Eternal law in the thought of Thomas Aquinas

ABSTRACT

This paper is a slightly modified version of the keynote lecture given at the 2023 annual conference of the Catholic Theological Association of Great Britain. The theme of the conference was the role of law in the Christian life. The paper opened the conference by following the theological lead of the Common Doctor, St Thomas Aquinas, who treats theology as about God and all things, including law, in relation to God. In particular the paper looks at Aquinas’s understanding in the Summa Theologiae of God as the eternal law. It examines how the eternal law meets Aquinas’s criteria for what counts as a law, and links eternal law to other law, such as natural law, as well as to the doctrines of the Trinity, providence, the beatific vision, and Christology.

KEYWORDS:

• Thomas Aquinas
• eternal law
• Trinity
• providence
• natural law
• Jesus Christ

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

¹ See, for example, the earlier work of Rawls, Theory of Justice.

² E.g. Dimock, ‘Natural Law Theory’, 22.

³ Aquinas, Summa Theologiae, I.1.7.

⁴ Aquinas, Summa contra Gentiles, III.114.

⁵ Ibid., III.115.

⁶ Aquinas, Summa Theologiae, I–II.91.1; 93.1. Lottin, Psychologie et Morale, 63–67, argued that Aquinas’s inclusion of eternal law is influenced by the treatise on law in the Summa Theologica of the Franciscan Alexander of Hales. The particular treatise was in fact authored by Alexander’s pupil, John of la Rochelle. On the differences between the two Summae on this topic, see further Brock, Light That Binds, 34–40.

⁷ Aquinas, Summa Theologiae, I–II.93.1sed contra. Augustine’s concept of eternal law is in fact more extensive than that of Aquinas, because Augustine includes under it any created law promulgated in time that is not in principle open to change. See Dougherty, ‘Natural Law’, 583–84.

⁸ Aquinas, De Veritate, 5.1ad6.

⁹ Aquinas, Summa Theologiae, I–IIae.19.4.

¹⁰ Similarly, he speaks of ‘natural law’ only by other expressions until he reaches the treatise on law. On the reason for this, see Brock, Light That Binds, 38–39, 58–59. For some helpful commentary on the treatise itself, see Budziszewski, Treatise on Law.

¹¹ Aquinas, Summa Theologiae, I–II.91.1.

¹² Ibid., I–II.90.4.

¹³ Ibid., I–II.90.1.

¹⁴ Ibid., I.83.3–4.

¹⁵ Ibid., I.19.1.

¹⁶ Ibid., I.1.9.

¹⁷ For example, Vázquez, Commentariorum, 15; de Lorca, Commentariorum, 382–83.

¹⁸ Aquinas, Summa Theologiae, I.13.

¹⁹ Ibid., II–II.47–56.

²⁰ On the relationship between providence and eternal law and the different positions of some early modern commentators on this, see Collins, ‘God’s Eternal Law’, 499–504.

²¹ Aquinas, Summa Theologiae, I–II.90.4.

²² For Aquinas’s teaching on the Trinity, see Emery, Trinitarian Theology.

²³ Aquinas, Summa Theologiae, I–II.91.1ad2.

²⁴ Ibid., I.34.3.

²⁵ Ibid., I–II.93.1. See Emery, Trinitarian Theology, 195–200; Gaine, ‘God is an Artificer’.

²⁶ Aquinas, Summa Theologiae, I–II.93.4ad1.

²⁷ Ibid., I–II.93.5.

²⁸ Ibid., I–II.93.6.

²⁹ Collins, ‘God’s Eternal Law’, 498–99.

³⁰ Aquinas, Summa Theologiae, I.2.

³¹ Ibid., I.32.1ad3.

³² Ibid., I.43.5ad2.

³³ Ibid., I.44.4ad1.

³⁴ Ibid., I.3proem.

³⁵ Ibid., I–II.93.2.

³⁶ Ibid., I.12.1.

³⁷ Ibid., I.12.2–5.

³⁸ Ibid., I.12.10.

³⁹ Ibid., I–II.93.2.

⁴⁰ Ibid., I–II.91.2; 94.

⁴¹ See, for example, the illuminating study of Aquinas’s metaphysics of the natural law by Brock, Light That Binds. For natural law as a participation in eternal law, see Ibid., 33–60. For a treatment of eternal law in the context of what is known as the new natural law theory, see Grisez, Way of the Lord Jesus, 173–74; Finnis, Natural Law, 388–403.

⁴² Aquinas, Summa Theologiae, I–II.93.3.

⁴³ Ibid., I–II.93.3ad2.

⁴⁴ Ibid., I–II.91.5.

⁴⁵ Ibid., I–II.107.

⁴⁶ Aquinas, Summa Theologiae, III.9.2; 10. On Christ’s possession of the beatific vision, see Gaine, Did the Saviour See the Father?

⁴⁷ Aquinas, Summa Theologiae, I–II.106.1.

⁴⁸ Ibid., q. 108.

Additional information

Notes on contributors

Simon Francis Gaine

Simon Francis Gaine, OP, teaches theology at the Pontifical University of St Thomas Aquinas, Rome, where he is the Director of the Angelicum Thomistic Institute and Pinckaers Professor of Theological Anthropology and Ethics.