By the time of Abelard’s death, the Greek scientific writings of antiquity were starting to be recovered, often through translations from Arabic into Latin. In the second half of the century came the recovery of Aristotle’s lost treatises on logic, which dealt with such subjects as how to build a syllogism (an expression of deductive reasoning),how to prove a point, and how to refute false conclusions.
Yet the recovery of Aristotle posed certain new problems. For example, the Muslim philosopher Averroaues,whose comments accompanied the text of Aristotle’s Meta physics, stressed Aristotle’s own view that the physical world was eternal; since the soul—a nonphysical thing—was essentially common to all humanity, no individual human soul could be saved by itself. Obviously, this ran counter to fundamental Christian teaching.
Some scholars tried to say that both views could be true—Aristotle’s in philosophy and the Christian in theology. But this led directly to heresy. Others simply tried to forbid the reading of Aristotle, though without success. It was the Dominican Albertus Magnus (1193–c. 1280), a Swabian, and his pupil Thomas Aquinas (1225-1274), an Italian, who succeeded in reconciling the apparent differences between Aristotle’s teachings and those of the Christian tradition.
Aquinas’s best-known writings were the Summa Theologica and the Summa contra Gentiles. He discussed God, humans, and the universe, arranging his material in systematic topical order in the form of an inquiry into and discussion of each open question. First he cited the evidence on each side, then he gave his own answer, and finally he demonstrated the falsity of the other position. For him, reason was a most valuable instrument, but only when it reasonably recognized its own limitations.
When unaided reason could not comprehend an apparent contradiction with faith, it must yield to faith, since reason by itself could not understand the entire universe. Thus the “Angelic Doctor,” as Aquinas was called, worked out a systematic theology on rational principles, declaring that, since truth was indivisible, there was no contradiction between faith and reason, theology and science.