The question of whether or not he influenced Columbus aside, Bacon's use of mathematics to overlay geography revolutionized the science. He observed that at some places along a line in Egypt, no shadow was cast, while to one side of that line, shadows were cast northward, to the other side, southward. He further noted that in some of these locations, no shadow was cast twice a year (Tropics of Cancer and Capricorn). In discussing that part of the earth that is habitable, Bacon broke from Ptolemy. “I therefore insist that, though the habitable world known to Ptolemy and his followers is squeezed into a quarter of the total, far more than a quarter is, in fact, fit for habitation.”
Map from Imago Mundi BEINECKE RARE BOOK AND MANUSCRIPT LIBRARY, YALE UNIVERSITY
Many of these regions, Bacon went on, were not only habitable but habitated. “There is a boundless advantage in a knowledge of the places in the world for philosophy, theology, and the Church of God,” he wrote.
THE FIFTH SECTION OF THE WORK, “Optical Science,” was Bacon's most detailed. Along with botany, optics was probably the most advanced science in the Middle Ages, and experiments with lenses was the prime field of application. Optics had been one of Grosseteste's specialties, and he had passed on his interest to Bacon. Once again, however, Grosseteste's work was largely theoretical, an extension of al-Hazen and al-Kindi. Bacon rigorously applied geometry to the study of reflection, refraction, vision, and what he called the “multiplication of forces,” which was largely a theory of how sensory information was transmitted to and from humans. “Force” was used in a much broader sense than in contemporary science. It was essentially any emanation, and included such things as the refraction of light through a convex lens and the consequent creation of heat at the focal point.
In his discussion of light, Bacon made a leap, the significance of which he may well have been unaware. Departing from Grosseteste, who believed that light traveled instantaneously, Bacon asserted that light moved at a speed, but one so swift that it was imperceptible to humans. He didn't apply this to astronomical bodies—stars, for example—apparently believing that even at great distance light's progress would be too fast to measure.
As revolutionary as the first five sections of the Opus Majus were, it was in the last two that Bacon's greatest contribution to scientific history appeared.
CHAPTER TWELVE
Seeing the Future:
The Scientia Experimentalis of
Roger Bacon
• • •
THE HEART OF THE OPUS MAJUS, the section of the work that most lifted it above that of Bacon's contemporaries, was Part Six, “Experimental Science.” To Bacon, experimentation was a distinct discipline, separate from but vital to all others, because without experiment one could never be sure of the truth. “Without experience, it is impossible to know anything completely,” he wrote. For perhaps his greatest leap of insight, Bacon employed this analogy:
For there are two modes of acquiring knowledge, namely, by reasoning and experience. Reasoning draws a conclusion, but does not make the conclusion certain, nor does it remove doubt so that the mind may rest on the intuition of truth, unless the mind discovers it by the path of experience . . . For if a man who has never seen fire should prove by adequate reasoning that fire burns and injures things and destroys them, his mind would not be satisfied thereby, nor would he avoid fire, until he placed his hand or some combustible substance in the fire, so that he might prove by experience that which reasoning taught. But when he has had actual experience of combustion his mind is made certain and rests in the full light of truth. Therefore reasoning does not suffice, but experience does. (Emphasis added.)
This was the final break from classical scholasticism, and particularly the brand of pseudoscience that Bacon considered to have been so recently perpetrated by Aquinas. It was not enough to reason one's way to truth, no matter how sophisticated the argument. Reason followed experiment, not the other way around. “Hence in the first place there should be readiness to believe, until in the second place experiment follows, so that in the third reasoning may function,” he wrote. This is the first clear statement in Christian Europe of what the modern world recognizes as hypothesis-experiment-conclusion.
To demonstrate how experimental science worked, Bacon enunciated what was probably the first rigorous, step-by-step description of scientific method ever put on paper. He did this by use of an example, laying out a series of experiments to discover the exact nature of a rainbow.
The rainbow had enormous significance in the Middle Ages. Rainbows, like thunder, lightning, and other natural phenomena, had been objects of fascination since Neolithic times. They were mentioned specifically in scripture as the reminder of a promise that God made to Noah after the flood never to repeat such a cataclysm. Genesis 9:8–16 reads:
And God said, “This is the sign of the covenant I am making between me and you and every living creature with you, a covenant for all generations to come: I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth. Whenever I bring clouds over the earth and the rainbow appears in the clouds, I will remember my covenant between me and you and all living creatures of every kind. Never again will the waters become a flood to destroy all life. Whenever the rainbow appears in the clouds, I will see it and remember the everlasting covenant between God and all living creatures of every kind on the earth.”
It was thus generally believed that only God could make a rainbow. It was permissible to try to deduce the nature of the phenomenon, but only with the proviso that it was divinely created. That the rainbow effect manifested itself in a variety of different circumstances—water dripping off a raised oar, light passing through a hexagonal crystal, or drops of dew on grass in the morning—only served to increase the wonder of God's presence. As a result, uncovering the nature and causes of the rainbow had become one of the preeminent scientific problems of the day, akin to modern astrophysicists trying to understand the makeup of black holes.
Bacon began with a history of rainbow theory. Aristotle, who had not been limited by the assumption of divine cause, had described a rainbow as the base of a cone in which the sun was the apex and the axis (center line) passed through the eye of the beholder to the center of the base. He believed that light reflected off individual raindrops, with colors created by different combinations of bright and dark. Both Avicenna and Averroës had discussed rainbows as well, and by the thirteenth century there was general agreement that two substances of different densities (air and water, for example) must be involved in order to create the combinations necessary to produce a spectrum.
Grosseteste had accepted the Aristotelian conical construct but claimed that rainbows were caused by refraction, with reds appearing in places where the rays were most concentrated and blues where the concentration was less, the differences being caused mostly by cloud density. Albertus Magnus had agreed that refraction was the cause but believed that light was refracted in individual raindrops, then projected onto solid material in clouds. The variety of colors, Albert asserted, was due to the difference in the density of the cloud.
From this base, Bacon then used the method he had just laid out to produce a huge advancement on anything that had come before. He returned to Aristotle's notion of reflection, theorizing that refraction was impossible since an axis always existed between the center of the rainbow, the observer's eye, and the sun, regardless of any movement by the observer. Then he measured the height of a rainbow when the sun was at the horizon at 42 degrees, noted that as the sun rose in the sky, the rainbow receded, and concluded that when the sun is higher than 42 degrees, it was impossible for a rainbow to appear. Then, based on the observation that people in different locations all see a rainbow if conditions were favorable, he deduced that it was reflection off a myriad of raindrops that produced the effect, not off any individual one.
Bacon used only the most primitive instruments for his experiments, and some of his deductions were incorrect. For one thing,
a rainbow is formed by a combination of reflection and refraction (two refractions, actually). His own contributions, the maximum angle of the sun to the horizon and the role of a myriad of raindrops, were advances in the theory but not, obviously, the final word.*4 But Bacon never pretended to have the complete and accurate explanation.
Unlike his predecessors, particularly the Dominicans against whom he was struggling, his paramount assertion was that experimentation should be an ongoing process, that the search for truth does not end when one finds a convenient explanation that fits a predetermined conclusion. His aim, as he told the pope, was not to set forth the final truth of the matter—to achieve that, he insisted, further experimentation was needed—but rather to demonstrate method and plead for its inclusion in the curriculum.
He wrote to Clement:
Reasoning does not attest these matters, but experiments on a large scale made with instruments and by various necessary means are required. Therefore no discussion can give an adequate explanation in these matters, for the whole subject is dependent on experiment. For this reason I do not think that in this matter I have grasped the whole truth, because I have not yet made all the experiments that are necessary, and because in this work I am proceeding by the method of persuasion and of demonstration of what is required in the study of science, and not by the method of compiling what has been written on the subject. Therefore it does not devolve on me to give at this time an attestation possible for me, but to treat the subject in the form of a plea for the study of science.
Use of this method would open up vast new areas of knowledge. Bacon outlined this process in the “three prerogatives of experimental science.” They were 1) experimental science confirms conclusions to which other scientific methods already point; 2) it reaches results that take their place in existing sciences but are entirely new; and 3) it creates new departments of science.
Here is the starkest contrast between Thomas Aquinas and Roger Bacon. Once all the questions of the extent of Bacon's actual knowledge or contribution to science and Aquinas's fundamental motivation or the soundness of his logic are cut away, this simple difference is left: Roger Bacon wanted working hypotheses to be subjected to experiment, experience, and revision, and Thomas Aquinas insisted that arguments be accepted in the abstract and on faith—in every sense of the word.
Bacon entreated Clement to apply scientific method to the production of better instruments so that observation and experimentation might proceed at a faster pace. There were immediate practical benefits to this plan. Experiments with plants, herbs, and natural substances would yield remedies that could ward off disease and extend life, and would also yield better tools and weapons. If the forces antagonistic to Christ employed experimentation first and thus created better weapons sooner, it could spell disaster for the Church.
BACON REAFFIRMED HIS COMMITMENT TO REVELATION and faith in the final section of the Opus Majus, “Moral Philosophy.” He saw the quest for truth in science as a deeply religious act, without which there could be no genuine triumph of God. The increased knowledge gained by experiment would only serve to prove the primacy of the scriptures and discredit those who would question God's word as revealed in the Bible. It was the legalistic approach of Aquinas, denying the truth of experiment, that was a threat to God and the Church.
Moral philosophy was therefore the highest of the sciences, that to which the proper exercise of the other sciences led. Experiment, as a prerequisite to moral philosophy, would not cause man to turn away from God and faith but rather to embrace them more fully. “[Moral philosophy] in the first place teaches us to lay down the laws of and obligations of life; in the second place it teaches that these are to be believed and approved, and that men are urged to act and live according to those laws.”
If the Church had adopted this view, it would have freed Christianity to be the leader in scientific inquiry without sacrificing the faith of revelation. It would have allowed the Church to promote the search for empirical knowledge within a code of scientific ethics that would have preserved the fundamental beliefs in Christ and scripture that it held dear. While certainly, as knowledge advanced, some of the literal interpretations of scripture-as-science would have come into question (as indeed they have today), the issues could have been resolved under ecclesiastic mandate. The Church, in refusing to accept this position, did not prevent scientific advancement—although it was postponed for three centuries—it merely assured that when science did regain its momentum it would be as adversary to Christianity, not partner.
THE MANUSCRIPT BROKE OFF ABRUPTLY in Part Seven. Bacon had mentioned that he intended to include a section on civil law at the end, which would have made perfect sense as a closing argument. Perhaps he ran out of time and felt the need to dispatch the manuscript to Viterbo. Perhaps he completed the section but could not have it transcribed. What is known is that even before he dispatched the Opus Majus to the pope he decided that perhaps it was too long or too complex and began work on a shorter version, which he called the Opus Minus. Later he completed yet a third version, the Opus Tertium, which was probably intended as a supplement. In the Opus Tertium, in addition to an overview of his scientific arguments, Bacon included a good bit of biographical information and social commentary. It is from this document, which was never sent to Clement, that we get much of what we know of Bacon's life and circumstances.
What Bacon did send to the pope was not simply the Opus Majus and the Opus Minus, but also an additional work, De Multiplicatione Specierum (On the Multiplication of Species). Although Bacon used species largely synonymously with forces, this was a far more technical treatment of multiplication of forces than that in the Opus Majus and was evidently included to give Clement an example of what might actually be taught in the universities. Bacon here provided more detail on his theory of perception, awareness, and how images were transmitted not only to the eye but to the brain—or the soul—as well.
To complete the package, Bacon bundled everything into the arms of his prize student, a boy known only as John, a living example of his methods:
The boy present, who in the midst of great poverty and with little instruction by devoting scarcely a year to increasing his knowledge has so widened his field that all are surprised who know him. For I say fearlessly that although some may know more about philosophy and languages, and many may excel him in various ways, yet there are none among the Latins who surpass him in every respect, and he is a match for all of them in some things; in some points he excels them. There is no one among the Latins but may listen with profit to this boy. No one so learned, that this boy may not be indispensable in many ways. For although he has learned all that he knows by my counsel, direction, and help, and I have taught him much by written and spoken word, nevertheless he surpasses me, old man though I am, in many ways, because he has been given better roots than I, from which he may expect flowers and wholesome fruits which I shall never attain.
And so, in mid-1268, John set off for Viterbo.
Centuries later, in a backlash precipitated by the cult of personality that grew up steadily around Bacon's memory, and particularly by the assertion that he was a man ahead of his time, some scholars chose to deprecate the magnitude of Bacon's achievement with the Opus Majus. They pointed out that the manuscript was riddled with factual errors and inaccuracies and that Bacon subscribed to superstition, attributing magical powers to astrological bodies, for example. They observed that there was a paucity of original research and that much of his work was derivative, merely an extrapolation of the thinking of men like Robert Grosseteste and Peter Peregrinus. They argued that when Bacon used the terms “experiment,” “experience,” and “mathematics,” he did not do so in the modern sense but in a narrowly medieval context. They said, moreover, that he was unduly critical of his contemporaries, particularly Albertus Magnus, who was, after all, as interested in the natural sciences as was Bacon himself. They claimed he was jealous and bitter, particularly of those scholars with a
dvanced theological degrees from Paris, who had justifiably gained the worldwide respect and repute that Bacon himself craved, and that this colored his judgment and biased his conclusions.
The wonder of the Opus Majus is that it is possible to grant each of these denunciations and still be awed by the depth of Bacon's achievement. For though it is true that he built on the work of others—which he never denied and indeed went to great pains to point out—no one else drew knowledge together into as coherent and persuasive a whole. The Arabs hadn't done it, Grosseteste hadn't done it, Albert hadn't done it, and Aquinas certainly hadn't done it. What is so crucial about Bacon's work is that it created a clear signpost to the future, a method by which to gain a deeper, more significant, more profound knowledge of both the world in which we live and the nature of the eternal. When Stephen Hawking concluded A Brief History of Time with the words “If we find the answer to [why it is that we and the universe exist] it would be the ultimate triumph of human reason—for then we would know the mind of God,” he was following the trail blazed by Roger Bacon.
BY THE FALL OF 1268, Bacon's prospects for precipitating reform in the Church never seemed better. In the spring of that year, Frederick's grandson Conradin, “the last of the Hohenstaufens,” then fifteen, had come to Italy to raise an army to retake Sicily from Charles d'Anjou. In August he was defeated at the Battle of Tagliacozzo. Conradin escaped after the battle but was soon captured, and two months later, despite Clement's personal abhorrence, Charles had him publicly beheaded. Still, the papacy was secured against the invader, and Clement could finally turn his attention to internal reform.
Clement, with his keen mind, determination, and deft political skills, might have been one of the great popes, perhaps even rivaling Innocent III himself. But in November 1268, after less than four years in office, his ambitions unfulfilled, Clement died, and with him Roger Bacon's opportunity to blend scientific curiosity into theology died as well.
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