Aquinas Synthesizes Aristotle and Christian Theology in the Summa Theologiae
A Dominican friar builds five arguments for God's existence out of purely Aristotelian premises
Quick facts
- Aquinas's dates
- c. 1225-1274
- Summa Theologiae composed
- 1265-1274 (unfinished at death)
- Key argument
- The Five Ways (proofs of God's existence)
- Aquinas died
- March 7, 1274
What happened
Thomas Aquinas, born around 1225 and a Dominican friar, composed the Summa Theologiae between 1265 and his death in 1274, a comprehensive work that draws on the newly recovered Aristotle to address nearly the whole of Aquinas's philosophical and theological concerns. Aquinas held that sound theology presupposes sound philosophical argument, and in the Summa's first part he offered five arguments, the Five Ways, for God's existence, three of them cosmological arguments resting on the claim that an infinite regress of causes is impossible. Each of the five ends with a version of the same formula: this is what everyone calls God.
Why it matters
Aquinas's synthesis gave Aristotelian philosophy a permanent home inside Christian theology, and the Summa became the central reference work of scholastic philosophy for the rest of the medieval period and beyond, shaping Catholic philosophy so thoroughly that Thomism remains a live philosophical school today.
How we know
The Summa Theologiae survives complete and has been continuously copied, printed, and studied since the 13th century; Aquinas's authorship and the work's composition dates are corroborated by contemporary biographical accounts from his Dominican order and by his other datable writings.
Sources
- Stanford Encyclopedia of Philosophy. Aquinas · Reputable sourceplato.stanford.edu · The domain "plato.stanford.edu" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- Internet Encyclopedia of Philosophy. Thomas Aquinas · Reputable sourceiep.utm.edu · The domain "iep.utm.edu" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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