Immutability and Incarnation

It is often taken for granted that arguments for God's existence are a staple of Christian apologetics. However, while immense effort has been expended on the premises of arguments for God, apologists have given much less attention to the implications of their conclusions for theology more generally. Having copiously established a First Cause or an Unmoved Mover, we hastily reason that this must be the Christian God, or at least the generic God of monotheism (“and this we call God”).

In Five Proofs of the Existence of God, the philosopher Edward Feser offers us yet five more arguments for God.¹ However, the God found in the concluding statements of his arguments looks quite different from the God found in the Bible. Is Feser’s First Cause the God of Abraham, Isaac, and Jacob?

I want to suggest that when we evaluate the theological implications of Feser’s Aristotelian Proof, we find a God that is incompatible with the God of the Bible. As such, Christians should give serious pause before adopting this argument as their own.

First, I will summarize the key thrust and relevant conclusions of Feser’s argument. I will then argue that the implications of this argument, in particular its strong view of God’s immutability (i.e. unchangeableness), are in tension with what we find in Scripture, and that the argument therefore has undesirable theological implications. Finally, I will consider two responses to this problem, one by Feser and another by Eleonore Stump, and argue that they are both unsuccessful.

The conclusion to draw is that more work needs to be done in the area of immutability and the incarnation. The lesson for Christians is this: before simply adding new arguments to our apologetic toolbox, we would do well to investigate their theological implications — and whether they are actually arguing for the God of the Bible that we worship.

Feser’s Aristotelian Proof

The first argument in Feser’s book is the Aristotelian Proof.² Feser models this argument after Aristotle’s own classic argument for an Unmoved Mover. Modernizing it and clothing it in the language of analytic philosophy, Feser’s argument is for a purely actual actualizer.

The argument begins with the observation that change occurs. For Feser (and Aristotle), change involves the actualization of a potential. My coffee is currently hot, but then it cools down; it goes from potentially cool to actually cool. Feser observes that whenever change occurs in this way, the movement from potential to actual requires something else that is already actual to make it happen. So, for instance, the coffee changing from potentially cool to actually cool requires something already actual — the cool air in the room — to bring the change about.

Employing ad infinitum reasoning, Feser concludes that unless this hierarchical (not temporal) series at this moment has a purely actual actualizer which itself does not require something else to actualize it, the chain would go on infinitely and nothing would ultimately be actualized. Thus, there must be a purely actual actualizer, which itself has no potentialities that need to be actualized, in order to ground the series and “move” everything else without itself having to be moved.

While the specific steps in Feser’s argument are fascinating and have already produced cutting-edge metaphysical dialogue,³ my concern here is with the theological implications underpinning the conclusion of his argument. The first implication is what we might call strong divine immutability. As Feser puts it: “God is pure actuality, devoid of potentiality.”⁴

The second implication, which Feser draws out from what it means for something to be purely actual, is divine simplicity: God has no parts of any kind, including any metaphysical parts. This is because if God had any parts, then they could potentially be separated. But God cannot have any potentialities. In fact, Feser notes that his Aristotelian argument, and indeed all the arguments in his book, “entail that there must be a cause which is in no way a mixture of actuality and potentiality or of essence and existence … As arguments for a First Cause, they are ipso facto arguments for an absolutely simple … cause.”⁵

God’s simplicity is crucial for Feser because it is what makes God special and worthy of worship:

[T]o deny that God is simple … is implicitly to deny his uniqueness and ultimacy … [S]uch a denial makes of God a mere instance of a genus, it reduces him to the status of a member of a pantheon of gods, and it does so even if we think of him as the unique member. … We would … have reduced God to what is, in essence, nothing more than a kind of superangel. Worshipping him would therefore constitute a kind of idolatry.⁶

To summarize the theological implications so far, then: if God was capable of change — if God had any potentials at all — he would not be God. Thus, he must be pure actuality itself. Further, if God was merely a being among other beings, he would not be God; he must be pure Being itself. Feser’s argument, in short, leads to the existence of the God of classical theism.

A Difficulty for Classical Theism

Merold Westphal notes that one danger for classical theism is that it begins with the wrong starting point: human reason rather than divine revelation. It is not that thinking of God as the First Cause of the universe is factually wrong per se. Rather, it is that “this language has its provenance in a project that can be traced from Anaxagoras to Nietzsche … and that is deeply antithetical both to authentic philosophy and to authentic theology.”⁷ The danger is that this approach ultimately leaves us “with the God of the philosophers instead of the God of Abraham, Isaac, and Jacob.”⁸

In contrast to the purely actual God of classical theism, the God of Israel in Scripture seems to be capable of profound change. In the incarnation, for instance, the second person of the trinity took on a human nature in addition to his divine nature, “being born [γίνομαι] in human likeness” (Phil 2:7). Christ the Word “became [γίνομαι] flesh” (John 1:14). This language in the New Testament quite literally has the sense of change and becoming: “to experience a change in nature and so indicate entry into a new condition, become someth[ing]” (BDAG, s.v. γίνομαι 5).

Now classical theists, for their part, are not unaware of this difficulty. In The God of the Bible and the God of the Philosophers, for instance, Eleonore Stump takes very seriously the biblical challenge to classical theism:

By contrast with these biblical representations of God, to many people the God of classical theism seems unresponsive, unengaged, and entirely inhuman. That is because, on classical theism as it is often interpreted, God is immutable, eternal, and simple, devoid of all potentiality, incapable of any passivity, and inaccessible to human knowledge. So described, the God of classical theism seems very different from the God of the Bible.⁹

Stump proposes to address the problem by affirming the biblical truth that God does change (and even suffers), but by maintaining that this occurs exclusively within Christ’s human nature. So, for instance, she says: “The person who wept over Lazarus was God — God in his human nature but still God.”¹⁰ In this qualified sense, then, “it is true to say that God suffers and that God dies.”¹¹ Nevertheless, “[i]n his divine nature, God neither suffers nor dies, since neither suffering nor dying is compatible with the divine nature; but God does suffer and die in the human nature God has assumed.”¹² Thus, for Stump, it is possible for God to change and suffer and die, but only within God’s human nature, never in his divine nature. It thus appears that, in this qualified sense, classical theism may be able affirm these biblical truths after all.

However, there are still questions. For one thing, locating God’s suffering within Christ’s human nature only addresses the problem for one person of the trinity. What about the Father and the Holy Spirit? In Psalm 78:40, for instance, it appears that the Father can suffer; the psalmist laments about the ways that Israel has grieved God: “How often they rebelled against him in the wilderness and grieved him in the desert!” Likewise, in the New Testament Paul commands his readers, “do not grieve the Holy Spirit of God” (Eph 4:30). In both of these cases, the other members of the trinity seem capable of being grieved, capable of suffering. Do the Father and Holy Spirit therefore also require a human nature on Stump’s view?

There is a further problem with locating God’s ability to change or suffer exclusively within God’s human nature: God has not always had a human nature. Indeed, the notion of God “taking on” a human nature would itself seem to be a form of change, and thus violate God’s immutability. In an attempt to address this problem, Stump is forced to affirm that in fact a human nature is something God in his eternal changelessness must always have:

If God is eternal, then God’s having an assumed human nature is not something characteristic of God at some times but not at others. It is something characteristic of God always. On this view, God is never in the state of not having an assumed human nature. For this reason, on the understanding of God as eternal, God is never unable to suffer and die. The capacity for suffering and dying is something characteristic of God always, in the human nature whose assumption is always with God.¹³

So, for Stump, technically speaking, God cannot “take on” a human nature. In order not to change, God must always have a human nature. Does this solve the problem? Perhaps. However, in solving this problem, it appears that Stump introduces a bigger one.

A Fly in the Ointment: On the Necessity of the World

The problem with saying that God in his changeless eternity must always have a human nature is that a human nature presupposes the existence of the world. Thus, in attempting to avoid God’s changing by taking on a human nature, Stump unwittingly commits herself to the necessary existence of the world: creation must exist because a human nature must always exist in God. This is a problem the philosophical theologian Ryan Mullins has elsewhere called “modal collapse.”¹⁴ If we say that the second person of the trinity must always have a human nature, and if a human nature requires creation, then, “[t]his makes God’s essential nature dependent upon creation.”¹⁵ In short, it means that God “is not free to exist without creation … God must exist with creation.”¹⁶ So, Stump’s commitment to strong immutability entails that God must be dependent on the universe, which in turn violates his freedom and sovereignty. There is a fly in the ointment.

More recently, Edward Feser has also attempted to address the problem. While he does not address the incarnation directly, towards the end of his book he does briefly attempt to explain how it could be that God appears to change even though God is incapable of change. He does this by appealing to so-called Cambridge changes.

Suppose, he says, that Socrates becomes “shorter than Plato, not because Socrates’ height actually changed but only because Plato has grown taller.” This is not “a real change in Socrates but what Geach called a mere ‘Cambridge change’ and therefore involves the acquisition of a mere ‘Cambridge property’.”¹⁷ In a nutshell, everything we might think is a change in God is really just a change in the world. Rather unintuitively, for Feser this even includes God’s actions, such as creating the world: “just as Socrates’ being shorter than Plato is a mere Cambridge property …, so too is God’s having created the world a mere Cambridge property (because it involves the world’s coming into being rather than any change in God himself).”¹⁸ It thus appears that we must conclude that even something like the incarnation, which appears to be a change in God, is really only a change in the world too.

I question Feser’s solution. For one thing, it is unclear whether this tidy stopgap solution takes the language of Scripture seriously enough; it seems to outright deny the “becoming” language of the Greek of the New Testament that describes the incarnation. Did the Son becoming human really involve no change in the Godhead whatsoever? While Stump’s approach at least tries to take this seriously, Feser’s approach simply sidesteps it.

I am also doubtful whether this is a way anyone would ever speak about the incarnation or God’s other actions if it were not for the need to avoid saying that God changes. It seems that what is really going on is that, having started with human reason, Feser must now downplay revelation to fit his metaphysics.

A more practical spiritual problem for Feser’s solution also bears brief mention. If when thinking about God we insist that only the world changes, this would appear to lead to a kind of functional atheism. The easiest way to see this is by considering the problem of petitionary prayer. Since, on Feser’s view, prayer produces no change in God, this means the only thing our prayers really change is ourselves. They might inspire us or provide us with comfort, but they will never affect God — indeed, nothing ever can or will. In my opinion, this effectively reduces prayer to a kind of psychological self-help practice; it cannot produce any changes in God, only possibly in us. I do not think I could ever pray believing this.

Conclusion

In summary, we have seen that Feser’s Aristotelian Proof for a purely actual actualizer or Unmoved Mover yields problematic theological conclusions. The Unmoved Mover does not resemble the God of the Bible; he remains unmoved by our prayers or by anything else. Further, we have seen that two attempts by prominent classical theists to address this problem fail. Eleonore Stump’s attempt to locate God’s changing and suffering exclusively within Christ’s human nature does not explain how the Father or Holy Spirit could suffer, and it also appears to lead to a modal collapse, making God’s nature parasitic upon creation. We also considered Feser’s own attempt to explain the apparent changes of God in Scripture by appealing to so-called Cambridge changes. However, aside from the fact that this solution does not even attempt to take seriously the language of Scripture, we also saw that it appears to lead to a kind of fatalism where our most earnest and heartfelt prayers do not change God, but only ourselves.

It seems, then, that classical theists still have more work to do in the area of immutability and incarnation. They need a better account of God’s attributes that can avoid a modal collapse. Perhaps even more importantly: they need a better starting point, divine revelation rather than human reason.

The lesson for apologetics is a sobering one. While it is tempting for Christians to place any tool they can find into their apologetic toolbox, this must be done with care. There are myriad and conflicting views of God underlying different philosophical arguments. In order to discern which of these can be safely and consistently utilized within one’s overall theological framework, apologists must accept the call to become more than apologists only; they must become theologians in their own right.

The importance of the task calls for nothing less. Rightly understood, apologetics is thus ultimately an invitation into a deeper understanding of God that flows naturally into theology; surely, its proper end.

[1] Edward Feser, Five Proofs of the Existence of God (San Francisco: Ignatius Press, 2017).

[2] Feser, Five Proofs, 17-69.

[3] Graham Oppy, “On stage one of Feser’s Aristotelian proof,” Religious Studies 57 (2021): 491-502; Edward Feser, “Oppy on Thomistic cosmological arguments,” Religious Studies 57 (2021): 503-522.

[4] Feser, Five Proofs, 189.

[5] Feser, Five Proofs, 195.

[6] Ibid., 189-90.

[7] Merold Westphal, Overcoming Onto-Theology: Toward a Postmodern Christian Faith (New York: Fordham University Press, 2001), 13.

[8] Westphal, Overcoming Onto-Theology, 13.

[9] Eleonore Stump, The God of the Bible and the God of the Philosophers (Milwaukee, WI: Marquette University Press, 2016), 18.

[10] Ibid., 101.

[11] Ibid.

[12] Stump, The God of the Bible and the God of the Philosophers, 101.

[13] Ibid., 100-1.

[14] Ryan T. Mullins, “Simply Impossible: A Case Against Divine Simplicity,” Journal of Reformed Theology 7, no. 2 (2013): 196.

[15] Ibid., 196.

[16] Ibid., 195-6.

[17] Feser, Five Proofs, 196.

[18] Ibid.