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Inseparable operations and the human operation of Christ

Published online by Cambridge University Press:  31 October 2023

Steven J. Duby*
Phoenix Seminary, Scottsdale, AZ, USA


The recent recovery of the teaching that the three divine persons share one operation in their outward works raises the question of whether or in what sense the human operation of Christ belongs to the Son alone. My thesis is that all three divine persons move and support the Son's human operation while the Son alone is the proper subject of his human operation. In order to substantiate this thesis, I will consider two main issues: (1) the relationship between divine movement and human energy and (2) the relationship between nature and person in Christ's human action.

Research Article
Copyright © The Author(s), 2023. Published by Cambridge University Press

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1 Augustine, De trinitate libri XV, 2 vols, ed. Mountain, W. J., Corpus Christianorum Series Latina 50–50A (Turnhout: Brepols, 1968)Google Scholar, 4.21.30 (1:202–3).

2 See especially Vidu, Adonis, The Same God Who Works All Things: Inseparable Operations in Trinitarian Theology (Grand Rapids, MI: William B. Eerdmans, 2021)Google Scholar. See also idem, ‘The Incarnation and Trinitarian Inseparable Operations’, Journal of Analytic Theology 4 (2016), pp. 106–27; Wittman, Tyler R., ‘The End of the Incarnation: John Owen, Trinitarian Agency, and Christology’, International Journal of Systematic Theology 15 (2013), pp. 284300CrossRefGoogle Scholar; idem, ‘On the Unity of the Trinity's External Works: Archaeology and Grammar’, International Journal of Systematic Theology 20 (2018), pp. 359–80; Holmes, Stephen R., ‘Trinitarian Action and Inseparable Operations: Some Historical and Dogmatic Reflections’, in Oliver D. Crisp and Fred Sanders (eds), Advancing Trinitarian Theology: Explorations in Constructive Dogmatics (Grand Rapids, MI: Zondervan, 2014), pp. 6074Google Scholar; Kieser, Ty, ‘John Owen as Proto-Social Trinitarian? Reinterpreting Owen and Resisting a Recent Trend’, Scottish Journal of Theology 74 (2021), pp. 222–34CrossRefGoogle Scholar; White, Thomas Joseph, The Trinity: On the Nature and Mystery of the One God (Washington, DC: Catholic University of America Press, 2022), pp. 520–33CrossRefGoogle Scholar; Duby, Steven J., Jesus and the God of Classical Theism: Biblical Christology in Light of the Doctrine of God (Grand Rapids, MI: Baker, 2022), pp. 202–29Google Scholar.

3 Cf. Augustine, De trinitate, 4.21.30 (1:202–3); Aquinas, Thomas, Super Evangelium s. Matthaei lectura, 5th edn, ed. Cai, R. (Rome: Marietti, 1951), 3.2.305Google Scholar (p. 47).

4 Vidu, The Same God, p. 181.

5 Ibid., p. 193.

6 Ibid., p. 209; see also pp. 200, 202–7, 210, 212–5.

7 Translations from the Bible are the author's.

8 The verb κινούμɛθα in Acts 17:28 might be taken as middle or passive. If it is in the middle voice (we move ourselves), it is still a moving done ‘in [God]’ and thus by God sustaining and preveniently moving us. If the verb is in the passive voice (we are moved), the implicit agent by whom we are moved would have to be God, in which case our dependence upon God's prior movement remains clear.

9 See further Aristotle, Aristotelis Physica, ed. W. D. Ross (Oxford: Clarendon, 1950), 3.1.200b–3.2.202a; John of Damascus, Dialectica, in vol. 1 of Die Schriften des Johannes von Damaskos, ed. Bonifatius Kotter (Berlin: de Gruyter, 1969), fus. ξβ’ (pp. 129–31); Thomas Aquinas, Commentaria in octo libros Physicorum Aristotelis, in vol. 2 of Opera omnia, Leonine edn. (Rome: ex Typographia Polyglotta, 1884),, 3–5 (pp. 109–10); Thomas Aquinas, Summa theologiae [hereafter ST], in vols 4–12 of Opera omnia, Leonine edn. (Rome: ex Typographia Polyglotta, 1888–1906), I–II.9.1, 3 (6:74–5, 77–8).

10 Cf. e.g. Aquinas, In Phys., 2.1.3 (p. 56); Aquinas, In duodecim libros Metaphysicorum Aristotelis expositio, ed. M.-R. Cathala and R. M. Spiazzi (Turin-Rome: Marietti, 1950), 5.14.955 (p. 256); 9.1.1776 (p. 425); 9.7.1848 (p. 444); Aquinas, ST, I.2.3 corp. (4:31).

11 When the terminus or effect remains within the acting subject, it is called an ‘immanent’ action. When the terminus or effect is produced outside of the acting subject, it is called a ‘transitive’ action (see e.g. Aquinas, In Metaphys., 9.8.1865 (448); Aquinas, Summa contra gentiles [hereafter SCG], in vols 13–15 of Opera omnia, Leonine edn. (Rome: Typis Ricardi Garroni, 1918–30), 2.1 (13:271); Aquinas, ST, I.27.1 corp. (4:305); Alsted, Johann, Metaphysica (Herborn, 1613), 2.6 (pp. 263–4)Google Scholar).

12 See e.g. Aristotle's distinction between the actuality of form (ἐντɛλέχɛια) and the exercise of a power or habit (ἐνɛργɛῖν) in Aristotelis De anima, ed. W. D. Ross (Oxford: OUP, 1956), 2.1.412a. See also Thomas Aquinas, De potentia, in vol. 2 of Quaestiones disputatae, ed. P. Bazzi et al. (Turin-Rome: Marietti, 1965), 1.1 corp. (pp. 8–9); Alsted, Metaphysica, 1.3 (p. 48); 1.13 (pp. 123–4, 132). Sometimes ‘energy’ can be associated especially with immanent (rather than outward or transitive) acts. For example, John of Damascus discusses ‘energy’ as the ‘natural power and movement’ that is ‘implanted’ in every essence – ‘energy’ as ‘fundamental energy’ (ἡ τροπὴ ζῴου ἐνέργɛια) or ‘life itself’, which, for rational creatures, includes rational thought. John also calls this ‘simple and unrelated energy’ (ἁπλῆ καὶ ἄσχɛτος ἐνέργɛια) in contrast to outward ‘actions’ (πράξɛις) (e.g. speaking and walking) (Expositio fidei, in vol. 2 of Die Schriften des Johannes von Damaskos, ed. Bonifatius Kotter (Berlin: de Gruyter, 1973), 2.23 (p. 93); 3.15 (p. 145)). However, when the primary actuality of nature itself (esse, actus primus) is distinguished from all consequent immanent and outward acts (actus secundi), it is typical to link the term ‘energy’ with the latter (including both immanent and outward secondary acts).

13 John of Damascus, Expositio fidei, 3.15 (p. 144); Aquinas, ST, III.19.1 ad 3 (11:241); Bartholomäus Keckermann, Systema logicae, tribus libris adornatum, in vol. 1 of Operum omnium quae extant (Geneva: Petrus Aubertus, 1614), 1, sect. prior, 17 (p. 624); Alsted, Metaphysica, 1.27 (p. 222); Francis Turretin, Institutio theologiae elencticae, 3 vols., 2nd edn (Geneva: Samuel de Tournes, 1688), 14.2.3 (2:412); Mastricht, Peter van, Theoretico-practica theologia, 2nd edn (Utrecht: van de Water et al., 1724), 5.4.13Google Scholar (p. 540). The notion that essence or form is what shapes and facilitates actions is granted conciliar status at the Council of Chalcedon, where Leo's letter to Flavian affirms that ‘each form [of Christ] does what is proper, with the communion of the other’, and at the Third Council of Constantinople, where the exposition of the faith affirms Leo's teaching and speaks of Christ's ‘two physical energies’ and of each nature ‘energizing proper things’. See Council of Chalcedon, ‘The letter of Pope Leo to Flavian’, in Norman P. Tanner (ed.), Decrees of the Ecumenical Councils – Volume One: Nicaea I to Lateran V (Washington, DC: Georgetown University Press, 1990), p. 79; Third Council of Constantinople, ‘Exposition of faith’, in Decrees of the Ecumenical Councils, pp. 128–9.

14 On different senses of the word ‘subject’, see e.g. Aristotle, Aristotelis Metaphysica, ed. W. Jaeger (Oxford: Clarendon, 1957), 7.13.1038b (p. 156); John of Damascus, Dialectica, fus. ιζ’ (p. 86); Aquinas, In Metaphys., 7.13.1567–8 (p. 378); Polanus, Amandus, Logicae libri duo (Herborn: Corvinus, 1590), 1 (pp. 21–3)Google Scholar; Keckermann, Systema logicae, 1, sect. prior, 20 (pp. 631–3); Alsted, Metaphysica, 1.24 (pp. 180–2).

15 So e.g. Bonaventure: ‘a person acts by virtue of nature, whence that virtue and operation belongs to a certain person’ (Commentaria in quatuor libros Sententiarum, vol. 3, in vol. 3 of Doctoris seraphici s. Bonaventurae opera omnia (Florence: ex Typographia Collegii S. Bonaventurae, 1887), corp. (p. 126)). Cf. e.g. Aquinas, ST, I.77.1 ad 3 (5:277); III.19.1 ad 4 (11:241); Aquinas Compendium theologiae, in vol. 42 of Opera omnia, Leonine edn. (Rome: Editori di San Tommaso, 1979), 1.212 (p. 165); Polanus, Amandus, Syntagma theologiae christianae (Hanover: Johannes Aubrius, 1615), 6.15Google Scholar (p. 374).

16 See e.g. Gisbertus Voetius and Engelbertus Beeckman, De libertate voluntatis, in Disputatio philosophico-theologica (Utrecht: à Waesberge, 1652), 4 (no pagination); Turretin, Inst., 6.5 (1:557–61); Mastricht, Theoretico-practica theologia, 3.10.10, 29, 33 (pp. 390–1, 395–6, 398–9). My thanks to Professor Andreas Beck for providing a copy of the text of the Voetius disputation cited here, which Professor Beck discovered several years ago.

17 In debates about the relationship between divine and human action, some theologians express concern that the term concursus literally suggests that divine and human action occur in the same order of being, implying that they might be in competition with one another. A very brief description of some of the underlying concerns can be found in Taylor Patrick O'Neill, Grace, Predestination, and the Permission of Sin: A Thomistic Analysis (Washington, DC: Catholic University of America Press, 2019), pp. 96–102. Happily, however, the Reformed authors’ discussions of divine and human action cited above make clear that divine and human action do not take place in the same order of being and thus do not stand in competition with one another. This makes their use of the term concursus, if somewhat confusing in certain circles, nevertheless materially unobjectionable to those who want to stress that God can and does move and act through creatures as subordinate causes.

18 The Synopsis purioris theologiae, for example, states that God concurs with creatures ‘so that by his own action he immediately flows into the action of the creature, so that one and the same action from the first and second cause is said to proceed, to the extent that from this one work or ἀποτέλɛσμα exists’ (Johannes Polyander et al., Synopsis purioris theologiae, 4th edn (Lugduni Batavorum: Elsevier, 1652), 11.13 (p. 111)). Voetius remarks that physical premotion is treated either as a ‘principle exciting’ and thus distinct from our action or as an action ‘virtually going over [going forth with our action to an effect]’ and thus identified with our action (De libertate voluntatis, 4). Turretin writes that it is not absurd to have two causes for the same effect when those two causes, both ‘totally acting’, are ‘of a diverse order’, and when ‘the action of each cause is, in the end [demum], one, by which they concur to the effect’ (Inst., 6.5.15 [1:562]). It seems to me that Turretin's word demum is important here, for it implies that the divine and creaturely actions are not totally identical but are, instead, unified in a particular way, namely, with respect to their endpoint (one and the same effect).

19 Turretin, Inst., 6.5.14 (1:561).

20 See Thomas Aquinas, Quaestio disputata de unione Verbi incarnati, in vol. 2 of Quaestiones disputatae, 10th edn, ed. P. Bazzi (Rome-Turin: Mariett, 1965), q. un., a. 4 corp. (p. 432); Aquinas, ST, III.3.1 ad 3 (11:53–4).

21 The brief account offered here is indebted to Aristotle, Physica, 2.1–2.192b–194b; Metaphysica, 5.4.1014b–1015a (pp. 91–2); Boethius, Contra Eutychen, in The Theological Tractates, The Consolation of Philosophy, trans. H. F. Stewart et al., Loeb Classical Library 74 (Cambridge, MA: Harvard University Press, 1973), 1 (pp. 76–81); John of Damascus, Dialectica, fus. μα’ (p. 107); Aquinas, In Phys., 2.1–2 (pp. 56–60); Aquinas, In Metaphys., 5.5 (pp. 221–4); Aquinas, De unione Verbi incarnati, q. un., a. 1 corp. (p. 422); Alsted, Metaphysica, 1.3–4 (pp. 41–53). Further discussion of the diverse use of ‘nature’ can be found in Johannes Zachhuber, ‘Nature’, in Mark Edwards (ed.), The Routledge Handbook of Early Christian Philosophy (London: Routledge, 2021), pp. 27–40.

22 Cf. Danker, Frederick William et al., A Greek-English Lexicon of the New Testament and Other Early Christian Literature, 3rd edn (Chicago, IL: University of Chicago Press, 2000), p. 1069Google Scholar.

23 On the one hand, nature as a principle of motion can be taken as that by which someone will gravitate toward certain things and be affected in certain ways. On the other hand, nature as a principle of motion or, more particularly, a principle of operation can be taken as that by which one produces actions and effects in pursuit of an end. See further John of Damascus, Dialectica, fus. λα’ (pp. 93–5); μα’ (p. 107); John of Damascus, Expositio fidei, 2.22 (p. 88); 3.15 (pp. 144–5); Aquinas, In Phys., 2.1.4–5 (pp. 56–7); Aquinas, In Metaphys., 5.5.809–15, 819 (pp. 222–3); Aquinas, De pot., 1.1 corp. and ad 9 (pp. 8–9); Aquinas, De unione Verbi incarnati, q. un., a. 1 corp. (p. 422); a. 5 ad 4 (p. 434); Aquinas, Compendium theologiae, 1.212 (p. 165); William Ames, Theses logicae, in Philosophemata (Amsterdam: Janssonius, 1651), 58 (p. 165); Alsted, Metaphysica, 1.3 (p. 43). John of Damascus in particular distinguishes between a ‘movement [κίνησις] in one [that is caused] by another’ (i.e. passion) and an ‘effective movement’ (κίνησις δραστική, i.e. action) wherein something is moved ‘of itself’ or has in itself ‘active power’ and the ‘cause of energy’ with which to affect another (Dialectica, fus. νγ’ (p. 123); Expositio fidei, 2.22 (p. 88); 2.23 (p. 94)). In this connection, one can say that the energy or active movement of the created agent is caused by God, but then, in virtue of now being activated, the creature is itself determined to be an efficient cause with respect to another created being and thus directs its powers to that undertaking.

24 John of Damascus, Expositio fidei, 3.11 (p. 131); Aquinas, In Metaphys., 7.13.1570–1 (p. 378); Aquinas, ST, III.4.4 (11:82–3); Alsted, Metaphysica, 1.3 (pp. 43–4); 1.16 (pp. 143–6).

25 The same judgement expressed in similar language can be found in Bonaventure, In Sent., (p. 127); Aquinas, In Phys., 2.1.3 (p. 56), but the particular axiom actus sunt suppositorum, with small variations, is present in, e.g. Aquinas, ST, I.39.5 ad 1 (4:405); 40.1 ad 3 (4:412); 77.1 ad 3 (5:277); II–II.58.2 corp. (9:10); III.3.1 corp. (11:53); III.19.1 ad 3 (11:241); III.20.1 ad 2 (11:248); Aquinas, Compendium theologiae, 1.212 (p. 165); Polanus, Syntagma, 6.15 (p. 374); Alsted, Metaphysica, 1.3 (p. 53); Johannes Maccovius, Loci communes theologici, 2nd edn, ed. Nicolaus Arnoldus (Amsterdam: Elzevirii, 1658), 30 (p. 242); Turretin, Inst., 14.12.7 (2:478). The statement that actions pertain or belong to supposits or ‘singulars’ is sometimes attributed to Aristotle, Metaphysica, 1.1.981a (p. 2): αἱ δὲ πράξɛις καὶ αἱ γɛνέσɛις πᾶσαι πɛρὶ τὸ καθ’ ἕκαστόν ɛἰσιν (‘actions and generations all are concerning the individual’); cf. e.g. Aquinas, ST, III.20.1 ad 2 (11:248). In context, Aristotle's point is that experience pertains to individuals, making it apparently superior to practical knowledge of universals, since acting upon and generating or producing things is directed toward particular beings, not toward universals per se. Aquinas’ commentary on the Metaphysics may provide a clue as to why he and others think this text in Aristotle is relevant to claiming not only that actions are directed toward particular beings but also that actions are produced by particular beings. If ‘universals are not generated or moved, except per accidens, inasmuch as this belongs to singulars’ (Aquinas, In Metaphys., 1.1.21 (p. 9)), then it would logically follow that it is never the universal but only the individual who has the universal that will perform actions. On a somewhat different note, for Aquinas, the notion actus sunt suppositorum applies even when, strictly speaking, an action is most directly performed by one part of the composite person (e.g. the eye or the hand) (ST, 75.2 ad 2 (5:197); II–II.58.2 corp. (9:10)). See also the counterbalancing point in Aquinas, Compendium theologiae, 1.89 (p. 112), where it appears that one part of the person (e.g. the soul) is more directly and properly called the subject of an action. This is discussed further in Carl, Brian T., ‘Action, Supposit, and Subject: Interpreting Actiones Sunt Suppositorum’, Nova et Vetera 17 (2019), pp. 545–65CrossRefGoogle Scholar.

26 A human being will act, then, not only in virtue of what is natural or common to human beings but also in virtue of certain factors unique to this or that particular human being. In attempting to recover the important notion that human beings are and ought to be governed by their God-given nature even in a ‘postmodern’ age, it is important to remember that human beings are also not totally reducible to their common nature.

27 Cf. Aquinas, ST, III.4.4 corp. (11:82).

28 John of Damascus, Expositio fidei, 3.13 (pp. 136–7); 3.14 (pp. 137–8); 3.15 (pp. 146–7); 3.19 (pp. 160–2).

29 Ibid., 3.15 (pp. 145–6, 150–1); 3.19 (pp. 160–2). Cf. also Leo's letter taken up at Chalcedon, where he remarks that ‘each form [of Christ] does what is proper to it’. However, Leo also states that the acts and sufferings of Christ are of and in one nature or the other, which leaves room for the clarification that it is, strictly speaking, the person of Christ who is the acting and suffering subject in the incarnation (‘Letter of Pope Leo to Flavian’, pp. 79–80).

30 John of Damascus, Expositio fidei, 3.14 (p. 137).

31 Ibid., 3.14 (p. 138); cf. 3.15 (pp. 146, 150–1).

32 Ibid., 3.15 (p. 144).

33 See e.g. Aquinas, De unione Verbi incarnati, q. un., a. 5 corp. (p. 434); Aquinas, ST, III.3.2 ad 3 (11:56); Keckermann, Systema logicae, 1, sect. prior, 20 (p. 633); Ames, Theses logicae, 73 (p. 166); Turretin, Inst., 14.2.2–3 (2:411–2); Mastricht, Theoretico-practica theologia, 5.4.13 (p. 540).

34 John of Damascus, Expositio fidei, 3.14 (p. 138).

35 For more discussion of the Son's humanity as an instrument in dialogue with Cyril of Alexandria, John of Damascus, and Aquinas, see Duby, Jesus and the God of Classical Theism, pp. 157–61.

36 Aquinas, SCG, 4.41 (15:141–2).

37 Aquinas, ST, III.19.1 corp. and ad 1–2 (11:239–40).

38 Aquinas, ST, III.19.1 ad 1 (11:240). Cf. Aquinas, Compendium theologiae, 1.212 (p. 165).

39 Cf. e.g. Bonaventure, In Sent., corp. and ad 2 (p. 30); Aquinas, ST, III.3.8 (11:70).