By Boethius’s time, Greek was already a dead language in western Europe. During the barbarian invasions and the Dark Ages that followed, the power to read and write Latin became the privileged property of a tiny few. It was only the relentless reproduction of Boethius’s works, by generations of forgotten monks and scribes from Subiaco and Monte Cassino in Italy to Lindisfarne in Ireland, that allowed some fragments of that Greek legacy to enter the Western consciousness. When writers talk about the monks of Ireland “saving civilization,” this is what they mean: how from the age of Charlemagne to the Crusades, they copied and recopied the manuscripts of Boethius, alongside Saint Augustine, Cicero and Virgil, and Saint Jerome’s Latin Bible.11
Because in the end, it was Boethius who counted most for the future of Europe and its reeducation, once the worst of the barbarian disruptions were over. His translations of Aristotle’s logic were crucial.‖ Boethius revealed that logic is not some remote ivory tower discipline. Instead, it thrusts us into the real world, by focusing on what we can say with certainty about the world around us and the necessary relationship between language and truth.
Aristotle’s logic grew out of Plato’s dialectic, that relentless process of “asking questions and giving answers, affirming and denying” that Socrates had said was necessary to arrive at truth.12 But how does the process really work?
Plato and his Neoplatonist followers tended to treat dialectic as a rather mysterious discipline, an inward turning of the soul that allowed it to join up with a transcendent and abstract reality. Aristotle, by contrast, set out to dispel the mystery by bringing logic down to earth. Finding out how one true assertion (all human beings die) leads to another (someday I will die) turned out to be a straightforward process based on a set of rules: the rules of inference.
Those rules, Aristotle pointed out, rest on certain self-evident laws, such as the law of identity (whatever else it is, A is always A), the law of contradiction (A cannot be both B and not B), and the law of “excluded middle.”a But in the end, all inferences that are true have to come in two forms.
They are either deductive, meaning that given one or more true premises, the conclusion we draw is necessary; or they are inductive, meaning that given one or more facts—such as the things we know through observation—the conclusion we draw is reasonable. The classic deductive inference (actually taken from Aristotle’s Categories) is “All men are mortal; Socrates is a man; therefore Socrates is mortal.” Usually a good deductive inference goes from greater generalities to lesser ones: “All dogs are mammals; all Lab retrievers are dogs; therefore all Lab retrievers are mammals.” By contrast, inductive logic usually (though not always) goes from the lesser to the greater. “I have five friends who have white beards; all five are over fifty years of age; therefore all men with white beards are over fifty years of age.”
Inductive logic offers a source of new knowledge, based on empirical observation. Atristotle recognized the value of induction; his own sciences were founded on it.13 Still, his real focus was always the logic of deduction. How can we be sure that what we say about the world and the things and people in it is necessarily, and without fear of contradiction, true? After all, there might be men under fifty with prematurely gray hair who end up with white beards.
On the other hand, Socrates’s mortality, like the dog’s status as a mammal and the frog’s nature as an amphibian, becomes part of the definition of who they are (what Aristotle called their essence). Aristotle called these true deductive inferences syllogisms. All syllogisms follow the same basic structure as the “Socrates is mortal” example. Each contains two premises or assumptions (called major and minor) and the inescapable conclusion we have to draw from them.
All human beings are rational.
Some human beings are Americans.
Therefore, some Americans are rational.
Or:
No horses have claws.
All Appaloosas are horses.
Therefore, no Appaloosas have claws.
Aristotle showed that every valid syllogism fit one of four basic patterns, although his followers in the Middle Ages claimed to discover more than four. Far more important, Aristotle showed (or seemed to show) that by linking one valid syllogism to another regarding a single subject, such as biology or ethics or even the nature of God, one could build a conceptual chain of reasoning that would inevitably lead, link by link, from one set of necessary truths to another, all the way to the highest truths of all.
In effect, Aristotle’s logic offered the possibility of creating a universally true science out of anything—or of deconstructing claims of being a science. Aristotle had used his logical arguments to challenge Plato’s theory of Forms or Pythagoras’s assertion that all things were made from number, on the grounds (as the third man argument showed, for example) that they made no logical sense. Not everything that makes deductive sense may be true.b But if it doesn’t fit into a syllogism, Aristotle concluded, then don’t bother asking if it’s true or not.
Thanks to Boethius, Aristotle’s logic was now available to apply the same test to Christianity’s weightiest assertions about God, heaven and hell, and the Church’s most cherished views about human beings and nature.
At first, this seemed a positive development. Indeed, the first man to use Boethius and Aristotle to open the mind of the Dark Ages would become pope in 999 as Silvester II. Before assuming the papacy, Gerbert of Aurillac embodied the new spirit spreading across Europe as it approached the landmark date of 1000 CE, thanks in large part to Boethius. Men like Gerbert had realized that they were witnessing not the end of the world, as some had feared, but a new beginning.14
The last wave of barbarian attacks on Europe, including the Vikings, had finally receded. Charlemagne’s Holy Roman Empire, which came apart with his death in 814, had been successfully restored, with the imperial title in the hands of strong Saxon kings (one of them made Gerbert pope). Life was returning to a settled pattern for the first time in centuries. Europeans were finally free to wake up, look around, and sift through the rubble to find what was valuable and useful for building the new future.
Gerbert was the greatest teacher and scholar of his generation. He was an avid collector of ancient manuscripts (he traveled to the rough borderlands of Muslim Spain to find texts he wanted), and endlessly and confidently curious. He was also the first man in western Europe to lecture on Boethius’s logical treatises. As the scholar R. W. Southern has put it, it was Gerbert who made Boethius “the schoolmaster of medieval Europe” and made Aristotle’s logic the centerpiece of an education based on the seven liberal arts.15
The idea of the “liberal arts” (so called because it was the education fit for liberi, or free men, as opposed to slaves) was a late Roman invention.c16 Gerbert had a deep interest in its more advanced elements, the so-called quadrivium. For arithmetic, he revived that lost ancient calculator the abacus. For the study of music, he invented a stringed instrument, the monochord, for demonstrating to students the Pythagorean precision of musical intervals. For geometry, Gerbert wrote a commentary on Euclid and helped to revive an interest in astronomy in the West by telling friends about a marvelous Arab device he had discovered on his travels to Spain, the astrolabe.17
However, Gerbert’s first loves were the subjects of the trivium, especially rhetoric and logic. His insistence that students learn the rules of logic before embarking on anything else made Aristotle the founder of the medieval university curriculum.18
Aristotle turned out to be particularly valuable to teachers. His logic gave them a clear and orderly way to present unfamiliar material to students, by boiling everything down to a series of easy-to-learn syllogisms: If A is true, then B must also be true; if B is true, then C must be true; and so on. It also left plenty of room for what every teacher loves or should love, namely tests of memorization and brainteaser-style exercises—and all with the confidence that everything that was being presented was deductively, and therefore necessarily and indis
putably, true.
So why not theology and Christian dogma? Christianity, after all, offered a feast of rational truths of the highest order: Every important thinker since Augustine had said so. So it is hardly surprising that by 1050, Aristotle’s logic had found a home not only in the liberal arts curriculum, but at the desks of Europe’s most influential theologians.
Berengar of Tours was the student of Gerbert’s most distinguished pupil, a priest named Fulbert. Fulbert had founded one of the first and most influential medieval schools in the cathedral town of Chartres. Many called him the Socrates of France—a sign of how an interest in things classical and Greek was already reviving. For his part, Berengar proclaimed logic to be “the art of arts” and asserted that it was the true sign of a great mind to turn everything into syllogisms. Reason could decide any and every issue, he said, including matters of Christian doctrine. Anyone who failed to apply the test of reasoned logic to the assertions of religious dogma was denying his own nature, Berengar said, “for it is by his reason that man resembles God.”19
Few were willing to be as bold as Berengar. The most famous Christian thinker to apply the techniques of logical demonstration directly to his understanding of God was the bishop of Canterbury named Anselm. Anselm was always careful to present his work as harmonizing, not testing or challenging, the teachings of Scripture and the Church Fathers. Still, he loved the thrill of the intellectual chase as much as any scientist. When he was working out his groundbreaking logical proof for the existence of God, his medieval biographer tells us, he lost all taste for food or drink or even attending Mass—until the truth broke through “and filled his whole being with the greatest joy and exaltation.”20
Anselm’s famous “ontological” proof is a model of clarity and simplicity (I was able to memorize it as a child of four).21d But like Anselm’s other syllogisms, it is also a model of religious orthodoxy, blending cold logic with heartfelt piety. Taken together, they extend the Church’s assumptions about the Trinity and the Incarnation of Christ. They never challenge them. It was Anselm who coined the most famous phrase of the Middle Ages: “I believe [in God] in order to understand.” He was not devaluing reason or logic: just the opposite. He was simply reminding readers of where his, and their, priorities needed to be.
Berengar died in 1088 and never earned a sainthood. Anselm, who died at Canterbury in 1109, did. Yet the truth was, he and everyone else were playing with fire. The problem with Aristotle’s logic is that once it gets started, it is very hard to stop. It can become a kind of compulsion as it moves from examining one set of conventional beliefs and assumptions after another, overturning everything in sight. Logic is, to borrow William Blake’s phrase, self-delighting. The experience can be so exhilarating that we fail to notice where we are headed.
In Peter Abelard’s case, it led him right to the brink of disaster and cost him a more terrible price than even his many enemies would have wished.
If Aristotle had had a younger son, he might have wanted him to be like Peter Abelard. Abelard was born in Brittany in 1079, the home of quick-tempered, quarrelsome Celts and a land not so different from Aristotle’s Macedonia. His father was a feudal lord, a chain-mail-clad warrior like the ones we see in the Bayeux Tapestry.
Well built and fit, Peter would almost certainly have become the same except that Abelard père had a strong respect for book learning. In an age and a region where nearly every layperson was illiterate, Lord Abelard of Le Pallet was an exception. So in between practice sessions with sword and buckler, he sent seven-year-old Peter for lessons with a local grammaticus, a cleric who taught Latin.22
What had been interesting to the father became a passion for the son. By the time he was a teen, Peter Abelard imbibed enough Cicero, Seneca, Virgil, and Ovid to decide to exchange “Mars for Minerva,” as he later put it, and begin serious study for a career in the Church. Like the other boys, Peter would have squatted on the stone floor in a large unheated room day after day, shivering in the cold while their teacher unveiled for them the mysteries of the trivium: first Latin grammar, then Latin rhetoric, and finally Aristotle’s logic, or dialectic, as contemporaries called it.
It fascinated the quick-witted teenager. In a school like his, books (like chairs) were scarce. Memorization was the rule of the day, and before long Peter had stocked his brain with a lifetime’s arsenal of quotations and rules from the major texts of early medieval logic, above all Aristotle’s Categories in Boethius’s translation.23
“I preferred the art of dialectical exercise,” he later wrote, “among all the teachings of philosophy, [so] I exchanged literal arms for these, and sought instead of the trophies of war those of disputation.” His role model was Aristotle himself, and his classmates nicknamed him the Peripatetic of Pallet.24 In fact, Peter Abelard became a kind of intellectual knight-errant, wandering the countryside wielding his syllogisms like a razor-sharp sword in order to slice and dice his opponents one after another, starting with his own teachers.
His instructor at Loches was a distinguished scholar named Roscelin. After a few months, Roscelin became so frustrated with his insolent, arrogant pupil that he sent Abelard along to Paris to irritate another famous master, William of Champeaux. William also got fed up with being beaten in every argument—“by logic I compelled him to change his opinion,” Abelard wrote proudly, “indeed to abandon it”—and finally expelled Abelard from his school at the Notre Dame Cathedral. Peter Abelard found himself on the street, armed only with his mind and his Aristotle, wondering what to do next.
With entrepreneurial bravado, Abelard decided to open his own school. He was confident that the very qualities that infuriated his superiors—his insolence, his precocious abilities, his flashing charisma—would attract him to students. He was right. Within a couple of years, Abelard had drawn enough pupils eager to learn the rules of logic that by 1108, at age twenty-nine, he became the dominant intellectual figure in the city.
Young men from across France came to Abelard’s classes. These were held outside the city limits on the Left Bank of the Seine near the Abbey of Ste. Genevieve so that his rival William of Champeaux, now archdeacon, could not invoke the bishop of Paris’s authority to shut him down. However, it was still close enough to Notre Dame “that I could lay siege, as it were,” Abelard later explained, “to him who occupied my [rightful] place,” namely William of Champeaux.25 Students abandoned his rival’s school to flock to the Left Bank (the home of French students ever since), listening and arguing, disputing and quoting favorite one-liners as they wandered the narrow streets, their minds filled with Aristotle, Boethius, Porphyry—and Abelard.
He was without doubt a superstar. No one was quicker on his feet in handling a difficult logical problem, no one was more devastating in his critique of a rival (Abelard at one point sat in on William of Champeaux’s classes just to heckle and torment him). And no one was more eloquent in his praise of the value of Aristotle’s logic for arriving at truth.
Abelard told his students that the word logic came from Logos, the divine Word in St. John’s Gospel. “In the beginning was the Logos”; but logic obviously came a close second.26 By using logic and dialectic, he told them, they could open new vistas in the study of theology. In fact, he seems to have been the first to coin the term theologia (logic plus theos, or God) in the modern sense. He was also the first to create the techniques by which theology could become as rational and logically disciplined a subject as philosophy—the techniques later called scholasticism.27
Abelard encouraged students to collate the Church Fathers’ different opinions, or glosses, on specific passages from the Bible. Then they compared those with the original passages to arrive at a definite conclusion as to who had been right and who had been wrong. Nothing is infallible outside Scripture, he told them; even the apostles and Church Fathers sometimes err.28 It was up to his students to decide, based on the evidence and their own reason. After all, Abelard proclaimed with echoes from Berengar of Tours, man’
s reason was what made him the image of God. “In fact,” Abelard once told his class, “you are gods!” The students yelled and cheered. Then they hoisted Abelard on their shoulders and carried him through the streets.
Some worried about where all this was heading, but not Abelard. “My students clamored for human and philosophical reasons,” he wrote later in his defense. “They did not need affirmation but rather intelligible explanations.” In the end, Abelard concluded, “no one can believe something which he has not first understood.”29 As for whether all this cold-eyed logical examination might lead minds astray into skepticism and doubt, Abelard replied: Never fear. “Careful and frequent questioning is the basic key to wisdom.” He added what is probably his most famous maxim: “By doubting we come to question, and by questioning we perceive the truth.”30
Anselm said I must believe so that I can understand. Abelard now reversed the formula: I must understand so that I can believe. Faith without reason was merely supposition, an opinion or guesstimate (aestimatio). Abelard’s most famous work, Sic et Non, compared 150 passages from Scripture and the Church Fathers that contradicted one another. The only way to sort out the mess, Abelard was saying, was through reason and logic. The only way Christianity could make itself a believable faith was by responding to our natural inclination to question its foundations.31
Given all this, what is amazing is not that Abelard got into trouble with the authorities, but that he didn’t get into more trouble sooner. In fact, he might have been left alone altogether if, in the spring of 1119, he hadn’t made a fatal mistake. A canon of Notre Dame named Fulbert (no relation to Gerbert’s famous pupil) needed a private tutor for his niece Héloïse. He asked Peter Abelard. Abelard agreed.
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