Thomas Aquinas

Thomas Aquinas was a thirteenth-century Dominican friar whose work synthesized Aristotelian philosophy with Christian theology and set the terms for nearly every subsequent argument about God in the Western tradition. He studied under Albert the Great in Paris and Cologne, and held a chair in theology at the University of Paris twice. His major work, the Summa Theologiae, is unfinished. He stopped writing in December 1273, having had what he described only as an experience after which “everything I have written seems to me like straw.” He died three months later on the road to the Council of Lyon.

For OTS purposes Aquinas is the natural anchor of the Cosmological Argument node: the Five Ways in the Summa are the medieval starting point for nearly every later argument from contingency, causation, or motion. He is also the medieval high-water mark for the conviction that natural reason, working without revelation, can establish the existence of God, a conviction that the modern arguments will spend several centuries questioning.

Aquinas’s influence on this corpus is structural rather than direct. He is rarely cited by the analytic philosophers Margaret Halloran reads in her seminars, but he is in the room. The Cosmological Argument, the distinction between essence and existence, the doctrine of divine simplicity: all of it traces back through him.