Thomistic Animalism

Abstract

Animalism, according to its strongest proponents, is the view that human beings are ‘essentially or most fundamentally animals’. Specifically, ‘we are essentially animals if we couldn't possibly exist without being animals’ (Olson 2008). Although contemporary animalism offers an account superior to its Lockean competitors, Olson's ‘biological approach’ has certain limitations, particularly in its denial of any psychological continuity whatsoever as either necessary or sufficient for individual persistence through time. I propose a number of amendments towards a Thomistic variety of animalism that avoids these difficulties. Although prone to misinterpretation, animalism understood properly is compatible with Aquinas's theory of subsistent intellect. Against recent challenges, I defend the view that Thomistic animalism not only is intelligible, but is indeed crucial for understanding Aquinas's view of human nature and rationality.

I. Introduction

Among the animals, some are persons. Certainly we include human beings among the animals that are also persons, but we need not assume that we are the only members of this sub-class of animals. Should we someday discover a species of rational parrots or society of intelligently conversant donkeys—or for that matter, any philosophically competent Martians who are able to communicate and think like us—we should include all of these as animal persons as well. While all human animals are persons, however, not all persons are human animals. Indeed, some persons are, plausibly, not any kind of animal or corporeal creature at all: such spiritual persons include what are believed by some to be angels, or God.

Each of the above statements can be challenged by philosophers, of course, including certain animalists—those who hold generally that human beings are animals. In particular, to the question, ‘Can there be human animals who are non-persons?’, the reply that emerges from the foregoing paragraph is no. However, this response is unfashionable among contemporary animalists, the majority of whom insist upon the existence of human animal non-persons. This essay argues that the reasons offered for the latter claim are unjustified. Indeed, the major claims of animalism are entirely compatible with the foregoing summary, and perhaps surprisingly to some, would be embraced within a Thomistic metaphysics on a largely naturalistic basis. In this essay, therefore, I defend a naturalistic account of animalism in the context of Thomas Aquinas's metaphysics of the human being. Aquinas's thought, I aim to show, clearly supports a variety of animalism, but one that avoids a problematic concept of human non-persons.

In §II, I firstly offer some remarks on one contemporary account of what animalism is. Since the view is prone to misinterpretation, upon which many challenges may be supported, I then discuss potential misconceptions of animalism in §III, and offer clarificatory solutions: these are given with particular recourse to Thomistic metaphysics, in order to illustrate the unproblematic compatibility between Thomism and contemporary animalism. Finally, in §IV, I raise the prospect of a specifically Thomistic variety of animalism, and consider whether it overcomes some of the difficulties faced by contemporary animalism, as well as some challenges that pertain uniquely to Thomism.

II. What is Contemporary Animalism?

Animalism, Eric Olson remarks, is ‘not a very nice name, but I haven't got a better one’. Aside from the trivial fact that some may not find the name aesthetically pleasing, animalism is also controversial and often misunderstood. As with many theories obscured by controversy, there are several possible varieties of animalism.² However, I will focus my remarks on arguably the most prominent contemporary account, the version of animalism defended by Olson.

According to Olson, animalism is the view that human beings are ‘essentially or most fundamentally animals’.³ Specifically, ‘we are essentially animals if we couldn't possibly exist without being animals’. Olson presents this view in what he calls the ‘Thinking Animal Argument’:

1. 1. There is a human animal sitting in your chair.

2. 2. The human animal sitting in your chair is thinking.

3. 3. You are the thinking being sitting in your chair; the one and only thinking being sitting in your chair is none other than you.

4. 4. Hence, you are that animal. That animal is you.⁴

Olson's argument has already generated much interesting discussion⁵, so it will not be my aim to address all of the major points merited by his account. In what follows, I wish to raise a problem vis-à-vis three implications of Olson's argument concerning the metaphysical relation between human animals and persons.

First, the ‘Thinking Animal Argument’ purports to show that there is a particular way we should think of the relation between animals and human beings: precisely, that a relation of strict identity holds between these concepts. The thinking being is an animal, and it is the animal that thinks. Thus, in fully operative human beings, the person just is the animal, and the animal just is the person. This argument rules out the possibility of claiming that the relation between person and animal is a constitution relation: that is, it excludes the supposition that we are persons constituted by some animal aspect, just as the statue of John Witherspoon in Princeton is his represented figure constituted by some bronze stuff. Olson's argument entails that we should not conceive of persons as being constituted by animals in the way that a represented figure is constituted by some material stuff.

Second, animalism is one solution to what we may call a ‘person-animal problem’, but—perhaps contrary to initial appearances—it does not offer a resolution to the mind-body problem. The reason animalism does not purport to offer a solution to the mind-body problem is that it rejects outright certain fundamental premises of the mind-body debate: in particular, contemporary animalists deny a standard view that assumes ‘mind’ and ‘body’ as conceptually and metaphysically opposed entities, between which an explanatory gap is interposed. Animalism assumes no such distinction between mind and body, although it does assume a conceptual distinction between the animal and the person: nevertheless, on the animalist's account, no problematic metaphysical or explanatory gap occurs.⁶ Animalism therefore purports to circumvent many of the problems faced by contemporary philosophers of mind, simply by positioning itself outside of certain more mainstream discussions on the metaphysics of human nature.⁷ However, as will be discussed below, none of this entails that animalism circumvents all of the difficulties associated with activities of mind traditionally associated with the concept of a person.

Third, Olson calls his argument in general ‘the biological approach’. This is ‘the view that you and I are human animals, and that no sort of psychological continuity is either necessary or sufficient for a human animal to persist through time’.⁸ On his view, the argument for animalism rules out the conviction that our identity consists in mental continuity. That is, he rejects the premise that mental continuity is a necessary or sufficient condition for an individual's persistence. On his account, this entails that each of us once was, and may someday become, a non-person: such is, e.g., the fetus in the womb, or a patient in a persistent vegetative state. But such conditions for existing as a non-person are irrelevant as far as our persistence qua animals is concerned, given that personhood – the criterion for rational thought – is neither necessary nor sufficient for our persistence over time qua animals. According to Olson, therefore, it is sometimes possible to become or exist as a human animal without being a person: for not all human animals are persons. For example, ‘human beings in a persistent vegetative state are biologically alive, but their mental capacities are permanently destroyed. They are certainly human animals. But we might not want to call them people. The same goes for human embryos’.⁹

Olson assumes here, as do many philosophers, that the criterion for personhood depends on the immediate functionality of some capacity. Persons exist if and only if they are able to do something: i.e., to exercise immediate capacities for mental activity, the immediate capacities which seem to be absent in one who suffers from a persistent vegetative state or a human embryo at an early stage of development. But it is not prima facie obvious that the absence of mental functioning in a human being necessarily implies that a human animal can exist without the existence of a person. The apparent absence of immediately exercisable capacities does not require the absence of all exercisable capacities tout court: one may still possess exercisable capacities in a more primary sense. This appears to be the case for normal developing embryos, whose primary capacities are normally actualized into secondary, exercisable capacities, given the fulfillment of standard external conditions.

But why should this point about the possibility of personless animal humans be a necessary implication of the Thinking Animal Argument? I will argue in §IV that this feature of the contemporary approach renders the animalist vulnerable to the central objection against contemporary animalism, what philosophers call the ‘transplanted cerebrum objection’. Contemporary animalists arguably would have a stronger and more coherent account to offer, were this stipulation left out. In the remainder of this paper, I will argue that the Thinking Animal Argument need not entail what Olson assumes of it, especially where the metaphysics of life and personhood are concerned. In particular, Aquinas's metaphysics provides an intriguing juxtaposition with the standard assumptions concerning the conceptual relation between persons and animals. For Aquinas is an animalist himself, but his version of animalism, I will argue, avoids the problem faced by Olson's account.

III. Misinterpretations of Animalism

Animalism, I have said, is prone to misinterpretation. So it will be helpful to offer some elucidation on what animalism is not, contrary to some common interpretations of it. In particular, clarification of animalism will be made in the context of Thomistic metaphysics.

First, animalism does not necessarily assume the thesis that we are nothing but animals like snails, snakes, or sea-lions. An extreme version of this so-called ‘nothing buttery’ approach is material reductionism, the view that we are ‘nothing but’ material processes and aggregates, or complex collections or aggregates of lowest level physical elements.¹⁰ Complex arguments for material reductionism have been proposed, for instance by Paul and Patricia Churchland.¹¹ There are many independent reasons to find this sort of view implausible, but in any case it is unnecessary to give a full critique here, since one should not assume that animalism is conceptually related to material reductionism at all. Olson himself denies that his view implies material reductionism. Although animalism does imply that human beings are a kind of material thing, it does not imply that we are nothing but material things.

Still, it can be expected that some will remain skeptical of this conclusion, even if it is conceded that animalism rejects material reductionism and its various implications. The statement, ‘We are animals’, may appear to contradict a commonsense assumption that human nature exemplifies exceptional qualities within the natural world. But that is to prejudice the discussion from the start. For the claim that ‘we are animals’ in no way whatsoever entails that human beings are unexceptional in nature. Indeed, recognition that we are animals is rather the starting point for comprehension of human beings as a truly exceptional kind of animal.¹² In response to such skeptics, it may be helpful to rephrase the proposition ‘we are animals’ to ‘we are a kind of animal’. Aquinas himself appears to argue that there is no such thing as an animal simpliciter: animality as such does not exist as something fully actualized, since the term ‘animal’ is not fully determinate of a concrete substance. In his seminal text, De Ente et Essentia (On Being and Essence), he clarifies that the term ‘animal’ names a genus, undifferentiated by any specific difference; the latter merely describes some potential aspect of a group of related beings, i.e. a species-kind. According to Aquinas, however, there is no obvious difficulty in the claim ‘human beings are animals’, as a form of general description of our nature within its proper context.

It therefore seems undeniable that ‘we are a kind of animal’, particularly where such a claim unproblematically entails human exceptionalism within the animal kingdom. As Olson and other animalists have observed, however, this view has received surprisingly widespread resistance. The reasons for persisting anti-animalism are worth examining. It might be thought, for instance, that although we may say that ‘we are a kind of animal’, the use of the term ‘animal’ here is equivocal or, at best, analogical with its sense in the proposition, ‘A zoo houses many exotic animals’. For instance, Aquinas distinguishes between analogical and univocal senses of a term in order to argue that our descriptions of God in relation to human creatures always employ analogical or metaphorical terms. Thus the action terms employed in the propositions ‘God so loved the world’ and ‘God smote the Egyptians’ contain in some aspects the same and in other aspects different meanings, relative to the human capacities for loving and smiting. They are not univocally related, since it would be prima facie ridiculous to interpret ‘God spoke to Moses’, for instance, as meaning that God speaks literally in just the way that we speak: i.e., with tongue, lips, and facial muscles.¹³ And it is on similar grounds that animalism might be challenged: when one speaks of ‘the rational animal’ and ‘the animal kingdom’, the term ‘animal’ is not being used univocally, i.e., both having one and the same sense or meaning.

But this objection is rather implausible, for the following reasons. First, God's alterity to creatures is radically unlike our own otherness in relation to non-human animals: there can hardly be a reasonable comparison between these relations. And this objection seems tantamount to denying that human beings participate in a biological nature: but this is, of course, absurd. We possess a biological form of life as do all other animal species, and we also share (with at least the higher-level animals) an extensive range of powers and capacities, psychological as well as physiological. On Aquinas's account, these capacities include perception, certain modes of cognition (such as memory, learning, and imagination), as well as many of the emotions, and voluntary movement.¹⁴ Such a view is inherited from Aristotle, and it implies that many animals other than ourselves are also agents.¹⁵ On my account, therefore, there is no obvious objection to claiming that higher-level animal movements are ‘actions’.¹⁶ The empirical sciences widely support the Aristotelian-Thomistic account of the many sense-level faculties, including voluntary movement, that are shared with the other animals.¹⁷ To deny the latter is to ignore such findings, and to contradict the most commonsense observations of amateur naturalism.

A second reason for rejecting the objection from analogy is that, as already mentioned, there is no individual subject wholly designated by the term ‘animal’. For Aquinas, the term ‘animal’ is a description that characterizes the genus of a thing, and therefore by implication is an under-description of it. However, this consideration multiplies the difficulties for the objection from analogy: for what could it mean to claim that human beings are only ‘animals’ by analogy, if the term ‘animal’ simply designates a kind of undifferentiated potentiality within living, corporeal creatures? Biological life forms are specific to natures: human animals have a particular mode of corporeality, as do orca whales, wolves, and warblers.¹⁸

However, the objection from analogy may find expression in another alternative solution. One may claim that ‘animal’ is analogous not only across the terms ‘human animal’ and ‘zoo animal’, but also across, e.g., ‘cat animal’, ‘catfish animal’, and ‘catbird animal’. This solution thus assumes all applications of the term ‘animal’ are a usage that is only analogous, rather than univocal, across all diverse species of the genus ‘animal’. For instance, the locomotive capacities and characteristics of self-moving creatures that inhabit land, sea, and air are respectively so extraordinarily diverse that, one may argue, we ought not to apply a term univocally to all of them. Although this solution has a certain guise of consistency, it misunderstands Aquinas's concept of a genus-term, which assumes that there is some essential feature that is fundamentally shared by all members included under that genus-term, without assuming that all essential features of any particular species are fundamentally shared under it. Thus, the genus-term ‘number’ applies to the ‘number one’, ‘number two’, and ‘number three’, where each has a specific difference (a species-making difference) based on a quantity, but each remains ‘a number’ univocally.

It follows from the foregoing that although animalism insists on our corporeal or bodily nature, it does not assume that we are nothing but our bodies. However, if one believes that animals are nothing but bodies, and is faced with the statement, ‘We are animals’, then one can only conclude that we are nothing but bodies. On this interpretation, animalism excludes the view that we are more than merely bodies. Reasonably for most, this entails a cost too high to accept, and therefore animalism ought to be rejected in order to sustain the view that we are rational minds: minds governing bodies, or persons supervising animals. The latter account is standardly attributed to Descartes, who claims that our bodies are animals in the same way that animals are machines, but that we are not identified with our bodies.¹⁹ He famously remarks in the Meditations: ‘I rightly conclude that my essence consists entirely in my being a thinking thing…it is certain that I am really distinct from my body, and can exist without it’.²⁰ Since Descartes sees a strict identity between the ‘I’ and the res cogitans (the thinking substance), he claims that we are not animals: for we are not our bodies.²¹

As mentioned earlier, animalism is distinctive in circumventing the mind-body debate in contemporary philosophy. Even if only implicitly, the animalist rejects, any Cartesian assumption that bodies are metaphysically opposed to minds. The rejection of substance dualism is of course resonant with Aristotelian-Thomistic thought, but the latter point seems yet to be explicitly acknowledged by most animalists. Aristotle's doctrine of hylomorphism, appropriated later by Aquinas, precludes the Cartesian distinction which pervades debates in contemporary philosophy of mind, since hylomorphism entails (inter alia) that body and mind are interdependent, correlative concepts. Even a decomposing body, Aquinas argues, is ‘neither form nor matter nor existence, but the composite of formed matter, the thing’.²² Olson corroborates this rejection of conceptual isolation of the body, but goes further: ‘What does it mean to say that your body is an animal…? I have never seen a good answer to this question. So I will talk about people and animals, and leave bodies out of it’.²³

IV. Is a Thomistic Animalism Possible?

I now approach the central question of this paper: whether Aquinas can be understood as a kind of animalist. So far, I have suggested that the major points of appeal held by animalism are entirely compatible with an Aristotelian-Thomistic metaphysics. But I have also alluded to one crucial issue which remains open: why should the emphasis not be on persons rather than animals? Why should we not speak of ‘Thomistic personalism’, in place of ‘Thomistic animalism’? Plausibly, these could be regarded unproblematically as interchangeable, as long as the term ‘person’ does not necessarily exclude the concept of an animal, and vice versa. There could very well be a personalist account that accepts our animality, not as a constituent part of us, nor as employing a merely analogical sense of the term ‘animal’, but rather as a fundamental aspect of an essential and univocal description of human nature.²⁴

A difficulty with this latter approach, however, is that contemporary personalism is characteristically understood as absolutely incompatible with animalism, and accordingly, animalists typically reject personalism.²⁵ Arguably, such has been the case since Locke first proposed a distinction between ‘human being’ and ‘person’, asserting that we are fundamentally persons.²⁶ A ‘person’, according to Locke, is a ‘thinking intelligent Being, that has reason and reflection, and can consider it self as it self, the same thinking thing in different times and places; which it does by that consciousness, which is inseparable from thinking’.²⁷ Paul Snowdon explains that ‘person’ is a concept not essentially linked ‘to any persisting substantial item, such as a whole body, or a significant body part, or to any other sort of substantial items which there might be. […] On the Lockean conception a person can migrate between substances, of whatever kind’.²⁸ So long as there is psychological or mental continuity in the hypothetical trans-migration from one subject to another, personal identity or individual survival of the person obtains.

In contrast with the animalist's ‘biological approach’, Locke's ‘psychological approach’ asserts that only some psychological relation is sufficient for personal survival. The cessation of consciousness, memory, and self-awareness entails the termination of our lives as persons: the survival of our bodies alone is neither necessary nor sufficient for our survival as people. But this is a view that no Thomist could accept, for reasons that are obvious.²⁹ On Aquinas's hylomorphic account, we have bodies as essentially as we have minds, and according to a certain interpretation of his arguments, both the body and the mind are necessary for our survival.³⁰ Given the post-Lockean preconceptions surrounding the contemporary concept of a person, it therefore appears more appropriate to identify Aquinas as an animalist than a personalist: in any case, Lockean personalism is surely incompatible with animalism. At the same time, Thomism unproblematically affirms the thesis that we are essentially persons, without such a claim conflicting whatsoever with the thesis that we are also essentially animals: for the essential definition of a ‘rational animal’ entails that no rational animal can simultaneously fail to be a person.

For Aquinas, as for Aristotle, the concept of body involves a thing that is already substantially enformed. In De Ente et Essentia, Aquinas contrasts two concepts pertaining to the term ‘body’. The first ‘means a thing of a form such that it can occupy three dimensions, but stopping there: in other words, the form produces no further perfection, so that anything extra lies outside the meaning of body so understood’.³¹ The second concept indicates ‘a thing of a form such that it can occupy three dimensions…[and where] the animating soul isn't a different form from the one enabling the thing to occupy three dimensions… […] And in this way the animal form was implicit in the form of the body, body being its genus’.³² These contrasting accounts present, firstly, an impressive anticipation of Cartesian substance dualism and its claims concerning the res extensa, or ‘body’ as an extended thing. Secondly, Aquinas presents an understanding of ‘body’ as hylomorphic, or already enformed by the soul, such that the two cannot be metaphysically differentiated, even if they are sometimes separately definable.

This metaphysical context provides a compelling case for understanding Aquinas as an animalist. However, an important caveat is needed, as Christopher Hughes notes:

[C]ontemporary philosophers (whether animalists or personalists) have a conception of human animality that is very different from Aquinas’. As contemporary philosophers usually think of it, being a human animal (belonging to the species Homo sapiens) is a biological property, but not a psychological property – at least, not a psychological property in the sense that being a human animal implies actually having psychological properties such as consciousness, or understanding, or will…. [B]y Aquinas's lights [though], being a human animal implies actually having a human intellect, and actually having a human intellect implies actually having the powers of understanding and will.³³

An implication of this passage is that human beings, understood essentially as ‘rational animals’, are not simply rational minds added to or superimposed on some generic animal nature: rather, they are fundamentally animals, and indeed instantiations of a special kind of animal. Specifically, human beings are animals of the rational kind, with powers and capacities that are exceptional within the natural world. Given the necessary fusion of psychological and physical properties, functions, and activities fulfilled in accordance with the nature of the species-kind, it seems prima facie obvious that Aquinas need not contend with the ‘person-animal problem’. The intelligibility of his biological account—a description of ‘man’ as a human being—necessarily includes psychological concepts—those attributed by Lockeans as pertaining exclusively to ‘persons’. Aquinas thus avoids contentious difficulties raised by the Lockean distinction between ‘human beings’ and ‘persons’.³⁴

A consideration of Aquinas's approach to action may raise a difficulty on these points.³⁵ Aquinas distinguishes between actus humani, human acts, and actus hominis, acts of man. Acts of man, or of a human being, are those movements found in a human being but not attributable to him qua human: for instance, acts of biological growth and digestion are ‘natural’ rather than ‘human’. Human acts, in contrast, proceed from reason, knowledge, and will, as faculties proper to our rational nature, rather than to animals or plants generally. Furthermore, Aquinas appears to assume a kind of equivalence between human acts and moral acts: ‘If an act is not deliberate…such as stroking the beard or moving a hand or foot, it is not properly speaking a human or moral act…. And so it will be indifferent, that is, outside the class of moral acts’.³⁶ It seems entirely possible to interpret Aquinas's remarks as distinguishing fundamentally between the biological organism ‘man’ and the rational, self-aware ‘person’.

This would be a misguided interpretation, however. First, Aquinas's differentiation is between kinds of actions, and does not constitute an ontological division within human nature itself. There is a contrast, of course, between our actions that are freely chosen, for which we have moral responsibility, and those actions that are performed without free choice—for instance, the absent-minded stroking of one's beard. Second, Aristotle's prior view on the matter, that choice (prohairesis) is ‘the origin of [human] action (praxis)’, is entirely compatible with his insistence that humanity be essentially defined as ‘rational animal’.³⁷ It is possible that placing an excessive sharpness on the distinction between actus humanus and actus hominis risks prying apart the essential features of our nature, ‘rationality’ and ‘animality’. On the Thomistic-Aristotelian view, these features are necessarily inextricable. We are not merely ‘rational beings’ or ‘rational agents’: we are ‘rational animals’, and our particular mode as animal agents involves, at once, both certain powers shared with other animal creatures as well as certain powers shared with other created rational beings.

Thomistic animalism, as we have seen, offers an account of animal persons without ontologically reducing such persons to animals. Analogously, an explanation of the agency possessed by such animal persons successfully resists reductive explanations of action in terms of mere bodily movements. The claim that action includes ‘bodily movement’ in its essential meaning nowhere implies such reduction, just as the claim that human beings are animals in their essential meaning does not imply that human nature is reduced to mere animal nature. Action is not mere bodily movement, but it may be understood as a kind of movement: i.e., movement that is voluntary and sometimes also intentional, with the necessary involvement of certain psychological processes.³⁸ Rather than posing an obstacle for Thomistic animalism, Aquinas's account of action affirms it, by presenting a concept of action as that possessed by embodied creatures.

What are other problems that arise uniquely for Thomistic animalism? Firstly, it may be thought that the plausibility of a Thomistic variety of animalism may be threatened on account of Aquinas's views on subsistent intellect. For at times Aquinas speaks of the soul as if it is a substance; he writes in Quaestio Disputata de Anima: ‘Understanding needs no bodily organ, the human soul can act in its own right, and so must be able to subsist in its own right as itself a thing’.³⁹ If the soul has subsistence apart from the body, then it certainly seems as if Aquinas should conclude that our survival requires only the survival of the soul. One might construe this claim in a Lockean way, such that ‘soul’ denotes any psychological activity existing even in one who survives death. His account would then be in agreement with the ‘psychological approach’ of Lockean personalism, and therefore, ‘Thomistic animalism’ appears false or impossible by Aquinas's own lights.

What response might one offer to this objection? First, it becomes clear later in this same disputed question that Aquinas believes that the nature of the soul as substance is only partial. Again in the same Quaestio, Aquinas remarks that ‘although a human soul can subsist by itself it hasn't a complete specific nature of its own’.⁴⁰ For ‘even if soul has a complete existence it doesn't follow that body is joined to it incidentally. For one reason, soul shares that very same existence with body so that there is one existence of the whole composite; and for another, even though soul can subsist of itself, it doesn't have a complete specific nature, but body is joined to it to complete its nature…’.⁴¹

Second, because of his requirement that the body be joined to the soul in order to ‘complete its nature’, Aquinas argues that there remains at least some diachronic dependence of the mind on certain corporeal processes, even if intellectual understanding in itself does not require a bodily organ. For ‘immateriality is what makes things actually intelligible’.⁴² The context of this remark, however, is that sense perception and imagination, corporeal changes, are necessary for the operations of theoretical intellect, since ‘the forms of things in nature don't exist on their own account outside matter, but in matter’. Accordingly, he elaborates: ‘Understanding is an activity which as regards its source is the soul's alone: for soul doesn't use a bodily organ to understand, as it does the eye to see. Body, however, shares in the activity by providing its object, since the images we understand can't exist without the bodily organs’.⁴³ Thus he adopts Aristotle's approach on the issue: that ‘the things we understand are not things existing as understandable themselves but things we sense and then make understandable’.⁴⁴

I end by considering a final objection to Thomistic animalism, which simultaneously constitutes the central objection for the contemporary account. The objection from the transplanted cerebrum proceeds: imagine a perfect technology that transplants your brain to another body. The transplanted brain, or just the cerebrum, would convey with it all of your memories and psychological features. This operation would not move an animal with it, but you would move: therefore, you are not an animal. As Olson explains, it seems to follow ‘that you are not that animal, or indeed any other animal. Not only are you not essentially an animal. You are not an animal at all, even contingently. Nothing that is even contingently an animal would move to a different head if its cerebrum were transplanted. The human animals in the story stay where they are and merely lose or gain organs’.⁴⁵

Hughes raises a version of this challenge specifically aimed at a Thomistic variety of animalism, based on Aquinas's assumptions concerning embryogenesis and ensoulment.⁴⁶ Given what is now understood to be flawed medieval science, although the widely received view at the time, Aquinas had supposed that the rational soul was created and infused by God only later in fetal development, around the sixth week.⁴⁷ Therefore Hughes imagines the following hypothetical conversation between two people observing a fetus in the womb, around the time of ensoulment:

1. A: Can you see the heart beating?

2. B: Yes.

3. A: The fetus has moved a bit. Can you still see the heart beating?

4. B: I don't know.

5. A: What do you mean?

6. B: Well, I can see a heart beating, but I don't know if it's the same heart I was seeing before.

7. A: Why ever would it be a different heart?

8. B: Because the moment at which the fetus moved might have been the moment at which soul creation and infusion took place.⁴⁸

Hughes argues that since ensoulment is the substantial change of the coming-to-be of a human being, everything preceding that moment—the flesh and body parts, including the heart of the fetus, and other accidents—are, as he says, ‘all gone. Nothing that belonged to the fetus at the six-week point of the pregnancy is still around when the human being starts to exist. […] But this is a reductio. With luck, you can see a fetal heart beating in a sonogram, six weeks into a pregnancy’, and so on through the moment of birth. As with the transplanted cerebrum case, it appears that the animal life that existed before ensoulment is not strictly identical with the person created at the moment of soul creation and infusion.

Hughes believes that Aquinas's account of ensoulment is an insurmountable problem for the coherence of Thomistic animalism. But he fails to consider that there are relevant empirical facts in this case, facts to which Aquinas could not possibly have had access during his lifetime, but which certainly would have changed his judgment about ensoulment. Modern embryology supports a metaphysics of immediate ensoulment, entailing that substantial change of the coming-to-be of a human being occurs at the moment of conception. On this revised account, Thomistic animalism resists Hughes's challenge, for a human individual clearly has persistence conditions dependent on biological continuity. In any case, even without the pertinent scientific facts concerning genetics and fertilization, Aquinas denies that one could exist as a fully formed animal organism without simultaneously existing as a human person. So although Hughes's objection is an interesting one, it is not as insurmountable as he thinks.

In response to the transplanted cerebrum case, one might also consider that conceivability does not always entail metaphysical possibility. Our intuitions in response to such far-fetched scenarios are not as reliable as we think. Most people, seemingly influenced by Locke or Descartes, think that you would go along with the transplanted cerebrum, leaving behind your body. An animalist, in contrast, would pose the question from another perspective: i.e., why not think of the transplanted cerebrum case from the perspective of one's body? That is, what if your body required a new brain in order for it to survive?⁴⁹ It is simply not obvious that the brain recipient would not be you. Indeed it seems to accord with an eminently commonsense philosophy to conclude that an animal in need of a new cerebrum will remain the same animal with merely a new body part—assuming such a surgery could ever be successfully carried out.

On the latter view, what remains is one and the same rational animal, with powers at once rational as well as animal. A Thomistic variation of animalism, I have argued in this essay, is particularly well equipped to explain why this conclusion is a compelling one. Instead of providing new arguments for why animalism is true, this essay has made the case that contemporary animalism holds a natural compatibility with Aquinas's metaphysics of the human person. Perhaps surprisingly, Aquinas anticipates the major objections raised by thinkers in the wake of Descartes and Locke, and dispatches potential difficulties to support the singular claim that human beings are animal persons, from the inception of an individual's corporeal life to its biological end.