In page after page of the Summa, Aquinas will calmly and tentatively assert a position. Then he looks around at all the counterpositions and objections. He examines whether they hold up under scrutiny; if not, he quietly refutes them and moves on to the next question. At one stroke, a Christian dialectic was born, more sophisticated than Abelard’s and more all-embracing than Anselm’s, because it stands on a reading of Aristotle’s entire corpus.
The overriding issue for Aquinas is, “Is it true?” His Averroist colleague Siger of Brabant had asserted that if it was in Aristotle, then it must be true. Not necessarily, Aquinas says. He cites the Philosopher (as he calls Aristotle in both Summas) more often than any other non-Christian thinker. But he also finds powerful insights in Plato, in Saint Augustine, and in Dionysius the Areopagite.‖ Citations from the Bible always clinch the argument.
Aquinas’s point is always that we humans are down here, while the ideas and celestial beings and the supreme eternal truths are all up there. Everything that Plato and Neoplatonists and Saint Augustine said were the most intelligible and true are also the most removed from our experience. Why? Maybe because the human mind tends to be dazzled and confused by too much divine wisdom.23 Maybe that’s why God decided to put us in the cave in the first place, Aquinas is hinting. He didn’t want us overwhelmed by too much light at once.
Since we are human beings, then, we have to start with what we know in order to get our bearings. That means the Bible and divine revelation, of course. But it also means the realm of the senses, and here Aristotle points the way. “As Aristotle himself shows,” Aquinas writes in the Summa Contra Gentiles, “man’s ultimate happiness consists of seeking the knowledge of truth” through reason.24 Then as we move forward, we discover that truths human and divine, the objects of reason and those of faith, actually reinforce each other. They don’t form parallel tracks, as Averroës claimed. They ultimately converge: not just in God their Supreme Creator, but in ourselves as human beings.
Aquinas’s God is not Aristotle’s Prime Mover. He is a beneficent Creator and creative Architect, a composite figure from Scripture and Plato’s Timaeus. However, Aquinas’s God shares one important characteristic with Aristotle’s Unmoved Mover: He is the ultimate source of all movement and change. “Whatever is done by nature must be traced back to God as its first cause.”25 In fact, we live in a world blessed by the very act of creation. Quoting Aristotle again, “Nature creates nothing in vain”—and neither does God.26
God’s supreme reason dictates the structure of both the supernatural and the natural order, since both reflect His eternal purpose. Truths about the first are revealed to us in the form of divine law, which means Scripture. Truths about the second are revealed to us through our senses, by means of the laws of nature.
Lex naturalis, natural law, is a cornerstone of Aquinas’s system and his most consequential contribution to Western thought. Natural law, he says, is apparent in the regular workings of nature, including the movements of the planets and in the growth and formation of living things; in the self-evident truths of mathematics and geometry; and in the logical workings of the human mind.
However, it takes reason to see them and recognize them as laws. Dogs and cows live their lives in accordance with the laws of nature, from birth to death. But they lack the power to wonder why or how. Human beings, on the other hand, do. “The natural law is nothing else than the rational creature’s participation in the eternal law.… Human reason cannot have a full participation of the dictate of the divine reason,” Aquinas writes, “but [only] according to its own mode, and imperfectly.” That imperfect way of seeing, however, supplies us with enough common principles so that we can understand the phenomena around us and see how God’s creatures divide into separate species and genus; notice how the planets are different from the stars; understand why murder is wrong and why justice is necessary in every human community; and recognize the place of each within the whole. In short, the laws of nature are the foundation of all our knowledge and conduct in the world.
Take natural law away, and we are helpless to do anything or find happiness, even with divine revelation at our elbow (just as some people never bother to open the Gideon Bibles in their hotel rooms). Take up the laws of nature and study them, and suddenly every aspect of existence is bathed with a new significance that eventually our reason traces back to God.
Aquinas fully endorsed Aristotle as our guide for grasping and analyzing those laws. Like Aristotle, Aquinas believed that to fully know something means understanding its essence; that in turn depends on discovering its purpose by observing its interactions with everything else. This applies to objects both man-made and made by nature. We learn that God has designed a horse for riding, for example, and a bird’s wing for flying, and man’s sexual organs for reproduction, just as the carpenter makes a chair for sitting.
This is a long way from our idea of science today. But for Aquinas, who was a theologian and not a scientist, the crucial point was that Aristotle had made substance and essence the point at which the material and the ideal meet. This includes man. Human beings cannot escape their corporeal nature, nor should they try. The isolated soul is not enough. It cannot actually exist except through something else, namely a material body. The human being is a soul within a body, the junction point of the two halves of divine creation, body and spirit. He is (in a true sense) the man in the middle.
Aquinas’s vision of creation turned Aristotle’s ordered nature into a Neoplatonist hierarchy in which “a wondrous linkage of beings” connects each and every creature to its Divine Creator. For Aquinas, every link in the chain marks a distinct advance toward divine perfection over the one just below.27 As we run down the hierarchy from spirit to mind to matter, God is more perfect than the angels, and the angels are more perfect than human beings. Running up the same hierarchy, we perceive that the bee is more sentient than the flower; the bird is more sentient than the bee; the pig is more sentient than the bird; the dog is more sentient than the pig; and so on.
And in the middle is man, the highest and most rational of material beings but also the lowest of the spiritual beings, “the boundary line of things corporeal and incorporeal.” Human beings occupy a crucial place in Aquinas’s ordered nature. They are the one material being gifted with a soul. They are also the one spiritual being gifted with a mind, meaning an active intelligence ready to take on the challenges the material world offers.
To deny the power of our own reason is in effect throwing away one of God’s greatest gifts. So would be refusing to take on the challenges life offers, from riding a horse and studying the planets to balancing a checkbook. Our goal must not be to retreat from the world. Aquinas the former monk left room for a life of renunciation and contemplation as an expression of divine grace and the highest faith. For everyone else, however, our goal must be to bring man’s unique fusion of body, mind, and spirit to its highest perfection.
The Thomist vision is appealing, even inspiring. Aquinas’s works are a landmark not only in medieval thinking, but also for the future. Being human means understanding the reality around us not because God commands us to, but because that is what our mind does as part of its nature. The Augustinian and the Neoplatonist mind passively contemplates the world and waits for a connection to a higher truth to be revealed. Aquinas saw the mind as Aristotle did, as actively analyzing that world in order to forge those connections for itself.
The Aristotelian and Thomist mind works: it doesn’t just wait around to recover something hidden or something lost. This includes the laws governing nature as understood by science and the laws that govern our own behavior in terms of morality and ethics. By 1240, Aristotle’s Ethics had finally found a translator not from Arabic but the original Greek; and Aquinas made heavy use of it.28
Just as Aquinas deployed Aristotle’s science of substance to shed new light on the Christian doctrine of the Eucharist, so he used Aristotle’s ethics to understand the nature of sin.a In or
der to commit murder or commit adultery, he concluded, we have to intend to commit that action. It must be an active choice made voluntarily, free from compulsion (someone is holding a gun to our head or our children hostage) and error (I didn’t realize the woman I was having sex with was not my wife).
Although a good intention cannot redeem a bad action, like stealing from the rich to give to the poor, it can redeem an action’s unintended consequences, as when the man defending his own life ends up killing his attacker.29 For Aquinas as for Aristotle, human freedom boils down to the power to make choices. In the end, the morality of our actions must always be judged by the active will and the intentions behind them. It also implies the freedom to choose good over evil and the mental capacity to know the one from the other (which is why dogs and infants can’t commit mortal sins).
From Aquinas’s point of view, the pagan virtues outlined by Plato and Aristotle, and Christian virtues like charity and humility, are mutually reinforcing. Both reflect a knowledge of God’s laws for men. The difference is merely that one was and is learned in the natural realm; the other is learned in the divine realm of God’s Revealed Word.
In other chapters of his Summa Theologica, Aquinas demonstrates how the laws of nature could unlock the mysteries of why and how human beings built communities, how and why they framed laws, and how they interacted with one another in society. His analysis of the role of natural law in politics would set off a revolution that had huge consequences for the future.b
In all his works, however, Aquinas refused to simply recycle Aristotle, as the Averroists had. He pointed Aristotle in entirely new directions and raised him to a higher, more relevant level for the Western future. For Aristotle, it was man’s nature to know things. For Aquinas, to know is to be in an existential sense; to know the world is to be part of the world ourselves. God has put us into the world for a purpose, His purpose. We need to use and understand that world to catch a glimpse of that purpose, and thus a glimpse of God Himself.
Through the study of natural law, Aquinas believed, science and philosophy could arrive at a theological truth through reason alone, namely the existence of God. “It was necessary for man’s salvation,” Aquinas wrote, “that there should be a knowledge revealed by God [by] the philosophical sciences [to be] investigated by human reason.”30
Far from being a distraction from holy things, as St. Bernard had claimed, this earthly order is their complement. The fact that man has two aspects, the material and the spiritual, does not mean conflict or compromise: “Grace does not replace nature, it perfects nature.” It’s Aquinas’s most famous aphorism, and it simply means we can merge the two halves of ourselves into a single higher whole—just as Thomas Aquinas had merged Aristotle and Christianity into a single system.
The Summa was unfinished at Aquinas’s death in 1274, and the gaps show. For all his genius, his grasp of the physical sciences remained fairly primitive. Aquinas never used his analysis of natural law to shed new light or open new directions in biology or astronomy or physics. In the phrase of the great Thomist scholar Étienne Gilson, he did not have the heart for the task. Perhaps if he had, his followers could have helped to reconcile the Catholic Church with the major revolutions in scientific thinking that would come during and after the Reformation.
All the same, Aquinas had achieved what no one had before or since: a fusion of Platonized Christianity with Aristotle’s science of man. It is one of the great achievements of Western civilization. But it didn’t last. Even before Aquinas’s death, the old opposition would reassert itself. He would be forced to leave the University of Paris and die in his former home of Naples while the intellectual battle raged around him.
Exactly three years later in 1277, on the third anniversary of his death, the teachings of Aquinas came under a formal ban along with those of Averroës and Aristotle. The clash between Aristotle and Plato was about to enter a new, more critical phase, as it passed beyond the cloisters and the universities. Its new battleground would be the field of politics, with the fate of the papacy and the Church itself hanging in the balance.
* * *
* Aristotle’s other texts on logic, including the Prior Analytics and his treatise on logical errors, De Sophistici Elenchi, found translators a little earlier. The mature Abelard was aware of this “New Logic” of Aristotle, in addition to the “Old Logic” via Boethius. By the thirteenth century, they were a standard part of the medieval curriculum.
† The outraged pope excommunicated him.
‡ When Aquinas arrived in Paris, the University of Toulouse was circulating placards boasting of their Aristotle expertise. Come to Toulouse, they read; we’ve got here what’s been forbidden to you in Paris.
§ Albert was a Dominican, like Aquinas. The other teaching order at Paris, the Franciscans, were devotees of Saint Augustine. Since they were not formally subject to the papal regulations of the university, the Dominicans were free to pursue the study of Aristotle—one reason their classes were always popular and why the conflicts between university authorities and the Dominicans became so bitter. Albert finally left Paris in 1248 for Cologne, and Aquinas went with him, returning only in 1252.
‖ Albert the Great had a strong interest in the Pseudo-Dionysius, which he passed on to his most famous pupil. Aquinas even did a commentary on the Divine Names, and the Dionysian idea of hierarchy would be very important in Aquinas’s own thought.
a This is his famous doctrine of transubstantiation, later adopted by the Church as official dogma. The bread and wine in the Eucharist remain what Aristotle would have called accidents, meaning in appearance only. Their actual Aristotelian substance has been transformed by the priest into the body and blood of Jesus Christ. This was a change unlike any other in nature, Aquinas added, and quite irreproducible in other circumstances—all of which seemed to prove its miraculous character.
b See chapter 20.
Fifteen
THE RAZOR’S EDGE
What can be explained on fewer principles is explained needlessly by more.
—William of Ockham, Sum of All Logic
From God and nature all mortals born free and not subject to anyone else have the power voluntarily to set a ruler over themselves.
—William of Ockham, A Short Discourse on Tyrannical Government
I walk into a pub in Ockham in Surrey, England, population 391—not many more than when Ockham’s most famous son was born there in 1290. I order a pint of ale, leave a five-pound note on the bar, and go to use the toilet. When I come back, the barkeep has left me my change and my beer, poured into two half-pint glasses.
I look at him, and he says, “There’s your pint, mate.”
I reply, “I don’t understand. Why use two glasses when one will do?”
I’ve just employed Ockham’s razor, the most useful philosophical discovery of the fourteenth century. It’s also one of the most important for the future of the Western mind. Ockham’s razor has nothing to do with shaving, although its inventor, William of Ockham, did use it to slash to ribbons some of the Middle Ages’ most cherished notions. In an age when manuscripts were made from dried lambskin or parchment, scribes used a straight-edge razor to scrape mistakes off the parchment surface. Ockham’s razor is in effect a kind of eraser, to rub out the unnecessary duplication of ideas or principles or entities.
Why use two (or more) when one (or fewer) will do, is the principle that William of Ockham introduced into the medieval thought process. It grew out of his refinement of Aristotle’s logic and set off a revolution not only in philosophy, but in politics and religion. Before he died, Ockham’s razor would undercut the foundations of the medieval Church.
Ockham was an Englishman. In the 1200s, Paris had been the central battleground between the legacies of Aristotle and Plato. By 1300, the scene had shifted across the English Channel, to the University of Oxford.
In Paris, Franciscan friars had led the charge on behalf of a Neoplatonism inherited from Saint Bernard as wel
l as Saint Augustine. They demanded that Aristotle be condemned anew in 1271, along with Averroës and Aquinas. They even managed to get Aquinas’s religious order, the Dominicans, expelled from the university.1
At Oxford, by contrast, it was the Franciscans who were Aristotle’s champions. Their leader was Robert Grosseteste, the first Englishman to read through and absorb all of Aristotle’s writings in the original Greek.* This enabled him to make more accurate translations, including the first complete Latin edition of the Nicomachean Ethics. When Grosseteste died in 1253, he had turned Oxford into an Aristotelian stronghold. Two subsequent Franciscans would use Aristotle to push secular knowledge to new intellectual altitudes Thomas Aquinas never imagined.
The first was Roger Bacon. He was born around 1215, the same date as the Magna Carta. Many legends surround his life. One is that he discovered the secret of flight (not true, although he closely studied the mechanics of birds’ wings). Another is that he invented gunpowder: also not true, although Bacon’s writings do describe a mysterious explosive powder that had come from China and which he believed would increase its power if it were packed into a container.2
Bacon’s real story was interesting enough. He was the most compulsively curious man of the Middle Ages, a kind of English-speaking Leonardo da Vinci who found every aspect of nature, from birds’ wings and the manufacture of magnifying glasses to alchemical stoves and the planets, obsessively fascinating. He wanted to know everything about everything, including the history of the Bible. At one point he applied himself to studying Hebrew, Arabic, and Chaldean in order to unlock its hidden secrets of religion.3
Bacon wrote seminal works on astronomy, alchemy, geography, optics, mathematics, geometry, and the nature of language. He helped to reform the Gregorian calendar. He speculated about the possibility of using giant reflecting lenses to burn Saracen ships at sea and was arrested by the idea that Archimedes may have discovered the same thing.4 He threw himself into studying anatomy and did a study of the human optic nerve and lens that is probably the most accurate piece of medical research of the entire Middle Ages.
The Cave and the Light Page 29