiring different modes of ‘reading’, and leading to different outcomes, even if these were capable of correlation or even integration. Both natural philosophy and theology speak about God and the world; but they use different means of representation in doing so, and hence demand different interpretative approaches.59 Boyle thus advocated a ‘physico-theological’ reading of nature, seeing this as a spiritual exercise which moved away from a theoretical detachment from nature towards the cultivation of a reverential attitude towards the natural order, on account of what it represents.60
So what benefits did natural philosophy, as Boyle understood it, bring to those Virtuosi who practised it?61 England was severely shaken by the Civil War and its aftermath in the middle of the seventeenth century. It became clear that Christians might read the same Bible, yet draw different, and often radically divergent, theological and political conclusions from their reading—without being able to agree upon any ultimate authority by which such interpretative disputes might be resolved.62 Three broad strategies may be discerned as emerging from this period of social and intellectual confusion. The first, famously advocated by John Locke in his ‘Letter Concerning Toleration’ (1689), was that since such religious disagreements could not be resolved consensually by any existing authority, it was necessary to find ways of tolerating such disagreement.63 The second was to suggest that human reason stood above the ambiguities and uncertainties of biblical interpretation experienced by religion. By recognizing the supreme authority of human reason, such seemingly insoluble disputes could be resolved, if they could not be avoided.64
The third approach is Boyle’s: engaging with the natural world allows a clarity of thought and the application of processes of confirmation which minimize disagreement. As Stephen Gaukroger points out, Boyle argued that ‘an empirical understanding of the natural world can be promoted as revealing God’s purposes in a way that avoids sectarianism.’65 Boyle clearly saw natural philosophy as a way of engaging theological questions that was free of the confessional religious commitments and tensions that had arisen in England since the English Civil War. Natural philosophy was a means of doing theology, shorn of the inconclusive debates of the age concerning ecclesiastical authority and biblical interpretation. From about 1690, ‘physico-theology’ (from the Greek term physikos, ‘natural’) came to be seen as a form of theology which arose from the application of the methods of natural philosophy.
Engaging the world of nature thus transcended religious partisanship—a point that is sometimes linked with suggestions of ‘Latitudinarianism’ within the Royal Society in the late seventeenth century.66 Its focus on pursuing a natural philosophy gave a coherence to the institutional identity of the Royal Society, particularly during the period of religious and political instability preceding the ‘Glorious Revolution’ of November 1688. Although Boyle did not, to my knowledge, develop this point, the pursuit of a natural philosophy clearly enabled the emergence of an international scientific ‘Republic of Letters’, in which national and religious concerns were seen as subordinate to a more universal understanding of the natural world, resting on certain agreed methods of investigation and reasoning.67
Yet Boyle’s most interesting reflections on the utility of natural philosophy concern the quality of the human engagement with nature it facilitates, which is clearly understood to be affective, not merely cognitive, eliciting admiration and wonder as well as understanding.68
The Book of Nature is to an ordinary Gazer, and a Naturalist, like a rare Book of Hieroglyphicks to a Child, and a Philosopher: the one is sufficiently pleas’d with the Odnesse and Variety of the Curious Pictures that adorne it; whereas the other is not only delighted with those outward objects that gratifie his sense, but received a much higher satisfaction in admiring the knowledge of the Author, and in finding out and inriching himself with those abstruse and vailed Truths dexterously hinted in them.69
The image of hieroglyphics immediately points to the need for an observer to be trained in the symbols or language of nature, if it is to be understood.70 The natural philosopher is privileged and educated, and thus able to see aspects of the natural world that would not be accessible to the unlearned—a theme we noted in the previous chapter (pp. 61–2).
Boyle can be seen a transitional figure between an anthropocentric view of the natural world, which holds that it was created for human benefit, and a more expansive view hinted at in the writings of John Ray in the 1690s, and stated more explicitly two decades later by writers such as William Derham, who remarked that an increasing appreciation of the vastness of the universe offered a ‘far more extensive, grand, and noble view of God’s works’ than that of the ‘old vulgar opinion, that all things were made for man’.71 Hints of this older view are still found in Boyle’s works; it is, however, clear that a process of recalibration of both the status and responsibilities of humanity within the natural world was in the process of emerging.
The forms taken by the ‘natural philosophy’ of the seventeenth century cause some difficulties for those historians of the natural sciences, anxious to trace the historical origins of their disciplines, yet who struggle to cope with the obvious interest shown by writers such as Kepler, Galileo, Boyle, and Newton in questions of theology, which they clearly considered to be part of their ‘natural philosophy’.72 These cannot be dismissed simply as deferential gestures to a religious culture, in that at multiple points theology is allowed to inform the interpretation of nature—for example, in Kepler’s grounding of mathematical archetypes in the mind of God.73 Newton himself was clear that God had to be included within the purview of any responsible natural philosophy. His General Scholium declared that ‘discoursing’ of God ‘from the appearances of things, does certainly belong to Natural Philosophy’.74 This naturally leads us to consider the importance of Newton for the shaping of early modern natural philosophy in greater detail.
Isaac Newton’s Philosophiae Naturalis Principia Mathematica (‘The Mathematical Principles of Natural Philosophy’, 1687), is probably the best-known work of natural philosophy, and continues to attract close attention from historians and philosophers. Yet both this work, and Newton’s intellectual achievements in general, still tend to be read through the distorting prism originating from the French Enlightenment, which adopted Newton as a mascot for its own naturalist cultural projects.75 Phrases such as ‘Newtonian scientific worldview’ or ‘clockwork universe’ are still widely used to refer to this modernist, secular, and naturalistic interpretation of Newton’s natural philosophy.76 Newton certainly came to be associated in popular writing with the idea of a ‘clockwork universe’, despite the fact that he did not in fact develop such a notion, and the lines of argument he developed actually point against it.77
But how did this misreading of Newton take place? It is relatively easy to understand how Newton was adopted as a figurehead by movements with their own ideological agendas, anxious to draw upon his unparalleled international reputation as a genius.78 Yet the development of Newton scholarship in the twentieth century also contributed to this partial and inadequate account of Newton’s overall intellectual vision, including his natural philosophy. As Robert Iliffe points out,79 early twentieth-century studies of Newton focused on his mathematics, physics, and chemistry. His ‘alchemical’ and theological writings were at this stage often seen as peripheral to any serious study of scientific progress, if not deplorable aberrations from scientific orthodoxy, and his anti-Trinitarian theological views treated as if they were anticipations of the Enlightenment criticisms of the perceived irrationality of the doctrine of the Trinity.80 However, intense recent scholarly activity has led to a revision of our understanding of this period.81
By the late seventeenth century, natural philosophy had bifurcated into two distinct strands.82 On the one hand was a speculative natural philosophy, exemplified by Descartes’s vortex theory of planetary motions, which was characterized by the formulation of speculative hypotheses without attempting to ground these in experiment or observation, even if it was conceded that such hypotheses would aim to ‘save the phenomena’.83 On the other hand was an experimental natural philosophy, characterized by its commitment to observation and experiment, and hostile to the use of speculative hypotheses.
Although Newton was initially sympathetic to the form of natural philosophy set out in Descartes’s Principia Philosophiae (1644), he clearly moved away from such an approach. In his letter of 10 June 1672 to Henry Oldenburg, the first Secretary of the Royal Society, Newton made clear his own commitment to an experimental natural philosophical method:
The best and safest method of philosophizing seems to be this: first to search carefully for the properties of things and establish them by experiments, and then more cautiously to assert any explanatory hypotheses. For hypotheses should be adapted to the properties of things which require to be explained (ad explicandas rerum proprietates tantum accommodari debent), and are not to be used to determine them (non ad determinandas usurpari).84
Newton restated his commitment to such an experimental philosophy in a late reflection of 1715, in which he summarized his overall method thus:
It is not the Business of Experimental Philosophy to teach the Causes of things any further than they can be proved by Experiments. We are not to fill this Philosophy with Opinions which cannot be proved by Phaenomena. In this Philosophy Hypotheses have no place, unless as Conjectures or Questions proposed to be examined by Experiments.85
But did such reflection on phenomena lead to understandings of the world that were probably true, or perhaps even certainly true? In the 1660s, there was intense cultural suspicion within the circles of the Royal Society of the dogmatic certainties of religious ‘enthusiasts’, which had caused such social and intellectual disruption during the recent English Civil War. For most members of the Royal Society, it was important to remain ‘modest in opinions, avoiding both peremptory dogmatism and an unwarrantable Scepticism’.86 As Niccolò Guicciardini points out, the intellectual ethos of the Royal Society was ‘probability through patient collection of facts’, accompanied by a ‘sceptical avoidance of dogmatic certainty’.87 Joseph Glanvill’s Vanity of Dogmatizing (1661) reflects this distaste for ideological dogmatism and personal arrogance, which led to suspicions of the idea that the intellectual certainties of geometry had any parallel in an experimental natural philosophy.88 While Newton was aware of the limits of offering mathematical accounts of the natural world, his emphasis on the mathematization of nature placed him somewhat on the periphery of the prevailing consensus of the Royal Society.
This method was put into practice in his Philosophiae Naturalis Principia Mathematica (1687). To explore Newton’s approach, we shall consider what is probably the best-known instance of its application—the formulation of the principle of universal gravitation, and its application as a unifying principle in correlating terrestrial and celestial mechanics.89 The background to this is an explanatory difficulty that remained unresolved concerning Kepler’s theory of planetary orbits: why did the planets orbit in ellipses around the sun? In fact, why did they orbit around the sun at all? What was the physical basis for Kepler’s geometrical summaries (they were not yet described as ‘laws’) of the observed orbital motion of a planet around the sun?90 Newton was aware of the main themes of Kepler’s account of planetary motion, having encountered these indirectly (probably in 1685 or 1686) through Ishmaël Boulliau’s Astronomia Philolaica (1645).
During the 1660s, Robert Hooke began to frame a possible explanation, based on the notions of inertia and gravitation. The orbital motion of a planet, he suggested, was the consequence of ‘compounding’ its inertial motion along a straight line with an attractive motion towards the sun, resulting from its gravitational attraction.91 Yet Hooke experienced difficulties in expressing his physical principles of celestial mechanics mathematically, and in November 1679 wrote to Newton asking for his assistance. Scholarship remains divided on whether the eighteenth-century French mathematician Alexis-Claude Clairaut was right when he suggested that Hooke’s analysis makes it clear that there is a considerable distance separating ‘a truth that is glimpsed and a truth that is demonstrated’.92
Despite some questions which remain about the originality of Newton’s concept of universal gravitation, there is little doubt that Newton was able to mathematize this notion—and in doing so, demonstrated the potential of his natural philosophy to explain the deep structure of the solar system.93 The first two books of the Principia offered an essentially mathematical account of motion, without any commitment to metaphysical or ontological entailment. In the third book, Newton turns to consider how the mathematical and physical realms are to be correlated.
Two points may be highlighted. First, Kepler had established three general principles underlying the orbits of the planets; he was, however, unable to explain these principles. Newton was able to show that all three of what he now named Kepler’s ‘rules’ (regulae) of planetary motion could be explained on the basis of his theories of inertia and universal gravitation. Kepler had identified some important patterns; Newton demonstrated why those patterns existed in the first place, at the same time offering a predictive account of the future movements of the planets. He also extended their scope, asking his astronomer friend John Flamsteed to make precise observations of the movements of the four moons of Jupiter in December 1684, which he was able to show conformed to Kepler’s orbital rules.94 Moons orbiting planets beyond the earth thus obeyed the same laws of motion governing the moment of the planets round the sun. The forces that governed motion on earth seemed to work everywhere, in the same way. For example, Newton was able to show that celestial motion under an inverse square law of gravitational attraction would take the form of an ellipse (observed in the orbits of planets) or a parabola (observed in the orbits of certain comets).95
Second, Newton showed that the same fundamental rules that applied to motion below the moon (i.e., on earth) also applied beyond the moon (i.e., in the case of the planets). The importance of this point is easily overlooked today, when the notion of the ‘sublunary’ world no longer has the imaginative significance that it did for many in the seventeenth century (see pp. 53–4). Newton’s analysis demonstrated that the same fundamental principles seemed to operate throughout the known universe of his day. This is an important example of ‘theory unification’, demonstrating how terrestrial phenomena such as the tides of the sea (and the falling of apples) and celestial phenomena such as the movements of the moon and planets could all be accounted for on the basis of the same principle of universal gravitation.96 What had once seemed to be disconnected could now be held together within the scope of a grander theoretical perspective, suggesting that the universe was more ordered and coherent than some had feared. Newton’s international reputation as a genius often rested on this seemingly preternatural capacity to make connections between apparently disconnected phenomena.97
Newton’s demonstration of cosmic coherence showed that certain fundamental forces and principles seemed to apply throughout the observable universe, and even to be transferable to the social and political orders.98 Alexander Pope’s tribute to Newton following his death in 1727 is well known, taking its cue from Newton’s remarkable illumination of the nature of light, set out in his Opticks:99
All Nature and her Laws lay hid in Night.
God said, Let Newton be! and All was Light.
Other poetic celebrations of his genius went further, often suggesting a link between Newton as a natural philosopher and the enhanced appreciation of the natural world that resulted from the penetrating cosmic vision he created. Significantly, at this stage Newton is often presented as a sage or visionary who empowers the poetic imagination, not someone who suppresses that imagination and restricts its scope.100 Yet it has to be conceded that Newton’s emphasis on the regularity and order of the natural world was too easily reconceptualized in mechanical metaphors, such as a ‘clockwork universe’ or God as a ‘watchmaker’—an image that was artfully redeployed by William Paley in his Natural Theology (1802) to reaffirm the rationality of religious belief.
We have already noted how the early modern concept of natural philosophy wove together domains of thought that today would be understood to belong to quite distinct disciplines—such as physics, biology, philosophy, mathematics, theology, and music. Yet more needs to be said about the form of natural theology that emerged in this period, and its importance for any understanding of the focus and limits of natural philosophy. Like many in this age, Boyle saw a seamless connection between the study of nature and religious belief. He considered that ‘the Discoveries [natural philosophers] make in the Book of Nature’ would lead them and others to ‘be excited and qualifi’d the better to admire and praise the Authour, whose Goodness does so well match the Wisdom they celebrate’.101 This recognizable variant of the ‘Priest in the Temple of Nature’ motif emphasizes the importance of the natural philosopher’s relationship with nature, seeing it not simply as an object for study, but as a potential source of wisdom.102
Religious concerns are an integral part of any account of the development of early modern natural philosophy, not least in their potential to offer a motivation for the attentive observation of the natural order.103 Galileo may have had differences with the institutional church of his day; this did not stand in the way of his productive engagement with questions of theological interpretation. Newton himself appears to have carefully demarcated his views about God arising from his natural philosophy (such as the concepts of space and action at a distance) from his more explicitly theological views, based on a reading of the Bible.104 Others, however, recognized that religious concerns offered a powerful motivation for the detailed study of nature as creation.
For example, Boyle notes that many philosophers, irrespective of their religious commitments, ‘have been, by the contemplation of the world, moved to consider it under the notion of a temple’.105 This motif of a ‘priest in the temple of nature’ should not be seen as a reversion to some natural religion, but rather to highlighting the privileged role of the natural philosopher, who having discerned the beauty and complexity of the natural world, feels obliged to revere, respect, and tend nature—and encourage others to share in this worship.106 Boyle was clear that an attentive engagement with the natural world was both cognitive and affective, changing both thought and behaviour.107 As Scott Mandelbrote has pointed out, Boyle and others held that ‘a cause and a consequence of the impulse to natural theology’ was the desire to worship the creator through ‘a proper appreciation of the form of his creation’.108
The category of ‘physico-theology’ dates from this period, and first makes its explicit appearance in Walter Charleton’s The Darknes of Atheism Dispelled by the Light of Nature: A Physico-Theologicall Treatise (1652).109 The prefix ‘physico-’ derives from the Greek term physis, ‘nature’. Some have interpreted physico-theology as anticipating the agendas of the Enlightenment; others have seen it as offering a defence of the rationality of Christianity in an age of growing secularization.110 In general terms, however, ‘physico-theology’ appears to be have been understood as a form of theology developed on the basis of the methods of natural philosophy—a knowledge of God drawn from reflection on the ‘Book of Nature’, rather than a knowledge of God based on reflection on the ‘Book of Scripture’.111 From the standpoint of orthodox Christian theology, such an approach would focus on the doctrine of creation, but would have nothing to say about the more controversial matters of Christology or the doctrine of the Trinity—two matters on which some natural philosophers, such as Newton, were reluctant to comment publicly.112
This might suggest a parallel between physico-theology and Deism, an approach to religious belief which focuses on the notion of God as creator and lawgiver. It is certainly true that Newton’s ideas were a catalyst to the emergence of both these movements;113 yet the nature of that catalysis was different in each case. The term ‘Deism’ designates a broad spectrum of individual opinions, rather than a well-defined coordinated movement, characterized by varying degrees of scepticism concerning both the rationality and utility of traditional religious beliefs. Deism takes too many historical forms to be plausibly enfolded within a single definition or history, even though it is helpful to think of it as a family of beliefs and attitudes.114
The intellectual origins of Deism, however, are perhaps better understood not to lie in ‘natural philosophy’, but rather in forms of rationalism that were critical or suspicious of certain traditional Christian doctrines, such as the incarnation and Trinity.115 Deism was thus framed antagonistically, in that it defined itself in relation to what it deemed to be incorrect. Deism and physico-theology may converge in at least some of their conclusions; yet these are attained by divergent intellectual pathways, and have different fundamental motivations.
It remains unclear whether physico-theology is to be distinguished from natural theology, or whether both represent potentially overlapping domains of a spectrum of knowledge. Some have suggested that physico-theology was ‘a distinctive intellectual project’, to be distinguished from natural theology, understood as an attempt to gain knowledge of God ‘by human reason alone’. Physico-theology should thus be seen as an essentially empirical approach to the natural world, which sought ‘to establish the compatibility of the new science with the biblical narrative’.116 While there are some difficulties with this view, not least the intellectual heterogeneity of the concept of natural theology,117 a case can certainly be made for suggesting that the introduction of the new term ‘physico-theology’ reflects a new and more empirically based approach to the relation of religion and the natural world.
This kind of approach offered a means of engaging religious questions without becoming involved in partisan and sectarian debates about the sources and norms of theology, which had become particularly significant in the fraught political and religious atmosphere following the English Civil War.
For Boyle, an early advocate of physico-theology, a theological understanding of the world may lie beyond the scope of natural philosophy; such a religious framework nevertheless offers an explanation of why such a natural philosophy is possible in the first place. In developing this general approach, Boyle sets out an important (and much-cited) distinction between ‘things that are above reason’ and ‘things that are contrary to reason’.118 This distinction is important in relation to Boyle’s concern that implications of excessively rationalistic views about nature impoverished human appreciation of its deeper meaning. Although Boyle’s caution about physico-theology partly reflects some theological concerns, his views fit in with the wider views of his culture—for example, echoed in Locke’s belief that God ‘providentially designs us with limited epistemic capacities in order to check our pride and to motivate us to seek perfection in God’.119
Margaret Osler has pointed out that scholarship has used two main metaphors to correlate Boyle’s natural philosophy with his theological interests.120 Some consider him to see theology and natural philosophy as two distinct and self-contained domains of thought which are nevertheless in harmony with each other; others suggest that he appears to use a method of a process of ‘appropriation and translation’, adapting concepts that originated from within a theological context to serve new purposes for natural theology. For Margaret Cook, this second model has the advantage of recognizing the ‘permeable, historically contingent boundaries between the two deeply connected discursive domains of theology and natural philosophy’,121 and perhaps helps us to understand why there are so many logical, empirical, and theological loose ends in the accounts of physico-theology of this age.
Newton did not himself contribute to the writing of such ‘physico-theological’ works; his natural philosophy, however, was widely taken up by others with such interests, and incorporated into tracts and sermons affirming the fundamental rationality of the Christian faith, which seemed to be confirmed by Newton’s dazzling demonstration of the ordering of the universe, grounded in its origins in the mind of God. The Boyle Lectures, established under the terms of the will of Robert Boyle and delivered annually over the forty-year period 1692–1732, represent perhaps the most sustained adoption of Newtonian natural philosophy in the service of theism in the early modern period.122 Poets such as James Thompson developed Newton’s natural philosophy as a tool for gaining an enhanced appreciation of the natural world, and coping with its seeming incoherence and instability.123 A good example of this is found in Thompson’s comparison of a ‘vulgar’ reading of the world as chaotic, dangerous, and threatening, with a superior reading through Newton’s ‘philosophic eye’. While others see disorder and lack of purpose, Newton allows us to see the harmony and order beneath the surface.124
Writing in 1611, before the dramatic interventions of the natural philosophy of Kepler, Galileo, and Newton, John Donne had expressed alarm at the implications of a ‘New Philosophy’ which ‘calls all in doubt’, seeming to rob the world of meaning and purpose. Donne’s ‘First Anniversarie’ had balefully proclaimed the fragmentation of a unified view of the world. ‘’Tis all in pieces, all coherence gone’.125 Newton, it seemed to many, had restored coherence to the world, showing its fundamental harmony and order.126 Like Kepler before him, he seemed to have achieved a harmonious synthesis, not merely of celestial and terrestrial mechanics, but of theology and natural philosophy.
Yet Newton’s legacy proved to be open to other interpretations. Newton had indeed highlighted the ordering and regularity of the universe; this subsequently led others—though not Newton himself—to compare the universe to a clockwork machine.127 And so what Herbert Odom nicely described as the gradual ‘estrangement of celestial mechanics and religion’ began to set in.128 By the end of the eighteenth century, Newton’s natural philosophy was associated with the notion of the created order as an autonomous mechanism which did not require divine support or intervention for its continuation.
In this chapter, we have considered what many regard as the ‘Golden Age’ of empirical natural philosophy. Yet the personal syntheses of Boyle and Newton began to fragment in the eighteenth century, and fall apart completely in the nineteenth. In the following chapter, we shall document this development, and reflect on its implications.