The Scientific Revolution of the 16th and 17th centuries was a defining moment in the history of Western Civilization. Modern science and the scientific method were born; the rate of scientific discovery exploded; giants such as Copernicus, Vesalius, Kepler, Galileo, Harvey, Newton, and countless lesser figures unlocked world-changing secrets of the universe.
It has often been observed that such a revolution occurred only once in human history, and in one particular culture: the predominantly Christian culture of early-modern Europe. This observation gives rise to several questions: What role, if any, did Christianity play in the birth of modern science? Did faith give rise to science? Did a mixture of faith and reason give rise to it? Was Christianity somehow responsible—perhaps even necessary—for the rise of modern science, as some historians have argued? In short, what, if anything, does religion have to do with the Scientific Revolution?
As long as science has existed, religionists have been attempting to reconcile religion and science. Recently, a new breed of scholars has asserted that religion itself—in particular Christianity—actually caused the birth of science. What are the facts of the matter?
Toward answering that question, let us first review some earlier and relevant historical developments; then we will turn to relevant highlights of the Scientific Revolution itself.
Science before the Scientific Revolution
Science was born in ancient Greece among the pre-Socratics, who were the first to look for natural explanations of the world around them. Thales’s claim that everything is made of water is significant because it assumes that the fundamental building block of the world is a natural substance. Embracing this naturalistic outlook, the Greeks of the classical and Hellenistic eras made important advances in astronomy, geometry, medicine, and biology—and established the fields of history, drama, political theory, and philosophy.
Philosophy was especially important. Plato and Aristotle—the philosophical giants of Greece—created two dramatically different philosophical systems, especially in terms of their metaphysics and epistemologies.1 Plato, in exception to the general Greek attitude, proposed that the world we experience is not fully real. He maintained that the individual physical objects we see are imperfect, corrupted reflections of those in a higher reality. Plato called this higher dimension the world of the Forms and held that knowledge of this realm can be reached only via intuition. Although Plato revered mathematics, he did so for its alleged ability to train the mind to receive the Forms rather than as a means of gaining understanding of the physical world. Plato had little interest in studying this world.
Aristotle, in contrast, was interested only in this world. He held that the objects of the physical world are fully real and thus worthy of study. Knowledge, he held, is gained not from groundless deductions or intuition, but ultimately from induction—from the study of the concrete, particular things we see, touch, smell, and hear around us. According to Aristotle, this world is real, and worth studying for the knowledge it brings: from knowledge of the beautiful stars in the night sky to that of the minutest details of slimy sea creatures. Aristotle was not only the creator of a philosophy supportive of science; he was a scientist himself, and his impressive work in biology (a science he founded) demonstrates a mind fully in touch with and keen on understanding the physical world.
Unfortunately the Greek scientists (even Aristotle) generally were not concerned with the practical applications of their studies and theories. Consequently, the practical but nonintellectual Romans who followed saw little value in keeping the Greek scientific traditions alive, much less expanding them. The Romans’ scientific writings were mere summaries of Greek works.
After the fall of Rome, science ground to a halt, along with virtually all other intellectual activity. The intellectuals of the period known as the “age of faith” turned their attention fully to the other world. Augustine, the most influential Christian theologian, was deeply influenced by Plato’s otherworldly philosophy. He regarded science as a “gratification of the eye” and, at best, as a “handmaiden” to religion.2 For him, faith in Christian doctrine took precedence over the conclusions of reason.
While Europe was entering its Dark Ages, the scientific achievements of antiquity were being discovered by the Islamic world. A translation movement begun in Baghdad led to all of the Greek scientific works becoming available in Arabic. Islamic thinkers mastered the works of Aristotle, Ptolemy, Galen, and others. Then, beginning in the 12th century, Europeans started discovering the impressive knowledge of the Islamic world, and a new translation movement began, this time from Arabic to Latin. These translations made available in Latin many works by Aristotle and other ancient writers, along with extensive commentaries by Arabic authors.
To the medieval Europeans who had been surrounded by ignorance and otherworldliness, Aristotle’s interest in and knowledge of the physical world was impressive and overwhelming. But the Church was ambivalent to the study of Aristotle until Thomas Aquinas brought his ideas into the mainstream of Christian thought. Aquinas attempted to synthesize Christian theology and Aristotelian natural philosophy, and specified what he saw as the proper domains of faith and reason.
Most importantly, Aquinas accepted Aristotle’s views of reason and the physical world: “Reason, Aquinas taught, is not a handmaiden of faith, but an autonomous faculty, which men must use and obey; the physical world is not an insubstantial emanation, but solid, knowable, real; life is not to be cursed, but to be lived.”3
The Thomist synthesis of Christianity and Aristotelianism became a dominant force in the Church, and remained so for centuries. Given the previously dominant “handmaiden” view of science, this amounted to the liberation of reason and a passkey for men to investigate this world.
This also led to Aristotle’s writings becoming the foundation of the first universities. These universities originated in cities such as Bologna, Paris, and Oxford during the 12th century. They provided a basic education in classic Greek and Roman texts—an education that would become widespread throughout Europe. By the end of the 13th century, Aristotle’s writings on metaphysics, cosmology, physics, meteorology, and natural history were required reading for all university students.
The liberation of reason by Aquinas led to the Renaissance. After centuries of obsession with the next world, the Renaissance was a rebirth of interest in this world, the world of nature and of living, breathing human beings. This can be seen vividly in the art of the period: The Renaissance artists learned how to look carefully at the physical world around them, and the figures in their paintings came to life in all three dimensions.
One outgrowth of Renaissance thought was the “natural magic” tradition, in which men looked for connections in nature that are not perceptually obvious or visible, which they labeled “occult” (meaning “hidden”). Examples of such connections included the attraction of iron to a magnet, the ability of the sunflower to follow the sun across the sky, the moon’s effect on the tides, and the effects of medicines. These connections were often thought of as “sympathies” or “antipathies,” in effect anthropomorphizing natural phenomena. In order to find these connections, men looked for special “signs” that God had placed on things. For example, the fact that a walnut looks like a brain was considered evidence that it might heal ailments of the brain. Men believed that grasping these hidden connections could be of great practical value, but they did not yet have a valid method for discovering or understanding them.
Several other factors contributed to the culture in which the Scientific Revolution would occur. Gutenberg’s development of the printing press in the 1450s made possible the inexpensive reproduction of books, making it vastly easier to spread new knowledge. The 16th-century Reformation splintered the Church into numerous warring camps, ending the Church’s monolithic dominance over the European intellectual scene. In the 15th and 16th centuries a series of voyages of discovery, aimed at finding new trade routes, yielded an explosion of information about exotic places, new plants, animals, minerals, medicines, peoples, languages, and ideas. These factors contributed to a culture in which man’s mind was receptive to new ways of looking at the world. The stage was set for the Scientific Revolution.
The Scientific Revolution: Key Developments
The year 1543 saw the publication of two monumentally important scientific works, and for that reason is often considered the beginning of the Scientific Revolution. The first was Andreas Vesalius’s On the Structure of the Human Body, which, with its astounding illustrations of the human body, founded the modern study of anatomy. Vesalius, a trained physician, was deeply influenced by the naturalism of the Renaissance—by the idea that the natural world merits our careful study. This led him to perform meticulous dissections of human cadavers and to hire an accomplished Renaissance artist to create the fabulously detailed woodcut illustrations for his book. The work of Vesalius inspired many followers who later made important anatomical and physiological discoveries.
But even more significant than Vesalius’s book was Nicolas Copernicus’s On the Revolutions of the Heavenly Spheres, published that same year, which presented his full description of the celestial motions centered on the sun, rather than the earth. For fifteen hundred years, all educated Europeans had accepted the Ptolemaic system of the cosmos, in which the earth is fixed unmoving at the center, and everything else revolves around the earth, in combinations of circular motion, within solid crystalline spheres. That the earth was stationary at the center of the cosmos was confirmed by both the Bible and by common sense. If the earth was rotating or traveling through space, objects thrown straight up into the air would not come down in the same place.
But Copernicus held that his system was not only more mathematically elegant than Ptolemy’s but that it constituted a true description of the cosmos. The heliocentric system of Copernicus formed the first link in a chain of astronomical observations, reasoning, and discoveries that included those of such great scientists as Tycho Brahe, Johannes Kepler, and Galileo Galilei, and culminated in a grand synthesis on the part of Isaac Newton, with his universal law of gravitation. This chain of discoveries would not have been possible without Galileo’s brilliant experimental investigations into the nature of free fall using pendulums and inclined planes. Galileo was the greatest of the early experimentalists of the Scientific Revolution, but he was not the only one. Galileo’s contemporaries William Gilbert and Francis Bacon also focused on the idea of systematic experimentation as the key to understanding natural phenomena. As the 17th century progressed, belief in the power of experimentation became widespread, and scientists invented new precision tools for performing observations and experiments. These instruments included the telescope, microscope, barometer, thermometer, precision clock, and vacuum pump.
Galileo was the first of many brilliant experimentalists who found ingenious ways of investigating the properties of nature. Another of these men, Robert Boyle, used the barometer and vacuum pump to discover the exact relationship between the volume of gas and the pressure exerted on it (known today as Boyle’s law). He also subjected alchemical ideas to systematic experimentation and rational analysis, and is thus considered one of the forefathers of the science of chemistry.
These new scientists were eager to share their ideas with like-minded others, and soon conceived of a completely new type of social organization: the scientific society. Scientific societies in Italy, France, England, and elsewhere made it much easier for scientists to meet and discuss their work, to perform experiments, and to report on scientific work being done in other countries. The earliest scientific society, to which Galileo belonged, was the Accademia dei Lincei (Academy of the Lynx) in Rome, which was succeeded by the more formal Accademia del Cimento (Academy of Experiment). By the 1660s, royally sponsored societies had been founded in France (Academie Royale des Sciences) and England (The Royal Society of London), and both had official journals for the publication of research done by their members.
The sciences most fundamental to the Scientific Revolution were astronomy and physics, but scientists also made significant discoveries regarding the nature of living things—for example, that blood circulates through the body, that reproduction begins with the union of egg and sperm, that sexual reproduction occurs in plants, and that life functions could be viewed as analogs of physical and chemical processes.
The most important discovery of the Scientific Revolution was the powerful new method of discovery itself. The modern scientific method relied on a combination of careful observation, controlled experiments, and the search for mathematical laws and their relationships. Historian of science I. B. Cohen points out
how novel and revolutionary it was to discover principles by experiment combined with mathematical analysis, to set scientific laws in the context of experience, and to test the validity of knowledge by making an experimental test. Traditionally, knowledge had been based on faith and insight, on reason [detached from observation] and revelation. The new science discarded all of these as ways of understanding nature and set up experience—experiment and critical observation—as the foundation and ultimate test of knowledge.4
This new method was ultimately an extension of Aristotle’s basic philosophical orientation: his metaphysics of this world and his epistemology of reason.
Unfortunately, Aristotle’s specific theories about physics and cosmology, such as his explanation of why heavy objects fall, proved to be incorrect. In addition, a number of Scholastic philosophers insisted on the truth of these Aristotelian theories even in the face of new observational evidence against them. As a result, many 17th-century scientists formed a very negative judgment of Aristotle, even as they accepted his basic philosophical orientation. As scientists such as Galileo and William Harvey pointed out, Aristotle had argued that all science must be tied to careful observation of the world. Philosophically, Aristotle’s this-worldly metaphysics and epistemology were the foundation of the Scientific Revolution. And it was owing to Thomas Aquinas that Aristotle’s ideas were back on the scene.
Science and Religion during the Scientific Revolution: God’s Two Books
During the Scientific Revolution there was little explicit conflict between science and religion, apart from Galileo’s famous clash with the Roman Inquisition. Scientists generally adopted (or at least did not openly reject) the religious views of their culture. However, in a significant reorientation between science and religion, men reconceived God as playing a much smaller role in the universe. One key to this reorientation was the metaphor of “God’s two books”—the Book of Scripture and the Book of Nature—which were considered equally deserving of man’s attention. This metaphor originated in Thomas Aquinas’s distinction between the realms of faith and reason, and was famously promoted in the 17th century by Francis Bacon:
Let no man upon a weak conceit of sobriety or an ill-applied moderation think or maintain, that a man can search too far, or be too well studied in the book of God’s word, or in the book of God’s works, divinity or philosophy; but rather let men endeavour an endless progress or proficience in both; only let men beware . . . that they do not unwisely mingle or confound these learnings together.5
Bacon’s warning about mingling the two books became very influential among his many 17th-century followers, and it became widely accepted that God’s two books should be studied quite separately. As far as religious belief was concerned, Bacon urged men to “give to faith only that which is faith’s.”6 This attitude was liberating for scientific work, keeping it largely unmolested by religion.
The opposite attitude—that religion is closely connected with the study of the physical world—had led to the Church’s persecution of Galileo. He had advocated an idea—that the earth moves—that conflicted with Biblical passages implying that the earth does not move.
Bacon’s writings were influential throughout the new scientific societies in Europe, but they were especially so in England, where the founders of the Royal Society of London referenced them explicitly. As a result of this influence, at the Royal Society, “no one ever presented a public case for a scientific fact with a theological argument.”7
Historians have often pointed out that many of the 17th-century English scientists had careers in the Church. But even these “theologian-scientists” sought to isolate their religious beliefs from their scientific studies, in effect leading “double lives”: “English scientists qua scientists kept out of the sacristy, English theologians qua theologians kept out of the rooms where experiments were performed.”8
Among the accomplished scientists, the two figures most famous for their strong religious beliefs were Robert Boyle and Isaac Newton. But even these two were careful to keep a separation between God’s two books. According to one historian, “When working as a ‘naturalist,’ Boyle sought to ‘discourse of natural things’ only, without ‘intermeddling with supernatural mysteries.’”9 Newton wrote extensively on religion, but his scientific books contained no religious arguments for his scientific conclusions. And when he was president of the Royal Society, “he banned anything remotely touching on religion.”10
The Clockwork Universe
Around the year 1600, when astronomers Tycho Brahe and Johannes Kepler came to Prague to accept employment from Holy Roman Emperor Rudolf II, they could not have failed to notice Prague’s great astronomical clock. Mechanical clocks had started appearing in Europe in the late 13th century, and had become widespread in larger cites by the mid-14th century. The first clocks had their innards exposed, so everyone could easily see how they worked. By the 16th century, clocks were generally built to conceal their inner workings. Many clocks, such as the ones in Prague and Strasbourg, did much more than just tell time; they indicated solar and lunar cycles, and marked key moments with startling animations such as crowing roosters and jousting knights.
The inside of a clock involved extremely complex motions that could even appear purposeful. This led some to start thinking that perhaps the entire cosmos was like this in some way. During the 17th century, men began seeing nature as essentially similar to a machine, and the clock became a favorite metaphor. In reaction to the natural magic tradition of the Renaissance, with its “sympathies” and “antipathies” and “occult” powers, the new view considered nature as a machine made of unconscious material parts controlled by external mechanical forces. In its extreme form, this led to the idea that all the phenomena of nature are produced by particles of matter in motion. When Robert Hooke looked at insects under the microscope, he was amazed at the intricate details he saw; these made him think of the insects as complex machines. Robert Boyle, one of the greatest champions of this new way of looking at the world, called it the “mechanical philosophy.”
The adherents of the mechanical philosophy had a variety of opinions about the nature of matter and mechanical forces. The Catholic priest Pierre Gassendi followed the atomist tradition from Democritus of ancient Greece, which held that all matter is composed of indivisible solid particles. Others such as René Descartes believed that matter is infinitely divisible. Some saw matter as completely inert, and others saw it as having some active capacities. Although Newton’s law of gravity operated without direct physical contact between objects, and was disputed by some for that reason, it was seen by others as still essentially keeping to the mechanical tradition.
From its first formulations, the mechanical philosophy invited charges of atheism because it suggested the world machine could run itself without the external help of a God. In defense of their piety, its proponents always stressed that they saw God as the creator and constant operator of this machine. Invoking a distinction between “primary” and “secondary” causes, they explained that God was, of course, the “primary” cause of all events, and that they were studying “secondary” mechanical causes. In this way, they gradually came to see God less and less as an explanation for anything.
As the culmination of the Scientific Revolution, Newton’s Mathematical Principles of Natural Philosophy demonstrated that the world works on essentially mechanical principles understandable by man. Although for Newton God was still actively adjusting and supporting the universe in its operations, many of his successors held that once the universe was up and running it shouldn’t require outside intervention.
When Thomas Aquinas claimed that there were theological truths that could be established by reason alone, he created the field of “natural theology.” Aquinas claimed that reason (and thus natural theology) could establish the existence of God and several of God’s characteristics. For the rest of the important truths of Christianity, one needed to turn to revealed theology: the domain of faith, revelations, and the Bible. Revealed theology was clearly needed to establish the central doctrines of Christianity, such as the Trinity and Christ’s role as redeemer of man for his sins.
The study of natural theology became popular in the 17th century, especially among English theologians. Many of the 17th-century scientists were excited about the discoveries they were making, and they associated this excitement and wonder with religious feeling. Robert Hooke expressed a common view:
’Tis the contemplation of the wonderful order, law, and power of that we call nature that does most magnify the beauty and excellency of the divine providence, which has so disposed, ordered, adapted, and empowered each part so to operate as to produce the wonderful effects which we see; I say wonderful because every natural production may be truly said to be a wonder or miracle if duly considered.11
Another Royal Society member spoke about “the lawful and religious delight which should result from beholding the curious and wonderful frame of this our visible world.”12 By the year 1700, natural theology had become so popular that it displaced much of revealed theology.
Robert Boyle—whose religiosity has already been noted—was one of the greatest champions of natural theology among the accomplished scientists of the era. He wrote voluminously about how science proved the greatness of God and how scientific research was a form of worship, and his book The Christian Virtuoso (where “virtuoso” meant “scientist”) described how doing science makes a man a better Christian. Although Boyle was no doubt sincere in his profession of religious belief, historian Richard Westfall has noted a major omission in Boyle’s writings. For all his professed devotion to Christianity, Boyle barely mentioned Christ and essentially ignored the core doctrine of his religion:
The scarcity of references to Christ in the many pages of Boyle’s disquisitions on religion is striking. . . . The idea of redemption did not play an important role in his thought on moral living; he considered the attainment of virtue as an intellectual choice dependent on a person’s comprehension of God. . . . The problems of morality were not pressing concerns in his personal life. He talked about sin like an American discussing cricket; he had heard about it but had never seen it close at hand. The Christian doctrine of redemption rang no response in his soul.13
The shift of intellectual focus from revealed theology to natural theology was a step away from the Christian God and toward the deist God, which in turn was a step toward a universe devoid of the supernatural.
Bearing in mind the key developments leading up to and during the Scientific Revolution, the prevailing religious attitudes of its scientists, and the gradual waning of God as an explanation for nature, we can return to a question raised at the outset of this article.
Was Christianity Necessary for the Birth of Modern Science?
In recent decades, many academic historians of science have rejected the idea that science and religion are incompatible, and they have written volumes in an effort to refute what they call the “conflict thesis”—the idea that science and religion are fundamentally in conflict. These historians have also acted as enablers for diehard religionists to argue that religion caused the birth of science. These religionists include the prolific Stanley Jaki, Benedictine priest and professor of physics; Ian Barbour, professor of religion and physics; Thomas Woods, a popular libertarian Catholic writer; and Rodney Stark, a sociologist of religion at Baylor University. For instance, Stark, the most prominent contemporary proponent of this view, devotes a chapter of his book For the Glory of God to the idea that Christianity laid the philosophical groundwork for the development of modern science, writing, “Christianity depicted God as a rational, responsive, dependable, and omnipotent being and the universe as his personal creation, thus having a rational, lawful, stable structure, awaiting human comprehension.”14
Although many of the 17th-century scientists had such a conception of God and the universe, this is no ground for attributing the rise of science to Christianity. Scientists were not studying the “supernatural” realm; they were studying observable nature, the identity of things, and causal relationships. And they were employing not faith but reason, observation, logic.
Had scientists tried to ground science in religion, they would have been utterly stifled. Where would they have turned? To God? He can’t be observed; this is both a tenet of religion and a simple fact. The only place scientists could have turned to “ground” science in religion is the Bible. What would they have found there?
The Bible certainly does not present God as “rational, responsive, and dependable” or the universe as “having a rational, lawful, stable structure” that is open to “human comprehension.” The Old Testament presents the natural world as created by a supernatural being who acts frequently to intervene in his creation, to make things act in contradiction to their natures—by, for instance, stopping the sun and moon from moving, turning a woman into salt, and making a bush speak. Likewise, the New Testament presents a world full of supernatural, unscientific, causally impossible events—from Mary being impregnated by a ghost, to Jesus walking on water, to a dead man rising from the grave. (And this is to say nothing of the moral atrocities perpetrated by God in the Bible—from His exterminating most of the human race in a flood to his torturing Job.) The whole Christian worldview entails the subordination of reality, identity, and causality to the whims of an alleged God for whom there is no evidence and who is therefore to be accepted on faith.
Why, then, did 17th-century scientists think of God as “rational” if they could not have gotten this idea from the Bible? The idea of a “rational” God, a God that somehow fit with nature, was a projection of their own minds—minds that were beginning to embrace a rational view of the world, and thus turning away from the philosophical and literary core of Christianity. After Aquinas introduced Aristotelian principles to the Christian world, Christian culture acted as an unwitting carrier of the pro-reason, pro-reality philosophy. Aristotle’s philosophy was always at odds with the supernatural and mystical core of Christianity, which is why Aquinas himself had to divide knowledge into two separate realms. In spite of its historical longevity, Aquinas’s theology was always an unstable amalgam of contradictory components, one of which is the foundation of science, the other of which contradicts it.
Modern science was born in a culture in which Christianity was the dominant religion, but modern science was not built on a Christian foundation. It was built on the implicit foundation provided by the pro-reason, pro-this-world philosophy of Aristotle. This is observable, historical fact.
The great discoveries of the Scientific Revolution demonstrated the awesome power of man’s rational mind. Since the fall of Rome, Christianity had dominated all cultural and intellectual activity in the West. But by the end of the 17th century, Christianity had lost its dominance in the realm of the intellect, and science had become the primary source of inspiration for those eager to use their minds.
Although explicit religious belief remained at high levels among the new scientists, it moved from the foreground to the background of their minds. Aquinas had segregated religion from reason, enabling reason to flourish. Revealed theology—true religion—was displaced by natural theology, dramatically loosening the shackles of religion and inspiring men to look at reality and think. The universe was increasingly seen as a machine that God had designed and then left alone, enabling man, through reason, to discover the laws of nature and to transform the world to suit his needs. A vestigial God remained as an “explanation” of the universe, but future generations would realize that God was not needed as an explanation for anything.
The claim from today’s religious apologists that the Scientific Revolution is rooted in religion—that science somehow came from faith—is historically and logically absurd. The foundation and cause of the Scientific Revolution was not religion or faith but observation and logic.