Thomas Aquinas: Summa Theologiae

Context

The Summa theologiae contributed prominently to the thirteenth-century academic debates raging at such universities as Paris, Bologna, Salerno, Oxford, Cambridge, Montpellier, Padua, Salamanca, and Toulouse and sparked by the recovery of the works of Plato and Aristotle. These Greek and Latin classics had been virtually lost to the Western world after the decline of the Roman Empire but, through their Arabic versions preserved by Muslim scholars, returned to Western circulation in the eleventh century, when Jewish scholars began to translate them from Arabic into Latin. This philosophical revival generated three competing schools of thought: realism, moderate realism or conceptualism, and nominalism. Realism, rooted in the philosophy of Plato, maintained that there are universals of goodness, justice, and beauty that exist apart from individual human acts of goodness, justice, and beauty. Summarized by the phrase universalia ante rem (universals exist before created things), realism claimed that a just act, for instance, is merely a shadow or imperfect copy of the reality of justice that exists independently apart from that act. Further, realism alleged that faith precedes knowledge as its foundation, namely, credo ut intelligam (I believe in order that I may know). Faith must be first because the existence of universals depends on the existence of an immaterial realm, which there is, by definition, no physical way to prove.

Conceptualism, rooted in the philosophy of Aristotle, maintained that universals indeed exist but do so in particular things as their common nature; thus humanity exists as the common nature of people. The reason why universals objectively exist is their correspondence to ideas in the mind of God. Summarized by the phrase universalia in re (universals exist in created things), conceptualism is the school that the Summa endorses and for which it offers the most powerful medieval defense. Conceptualism affirmed that knowledge precedes faith as its foundation, or, in the words of Aquinas, intelligo ut credam (I know in order that I may believe). Nominalism, the via moderna (modern way) challenging the Platonic and Aristotelian via antiqua (old way), maintained that universals do not exist in reality. Rather, they are nothing more than “names,” or linguistic handles, that humans have invented to conveniently describe the world; hence universalia post rem (universals after created things). In addition, nominalism divorced the realm of faith from the realm of knowledge, making the two entirely separate and having nothing to do with each other.

As a result, many nominalists held to a “double-truth model” in which the truths of faith (or theology) exist independently of, and may well contradict, the truths of knowledge (or philosophy). It was this idea that Aquinas found most damaging to Christianity and in need of refutation in that it denied that the truths of faith counted as knowledge and rendered such “truths” meaningless, as they would no longer correspond to objective facts. Aquinas combated the double-truth model by reconstructing Christian theology according to the philosophy of Aristotle. For Aquinas, faith is based on knowledge and reason: “Faith presupposes reason as grace presupposes nature.” By the time of Aquinas, Aristotle had already been subject to interpretation and study by leading Muslim thinkers like Ibn Rushd (known in the West as Averroës, 1126–1198) and leading Jewish thinkers like Moses ben Maimon (known as Maimonides, 1135–1204). In drawing on their scholarship, the Summa informs Christian thought with much of the best medieval Jewish and Islamic philosophy.