Thomas Aquinas

Thomas Aquinas was a thirteenth-century Italian Dominican friar, theologian, and philosopher whose synthesis of Aristotelian philosophy and Christian doctrine became the most influential intellectual framework in the Western Catholic tradition. He is the principal source of the natural-law theory on which much later conservative thought about morality, law, and the common good rests.

Aquinas holds an unusual position for conservatism: he is at once a theologian of the Church and a systematic philosopher whose arguments are framed to stand on reason accessible to all people, believers or not. His account of law as an ordinance of reason directed to the common good, and of natural law as a participation in a higher moral order, gives natural-law conservatism a foundation that does not depend on a single religious tradition for its premises.

Key Takeaways

• Thomas Aquinas (1225-1274), a Dominican friar and Doctor of the Church, synthesised Aristotle’s philosophy with Christian theology, supplying conservatism with its principal account of natural law.
• His Summa Theologiae defines law as an ordinance of reason for the common good and ranks natural law as the rational creature’s participation in God’s eternal law.
• Aquinas restated the criteria for a just war and grounded political authority in the common good, framing positions that natural-law conservatives still hold.

History And Context

Aquinas was born around 1225 at Roccasecca, near Aquino in the Kingdom of Sicily, to a noble family who opposed his decision to join the recently founded Dominican order. He studied under Albertus Magnus at Cologne and taught at the University of Paris, then the centre of Latin Christian learning. His career coincided with the recovery of Aristotle’s works in the Latin West through Arabic and Greek transmission, which forced a confrontation between Aristotelian philosophy and Christian theology.

Aquinas’s achievement was to integrate the two rather than choose between them. Where earlier thinkers had treated Aristotle as a threat to faith, Aquinas argued that grace perfects nature rather than destroying it, and that reason and revelation, rightly understood, cannot conflict. His major works are the Summa contra Gentiles and the unfinished Summa Theologiae (begun 1265), the latter organised as a systematic treatment of God, the moral life, and Christ.

He died in 1274 en route to the Second Council of Lyon. He was canonised on 18 July 1323 by John XXII, named a Doctor of the Church, and is known as the “Angelic Doctor.”¹ Later popes, notably Leo XIII in Aeterni Patris (1879), commended his thought as a model for Catholic philosophy, a recommendation that shaped the Catholic social teaching of the following century.

The Conservative Position

The natural-law theory of the Summa Theologiae is Aquinas’s central legacy to conservatism. In the questions on law (I-II, qq.90-97) he defines law as “an ordinance of reason for the common good, made by him who has care of the community, and promulgated.”² He distinguishes four kinds of law: the eternal law by which God governs creation, the natural law that is the rational creature’s participation in that eternal law, human law that applies natural law to particular circumstances, and the divine law given through revelation.

Natural law, on this account, is knowable by reason. Its first precept, Aquinas writes, is that “good is to be done and pursued, and evil is to be avoided,” from which the more specific precepts of practical reason follow by reflection on the goods to which human nature inclines.³ This claim, that there is a moral order written into human nature and accessible to reason, is the foundation of natural-law conservatism: it supplies a standard above positive law against which human enactments can be judged, and an argument that the state does not create morality but is bound by it.

Aquinas also restated the conditions of a just war. In the Summa Theologiae (II-II, q.40) he holds that a war is just only when it is declared by legitimate sovereign authority, fought for a just cause, and waged with right intention rather than for cruelty or domination.⁴ These three conditions remain the core of the Christian just-war theory that conservative thought on the ethics of force still draws upon. His treatment of political authority as ordered to the common good, and of the ruler as bound to serve it, likewise informs the conservative account of legitimate government and feeds into the later principle of subsidiarity.

The twentieth-century revival of natural-law thought rested heavily on Aquinas. The legal philosopher John Finnis, in Natural Law and Natural Rights (1980), reconstructed a Thomistic theory of basic human goods and practical reason in the idiom of analytic philosophy, providing natural-law conservatism with a modern restatement that engages contemporary jurisprudence directly.⁵ Aquinas also remains the principal authority for conservative accounts of virtue ethics, which treat the moral life as the formation of stable dispositions ordered to the human good.

Differing Positions

Critics in the modern liberal tradition, following David Hume, deny that moral conclusions can be derived from facts about human nature, and so reject the inference from nature to obligation on which Aquinas’s natural law rests. Defenders reply that Aquinas does not derive “ought” from a bare “is” but begins from the goods that practical reason grasps as worth pursuing.

Some Protestant and secular critics object that natural-law theory smuggles in theological premises under the appearance of universal reason. Thomists answer that Aquinas frames the natural law to be knowable apart from revelation, even as he holds that its ultimate ground is the eternal law of God, a distinction the tradition of Christianity and conservatism has long maintained.

References

1. “Canonization of Thomas Aquinas,” Pope John XXII, 18 July 1323; he was later named a Doctor of the Church. https://en.wikipedia.org/wiki/Thomas_Aquinas
2. Thomas Aquinas, Summa Theologiae, I-II, q.90, a.4. https://www.newadvent.org/summa/2090.htm
3. Thomas Aquinas, Summa Theologiae, I-II, q.94, a.2. https://www.newadvent.org/summa/2094.htm
4. Thomas Aquinas, Summa Theologiae, II-II, q.40, a.1. https://www.newadvent.org/summa/3040.htm
5. John Finnis, Natural Law and Natural Rights (Oxford: Clarendon Press, 1980). https://global.oup.com/academic/product/natural-law-and-natural-rights-9780199599141