The Cave and the Light

by Arthur Herman

  Bacon’s curiosity makes him sound amazingly modern, and in many ways he was. But his writings look back as much as they look forward, and the figure to whom he owes his greatest debt is without doubt Aristotle, whom he discovered through his admiration for Grosseteste.5 Aristotle’s works unlocked for Bacon a world of scientific investigation, above all a method of exploring the wonders of nature and understanding its underlying principles that sustained him until his death.

  In some ways, Bacon also looked beyond Aristotle. First, he believed that no natural or physical science could get anywhere without a firm foundation in mathematics. He called it the “gate and key” to all science. He quoted Boethius in his support, thus anticipating Galileo three centuries later. Second, more than any previous medieval thinker, Bacon grasped the empirical aspect of Aristotle’s thought: that knowledge ultimately comes to the knower via the senses, which supply the raw data that reason sorts and disentangles in order to arrive at the truth. “There are two modes of acquiring knowledge,” he wrote, “namely by reasoning and experience. Reason draws a conclusion … but does not make it certain [but] the mind may rest on the intuition of truth when it discovers it by the path of experience.” It’s a sentence that might have been written by John Locke or even David Hume.6

  His belief in the experimental method led him, despite his Franciscan vow of poverty, to raise huge sums to buy scientific instruments, alchemical equipment, and to collect unusual natural specimens—creating in effect Europe’s first laboratory. Bacon could also be scathing about the complacent ignorance of his own day. He once declared that he wanted every Latin edition of Aristotle burned because the translations were so inadequate. Above all, he excoriated the failure of the Church and universities to embrace the wisdom of the past, including Greek science. “The whole clergy is given up to pride, luxury, and avarice,” he writes at one point. “Their quarrels, their contentions, their vices are a scandal to laymen.” In short, the English Franciscan managed to anticipate the spirit of the Reformation as well as the scientific revolution.7

  Living as he did in the 1200s, Roger Bacon sometimes seems almost too good to be true. Still, it is worth noting that his magnum opus on how to reconcile Aristotle’s observation of nature with traditional theology was written at the behest of a friend who also happened to be pope. Bacon never doubted that the greatest discoveries of the sciences and the arts would be impossible without the revelation of God. “All that which our intellect is able to understand and know is small,” he writes, “compared with those things which in the beginning in its weakness it is bound to believe, such as the divine verities.…”

  At its heart, Roger Bacon’s vision of science owes a great deal to the Neoplatonist inheritance or even Saint Augustine. For Bacon, it was the inner light of reason that stirs our desire to unlock the mysteries of nature and art, including the divine light around us: one reason Bacon was so fascinated with the science of optics.8

  Roger Bacon, then, was a powerful Janus figure. He looks forward to the age of Galileo and Descartes and empirical science but also back to the Pseudo-Dionysius with reason’s divine illumination drawing man closer to God through the wonders of His creation. He hoped to bring about a complete reform of Christian education based on mathematics and science, a project that earned him an impossibly grandiose condemnation and papal house arrest, in 1277—oddly, the same year as the condemnation of Aquinas. Yet Bacon was clearly too oddball a figure to concern church authorities that he might one day lead a movement or cause them serious anxiety.

  That cannot be said of William of Ockham. Born a few years before Bacon’s death in 1294, he carried the Aristotelian legacy of the Oxford Franciscans into direct conflict with the Church’s most powerful figure, the pope himself.

  In retrospect, it seems bizarre that Ockham did not get himself into more trouble than he did. But the truth is that Ockhamism took hold of many of Europe’s best universities in the later 1300s and 1400s. “Some would profess it,” writes historian Étienne Gilson, “others would refute it, but nobody was allowed to ignore it.”9 The impact of his thinking would stretch far beyond the Middle Ages. Far more than Thomas Aquinas or even Bacon, Ockham is the true forerunner of the modern era.

  He started his studies at Oxford around 1310. Ockham† quickly made a name for himself as a master of Aristotelian logic and for solving one of the most troubling problems the medieval philosopher faced, namely the question of universals.

  What’s in a name? Shakespeare asked later. What indeed, medieval scholars wanted to know. Is a name more meaningful, or is something more true, when we utter it about an entire class of objects and persons instead of a single individual in that class? “All men are mortal” and “Socrates is mortal” are both true; so are “All dogs have four feet” and “Rover has four feet.” But while I can see and point to Socrates and Rover, who am I talking about when I mention “men” and “dogs”?

  In other words, do universal terms like men and dogs and feet (or souls or saints) refer to something genuine and real? Or do they operate merely as terms of convenience when we want to talk about multiple dogs instead of just one?

  Those medieval scholars steeped in Neoplatonism answered that universal terms or concepts do indeed refer to something real: the ideal Forms of which the individual instance is a material copy. To say “All men are mortal” is saying something different from saying that some individual man is mortal. A universal statement reveals a higher level of truth and knowledge, the Platonist affirms, than what we can know about individuals.

  Others said no. Universals, they said, were merely collective names with no larger significance. Any name (nomen in Latin) is nothing more than an utterance of the voice; reality is confined to the realm of individual men and dogs about whom we speak and refer. Before he died, Peter Abelard had refined this so-called nominalist position slightly. He said universals did refer to something genuine, namely the shared resemblance between men and dogs that we see and name. “When we maintain that the likeness between things is not a thing,” he wrote in his Treatise on Logic in 1140, “we must avoid it seeming as if we were treating them as having nothing in common.” All men and all dogs do in fact have certain characteristics in common; it is that commonality, one could even say the Aristotelian essence of a thing, to which the universal name “man” and “dog” and “animal” referred.

  This was the position on universals that Thomas Aquinas accepted (more or less), along with John Duns Scotus, the reigning Aristotelian at the time William of Ockham began his academic career. And it was this moderate realist position that Ockham proceeded to overturn, thus opening a new chapter in medieval thought and pushing the reliance on Aristotle in a radical new direction.

  No, Ockham concluded, there is no common nature shared by individual dogs or men that we call by a common name. No universal exists outside the mind; everything that is real exists only as individuals. When I say, “All men are mortal,” this is shorthand for saying, “Socrates is mortal,” “Plato is mortal,” and so on.

  Universals are nothing more than signs to Ockham—useful shorthand. They mean nothing in themselves, but as signs they empower us to manipulate concepts and form general hypotheses in our mind, without bothering to refer to every individual who makes up the class, whether it’s men or dogs or meteors or souls. In an important sense, the world we understand through reason is a fiction (at one point in his early writings, Ockham even uses the word). It is a mental construct that we have built up from the raw data supplied by our perception of those individual men and dogs and meteors that form the stuff of reality.

  Ockham didn’t use the term fiction to suggest that what we say about the world isn’t true; just the opposite. Science deals with real life; and logic is the language of science. But we shouldn’t mistake the logical gymnastics going on inside our heads for the reality going on outside. Science is about real things; logic, surprisingly perhaps, is not.10 Ockham saw this discovery as a return to the genuine A
ristotle, shorn of the Neoplatonic excrescences of previous scholars like Aquinas and Duns Scotus. Getting rid of the notion that classes of objects and persons have some meaningful existence outside the individuals who make it up will be liberating, Ockham said. It makes life, and truth, simpler.11

  Ockham’s famous “razor” principle extended the same principle to every branch of knowledge. If any idea or proposition is not required either as a matter of observation and demonstration or as a matter of religious faith, then scratch it out. Don’t clutter our brains with unneeded baggage; and don’t clutter our discussion about the world with them, either.

  Ockham’s razor cut to shreds everything that was left of Plato’s Forms and Neoplatonism’s metaphysics. For example, why assume that God must have created a World Soul in order to carry out the rest of creation, as Plotinus and Christian Neoplatonists always did? Why assume two Gods when one will do? Why assume a Great Chain of Being or a Celestial Hierarchy of divine emanations, if there is no direct evidence for them around us and we can talk about and understand the world without reference to either one? The same reasoning went for Thomas Aquinas’s notion that everything has an essence, which the Summa says stands separate from existence and is nature’s way of revealing the thing’s divinely designed purpose. Cut out the essence talk, and suddenly we can discuss individuals as they appear before us, whole and complete.

  Once Ockham’s razor got started, in fact, not much was left standing. That included Averroës’s “double truth.”12 We need only one truth, Ockham affirms, the one reason derives from our senses. Religious faith, including faith in God, is an entirely separate matter. Religion is a matter of belief and will, not of reason or logical truth. Ockham took it for granted that absolutely nothing could be proved about God in the light of reason, not even His existence.13 At best, we get probable hints of His existence when we examine nature. Otherwise, nature is a closed book as far as theology and dogma are concerned.

  Those are best left to the Church and those who control its doctrines, Ockham affirmed. As for the rest of us, let’s get on with life: freed of the burden of trying to reconcile faith with reason, we can plunge into the world with a new optimism and gusto—but also with the sense that we have been left pretty much to ourselves.

  This was a radical new position for the mind of the Middle Ages. The intimate connection between God and nature, and God and reason, had finally, decisively been severed.14 The prospect seemed both exhilarating and nerve-racking. Ockham, however, was unworried. We’ll let the Church worry about matters above, he told his followers. Let’s concentrate on understanding the world down here. Accordingly, there was a sudden new burst of interest in natural philosophy and science in Europe’s universities in the 1300s.

  Then events forced Ockham to come out of his deliberate detachment into the open. He was forced to choose sides in the biggest battle to sweep through the Church until the Reformation—and in so doing opened a new chapter in Western political thinking.

  In 1305—the same year the English captured and executed the Scottish warrior William Wallace, and the same year the French king Philip IV arrested the Knights Templar on charges of heresy—a new pope was elected, a Frenchman as it turned out, who took the name Clement V. His most urgent task was to clean up the mess left by an ugly two-decade conflict between his predecessor and the king of France over taxation of church revenues, the same king who had overthrown the Templars. That battle had already left one pope dead and Philip IV and his chief minister excommunicated. The battle was not going to be as easy to resolve, however, as Clement and his advisers liked to pretend.

  “The Lord says in John that there is one sheepfold and one shepherd.… Therefore there is one body and one head of this one and only church, namely Christ and Christ’s vicar, Peter and Peter’s successor.” Pope Boniface VIII had written this three years earlier in 1302, and it was that claim of papal sovereignty over Christendom that was the source of all the trouble.

  Ever since the emperor Constantine had invested dominion over the Church in the bishop of Rome,‡ successive popes had borrowed his Neoplatonist vocabulary of imperial authority to describe their own. The Catholic Church saw itself as a Platonic copy of the true Universal Church, the Body of Christ. And just as the Body of Christ has only one head, went the argument, so also must Christian society. God had indeed conferred the image of His own fullness of power (plenitudo potestatis) on his deputy or “vicar,” just as Eusebius and his colleagues had proclaimed: except that in this case the true vicarius Christi was the pope.

  When the last emperor disappeared from the West in 476, the bishop of Rome’s claim to that fullness of power seemed even stronger.15 On a chilly Christmas morning in 800, he was able to crown Charlemagne Holy Roman Emperor as if the empire were his to give, and no one questioned it—least of all Charlemagne. Indeed, any emperor or king who dared to challenge that papal sovereignty ran the risk of excommunication or a papal interdict suspending the sacraments within his territories and subjects. As the emperor Henry IV of Germany discovered in the 1100s and King John of England in the 1200s, getting out from under the cloud of papal disapproval could be a costly business—not only in time and money but in civil war. Still, as time went on and Europe’s secular authorities became more powerful, the claim that all final authority in Christian society belonged to the successors of Saint Peter began to grate. So when King Philip IV of France and Pope Boniface locked crowns over the question of who controlled the revenues of France’s churches, the king or the pope, far more was at stake than just money. Philip considered Boniface’s assertion of his authority an unwarranted intrusion on his own as God-bestowed ruler of his kingdom, and he said so.

  Boniface struck back with the most far-reaching declaration of papal sovereignty that anyone, even the great popes of the Dark Ages, had ever conceived. It came in a papal bull entitled Unam Sanctam or One Holy Realm, which stated that God had decreed that the world be ruled by two swords, one of temporal power and the other of spiritual power. The first was relegated to kings and other temporal rulers; the other belonged to the supreme pontiff and his priests.

  Boniface had no doubt about which was more important. “One sword ought to be under the other,” he proclaimed, “and the temporal power under the spiritual power.” He even stated that as spiritual intermediary, the lowliest parish priest was a higher power than the greatest king or emperor, and he quoted the Pseudo-Dionysius to that effect.16

  King Philip IV did not appreciate being relegated to the lower rungs of a pope-dominated Great Chain of Being. He also had a weapon the pope did not: an army. And so in 1303 he sent troops to the papal retreat at Agnani to arrest Boniface and bring him back to France for trial. Outraged and mortified, the elderly pope died on the way. Philip ignored the ensuing uproar; in his mind he had won his fight, and now he intended to make sure something like it never happened again.

  Through a combination of arguments and threats, he persuaded Boniface’s successor, Clement V, to move the entire papal government to the town of Avignon in France—ostensibly for the pope’s protection but in reality so he could keep Christendom’s supreme pontiff under his thumb. Clement reluctantly agreed, and so began what Italians called (understandably) the Babylonian Captivity and historians the Avignon papacy. For sixty-nine years Avignon—a city of ancient walls and bridges—was home to the papal curia and Holy See, while the Vatican sat vacant. In 1324, Avignon also became William of Ockham’s home, when he was summoned to teach philosophy there at the local Franciscan school.

  Coronation of an emperor by a pope, from a fifteenth-century manuscript. This gesture of divine benediction turned out to be a two-edged sword.

  For four years Ockham dutifully conducted classes and worked on his logical studies within earshot of the papal court. Then one day, the head of the Franciscan order, Michael of Cesena, came to town with a problem. Pope John XXII (the elderly Clement had died in 1314) had ordered Cesena to Avignon to defend himself against charge
s of heresy, specifically the claim that the Franciscan friars’ vow of poverty had followed the example not only of Saint Francis himself, but of Jesus Christ and the apostles, including Saint Peter.

  Cesena asserted that it was perfectly orthodox to teach that Jesus and the apostles owned nothing as their own. So why should his successors not do the same? The pope, for reasons obvious to any visitor to Rome or the sumptuous papal palace at Avignon, thought this a dangerous heresy and innovation. Cesena wanted to know, what did Brother William think? Ockham promised to look into the matter and get back to him.

  When he returned with his answer, he stunned both the pope and Cesena. There was no doubt, Ockham concluded, that the doctrine of apostolic poverty was sound. To Ockham, this was not a matter just of theology and belief, that realm “up there” in which the man of science avoids involving himself. This was a matter of empirical fact, confirmed by Scripture and other church sources. Therefore, Ockham explained, by daring to impose papal authority over a matter outside his jurisdiction, namely a matter of provable fact, it was Pope John XXII who was the real heretic, not Michael of Cesena or his fellow Franciscans.

  Cesena was delighted. Then his smile vanished. It was all too easy to imagine the pope’s reaction when news of Ockham’s opinion leaked out—and it would leak out in a small, self-absorbed world like papal Avignon. Shakespeare’s phrase about discretion being the better part of valor hadn’t been invented yet, but Cesena managed to persuade Ockham of the importance of the concept. That night, on May 26, 1328, Ockham, Cesena, and another Franciscan companion slipped out of their rooms, mounted horses, and lit out of Avignon for the border.