For us humans and for our salvation he came down and became incarnate, became human . . .Footnote 1
Introduction
According to the foundational creeds of orthodox Christian faith, the divine Son of God became incarnate and in so doing became human. It's widely held that physicalists (understood here as those who believe that human persons are wholly physical substances) have a difficult time making sense of this central Christian doctrine. The problem is seemingly straightforward: if physicalism is true, then the Son of God became a physical object and that seems impossible. Thus, Plantinga has famously argued:
If, however, as materialists assert, to be a human being is to be a material object, then the second person of the Trinity must have become a material object. If he has remained a human being, furthermore, he is presently a material object. But then an immaterial being became a material object; and this seems to me to be impossible. (Plantinga, (Reference Plantinga1999), 186)
And in a similar vein, Leftow complains:
To me, materialist christologies are non-starters. My intuitions say that [God the Son is identical to a human body] is flatly impossible. How could an immaterial thing become material? How could something relevantly like a soul became [sic] something relevantly like a stone? The answer it seems to me, ‘it couldn't’. (Leftow, (Reference Leftow, Marmodoro and Hill2011), 21)
Similar objections can be found elsewhere in the literature, but the lesson is the same: believers in the incarnation should be dualists.
This is a problem for those of us who think there are good reasons to be a physicalist who also wholeheartedly embrace the ecumenical creeds of the Church. If a physicalist incarnation really were impossible, we'd be forced to abandon either physicalism or the reality of the incarnation and I, at least, am not inclined to do either. My task, then, is to explore ways of reconciling them. Unlike Merricks (Reference Merricks, van Inwagen and Zimmerman2007), I'm not going to argue that physicalists have a better account of the incarnation than dualists nor will I advance an incarnational argument for physicalism. I'll be content simply to address some key objections to a physicalist incarnation and in so doing take an important step toward demonstrating the compatibility of physicalism and the doctrine of the incarnation.
Before I turn to the main work of the article, let me say something about the philosophical and theological framework that I'm going to assume beginning with my preferred version of physicalism. I'm going to assume the truth of animalism, the view that human persons are identical to human organisms. In fact, I'll assume a particular version of animalism, psychologically serious animalism, that I've discussed elsewhere (Sharpe Reference Sharpe2015). In that article I argued that we have good reason to take psychologically serious animalism seriously as an alternative to the standard sort of animalism that one finds in the work of Eric Olson and Peter van Inwagen. I realize that not everyone will find this view as attractive as I do, but even those disinclined towards this sort of animalism may be interested in its potential theological applications.
Second, I assume that the Son's becoming human was a matter of his being transformed into a human and not merely his assumption of a concrete human nature. That is, I'll assume a transformationalist, as opposed to a compositionalist, account of the Incarnation.Footnote 2 For what it's worth, I actually think assuming a transformationalist model of the incarnation makes the physicalist's task harder, as I think it's a bit easier to understand how a compositionalist model could accommodate physicalism.Footnote 3 Despite the additional philosophical complications it presents, transformationalism (to my mind at least) best captures the force of the Nicene claim that the Son of God became human as well as the witness of scripture (but this goes well beyond what I can argue for in this article). Combined with physicalism, this account of the Son's incarnation involves an immaterial divine person's being transformed into a human animal while remaining a divine person. Since this version of transformationalism involves the Son's being transformed into a physical substance, I'll refer to it as physicalist transformationalism. In what follows I explore the ways in which one might press objections to physicalist transformationalism based on kind membership and I aim to show that my preferred account of animalism motivates a principled and independently plausible avenue of response to these sorts of objections. I begin with an overview of kind essentialism and a popular account of the relation between kinds and modal properties.
Kinds, modal properties, and persistence conditions
Following Kripke's seminal work in the latter part of the twentieth century, it's been increasingly common for philosophers to accept some version of essentialism, the view that objects have some of their properties essentially, where an object, o, has a property, F, essentially just in case it is impossible for o to exist and fail to be F. Essential properties are contrasted with accidental properties, properties of an object that it may exist without instantiating. Of particular importance for our purposes are the essentiality of kind membership and constitution. According to kind essentialism, as that doctrine is typically understood, if something is a member of a kind, then it is essentially a member of that kind.Footnote 4 Thus, if K is a kind and o is a K, then o is essentially a K. Consider, for example, my dog Dexter. He is a canine and essentially so. It is impossible for Dexter, that very individual, to exist and fail to be a canine. Similarly, (most) animalists say, with human persons. We are biological organisms that belong to the primate species Homo sapiens. Thus, we are essentially organisms of that kind. It is impossible for a human person, like you or me, to exist and fail to be a human animal. Further, assuming that it's a necessary truth that animals are physical substances, then human persons are essentially physical substances.
Related to the doctrine of kind essentialism is a conception of the relation between kinds and persistence conditions popularized by David Wiggins. According to the standard Wigginsian picture, every kind is associated with a set of persistence conditions and, more generally, a set of modal properties.Footnote 5 On this view, an object has the modal properties it does in virtue of belonging to the kind associated with that set. We have, then, the standard account of kinds and modal properties (including persistence conditions):
(Kinds) For any kind K, there is a set of modal properties, M, such that necessarily, for any x, x is a member of kind K if and only if x has the members of M.
Applying (Kinds) to animals entails that if something is an animal, i.e. it belongs to the kind animal, then it has the modal properties associated with that kind; that is, (Kinds) entails
(Animal) Necessarily, for any x, if x is a member of the kind animal, then x has the modal properties, including persistence conditions, associated with animal.
Plausibly, modal properties like being essentially organic and being essentially physical are associated with the kind animal (and so members of that kind are essentially organically constituted). Additionally, assuming the persistence conditions associated with animal are purely biological, it follows that every individual animal has purely biological persistence conditions. The biological account of animal persistence can be traced back to, at least, Locke, who held that since ‘an animal is a living organized body’, ‘the same animal . . . is the same continued life communicated to different particles of matter, as they happen successively to be united to that organized living body’, where an organism's life is a special type of biological event (Locke (Reference Locke and Winkler1996), 137).Footnote 6 On this view, animals persist so long as their lives persist, i.e. so long as there is no disruption of the organism's vital biological processes.Footnote 7 Biological continuity, then, is both necessary and sufficient for animal persistence; hence, the following account of animal persistence:
(Biological persistence) Necessarily, for any x and y, if x is an animal at t1 and y is something that exists at another time, t2, then x = y if and only if y is biologically continuous with x.Footnote 8
With this basic account of kind membership and its relation to modal properties in hand, we have the makings of at least three related objections to physicalist transformationalism.
Three objections to physicalist transformationalism
Kind essentialism
Merricks (Reference Merricks, van Inwagen and Zimmerman2007) argues that physicalist transformationalism is inconsistent with kind essentialism.Footnote 9 Suppose that animal (or perhaps, more generally, organism) is a genuine kind, then it follows that all animals are essentially animals. If this is the case, then it is impossible for something to become an animal, where the relevant notion of becoming involves an object's acquiring a property that it previously lacked, since it is impossible for something to acquire an essential property. After all, if o is essentially K, then it is impossible for o to exist and not be a K and hence there's no time at which o exists and is not a K. But then it follows straightforwardly that it is impossible for the Son to become a human animal. Thus, animalist versions of physicalist transformational are incoherent and if, as Merricks urges, physical object is a genuine kind, then all forms of physicalist transformationalism are incoherent.
Constitutional essentialism
Marmodoro (Reference Marmodoro, Marmodoro and Hill2011) has argued, on Kripkean grounds, that physical substances are essentially physical and non-physical substances are essentially non-physical (or, as she puts it, incorporeal). If this is right, then physicalist transformationalism is impossible, as it would require a non-physical entity (e.g. the pre-incarnate Son) to become a physical entity. In the course of considering whether it would be possible for a computer to become a human, Marmodoro argues that
humans are essentially organic, qua belonging to a natural kind of such a type, while Deep Blue-K [a robot that replicates human appearance and behaviour] is essentially electronic, qua artefact of such a constitution. So Deep Blue cannot become/be another Kasparov [a Russian chess master]. On Kripke's argument, a human being cannot be embodied in a computer, since a human being cannot be constituted of silicon. (ibid., 214)
This argument draws it strength from the plausible idea that kind membership constrains compositional possibilities. In virtue of being members of a particular kind, individuals are essentially subjects of particular sorts of constitution, i.e. the sort of constitution associated with the kind in question. Accordingly, Marmodoro starts with a general thesis of human constitution:
(Human constitution) Being essentially organic is a modal property associated with the kind human animal.Footnote 10
In conjunction with (Animal), (Human constitution) implies that every human animal has the modal property being essentially organic. Human animal constrains the compositional possibilities of its members in that nothing could be a member of that kind and fail to be essentially organically constituted. As such, no human could become a robot (i.e. a member of a robotic kind), since members of robotic kinds are essentially electronic and nothing could be organically constituted and composed of silicon and metal. Parallel reasons imply that no robot could become human.
The argument has direct application to the possibility of physicalist transformationalism. We've just seen that if Marmodoro's Kripkean-inspired line of thought is correct, then modal properties like being essentially organic and being essentially physical are associated with the kind human animal such that every member of the kind has that property and, if that's correct, then it is impossible for a non-organic, non-physical being – like the pre-incarnate Son – to become a human animal. And this is just the conclusion Marmodoro draws:
God the Son is essentially a spiritual, that is, non-physical being. On this basis, it follows that the Son cannot come to be a material being . . . A human being is essentially constituted of flesh and bone. And if God the Son is non-physical, then he cannot come to be constituted of something physical. The Son cannot come to be constituted of matter any more than what is essentially made of flesh and blood can come to be constituted of cables and electronic chips. (ibid., 222)
Thus, we have a second reason for doubting the consistency of kind essentialism and physicalist transformationalism: to become a member of a kind, an entity must acquire the modal, including constitutional, properties associated with that kind. But the Son cannot acquire the constitutional properties associated with human animal, since he cannot become essentially organically constituted.
Persistence conditions
According to the version of physicalist transformationalism we're considering here, the Son's becoming incarnate is a matter of his becoming a human animal. Yet if the incarnate Son is an animal, then (Animal) entails that the Son has the persistence conditions associated with the kind animal. It's widely assumed, and I'm prepared to grant, that the persistence conditions associated with animal are purely biological, as stated in (Biological persistence). In conjunction with (Animal), (Biological persistence) entails that the incarnate Son has purely biological persistence conditions.
Independent of whether a biological account of personal identity for human persons is plausible, this is a problem for physicalist transformationalism. The pre-incarnate Son was not an organism and did not have purely biological persistence conditions. Hence, prior to the incarnation, the Son did not have the persistence conditions associated with the kind animal. Since it is impossible for something to change its persistence conditions,Footnote 11 the Son doesn't have purely biological persistence conditions post-incarnation. It follows that the incarnate Son is not a human animal, contrary to the animalist account of physical transformationalism under consideration here.
Psychologically serious animalism and physicalist transformationalism
The arguments of the preceding section present a serious challenge to physicalist transformationalism. Merricks's response to the first argument is simply to deny kind essentialism, on the grounds that all Christians – physicalists and dualists – have to reject kind essentialism. That physicalists have to reject kind essentialism, or so Merricks argues, is clear from the argument of the previous section. That dualists have to reject kind essentialism follows from his understanding of the dualist's account of the incarnation. According to Merricks, dualists hold that in becoming human, the Son had to become a human soul. Yet, since human soul is a natural kind, kind essentialism implies that nothing can become a human soul. Dualists, then, must reject kind essentialism and this gives Christians of all metaphysical stripes reason to reject kind essentialism. Luke van Horn (Reference van Horn2010) responds that Merricks is mistaken on this score because, given the dualist's understanding of what it is for a soul to be a human soul, human soul is not a natural kind and, hence, a dualist incarnation (at least the kind favoured by van Horn) is not inconsistent with kind essentialism. Thus, there are – contrary to Merricks's claim – essentialist-based, incarnational reasons to be a dualist.
There are also reasons to be dissatisfied with Merricks's treatment of the constitution and persistence conditions arguments. In a footnote, he considers an argument of the latter sort: ‘Some might worry, however, that if we say that God the Son became identical with a human body, we are somehow committed to “a bodily theory of personal identity” that rules out his having existed without a body’ (Merricks (Reference Merricks, van Inwagen and Zimmerman2007), 296, n. 20). He responds to this objection by proposing that the property being a body is an accidental property of bodies, much like the property being a professor is an accidental property of professors. While this proposal is made in the context of the persistence conditions argument, it undermines the constitution argument as well. Since objects do not have persistence conditions in virtue of accidental properties, physicalist transformationalists are not committed to a ‘bodily theory of personal identity’. Additionally, if being a body is an accidental property of bodies, then those things that are in fact bodies are not essentially so. While it may be true that, of necessity, all bodies are physically constituted, if the thing that is my body (i.e. me) is only contingently a body, then it does not follow from the fact that, necessarily, all bodies are physically constituted that my body is essentially physically constituted any more than my being essentially married follows from the fact that I am a husband and the necessary truth that all husbands are married. Similar considerations apply to the Son. Post-incarnation, the Son is identical to a physical organism, i.e. the one that is his body, but if being a body is an accidental property of that body, there's no contradiction in holding that his body is contingently organically constituted.
As a technical point this is correct, but it's not a response I find attractive. In relying on the general claim that every object instantiating the property being a body does so contingently, Merricks commits himself to the conclusion that non-divine human persons, like you and me, are contingently physical entities. While I'm perfectly willing to accept that the Son is contingently physical, and hence contingently organically constituted, I am willing to accept this on the grounds that, as the pre-existent Divine Son of God, the Son is no mere organism. Yet no such considerations hold for persons like you and me. We appear not only to be animals, but essentially so. Defending this claim goes beyond the scope of this article, so let me simply say that I find the essentialist intuitions underlying kind essentialism to be quite compelling. I would much prefer a response to the objections that didn't overthrow such deep-seated theoretical commitments.
How should a proponent of physicalist transformationalism respond, having rejected Merricks's way out? I suggest beginning with an alternative formulation of animalism. In previous work, I pointed out that the standard essentialist objections to animalism depend on the particular conception of the relation between kinds and modal properties expressed by (Kinds) and I noted there that animalists need not accept this conception and have good reason to consider rejecting it.Footnote 12 The preceding essentialist objections to physicalist transformationalism rely on this same conception of kinds and modal properties. Note that each of the objections assumes that:
(Animal) Necessarily, for any x, if x is a member of the kind animal, then x has the modal properties, including persistence conditions, associated with animal.
And, as we've seen, this is itself an implication of a more general principle relating kinds and modal properties,
(Kinds) For any kind K, there is a set of modal properties, M, such that necessarily, for any x, x is a member of kind K if and only if x has the members of M.
In all three of the arguments, the key move involves an inference from the Son's being a human animal (that is, being a member of the kind human animal) to the Son's having the associated modal properties, e.g. being an animal essentially, being essentially organic, and having purely biological persistence conditions. Since the fact that a kind is associated with a set of modal properties implies that every member of that kind has the associated modal properties only if (Kinds) is true, the key inference in both objections relies on (Kinds). Even though (Kinds) is widely accepted, we are not committed it in virtue of any particular theory of human persons or the reality of the incarnation. Hence, animalists can reject it and, for reasons having nothing to do with the incarnation, I think we should. In doing so, we need not reject all the kind essentialist intuitions that the typical Wigginsian picture is meant to capture. We need only reject the assumption that being a member of a kind is sufficient for the modal properties associated with that kind. Doing so opens up the possibility that members of the same kind may differ in their modal properties and this not only allows animalists to develop a novel response to the standard essentialist objections to animalism based on personhood, it also paves the way for a novel version of physicalist transformationalism, as I'll show presently.
To explain how members of a kind may differ in their modal properties I've suggested animalists follow the lead of Michael Burke (Reference Burke1994) and Michael Rea (Reference Rea2000) in holding that it is possible for an object to belong to multiple kinds while possessing the modal properties of only one, its so-called dominant kind. Following Rea, in the place of (Kinds), animalists should adopt:
(Dominant kind) Every object belongs to exactly one kind dominantly and for any kind K, there is a set of modal properties, M, such that necessarily, for any x, x has the members of M if and only if x belongs to K dominantly.
K is an individual's dominant kind, then, just in case that individual belongs to K dominantly. Dominant kind membership is a matter of what an object is most fundamentally. An object's dominant kind provides the metaphysically best answer to the question ‘what is it?’ and any answer that omits reference to this kind is, for that reason, metaphysically inferior. Of course this by itself does not tell us which of the many kinds an object belongs to is its dominant kind. To answer this question we need a criterion of dominance. Again, I suggest looking to Rea (Reference Rea2000):
(Dominance) For any x, x belongs to kind K dominantly just in case (i) x is essentially a K and (ii) for any kind K′ such that x is essentially a K′, x's being a K entails x's being a K′.
With (Dominant Kind) and (Dominance) in hand, we're ready to see how the incarnate Son could be an animal while denying both that he has an organic constitution essentially and that he has purely biological persistence conditions. We'll also be in a position to see how the incarnate Son could be an animal accidentally while holding that non-divine human persons, like you and I, are essentially animals.
On the version of animalism that I prefer, psychologically serious animalism, we non-divine human persons are animals whose dominant kind is human person. We are, most fundamentally and hence essentially, human persons. I take this to entail that we are both essentially human (and hence animals) and essentially persons. While we are essentially animals and essentially persons, we don't have the modal properties associated with either of those kinds (since, in our case, human person dominates both person and animal). Rather, we have the modal properties associated with the kind human person and so, I've argued, we have mixed persistence conditions: biological and psychological continuity are individually necessary and only jointly sufficient for our persistence.Footnote 13 We are essentially biological organisms, for whom biological continuity is necessary for continued existence, as well as essentially psychological entities, for whom psychological continuity is necessary as well. This may be controversial, but I am convinced that it best reflects our psycho-biological nature as rational animals.Footnote 14
While we non-divine human persons are essentially animals with partially biological persistence conditions, this is not true for the incarnate divine Son. On the version of physicalist transformationalism that I'm considering, the incarnate Son is a human person, and hence is a human animal. Yet, despite his being a human person, this cannot be his dominant kind. To see this, we simply need to consider (Dominance). Were the incarnate Son's dominant kind human person, then he would be a human person essentially (which he is not) and his being a human person would imply that for any kind K, such that the Son is essentially a K, the Son's being a human person entails his being a K (which it doesn't). The Son is not essentially a human person since he was not human prior to the incarnation (nor was it necessary that the Son take on human flesh) and, furthermore, the Son is essentially divine and being a human person doesn't entail being divine. So while the incarnate Son is a human person, he's not one dominantly. I don't wish to speculate much concerning the Son's metaphysical nature, so let me just say that it's reasonable to believe that the Son's dominant kind is something like divine person (of which there are two, and only two, other members). Since individuals have their modal properties in virtue of their dominant kind, the incarnate Son does not have the modal properties associated with either animal or human person even though he's both. Thus, there's no essentialist ground for objecting to the immaterial divine Son's becoming a living human organism.
Before turning to a detailed consideration of the three objections discussed above, we need to consider briefly an assumption on which my proposal relies. In proposing that the incarnate Son is non-dominantly a human animal, I'm assuming that it is possible for an individual to belong non-dominantly to a kind that other individuals belong to dominantly. Yet one may doubt whether this is possible.Footnote 15 Every animal is an animal of a specific kind, e.g. Dexter is a canine animal, Lulu is an ovine animal, Tilikum is an orcan animal, etc., and, in fact, it's quite plausible to think every individual animal dominantly belongs to a more specific kind than animal (e.g. its species). It follows that no animal dominantly belongs to the more general kind animal. Assuming this point holds for all general kinds (e.g. lumps vs lumps of bronze), then individuals will never non-dominantly belong to a kind that other individuals belong to dominantly. Thus, for any kind K, if anything belongs to K dominantly, then nothing belongs to K non-dominantly – contrary to what I've been assuming.
Luckily, one need not engage in special pleading in order to address this concern, as there are independently plausible cases of individuals non-dominantly belonging to a kind that others belong to dominantly. Consider, first, a case involving an artefact. Suppose that every lump is not merely a lump, but a lump of some specific sort. Suppose, further, that every statue is not merely a statue, but a statue of some specific sort (e.g. statue of x). Now consider Donatello's David. On the dominant kinds view I've been assuming, David is identical to its constituting lump.Footnote 16 Further, it's plausible to think that David is dominantly a statue of David and non-dominantly a lump of bronze. Since there are many lumps of bronze waiting around to be sculpted into statues and all such lumps dominantly belong to the kind lump of bronze, it follows that at least one object, David, non-dominantly belongs to a kind that others belong to dominantly.
Consider, second, cases involving non-cognitive human animals. Suppose we agree, as the objection invites us to, that every animal dominantly belongs to some more specific kind. On the version of animalism introduced in the last section, (non-divine) human persons are essentially psychologically endowed human animals. Hence, individuals like you and me are non-dominantly human animals whose dominant kind is human person. But this is not true of all human animals, as illustrated by early term, pre-cognitive foetuses and irreversibly non-cognitive humans in a persistent vegetative state. Such human animals are not psychologically endowed, much less essentially so. As such, human person cannot be their dominant kind, which I take to be human animal. Thus, even if every animal dominantly belongs to some more specific kind than animal, there are still cases of individuals (e.g. you and I) that non-dominantly belong to a kind, viz. human animal, that others (e.g. pre-cognitive foetuses and non-cognitive human animals in a persistent vegetative state) belong to dominantly. There is precedence, then, for holding that it's possible for an individual to be a non-dominant member of a kind that others belong to dominantly.
Physicalist transformationalism undefeated
To illustrate how the framework discussed in the previous section undercuts the objections to physicalist transformationalism discussed earlier, we'll briefly consider each of them in light of psychologically serious animalism.
Kind essentialism
The account of human persons that I briefly sketched above preserves the robust essentialist intuitions underlying kind essentialism without committing to the problematic claim that every animal is essentially an animal. On that view, non-divine human persons are essentially animals, as their dominant kind is human person and being a human person entails being an animal. The incarnate Son, on the other hand, is a human person (and hence an animal), but not dominantly so. On the version of kind essentialism motivated by the general account of kinds and modal properties I've recommended, an individual is essentially a member of a kind, K, if and only if it's either dominantly a K or dominantly belongs to some kind that necessitates its being a K. The account is neutral regarding non-dominant kind membership. In some cases, non-dominant kind membership is essential (for example, I'm essentially an animal and I belong to that kind non-dominantly), but it need not be. The account allows for non-dominant contingent kind membership.Footnote 17 Since the Son is dominantly a divine person and being a divine person involves, at the very least, being possibly non-physical, the incarnate Son is non-dominantly and contingently a human animal. We need not jettison kind essentialism in toto to account adequately for the Son's contingent animality.
Constitution essentialism
The psychologically serious account of animalism also explains why considerations of constitution essentialism fail to undermine physicalist transformationalism. We tend to think that animals are essentially biological organisms, and hence are essentially constituted of organic matter, on the grounds that properties like essentially being the subject of a biological life, essentially being a living organized body, and essentially being organic are associated with the kind animal. It's natural to assume, then, that all animals are essentially living organisms, essentially organically constituted, etc. But such reasoning relies on (Kinds) and apart from this assumption, there's little reason to think that every animal has these properties.
On the view I'm proposing, dominant kind membership, and only dominant kind membership, constrains an individual's compositional possibilities. So, for example, it is impossible for a dominantly human person to be wholly composed of silicon, as this is inconsistent with the modal properties associated with human person. But since constitutional properties are a proper subset of the modal properties associated with a kind, such restrictions are limited to dominant kind membership, in that only dominant members of a kind have the constitutional properties associated with that kind. Even though he is a human animal, the incarnate Son is most fundamentally, and hence dominantly, a divine person. For reasons outlined above, this is inconsistent with the incarnate Son's essentially being a biological organism. Nor could the Son be essentially organically constituted, as this is inconsistent with his possibly being non-physical, a property he has in virtue of being a divine person. Despite his being an animal, the incarnate Son is not subject to the compositional restrictions associated with that kind. On the account I'm proposing, then, there are no good reasons to think that the Son's being an animal entails that the Son is essentially organically constituted and there are good reasons to hold that although he is an animal, he is contingently composed of organic matter.
So, unlike Merricks's proposal, accommodating the contingency of the Son's being a living, physical organism does not require holding that all living organisms (at least the human ones) are contingently physical. This is as it should be, as I hold (along with most other animalists) that non-divine human persons are essentially biological organisms and, thus, they are essentially organically constituted. If we assume that organic constitution (i.e. exhaustive composition by organic matter at some level of decomposition) necessitates being a physical entity, then non-divine human persons are essentially physically constituted. The same goes for all other animals, as it's plausible to think that their dominant kind is either organism or necessitates their being an organism. The incarnate Son, on the other hand, as a fundamentally divine person and non-fundamentally living human animal, need not be essentially organically constituted or essentially a physical entity, even though he belongs to the kind human animal, as only dominant members of that kind have its associated constitutional properties.
It's a virtue of the account that I've been discussing that it explains how it's possible for a human animal to be contingently physical without implying that all human animals are contingently physical (or worse, that all physical entities are contingently physical). On the account I'm proposing, the Incarnate Son's contingent physicality does not imply that all human persons are contingently physical. We have the resources to hold that at least one physical object (the incarnate Son) is contingently physical while denying that all physical objects are contingently physical. And doing so is neither ad hoc nor unmotivated, since whether an object is essentially a living organized body or essentially a physical substance will depend on its dominant kind. From the mere fact that something is an animal, we cannot conclude that it is essentially a living organized body of organic composition.
Persistence conditions
Finally, it should be clear that the persistence conditions argument poses no more threat to physicalist transformationalism than the other two sorts of essentialist objections. You'll recall that, according to the persistence conditions objection, the incarnate Son could not be an animal, as this would imply that he has purely biological persistence conditions – which surely he does not. Again, the force of this argument turns on the claim that all animals have the purely biological persistence conditions associated with the kind animal. Once we have rejected this assumption, as I've argued we should, there's no reason to hold that every animal has purely biological persistence conditions, even though most do. (Non-divine) human persons have partly biological and partly psychological persistence conditions. The incarnate Son, though he's an animal, doesn't have biological persistence conditions at all, as biological continuity is neither necessary nor sufficient for his persistence.Footnote 18 Both sorts of human persons, divine and non-divine, are animals, despite the fact that on my view neither possesses purely biological persistence conditions. For animalists this should call into question neither our animality nor that of the incarnate Son, but rather the viability of the general relation between kinds and modal properties on which the objections rely. While much remains to be said about the account of human persons I've relied on (some of which I've said elsewhere) and its application to the incarnation (some of which I hope to say in future work), it should be clear that the account I've outlined here provides the resources to offer a novel and independently motivated solution to the kind membership objections to physicalist transformationalism.
Conclusion
As I noted at the beginning of this article, I've not discussed every objection to physicalist transformationalism. But I have discussed three important objections that any physicalist who believes in the Son's incarnation must address. I suspect, though, for all I've argued, some dualists will remain unmoved. For them, the immaterial Son's transforming into a physical organism just seems impossible.Footnote 19 This would be a problem were I attempting to argue for physicalism on incarnational grounds (as Merricks does), but this has not been my goal. I have other reasons for being a physicalist. My task has been simply to explore whether a physicalist with my commitments could make sense of the incarnation. Accordingly, I can live with some dualists continuing to object that a view like mine seems impossible. What I couldn't live with are arguments for its impossibility and I've dealt with three such arguments here. Despite not arguing for the superiority of physicalist treatments of the incarnation, I hope to have taken an important step to demonstrating the compatibility of physicalism and the incarnation.Footnote 20
