When it is Declared Contrary to Dogma by the Authority of Religion, it is a Heresy.
Orthodox and Heterodox Interpretations.
Some Independent Philosophers.
DOGMA.—After the invasion of the barbarians, philosophy, like literature, sought refuge in monasteries and in the schools which prelates instituted and maintained near them. But the Church does not permit the free search for truth. The truth has been established by the Fathers of the Church and fixed by the Councils. Thenceforth the philosophic life, so to speak, which had never been interrupted, assumed a fresh character. Within the Church it sheltered—I will not say disguised—itself under the interpretation of dogma; it became a sort of respectful auxiliary of theology, and was accordingly called the "handmaid of theology," ancilla theologiae. When emancipated, when departing from dogma, it is a "heresy," and all the great heresies are nothing else than schools of philosophy, which is why heresies must come into a history of philosophy. And at last, but only towards the close of the Middle Ages, lay thought without disturbing itself about dogma and no longer thinking about its interpretation, created philosophic doctrines exactly as the philosophers of antiquity invented them apart from religion, to which they were either hostile or indifferent.
SCHOLASTICISM: SCOTUS ERIGENA.—The orthodox philosophy of the Middle Ages was the scholastic. Scholasticism consisted in amassing and in making known scientific facts and matters of knowledge of which it was useful for a well-bred man not to be ignorant and for this purpose encyclopaedias were constructed; on the other hand, it consisted not precisely in the reconciliation of faith with reason, not precisely and far less in the submission of faith to the criticism of reason, but in making faith sensible to reason, as had been the office of the Fathers of the Church, more especially St. Augustine.
Scotus Erigena, a Scotsman attached to the Palatine Academy of Charles the Bald, lived in the eleventh century. He was extremely learned. His philosophy was Platonic, or rather the bent of his mind was Platonic. God is the absolute Being; He is unnamable, since any name is a delimitation of the being; He is absolutely and infinitely. As the creator of all and uncreated, He is the cause per se; as the goal to which all things tend, He is the supreme end. The human soul is of impenetrable essence like God Himself; accordingly, it is God in us. We have fallen through the body and, whilst in the flesh, we can, by virtue and more especially by the virtue of penitence, raise ourselves to the height of the angels. The world is the continuous creation of God. It must not be said that God created the world, but that He creates it; for if He ceased from sustaining it, the world would no longer exist. God is perpetual creation and perpetual attraction. He draws all beings to Himself, and in the end He will have them all in Himself. There is predestination to perfection in everything.
These theories, some of which, as has been seen, go beyond dogma and form at least the beginning of heresy, are all impregnated with Platonism, especially with Neoplatonism, and lead to the supposition that Scotus Erigena possessed very wide Greek learning.
ARABIAN SCIENCE.—A great literary and philosophical fact in the eighth century was the invasion of the Arabs. Mahometans successively invaded Syria, Persia, Africa, and Spain, forming a crescent, the two points of which touched the two extremities of Europe. Inquisitive and sagacious pupils of the Greeks in Africa and Asia, they founded everywhere brilliant universities which rapidly acquired renown (Bagdad, Bassorah, Cordova, Granada, Seville, Murcia) and brought to Europe a new quota of science; for instance, all the works of Aristotle, of which Western Europe possessed practically nothing. Students greedy for knowledge came to learn from them in Spain; for instance, Gerbert, who developed into a man of great learning, who taught at Rheims and became Pope. Individually the Arabs were often great philosophers, and at least the names must be mentioned of Avicenna (a Neoplatonist of the tenth century) and Averroes (an Aristotelian of the twelfth century who betrayed tendencies towards admitting the eternity of nature, and its evolution through its own initiative during the course of time). Their doctrines were propagated, and the ancient books which they made known became widely diffused. From them dates the sway of Aristotle throughout the middle ages.
ST. ANSELM.—St. Anselm, in the eleventh century, a Savoyard, who was long Abbot of Bec in Normandy and died Archbishop of Canterbury, is one of the most illustrious doctors of philosophy in the service of theology that ever lived. "A new St. Augustine" (as he has been called), he starts from faith to arrive at faith after it has been rendered sensible to reason. Like St. Augustine he says: "I believe in order to understand" (well persuaded that if I never believed I should never understand), and he adds what had been in the thought of St. Augustine: "I understand in order to believe." St. Anselm proved the existence of God by the most abstract arguments. For example, "It is necessary to have a cause, one or multiple; one is God; multiple, it can be derived from one single cause, and that one cause is God; it can be a particular cause in each thing caused; but then it is necessary to suppose a personal force which must itself have a cause and thus we work back to a common cause, that is to say to a single one."
He proved God again by the proof which has remained famous under the name of the argument of St. Anselm: To conceive God is to prove that He is; the conception of God is proof of His existence; for every idea has its object; above all, an idea which has infinity for object takes for granted the existence of infinity; for all being finite here below, what would give the idea of infinity to the human mind? Therefore, if the human brain has the idea of infinity it is because of the existence of infinity. The argument is perhaps open to difference of opinion, but as proof of a singular vigour of mind on the part of its author, it is indisputable.