It is often assumed that the relationship between Christianity and science has been a long and troubled one.

Such assumptions draw support from a variety of sources. There are contemporary controversies about evolution and creation, for example, which are thought to typify past relations between science and religion. This view is reinforced by popular accounts of such historical episodes as the condemnation of Galileo, which saw the Catholic Church censure Galileo for teaching that the earth revolved around the sun. Adding further credence to this view of history are a few recent outspoken critics of religion who vociferously contend that religious faith is incompatible with a scientific outlook, and that this has always been the case.

In spite of this widespread view on the historical relations between science and religion, historians of science have long known that religious factors played a significantly positive role in the emergence and persistence of modern science in the West. Not only were many of the key figures in the rise of science individuals with sincere religious commitments, but the new approaches to nature that they pioneered were underpinned in various ways by religious assumptions.

The idea, first proposed in the seventeenth century, that nature was governed by mathematical laws, was directly informed by theological considerations. The move towards offering mechanical explanations in physics also owed much to a particular religious perspective.

The adoption of more literal approaches to the interpretation of the Bible, usually assumed to have been an impediment to science, also had an important, if indirect, role in these developments, promoting a non-symbolic and utilitarian understanding of the natural world which was conducive to the scientific approach.

Religion also provided social sanctions for the pursuit of science, ensuring that it would become a permanent and central feature of the culture of the modern West.

God and the "laws of nature"

The remarkable scientific achievements of Isaac Newton (1642-1727) were neatly summarized in poet Alexander Pope's famous couplet:

Nature and Nature's laws lay hid in night God said: "Let Newton be!" and all was light.

Pope's laudatory verse makes the point, known to every student of physics, that Newton discovered some of the fundamental laws of nature. What is often less appreciated, however, is that part of the novelty of the Newton's achievement lay in his conviction that there were laws of nature there in the first place, awaiting discovery.

What, then, are laws of nature, and where do come from? During the Middle Ages, natural laws were understood to be moral laws that had been established by God. The injunction "Thou shalt not kill" was an example of one such law, assumed to be a universal rule that all civilized societies would observe. However, there was no corresponding notion of universal laws in the natural realm.

This idea - laws of nature in the scientific sense - was an innovation of the seventeenth century and was a consequence of the extension of God's legislative moral power to the physical world. One of the pioneers of this new understanding of laws of nature was the French philosopher and scientist Rene Descartes (1596-1650), who wrote that "God alone is the author of all the motions in the world." This was a radical claim for its time, for it challenged the prevailing view, inherited from the Greek philosopher Aristotle (384-322 BC), that the behaviours and interactions of material objects were governed by their internal properties. According to the Aristotelian worldview, which had held sway throughout the Middle Ages, nature had enjoyed a considerable degree of autonomy.

In the new science, however, natural objects were stripped of inherent properties and God assumed direct control of their interactions. In much the same way that the Deity had instituted moral rules, he was now thought to enact laws which governed the natural world. Robert Boyle, the father of modern chemistry and author of the eponymous law, observed that God's creation operates according to fixed laws "which He alone at first Establish'd." God's authorship of the laws of nature guaranteed their universality and unchanging nature. Descartes thus argued that because these laws had their source in an eternal and unchanging God, the laws of nature must themselves be eternal and unchanging.

Descartes also set out a law of the conservation of motion, again arguing for it on the basis of God's immutability. This idea that nature was governed by constant and immutable principles was an important precondition for experimental science.

The mathematician Isaac Barrow, who was Isaac Newton's predecessor in the famous Lucasian Chair of Mathematics at Cambridge, suggested that the only reason for having confidence that repeated experiments will yield general principles that hold true is because we can be assured that the laws of nature that God has instituted are constant. We have no reason to believe, he wrote, "that Nature is inconstant," for that would imply that "the great Author of the universe is unlike himself."

Mathematics and cosmic order

Closely linked to the new idea that nature was governed by universal and immutable laws was the introduction of mathematical explanation to the natural sciences. Again, this was something quite new.

While medieval thinkers had worked with mathematical equations in the spheres of optics, astronomy and kinematics, they had tended to regard these disciplines as something less than true science. The status of these "mixed mathematical sciences," as they were known, was a consequence of the Aristotelian understanding of mathematics and its relation to the other sciences.

One of the perennial questions in the philosophy of mathematics concerns the status of mathematical truths: Are they human constructions, or are they eternal truths that are embedded in reality? Plato had held the first position, Aristotle had adopted the second, and it was Aristotle's view that tended to prevail throughout the Middle Ages.

If mathematics was primarily a product of the human mind, it could be argued that mathematics did not necessarily provide true a description of reality. It might be allowed, however, that mathematical models, although not ultimately true, nonetheless provided the basis for accurate predictions. Hence, mathematical astronomy, while regarded as falling short of offering a true account of the nature of heavenly bodies and the causes of their motions, was regarded as useful because made it possible to predict their positions. Mathematical models were thus thought of as useful fictions.

It was a difference of opinion on this question that led to Galileo's confrontation with the Inquisition. Galileo had wanted to insist that the sun-centred Copernican model system was more than an helpful mathematical device - it was an accurate physical description. Thus, not only did Galileo champion a new astronomical model, he also held to a new model of astronomy. The Catholic Church, for its part, supported the prevailing view. With the benefit of hindsight, we might judge its decision to have been unwise, but it was consistent with the scientific consensus of the time.

As was the case for laws of nature, the idea that mathematical relations were real had a theological justification. Individuals such as Galileo, Johannes Kepler, Rene Descartes and Isaac Newton were convinced that mathematical truths were not the products of human minds, but of the divine mind. God was the source of mathematical relations that were evident in the new laws of the universe. Like the Bible, the "book of nature" had also been written by God and, as Galileo was to insist, this book was "written in the language of mathematics."

Other scientists shared this view. Johannes Kepler, who discovered the laws of planetary motion, argued that God had used mathematical archetypes in his creation of the cosmos. Because of this, he wrote, the old Aristotelian prejudice against the mathematization of nature was to be rejected:

"the reason why the mathematicals are the cause of natural things (a theory which Aristotle carped at in so many places) is that God the Creator had Mathematicals with him as archetypes from eternity in their simplest divine state of abstraction."

Descartes even claimed that God had created the laws of logic and mathematics, maintaining that the equation 2 + 2 = 4 was true only because God had so willed it. In support of the idea that God was a mathematician, Descartes quoted the biblical verse: "thou hast ordered all things in measure and number and weight" (Wisdom of Solomon 11:20). Newton subsequently described the cosmos as inhabited by an "infinite and omnipresent spirit' in which matter was moved by 'mathematical laws."

Identifying God as the author of mathematics was thus a crucial step in asserting the reality of mathematical relations, and it was this development which enabled the subsequent application of mathematics to the subject matter of physics. Combined with the idea of a divine legislator, this insight produced the modern view that nature is governed by mathematical laws.

Atoms and the world-machine

The new conception of a nature that was ruled by externally imposed laws was necessarily accompanied by a diminution of the role played by the intrinsic qualities of matter. As I've already noted, in the medieval understanding of nature, indebted as it was to Aristotelian science, the activities of material things were governed by their internal properties, usually understood in terms of such qualities as heat, cold, moisture and dryness. Aristotle had also imagined that objects had natural tendencies, or "final causes." Nature, in this scheme of things, was self-organising and was conceptualised as analogous in many respects to a living thing.

The seventeenth century saw the revival of an alternative conception of nature - the atomic or "corpuscular" theory that had been championed by the ancient Epicureans. According to this view, matter was made of minute particles that were more or less qualitatively identical. These particles were able to combine in various ways to form macroscopic matter, and the operations of nature were explained by the interactions of the invisible particles.

Such qualities as heat and cold could thus be accounted for in terms of the motions of minute particles, rather than being considered as inherent qualities of particular kinds of substances. The base units of matter were also imagined to fall within the explanatory range of the laws of nature. In much the same way that the movements of the heavenly bodies were expressed in terms of mathematical laws, so too were the movements of the minute corpuscles of matter.

Nature was also increasingly understood as analogous to a machine, rather than a living organism. For this reason, the new science was often referred to as "the mechanical philosophy." Just as machines were built and designed by human agents, the world was believed to exhibit evidence of design by a divine agent. (Aristotle, although a theist, had thought the world eternal and hence uncreated.)

Accordingly, the idea of "final cause" underwent a major change, and was now typically identified with God's purposes or designs. The idea that nature bore witness to the designs of a deity became a powerful justification for the pursuit of natural science. Indeed, while it is rightly thought that seventeenth and eighteenth-century natural science lent rational support to Christian belief, it is equally true that the natural sciences gained in social legitimacy because they were perceived to be theologically useful.

In each of these seventeenth-century developments - the emergence of natural laws, the mathematization of nature, the new mechanistic and atomic understanding of matter - God was imagined to be more intimately involved in nature than he had been in the medieval world picture. Indeed, this was the explicit intention of some of the principal agents of the scientific revolution, who argued that their new views of nature were more genuinely Christian than the supposedly "pagan" science of Aristotle.

There is an element of truth in the common assumption that the transition from medieval to early modern worldviews that took place over the course of the sixteenth and seventeenth centuries inevitably resulted in a secularization of the cosmos. Yet, many of the leading figures in the scientific revolution imagined themselves to be champions of a science that was more compatible with Christianity than the medieval ideas about the natural world that they replaced.

A renewed emphasis on the sovereignty of God is evident in all of these developments. This paralleled a movement simultaneously unfolding in the theological sphere with regard to the doctrine of justification. In an argument analogous to that which stripped natural bodies of their inherent causal virtues, Protestant Reformers insisted that inherent human virtues were not causally efficacious in bringing about justification.

The whole initiative for the process of salvation lay with God, whose eternal decree determined who would be justified. Developments in both spheres, the theological and the natural, are linked to renewed assertions of the sovereignty of God, and to the understanding of the exercise of that sovereignty in terms of eternal and unchangeable laws.

The "book of nature" and the "book of Scripture"

If physical objects were stripped of their intrinsic qualities in the new conception of nature, they were also denied any function as natural symbols. Throughout the Middle Ages, features of the natural world had symbolised theological and moral truths.

It is often thought that the rise of modern science caused the death of this rich symbolic world. In fact, it was the demise of symbolism, promoted in various ways by Renaissance humanists and Protestant reformers, which helped make space for the new science. Galileo's reference to "the two books" reminds us of important connections between the two modes of God's communication, nature and Scripture. For much of the Middle Ages, the "books" of nature and Scripture had been read together as part of a unified interpretive endeavour.

The link between the two books was provided by allegorical interpretation. Augustine and Thomas Aquinas had both argued that the literal meaning of Scripture is established by identifying the objects to which the words refer. The allegorical sense, however, was to do with the meanings of those objects. For the allegorical reader, the words of Scripture directed the senses to a natural world in which objects bore rich theological and moral meanings. Allegory, in short, was a technique for reading the world through Scripture.

Owing to the combined efforts of Renaissance humanists and Protestant reformers, the sixteenth century saw a decline in allegory and a renewed emphasis on the literal sense of the Bible. In his typically colourful prose Luther observed that allegorical readings were for "weak minds" and "idle men." The Reformation helped precipitate the collapse of allegory by casting suspicion on visual representation and symbolism generally.

An unintended consequence of these developments was that natural objects were no longer "read: for their theological and moral meanings. This in turn raised acute questions about how nature was to be understood, and its purpose in the divine economy. It is in this sense that the world was indeed desacralized at this time, although this was not a consequence of science, but rather a shift in Western sensibilities that helped make science possible.

One response to new questions about the intelligibility of nature was reconfiguration of nature in terms of mathematical relations. This solution is evident in Galileo's new deployment of the "book of nature" metaphor. The decline of allegorical readings of nature thus opened the way for mathematical readings.

Equally importantly, nature was increasingly regarded as a realm to be exploited for material benefit rather than for moral and theological edification. This led to attempts to master the natural world, which were themselves motivated by new literal readings of the creation narratives, and in particular the Genesis injunctions to subdue the earth and exercise dominion over it (Genesis 1:28; 9:2). Religious considerations thus provided important sanctions for the utilitarian orientation of modern science.

Francis Bacon and his successors in the Royal Society, for example, clearly saw themselves as attempting to regain the dominion over nature which Adam had forfeited as a consequence of his disobedience. As Bacon expressed it:

"For man by the fall fell at the same time from this state of innocency and from his dominion over creation. Both of these losses however can even in this life be in some part repaired; the former by religion and faith, the latter by arts and sciences."

Scientific activity thus came to be regarded as an integral part of a redemptive process. This more active engagement with the natural world was still pursued from theological motives, but clearly these were quite different from those of medieval allegorists.

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Could modern science have arisen outside the theological matrix of Western Christendom? It is difficult to say. What can be said for certain is that it did arise in that environment, and that theological ideas underpinned some of its central assumptions. Those who argue for the incompatibility of science and religion will draw little comfort from history.

What historical record also suggests is that insofar as modern science posits natural laws and presupposes the constancy of nature, it invokes an implicit theology. Most important of all, perhaps, religious considerations provided vital sanctions for the pursuit of scientific knowledge and, arguably, it is these that account for the positive attitudes to science which have led to the high status of science in the modern West.

This is not to deny that there have been those in the past who have opposed certain scientific views on religious grounds. This has been especially the case since the advent of Darwinianism, which met with a mixed reception in religious circles. It is often forgotten, however, that Darwinism met with a mixed reaction in scientific circles, too.

Those who have magnified more recent controversies about the relations of science and religion, and who have projected them back into historical time, simply perpetuate a historical myth. The myth of a perennial conflict between science and religion is one to which no historian of science would subscribe.

Peter Harrison is the Director of the Centre for the History of European Discourses at the University of Queensland and a Senior Research Fellow at the Ian Ramsay Centre in Oxford, where for a number of years he was the Idreos Professor of Science and Religion. He has published many books on the history of science, and is editor of The Cambridge Companion to Science and Religion.