What it argues
The Summa Theologica — "Summary of Theology" — is Thomas Aquinas's masterwork, composed between approximately 1265 and 1274. Aquinas died before completing it, leaving the Third Part unfinished. The Summa is organized as a series of questions, each answered through objections, a direct response (the "sed contra" and "respondeo"), and replies to each objection in turn. It is the most systematic statement of medieval scholastic philosophy and remains the primary reference point for Catholic philosophical theology. The complete work runs to several million words; most readers encounter it through selections.
The First Part (Prima Pars) addresses the existence and nature of God, creation, angels, and human nature. The Five Ways — Aquinas's five arguments for the existence of God — appear here and are among the most discussed arguments in the history of philosophy. Aquinas argues from motion, causation, contingency, degrees of perfection, and teleology to a first cause, necessary being, and governing intelligence. He is careful to note what philosophy can establish about God and what requires revelation; reason and faith are compatible and complementary, not rivals.
What it gets right
- 1.
Aquinas's Five Ways offer philosophical arguments for God's existence from motion, causation, contingency, degrees of perfection, and teleological order — without presupposing scripture.
- 2.
Faith and reason are compatible for Aquinas: reason can establish that God exists and is good; revelation discloses what reason cannot reach on its own.
- 3.
Natural law holds that moral norms are accessible to reason because they reflect the rational order of creation. All humans have some moral knowledge by nature.
What it covers
Who wrote it
Thomas Aquinas (1225–1274) was an Italian Dominican friar and philosopher born near Aquino in the Kingdom of Sicily. He studied under Albertus Magnus in Cologne and taught in Paris and Rome. His major works include the Summa Contra Gentiles and the incomplete Summa Theologica. Aquinas systematically integrated Aristotelian philosophy with Christian theology, shaping Catholic intellectual tradition for centuries. He was canonized in 1323 and declared a Doctor of the Church. The tradition of thought he founded, Thomism, continues to be developed in philosophy and law today.
