To understand Scholasticism as no vain accumulation of dull abstractions, we must see the thirteenth century not as the unchallenged field of the great Scholastics, but as a battleground on which, for seventy years, skeptics, materialists, pantheists, and atheists contested with the theologians of the Church for possession of the European mind.

We have noted the presence of unbelief in a small minority of the European population. Contact with Islam through the Crusades and the translations extended this minority in the thirteenth century. The discovery that another great religion existed, and had produced fine men like Saladin and al-Kamil, philosophers like Avicenna and Averroës, was in itself a disturbing revelation; comparative religion does religion no good. Alfonso the Wise (1252–84) reported a common disbelief in immortality among the Christians of Spain;21 perhaps Averroism had trickled down to the people. In southern France there were in the thirteenth century rationalists who argued that God, after creating the world, had left its operation to natural law; miracles, they held, were impossible; no prayer could change the behavior of the elements; and the origin of new species was due not to special creation but to natural development.22 At Paris some freethinkers—even some priests—denied transubstantiation;23 and at Oxford a teacher complained that “there is no idolatry like that of the sacrament of the altar.”24 Alain of Lille (1114–1203) remarks that “many false Christians of our time say there is no resurrection, since the soul perishes with the body”; they quoted Epicurus and Lucretius, adopted atomism, and concluded that the best thing to do is to enjoy life here on earth.25

The urban industrialism of Flanders seems to have promoted unbelief. At the beginning of the thirteenth century we find David of Dinant, and near its end Siger of Brabant, leading a strongly skeptical movement. David (c. 1200) taught philosophy at Paris, and entertained Innocent III with his subtle disputations.26 He played with a materialistic pantheism in which God, mind, and pure matter (matter before receiving form) all became one in a new trinity.27 His book, Quaternuli, now lost, was condemned and burned by the Council of Paris in 1210. The same synod denounced the pantheism of another Parisian professor, Amalric of Bène, who had argued that God and the creation are one. Amalric was compelled to retract, and died, we are told, of mortification (1207).28 The Council had his bones exhumed, and burned them in a Paris square as a hint to his many followers. They persisted nevertheless, and enlarged his views to a denial of heaven and hell and the power of the sacraments. Ten of these Amalricians were burned at the stake (1210).29

Free thought flourished in the southern Italy of Frederick II, where St. Thomas grew up. Cardinal Ubaldini, friend of Frederick, openly professed materialism.30 In northern Italy the industrial workers, the business classes, the lawyers, and the professors indulged in a measure of skepticism. The Bolognese faculty was notoriously indifferent to religion; the medical schools there and elsewhere were centers of doubt; and an adage arose that ubi tres medici, duo athei—“where there are three physicians two of them are atheists.”31 About 1240 Averroism became almost a fashion among the educated laity of Italy.32 Thousands accepted the Averroistic doctrines that natural law rules the world without any interference by God; that the world is co-eternal with God; that there is only one immortal soul, the “active intellect” of the cosmos, of which the individual soul is a transitory phase or form; and that heaven and hell are tales invented to coax or terrify the populace into decency.33 To appease the Inquisition, some Averroists advanced the doctrine of twofold truth: a proposition, they argued, might seem true in philosophy or according to natural reason, and yet be false according to Scripture and the Christian faith; they professed at the same time to believe according to faith what they doubted according to reason. Such a theory denied the basic assumption of Scholasticism—the possibility of reconciling reason and faith.

Towards the end of the thirteenth, and throughout the fourteenth and fifteenth centuries, the University of Padua was a turbulent center of Averroism. Peter of Abano (c. 1250–1316), professor of medicine at Paris and then of philosophy at Padua, wrote in 1303 a book, Conciliator controversiarum, designed to harmonize medical and philosophical theory. He earned a place in the history of science by teaching that the brain is the source of the nerves, and the heart of the vessels, and by measuring the year with remarkable accuracy as 365 days, six hours, and four minutes.34 Convinced of as-crology, he reduced almost all causation to the power and movement of the stars, and practically eliminated God from the government of the world.35 Inquisitors accused him of heresy, but Marquis Azzo d’Este and Pope Honorius IV were among his patients, and protected him. He was accused again in 1315, and this time escaped trial by dying a natural death. The inquisitors condemned his corpse to be burned at the stake, but his friends so well concealed his remains that the judgment had to be executed in effigy.36

When Thomas Aquinas went from Italy to Paris he discovered that Averroism had long since captured a part of the faculty. In 1240 William of Auvergne noted that “many men” at the University “swallow these [Averroistic] conclusions without investigation”; and in 1252 Thomas found Averroism flourishing among the University youth.37 Perhaps alarmed by Thomas’ report, Pope Alexander IV (1256) charged Albertus Magnus to write a treatise On the Unity of the Intellect Against Averroës. When Thomas taught at Paris (1252–61, 1269–72) the Averroistic movement was at its height; its leader in France, Siger of Brabant, taught in the University from 1266 to 1276. For a generation Averroism and Catholicism made Paris their battlefield.

Siger (1235?–? 1281), a secular priest,38 was a man of learning: even the surviving fragments of his works quote al-Kindi, al-Farabi, al-Ghazali, Avicenna, Avempace, Avicebron, Averroës, and Maimonides. In a series of commentaries on Aristotle, and in a controversial tract Against Those Famous Men in Philosophy, Albert and Thomas, Siger argued that Albert and Thomas falsely—Averroës justly—interpreted the Philosopher.39 He concluded with Averroës that the world is eternal, that natural law is invariable, and that only the soul of the species survives the individual’s death. God, said Siger, is the final, not the efficient, cause of things—He is the goal, not the cause, of creation. Led like Vico and Nietzsche by the fascination of logic, Siger played with the dismal doctrine of eternal recurrence: since (he argued) all earthly events are ultimately determined by stellar combinations, and the number of these possible combinations is finite, each combination must be exactly repeated again and again in an infinity of time, and must bring in its train the same effects as before; “the same species” will return, “the same opinions, laws, religions.”40 Siger was careful to add: “We say this according to the opinion of the Philosopher, but without affirming that it is true.”41 To all his heresies he appended a similar caution. He did not profess the doctrine of two truths; he taught certain conclusions as, in his judgment, following from Aristotle and reason; when these conclusions contradicted the Christian creed he affirmed his belief in the dogmas of the Church, and applied only to them, not to philosophy, the label of truth.42

That Siger had a large following at the University is evident from his candidacy for the rectorship (1271), though it failed. Nothing could better prove the strength of the Averroistic movement in Paris than its repeated denunciation by the Bishop of Paris, Etienne Tempier. In 1269 he condemned as heresies thirteen propositions taught by certain professors in the University:

That there is only one intellect in all men…. That the world is eternal…. That there never was a first man…. That the soul is corrupted with the corruption of the body…. That the will of man wills and chooses from necessity…. That God does not know individual events…. That human actions are not ruled by Divine Providence’.43

Apparently the Averroists continued to teach as before, for in 1277 the Bishop issued a list of 219 propositions which he officially condemned as heresies. These, according to the Bishop, were doctrines taught by Siger, or Boethius of Dacia, or Roger Bacon, or other Parisian professors, including St. Thomas himself. The 219 included those condemned in 1269, and others of which the following are samples:

That creation is impossible…. That a body once corrupted [in death] cannot rise again as the same body’…. That a future resurrection should not be believed by a philosopher, since it cannot be investigated by reason…. That the words of theologians are founded on fables…. That nothing is added to our knowledge by theology…. That the Christian religion impedes learning…. That happiness is obtained in this life, not in another…. That the wise men of the earth are philosophers alone…. That there is no more excellent condition than to have leisure for philosophy.44

In October, 1277, Siger was condemned by the Inquisition. He passed his last years in Italy as a prisoner of the Roman Curia, and was murdered at Orvieto by a half-mad assassin.45

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