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Mitzvah mistranslated: Reimagining Aquinas’ threefold division of ‘Old Law’
Published online by Cambridge University Press: 18 August 2025
Abstract
Thomas Aquinas argues that ‘Old Law’, comprised of the precepts found in the Hebrew Bible, should be divided into three types: moral, ceremonial and judicial. His system is meant to be instructive for Christian ethics, distinguishing between eternally, universally binding precepts relevant to Christians and other irrelevant or even forbidden ones. But Aquinas derives this threefold division from a mistranslated Vulgate passage from Deuteronomy where a singular noun, mitzvah, is translated as a plural noun: praecepta. Based on the original Hebrew, the verse actually supports a twofold division, not a threefold one. Aquinas’ system also runs into issues when it comes to sorting the precepts. To fix the sorting, retain the instructive benefit, and shed the biblical tension, we ought to keep Aquinas’ understanding of ‘moral law’, but discard the judicial and ceremonial categories in favour of one ‘cultural law’ category, in line with the popular Jewish philosophical division between chukim and mishpatim.
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References
1 Thomas Aquinas, Summa Theologiae [hereafter ST] 1/2.100.1–3, in S. Thomae Aquinatis Doctoris Angelici Opera Omnia Iussu Impensaque Leonis XIII P. M. edita, vols. 4–12 (Rome: Leonine Commission, 1888–1906). All translations are my own.
2 Ralph McInerny, Ethica Thomistica: The Moral Philosophy of Thomas Aquinas (Washington, DC: The Catholic University of America Press, 1997), p. 45.
3 ST 1/2.99.3.
4 ST 1/2.103.4.
5 ST 1/2.99.4.
6 ST 1/2.99.5.
7 Cited in ST 1/2.101.1.
8 In the body paragraphs, Aquinas uses most of the space to establish that the Divine Law ought to contain precepts that meet the conditions of each category, based on his vision of divinity. These arguments do not form a case for the threefold division itself; one can accept that precepts meeting the conditions of each category are present and still take issue with the system overall.
9 ST 1/2.99.4.
10 J. Budziszewski, Commentary on Thomas Aquinas’s Treatise on Divine Law (Cambridge: CUP, 2021), p. 69; n.b., Budziszewski was working with the Blackfriars translation, which retains the mistake.
11 Tanakh: A New Translation of the Holy Scriptures According to the Traditional Hebrew Text (Philadelphia: Jewish Publication Society, 1985).
12 ST 1/2.100.11.
13 This problem could be solved by suggesting an order for where laws fall by default, but Aquinas does not do this, and so we must treat the categories as coplanar.
14 Jean Porter, Natural and Divine Law: Reclaiming the Tradition for Christian Ethics (Toronto: Novalis, 1999), p. 137.
15 Brian Davies, Thomas Aquinas’s Summa Theologiae: A Guide and Commentary (Oxford: OUP, 2014), p. 220.
16 ST, Prologue.
17 See Francisco Suárez, Selections from Three Works: A Treatise on Laws and God the Lawgiver; A Defence of the Catholic and Apostolic Faith; A Work on the Three Theological Virtues: Faith, Hope, and Charity, ed. Thomas Pink (Indianapolis, IN: Liberty Fund, 2015).
18 Jean Porter, Recovery of Virtue: The Relevance of Aquinas for Christian Ethics (Louisville, KY: Westminster John Knox, 1990). See also Brian Davies, The Thought of Thomas Aquinas (Oxford: Clarendon, 1993).
19 See Pope St. John Paul II, Veritatis Splendor (Boston: St. Paul Books and Media, 1993), p. 101 n79.
20 See Lev. 26:46; Deut. 4:1, 5:1, 6:1, 7:11, 11:32, 12:1; 2 Kings 17:37; 1 Chron.22:13; Neh. 1:7.
21 ST 1/2.101.1, 3.
22 Moses Maimonides, Sefer ʻAvodah: Hilchot Me’ilah, The Laws of the Misappropriation (of Consecrated Property), trans. JPS (New York: Moznayim, 767 [2007]).
23 B. Yoma 67b.
24 Mishpatim must be rationally accessible: see Shemonah Perakim ch. 6, and The Guide for the Perplexed 3:26. Mishpatim must pertain to virtue: see Shubert Spero, ‘Rabbi Joseph Dov Soloveitchik and the Role of the Ethical’, Modern Judaism 23/1 (2003), pp. 12–31.
25 It is debatable whether this precept meets Aquinas’ standards for moral law. Though it seems to me to be reasonable and concerned with virtue, this may be because I have internalised an associated cultural/religious taboo.
26 ST 1/2.103.2.
27 Catechism of the Catholic Church, 2nd edn. (Huntingdon, PA: Our Sunday Visitor, 2000), §1154.
28 Catechism of the Catholic Church, §839.
29 ‘Catholic Catechism for Adults Revised to Clarify Catholics’ Understanding of Jewish Covenant’, Catholic News Agency (Washington, D.C.), August 28, 2009, https://www.catholicnewsagency.com/news/16964/catholic-catechism-for-adults-revised-to-clarify-catholics-understanding-of-jewish-covenant.
30 There is a good deal to be said here on Aquinas’ general attitude toward the Jewish role in salvation history and possible anti-Jewish colours in his determinations, though it goes beyond the scope of this paper. For more reading, see Jeremy Cohen, ‘Supersessionism, the Epistle to the Romans, Thomas Aquinas, and the Jews of the Eschaton’, Journal of Ecumenical Studies 52/4 (2017), pp. 527–53; and Edward A. Synan, ‘Some Medieval Perceptions of the Controversy on Jewish Law’, in Clemens Thoma and Michael Wyschogrod (eds), Understanding Scripture: Explorations of Jewish and Christian Traditions of Interpretation (New York: Paulist, 1987), pp. 102–24; Steven C. Boguslawski, OP, Thomas Aquinas on the Jews: Insights into His Commentary on Romans 9–11 (Mahwah, NJ: Paulist Press, 2008); and Matthew Tapie, Aquinas on Israel and the Church: the Question of Supersessionism in the Theology of Thomas Aquinas (Cambridge: James Clarke & Co., 2015).
31 Bruce D. Marshall, ‘Religion and Election: Aquinas on Natural Law, Judaism, and Salvation in Christ’, Nova et Vetera 14/1 (2016), p. 125.
32 If we do discard the ‘Jesus vs. messiah yet to come’ differentiation, both the twofold and threefold systems can see Jewish Torah observance as non-sinful if intent determines the moral status of keeping a precept. After all, as both Marshall and the Catechism point out, the advent of the Messiah is a core intent that Jewish and Christian religious practice have in common. See ibid.; and Catechism of the Catholic Church §840.
33 This objection also lands for a threefold system, as I cover at the end of the precept-sorting section.
34 ‘God is the efficient cause of infused virtue’. ST 1/2.55.4.
35 Ibid.
36 Ibid., reply to objection 2.
37 I wish to thank my reviewers for their insight, Dafydd Daniel for his guidance and Andrew Sontag, who was an enormous help on this project at every stage.