Based on David Wootton, The Invention of Science: A New History of the Scientific Revolution (Harper, 2015).
The Scientific Revolution occurred when new methods — mathematical reasoning and experimentation — were embraced, but at the time of the Revolution, both mathematics and experimentation had been known to Europeans for centuries. Geometry had been the basis of perspective painting during the Renaissance, and mathematics had been employed by astronomers. As for experimentation, al-Haytham’s Optics had been translated into Latin by 1230. The manuscript was widely read, and after 1572, so was the printed book. Optics could have served as a textbook for experimental science, but there is no record of any medieval scientist attempting to reproduce its findings. Instead, Optics was read as an authoritative text, widely discussed but never questioned.1 The centrality of mathematics and experimentation to the Scientific Revolution invites two questions: why were they so little used before the seventeenth century, and what brought them to the forefront of scientific practice?
David Wootton argues that the answers to these questions relate to a radical shift in the European view of the world and of knowledge. Medieval scholars viewed the world as cyclical. All necessary knowledge was either currently available, or had once been available but then lost. A scholar’s duty was the recovery and preservation of that knowledge. Aristotle and other classical authors were taken to be authoritative sources. Any puzzles or contradictions that arose from their writings indicated that some knowledge had been lost, or that the classical arguments were not yet fully understood. This view of the world began to collapse around 1500, and was replaced by one that imagined that progress was possible, and that the scholar’s role was discovery rather than recovery. The replacement of the first worldview with the second was a gradual process, taking more than a century. It wasn’t yet complete in 1632, when Galileo wrote Dialogue Concerning the Two Chief World Systems .2
The transition began with the discovery of the Americas, which demonstrated that it was possible to learn things that could not have been known to any earlier generation. It also demonstrated that Aristotle could be dead wrong.
The Cyclical World
A well-educated person living in, say, sixteenth-century Florence could be proud of his city’s accomplishments and its place in the wider world. He would be aware, though, that his city’s accomplishments did not match those of Imperial Rome or Classical Greece. The remnants of Roman and Greek sculpture and architecture could still be seen; scholars assiduously studied the works of Aristotle, Plato and Archimedes; Roman law and Roman philosophy were widely admired. The gross evidence of history showed that human societies rose and fell and rose again. This evidence was understood as showing not just ebb and flow, but repetition or cyclicality. Here, for example, is Giulio Cesare Vanini, writing in 1616:
Again will Achilles go to Troy, rites and religions be reborn, human history repeat itself. Nothing exists today that did not exist long ago; what has been, shall be.3
The notion that human affairs are cyclical was further buttressed by Christianity. The Church emphasized cyclicality by matching its rites with the recurrence of the seasons: the birth of Christ in the despairing depths of winter, his death and resurrection in the first days of spring. The Bible itself suggests a world without progress, for the first few generations of humans are already farming, composing music, and building boats and towers (well, at least one of each).
The affairs of scholars were consonant with the cyclical worldview. Medieval scholars were aware of Greek and Roman literature, but most of it had been lost to them. Their scholarship was largely a salvage operation that tried to organize and retain what little they had. Their situation changed dramatically when European armies began to push back the borders of Islam’s empire. Toledo was retaken in 1085 and Sicily in 1091. The madrasas in both places contained extensive libraries of Greek natural philosophy, Islamic commentary on that philosophy, and original Islamic science. A vigorous translation movement ensued, with some scholars spending the remainder of their lives translating these documents from Arabic into Latin. Europeans came to possess a vast body of new (to them) scholarship, and would spend generations organizing it and studying it.
A new sort of school, the university, began to appear in the twelfth century. By 1200 there were universities in Bologna, Paris and Oxford, and seventy more universities were established by 1500. A major university would have four faculties: arts, law, medicine and theology. A bachelor of arts degree was required for entry into the other faculties, which awarded masters degrees.4 The curriculum for the arts degree was built around the works of classical scholars, with Aristotle being pre-eminent among them. Their writings were taken to be definitive. Natural philosophy was much like theology in that “both disciplines were seen as the explication of authoritative texts.”5
The view that all useful knowledge had once been available, and that Aristotle was a reliable source of that knowledge, led the natural philosophers into error. For example, Aristotle argued that ice is heavier than water, but floats on top of water because of its shape. This claim could easily have been tested and shown to be false, but no tests were made. It also contradicted Archimedes, whose work was known to the mathematicians and astronomers of the time. But natural philosophers were logicians, while mathematicians and astronomers were mere calculators, so the philosophers continued to make this claim well into the seventeenth century.6
The universities, and the natural philosophers who inhabited them, raised Europe’s intellectual standards enormously; but by the early sixteenth century, the philosopher’s adherence to classical edicts had become obstructive. Leonardo da Vinci, in a tract unpublished at the time of his death in 1519, shows his frustration with the philosopher’s dictats:
No human investigation can be termed true science if it is not capable of mathematical demonstration. If you say that the sciences which begin and end in the mind are true, that is not to be conceded, but is denied for many reasons, and chiefly the fact that the test of experience is absent from these exercises of the mind, and without it nothing can be certain.7
A book describing New World voyages was published in 1507 under the title Lands Recently Rediscovered, reflecting the author’s conviction that there was nothing new under the sun. Nevertheless, it was the New World that precipitated the collapse of the cyclical worldview, and with it, the reclaim-and-preserve approach to scholarship.
A New World and a New Globe
The cosmology of 1500 was that of Aristotle. He divided the universe into two parts, the supralunary where nothing changes and everything moves in perfect circles, and the imperfect and sometimes chaotic sublunary. The sublunary consists of concentric spheres of the four elements, these being earth, water, air and fire. The four elements interact where earth emerges from water, and that interaction is what makes life possible.
Earth emerging from water, that was the puzzle. If the spheres had a common center, the sphere of water would totally encompass the sphere of earth and there would be no dry land for us to walk upon. Natural philosophers debated whether it was the sphere of earth or the sphere of water that had been displaced from the center of the universe, but they understood that it had to be one or the other. The amount of dry land on the earth-and-water globe could be as little as one quarter of its surface, in which case there were no significant lands yet to be found. But it could be as high as one half of the globe’s surface, in which case there were substantial undiscovered lands somewhere to the south of the Eurasian land mass. Such was the consensus by 1475.
There were a few dissenters. These included Robert Grosseteste (1175-1253) and Marsilius of Inghen (1340-96), who argued that there were no separate spheres of earth and water, and that the water simply lay in depressions on the earth’s surface. The writings of both authors were in print during the Renaissance.
There was also some contrary evidence. A map should show that the region of dry land is circular; but as Dante (yes, that Dante) noted in 1320, the maps showed otherwise. As well, the shadow of the earth cast on the moon during a lunar eclipse is circular, suggesting a single sphere. The philosophers’ faith in Aristotle held all the same.
The evidence that brought about the collapse of this cosmology was the discovery of the New World. Vespucci’s letter Mundus novus was published in 1503 and became enormously popular. The letter made clear that parts of the New World were antipodal to parts of the Eurasian landmass. This discovery flatly contradicted the Aristotelian model, and the scholarly consensus quickly dissolved. Illustrations depicting a single terraqueous globe began to appear in textbooks in the early 1500s, and the terraqueous globe was the new orthodoxy by 1538. Wootton argues that this event marks a turning point for science:
This is the first occasion since the establishment of universities in the thirteenth century on which a philosophical theory was destroyed by a fact.8
Why had this evidence succeeded in overturning the Aristotelian model, when earlier evidence had not? Wooten offers two explanations:
First, there was no disputing the importance of the discoveries of the New World, for the simple reason that they became matters of state, the concern of kings. How could scholars ignore what governments took seriously? Second, and even more importantly, these discoveries were new. When Andalo di Negro invoked the shadow of the Earth as seen in eclipses of the moon, or Dante invoked the shape of dry land in the known world, they were appealing to information that had long been available. It was easy to assume that these arguments had already been taken into account, somehow, somewhere, by the advocates of the [Aristotelian] theory, for in a manuscript culture no one can hope to have every relevant text to hand. But it was evident that Vespucci’s information was quite simply unprecedented: it needed to be addressed here and now.9
The Portuguese had a Word for It
For those whose science did not “begin and end in the mind,” the discovery of the New World overturned the cyclical view of history. They knew that the Greeks and Romans and Arabs had been unaware of the New World’s existence, and that Europeans had learned of it through their own efforts. This discovery showed that it was possible to learn entirely new things, that it was possible to surpass the Greeks and Romans. The world could be a place of progress rather than mere repetition.
The discovery of the New World also upended the hierarchy of scholarship. The discovery belonged to soldiers and sailors, or to the cartographers who made sense of their observations, but not to the Aristotelian scholars in their lecture halls. Progress had been made by those who were willing to directly engage the world; and engagement with the world, through observation or experiment, would henceforth define the new science.
The concept of progress was so revolutionary that new words were needed to express it. “To discover” is to find or recognize for the first time something that substantively increases human knowledge. Wootton argues that the major European languages did not have words to express this concept before 1486. However, they did have words meaning “to uncover,” and in the years around 1500, these words were repurposed to mean “to discover”. The first word to change was the Portuguese word descobrir. In 1486 Fernão Dulmo used it in the new way in his proposal to sail westwards to find new lands. The Italian counterpart of descobrir was discoperio. In 1504 Amerigo Vespucci used it repeatedly (in its modern sense) in a published description of his New World voyages. A study of book titles shows that words meaning “to discover” appear in Dutch by 1524, French by 1553, Spanish by 1554, and English by 1563.10
It is not just the historian’s research that tells us that science radically changed at this time: the people who lived through the change were conscious of it. Here is Louis Le Roy, writing in 1575:
There remain more things to be sought out than are already invented and found. Let us not be so simple as to attribute so much to the Ancients that we believe that they have known all and said all, without leaving anything to be said by those who come after them…How many secrets of nature have been first known in this age? I say, new lands, new seas, new forms of men, manners, laws and customs, new diseases and new remedies, new ways of the heavens and of the oceans, never before found out, and new stars seen. And how many remain to be known by our posterity? That which is now hidden, with time will come to light, and our successors will wonder that we were ignorant of them.11
Discovery began, Wootton argues, with the Portuguese sailing toward Asia, and with the cartographers who placed their travels within a global context. It spread from there to the mathematicians, then to the anatomists, and then to the astronomers.12
Beyond the Moon
The astronomy of the Renaissance was Ptolemaic astronomy. It used a bag of tricks (such as equants and epicycles) to make the observed motion of the planets consistent with Aristotle’s supralunary cosmology, in which the stars and planets moved in perfect eternal circles. The exploding of Ptolemaic astronomy was an early achievement of the Scientific Revolution.
Copernicus’s book On the Revolutions of the Heavenly Spheres (1543), which laid out the first heliocentric model of the solar system, is often taken to be the spark that set off that explosion. Its impact was actually quite muted. An unauthorized preface to the book had invited the reader to view the heliocentric model as a simple method for calculating the orbits of the planets, rather than as a physical description of the orbits. Almost all the book’s readers did exactly that.13 Wootton is able to find only three competent astronomers who embraced the physical reality of the heliocentric system within forty years of its appearance in print — and one of them later changed his mind.14
Instead, it was observation of the skies that led to the rejection of Ptolemaic astronomy. The nova of 1572 exhibited no discernible diurnal parallax, indicating that it was far beyond the moon. Measurements of parallax likewise put the comet of 1577 beyond the moon. These findings contradicted Aristotle’s assertion that all transitory phenomena are sublunary. Unfortunately, disputes over measurements — not all astronomers were good astronomers — diluted the impact of these findings.
Tycho Brahe published his account of the comet in 1588. His calculations showed that the comet’s path cut through the crystalline spheres that supposedly held the planets in place, leading him to reject the whole idea of the spheres. Galileo’s telescopic observations — of the mountains of the moon in 1609, and of sunspots in 1612 — demonstrated that the supralunary realm was neither perfect nor unchanging. Now, two key elements of Aristotle’s cosmology had been disproved, and Ptolemaic astronomy was looking shaky.
Galileo’s observation of the moons of Jupiter in 1610 provided tacit support for the heliocentric system: if Jupiter can have moons and orbit the sun, so can Earth. Galileo observed the phases of Venus in the same year, and showed that the observed phases could only occur if Venus orbited the sun. This finding did not prove the Copernican system correct (it was also consistent with Tycho Brahe’s system), but it was fatal to Ptolemaic astronomy.
Wootton offers five reasons for the dearth of experimentation before the seventeenth century.15 One reason was simply that scholars did not work with their hands, but each of the remaining reasons relates to the authority that medieval scholars granted to Aristotle and other classical writers.
First, medieval scholars presumed that they had an adequate knowledge of anything that Aristotle discussed at length. They also accepted Aristotle’s belief that sound knowledge was based upon logical deduction; for instance, they knew that all heavenly movement was circular because “if the movement was not circular, empty space would be opened up between the heavenly orbs, and this is impossible, as a vacuum is impossible.”16 Experiments could be usefully employed only if Aristotle had not pronounced upon an issue, and if scholarly logic had failed to clarify it. Those prerequisites didn’t leave experimentalists much room to maneuver.
Second, medieval scholars were influenced by the Greek search for eternal truths that transcended the physical world. Euclid’s geometry was true knowledge, while cartography was merely a skill. This mindset made the scholars unsuited for experiments, which involve an interplay between the abstract and the concrete.
Third, Aristotle had argued that the rules governing the behaviour of natural objects differ from those governing the behaviour of constructed objects. The former are internally designed and the latter have their design imposed upon them by the builder, and in each case, the objects follow the rules imposed by their design. This claim clearly undercuts experimentation, which assumes that natural and constructed objects follow the same rules. Francis Bacon, who regarded Aristotle as an impediment to progress, rejected this belief in 1620: “Artificial things differ from natural things not in form or essence, but only in the efficient.”17
Fourth, as argued above, the concept of discovery did not arise until the sixteenth century. Experimentation before this time was largely a matter of tidying up loose ends, of which there were presumed to be few.
By the sixteenth century, overseas exploration and commerce were significant activities in Europe, and the source of its growing wealth. Navigation was an important matter, and the behaviour of the compass was among the more important unresolved issues. Happily for Western science, the Greeks had not known about the compass, so the behaviour of the compass was a field that was open to experimentalists. William Gilbert began to study the compass, publishing On the Magnet in 1600. The book was innovative in two ways that have become part of modern science. First, On the Magnet began with an extensive literature survey, something that was made possible by the shift to printed books from manuscripts, whose distribution had been limited and haphazard. Gilbert’s explicit objective was to extend human knowledge, so his first step was necessarily to determine the current state of knowledge. Second, Gilbert’s path to new knowledge was the experiment, and On the Magnet reports the experiments and their results in sufficient detail that they can be replicated by the reader. Gilbert wasn’t presenting himself as an authority on magnetism, but rather as a witness to carefully staged events. The reader could witness the same events himself by re-staging them. In fact re-staging the experiments with independent witnesses was positively desirable. It would create a community of experts with common knowledge, a common methodology, and a common research agenda.
Galileo read Gilbert’s book, was impressed by his methodology, and designed his own experiments. In 1612, for example, he used a series of experiments to extend Archimedes’ principle.
Galileo was also peripherally involved in experiments that would strongly influence both science and (a century later) technology. It had been found that a suction pump could lift water only about 10 meters. Galileo and Giovanni Baliani proposed competing explanations for this phenomenon. Both of their explanations were opposed by Aristotelian philosophers, as they implied that it was possible to create a vacuum at the top of a sealed water-filled tube. Nature abhors a vacuum, doesn’t it?
An experiment was needed to answer this question. Gaspero Berti constructed a long tube, filled it with water, and sealed it at both ends. The bottom of the tube was placed in a tub of water and then unsealed. The height of the water column settled at about 10 meters. An empty space was left at the top of the tube, but Berti’s attempt to determine whether it was a vacuum was inconclusive.
Baliani’s theory had been that the height of the water column settled at 10 meters because at this height, the weight of the water column exactly balanced the weight of the air pressing down on the tub of water. This explanation appealed to Evangelista Torricelli, a disciple of Galileo, and he recognized that Berti’s experiment could be adapted to test it. He performed the same experiment, but with mercury replacing the water. The mercury column settled at a much lower height. Torricelli was able to calculate that the shorter column of relatively heavy mercury weighed the same as the taller column of relatively light water, as Baliani’s theory would have predicted.
Torricelli’s experiment captured the attention of European scientists. More than a hundred people independently replicated the experiment between 1643 (when Torricelli performed it) and 1662 (when Boyle’s Law was put forward).18 The experiment was also extended in several ways. One extension compared the height of a mercury column at the top of a mountain (where the weight of the air was presumably less) to its height at the bottom. Another replaced the mercury with wine: as wine is heavier than water but lighter than mercury, this experiment added a third data point to Torricelli’s original two.19 Other variations tested whether the empty space at the top of the tube was really a vacuum. The results of these experiments were widely reported and discussed. A community of experts had been born.
A New Ethos
European scholars now clearly recognized the usefulness of experiments. They also recognized that faster progress was made when they collaborated on a research program and exchanged their results. This recognition led to the formation of learned societies in Florence (1657), France (1656 and 1666) and England (1660).20 The English society was, of course, the Royal Society, whose motto is an explicit rejection of the old way of doing science. Nullius in verba. Take no man’s word for it.
- David Wootton, The Invention of Science, p. 326. ↩
- David Wootton, The Invention of Science, p. 74. ↩
- David Wootton, The Invention of Science, p. 75. ↩
- Edward Grant, The Foundations of Modern Science in the Middle Ages (Cambridge, 1996), pp. 36-7. ↩
- David Wootton, The Invention of Science, p. 71. ↩
- David Wootton, The Invention of Science, pp. 71-2. ↩
- David Wootton, The Invention of Science, p. 24. ↩
- David Wootton, The Invention of Science, p. 136. ↩
- David Wootton, The Invention of Science, p. 136. ↩
- David Wootton, The Invention of Science, pp. 59-60. ↩
- This passage was originally written in French. Wootton (p.62) takes his quote from the English translation of 1594, and I have updated it to modern English. ↩
- David Wootton, The Invention of Science, p. 106. ↩
- David Wootton, The Invention of Science, p. 145-6. ↩
- There is an interesting link between the New World voyages and the heliocentric model. In Book 1 of On the Revolutions Copernicus reviews the evidence, including the discovery of the New World, that leads him to reject Aristotle’s nested spheres in favour of a single terraqueous sphere. The former is inherently stationarity — the anchor at the center of the cosmos — while the latter can spin through space. (Wootton, pp. 137-8) ↩
- David Wootton, The Invention of Science, pp. 319-24. ↩
- David Wootton, The Invention of Science, p. 320. ↩
- Francis Bacon, The Great Instauration, 1620, quoted by Wootton (p. 323). “Efficient” here means efficient cause, the manner in which something is brought about. ↩
- David Wootton, The Invention of Science, p. 340. ↩
- Wine is about 10% heavier than water, so the wine column would have been 9 meters tall. The après party must have been terrific! ↩
- David Wootton, The Invention of Science, p. 341. ↩