I. Introduction
Scientific developments in both clinical end-of-life cases, such as the sustainment of ‘vegetal’ life functions of the body with a mechanical ventilator or a cardiopulmonary bypass machine, and ‘beginning’ of life cases, such as developments in cloning, have brought up new medical possibilities and hopes. Correspondingly, these possibilities have brought up new and complex philosophical issues, not only in ethics, such as the morality of the undertaking and use of such research, but also in more theoretical areas — these new developments press on metaphysical questions of how we are to incorporate these new cases into our conceptions of human life.1 Contemporary philosophers have begun to reinvestigate the Aristotelian framework of the soul and its potentialities or powers as helpful heuristics for explaining delineations of life and death. Although I am encouraged by the return to Aristotle’s works, it is important to note some potential misapplications of these Aristotelian conceptions, which, in the end, might mitigate the success of this revival.
This paper intends to investigate the various applications of the Aristotelian conception of potentiality in limit cases of life and death arising from developments in modern science. Specifically, this paper highlights the limitations of some contemporary applications of the Aristotelian conception of potentiality. Although I think this concept is possibly a powerful tool for investigating medically complex end-of-life cases, in its current usage, the term is often so far from its Aristotelian context that its philosophical rigor and, hence, usefulness is undermined. By investigating contemporary usages of Aristotle’s potentiality in cases of life and death, I will argue that a specific context is necessary for Aristotle’s conception of potentiality to be meaningfully applied. In particular, I hope to show that these complex cases of life and death might be meaningfully enlightened through the Aristotelian account of potentiality, but only given a substantially robust Aristotelian context which admits of a nature and a teleological ordered end to a particular type of substance. Given this metaphysical and teleological structure, one can argue that Aristotle’s conception of the soul as first actuality and his more nuanced conceptions of potentiality can help provide reasoned criteria for answers to limit cases of life and death. However, without this framework, the conceptions of potentiality are too weak and derivative to serve as the foundations for a philosophically robust analysis.
The order of the paper is as follows: first, I will survey other attempts, such as Jason Eberl (2008) and Alan Shewmon (2010), to delineate beginning and end-of-life cases that employ conceptions of potentiality in order to (a) map the various uses of potentiality currently on offer in cases of life and death and (b) show that these various uses are not robust enough to offer answers to the challenging cases of life and death in a non ad hoc way. In offering an appraisal of the situation, John Lizza (2014) and Joel Feinberg (2014) each suggest a way to make potentiality more specific, robust, and useful. Both Lizza and Feinberg point to the necessity of a more specified framework of ‘normal’ internal conditions and ‘important’ external conditions, to which the subject’s potentialities can be in reference to. Although a movement in the right direction, in the following section, I argue that the insufficiency of the current uses of potentiality is more specifically due to a lack of an Aristotelian conception of a teleological nature which directs the subject’s potentiality, and further that this Aristotelian framework of the subject’s nature can provide an answer to Feinberg and Lizza call for a context of normalcy of internal features and external environment in a more robust way. By analyzing more fully the account of the soul in Aristotle’s De Anima, including difficulties Lizza cites involving the spirituality of the Aristotelian soul, I argue for the necessity of a conception of nature that can contextualize the relevant sense of potentiality by giving a telos arising from the subject’s nature which orients that subject’s potentiality. I argue that these contextualizing components of nature and teleology are necessary for using a philosophically rigorous sense of potentiality. Finally, in section four, I turn back to the problematic cases of life and death, discussed by Lizza, Eberl, and Shewmon, in order to highlight how, given a more specific and robust conception of a teleological nature, my account can offer some distinctions in the difficult cases of life and death.
II. Potentiality and Critiques
I should note that, unlike the work of other scholars analyzed in this paper, I am not undertaking an analysis of Aristotelian potentiality in order to attempt to define death or to define at what point an embryo becomes a human. Rather, I am investigating this literature in order to analyze the uses of Aristotle’s senses of potentiality within these cases. My goal is not to arrive at a definition of death or the beginning of life, but to further define the metaphysical framework required for more meaningful usage of Aristotle’s conception of potentiality.
II.1 Aristotelian Definitions
First, it is necessary to review some of the key terms within the Aristotelian framework. All natural entities, i.e., beings that have a nature, are hylomorphic entities, meaning they are composed of matter and form. Such beings are substances, which are stable and independent unities, ‘neither said of a subject nor in a subject,’ such as an individual horse (Aristotle, 2a10-15).2 Aristotle posits his view of nature in Physics II.1, defining it as the internal principle and cause of motion and rest (192b10-15). A subject’s nature is the internal cause of its unique mode of moving itself and being moved. Aristotle continues in the Physics to highlight the link between his hylomorphism and his account of nature and causation, especially, as James Lennox puts it, ‘goal causation’ (2019: 100). In Physics II.8 Aristotle says, ‘Since nature is twofold, the matter and the form of which the latter is the end, and since all the rest is for the sake of the end, the form must be the cause in the sense of that for the sake of which’ (199a39-32). We’ll return to this account of a teleological causal nature in section III.
Substances can be either living or non-living. In living substances, the formal nature is the soul. In De Anima, the soul is defined as ‘a substance in the sense of the form of a natural body having life potentially within it’ (412a20-21).3 Since ‘substance is actuality,’ Aristotle then turns to distinguish two kinds of actuality by giving an analogy of (a) the state of having knowledge, say of Latin grammar, yet not actively thinking of it, and (b) the state of actually reflecting on a grammatical truth of the Latin language (412a21-30). Actuality, in the first sense, is having a capacity for an action, while actuality, in the second sense, is the actual operation of that action (412a25). According to this distinction, the soul is defined as the ‘first actuality’ of a natural body having life potentially, while the specific operations and actualizations of the powers of the soul, such as the actualization of the power of sight, would be the second actuality (412a30).
Aristotle further defines three types of souls: the vegetative soul, which directs nutrition and reproduction and is the baseline for sustaining life; the animal soul, which includes sensation, imagination, and desire and is the basis for locomotion; and finally, the rational soul which is proper to humans and is the basis for higher intellectual activity.
When, as in the case of animals or humans, there is more than one type of soul present in a subject, the levels are also understood as parts, powers, or potentialities of a soul, thus making them also relevant as examples of specific potentialities of the soul within Aristotle’s psychology. Aristotle gives an account of how each type of soul becomes a potentiality when it is part of a higher soul in De Anima II.3:
What holds in the case of the soul is similar to what holds concerning figures: for both figures and the ensouled, what is prior is present as a capacity in what follows in the series, for example, the triangle in the square and the nutritive in the perceptive. We must investigate the reason why they are thus in a series. For the perceptive faculty is not without the nutritive, though the nutritive is separated from the perceptive in plants. (414b28-415a3)
I take this to mean that the higher levels of souls build on each other such that the higher forms of soul inform the lower capacities in an integrated way.4 Thus, in an animal, the nutritive powers are different from the nutritive soul in a plant because they are taken up and directed by the higher sensitive powers. For example, a cow digests differently than both human digestion and plant photosynthesis, with its triple stomachs and double rumination, because its powers of movement allow it to take in nutrients in a higher way than plants. However, its narrow capacity for sensitive understanding limits its ability to secure food in a humanoid way. Similarly, animals move in response to their perceptions in order to fulfill the needs dictated by their essential functions. However, their actions are deterministically driven by a combination of instinct and circumstance: if a hungry lion comes across a gazelle, all else being equal, the lion will inevitably eat it.
In contrast, human perceptual locomotion is governed by reason. Humans deliberate about what actions to take in order to effectively pursue their basic needs. For example, if a starving person is presented with a meal, they may or may not choose to eat it, depending on how they reason through the situation based on their values (e.g., perhaps they are fasting for a political cause or protesting an injustice, and they decide not to eat because they prioritize the cause over their survival; or perhaps they are on a diet, etc.).5
Further, in Aristotle’s account, the different organs of the body correspond to the different levels of souls of plants, animals, and humans and are related to specific potencies. For example, the vegetative potency, or power of digestion, is essentially related to the organs of the mouth, stomach, and colon, and the vegetative power relies on these organs of the body to actualize the digestive activities. The case of organ use is an interesting and important example of the relationship of the body and soul in Aristotle’s psychology and is extremely important in debates over cases of life and death. I will return to the importance of organs later in my analysis.
II.2 Current Usage of Potentiality
Potentiality features prominently right from the beginning of Aristotle’s own account in De Anima II, in Aristotle’s definition of the soul as the actuality of a body that potentially has life. This definition might immediately give rise to controversy. Eberl, for example, has claimed, ‘At the most basic level, though, a body is ensouled if it is organized such that it is potentially alive’ (2008: 63). Eberl gets a lot of use from this notion of the organic body’s being ‘potentially alive’ in arguing that death should not be defined as irreversible. He highlights, for example, Aristotle’s assertion that ‘We must not understand by that which is capable of living what has lost the soul it had, but only what still retains it’ but notes that it remains unclear in certain cases such as cryopreserved body, at what point can we distinguish a ‘body’s having a sufficient degree of potentiality to be ensouled versus simply being able to become ensouled (again)” (De Anima: 412b25; Eberl 2008: 63). This seems to be the central question in these debates concerning life and death: at what level of a body’s potentiality for life does a body actually constitute a living being? It is on this question that the conception of potentiality is employed in its various senses. Eberl, for example, makes use of three different concepts of potentiality, which are central to this debate.
(1) Active and Passive Potentiality
This distinction arises most directly from Aristotle. Active potentiality means that the source of the activity stems from the entity’s internal powers, while passive potency is the subject’s ability to be acted upon by external sources (Lizza 2014: 150; De Anima: 412a28-29). Eberl indicates that active potentiality means that a being ‘has within itself everything necessary, given its proper design environment, to actualize itself in the relevant manner,’ while something with a passive sense of potentiality needs additional external factors to actualize its potentiality (2008: 66–67).6 He illustrates with the example of an embryo vs. an ovum and egg: an embryo has an active potentiality ‘for self-conscious rational thought and thus qualifies as a rationally ensouled person’ since it requires only the right environment, without any external saying agency for its development, while a sperm or ovum only have passive potentiality to develop in this way ‘because each must undergo the radical change that comes about through the process of fertilization, in which each cell ceases to exist on its own and forms a new composite substance: a rationally ensouled embryo (Eberl 2008: 66–67).
(2) Strong and Weak Potentiality
The distinction between strong and weak potentiality is distinguished by the presence or absence of a numerical change in the entity being actualized: ‘For something, X, to have a strong potentiality to become Y, it must be the case that X maintains its numerical identity as it becomes Y’ (Eberl 2008: 67). Eberl again illustrates this with the example of a sperm and ovum, which he argues are potentially human persons only in a weak sense. For Eberl, a subject is a human in the strong sense only if ‘it could come to be a human person while preserving its numerical identity, that is, it remains the same substance identical with itself throughout its development from a germ cell to a fully actualized human person’ (2008: 67). In Eberl’s example, since a sperm, in fact, undergoes a change in its substantial identity through fusing with the ovum and thus undergoes a substantial change in becoming a human embryo, it possesses a weak sense of potentiality. In Eberl’s analysis, there can be a coordination of weak vs. strong and active vs. passive potentialities, such that something can have a weak and passive potentiality for X or an active and strong potentiality.
(3a) Logical Possibility
Logical possibility is advanced by David Cole (1992) and is the shallowest notion of potentiality within the discussions. It denotes any possibility that is not inconsistent with itself or its given possible world (Lizza 2005: 30; Lamb 1992). Logical possibilities are sometimes used to discuss the potential future perfections in technologies: in the future, cryopreservation and resuscitative techniques might enable patients who now have no potentiality for life to retain such potentiality. Thus, given further advancements, a logical conception of potentiality might seem reasonable or useful (Cole 1992: 26). However, with David Lamb (1992), Lizza argues that the logical sense of potentiality is unrealistically lax, and we will return to Lizza’s alternative (3b) below.
II.3 Lizza and Feinberg’s Critique
Using these various senses of potentiality, especially the distinction between passive and active potentiality, Eberl has attempted to establish a principled reason that can establish a meaningful definition of death in the cases of a cryopreserved body and a patient with brain failure. In attempting to cash out the relevant sense of ‘active potentiality,’ Eberl invokes the notion of the vivifying principle’s ‘control’ over the body as a delineating principle. Thus, according to Eberl, a cryopreserved body can only be granted a weak sense of passive potentiality precisely because it lacks the relevant capacity of bodily control in its self-movement toward life. Thus, Eberl’s principle is that ‘[i]f a person cannot actually perform his vital metabolic functions, then he is dead’ (2008: 75). In contrast to Eberl’s analysis, Shewmon has argued that humans who are artificially sustained, such as those with total brain failure, should still be understood as ‘organically integrated’ and, therefore, alive (2010: 272).7
From this, Lizza has argued that
[e]ven if the distinction between ‘the potential for X with assistance’ and ‘performance X by an external agent’ is recognized along the lines of a distinction between active and passive potentiality, it is unclear how to apply this distinction, especially in the controversial cases (Lizza 2014: 255).
That is, it is unclear how these distinctions of active or strong potentiality can serve to distinguish these cases in a non ad hoc way. Lizza argues that both Eberl and Shewmon’s accounts hold similar difficulties since if
an artificially sustained human organism with no brain function has the potential for intellect and will, then I see no non-arbitrary grounds for not attributing this same potential to an artificially sustained decapitated human organism, the cryopreserved body, or to even a corpse (Lizza, 2014, 251).8
Further, Lizza highlights that delineating whether a being has ‘active potentiality’ rather than ‘passive potentiality’ wholly depends on ‘how the requisite disposition should be defined’ (2014: 253). He argues that it seems unclear ‘whether such a disposition can be defined in a non-arbitrary way to resolve the borderline cases’ specifically because an account of a context that would define the relevant dispositions is either lacking or so arbitrary so as to be lacking (Lizza 2014: 253). For example, on Eberl’s analysis, it is unclear if an adjacent case of a bypass patient, who needs bypass surgery precisely because he lacks a relevant sense of control over his vital functions, would actually qualify as living since it is unclear whether the patient has ‘in itself the power of setting itself in movement and arresting itself’ (Eberl 2008: 68). Lizza also cites the example of people who are living on artificial life-support, such as the iron lung, who, on this criterion, lack the relevant life powers of self-motion, saying, ‘[i]t would be absurd to consider them dead. Are they no longer ensouled when they can still exercise intellect and will, albeit through artificial support?’ (2014: 255) From this analysis, Lizza concludes that there is no way to actually determine in borderline cases when a subject has or does not have the relevant sense of potentiality since, on the grounds of the distinction between passive vs. active and weak vs. strong potentiality, neither Eberl and Shewmon’s accounts can give principled non ad hoc reasons which can distinguish a cryopreserved body from a bypass patient or an artificially sustained human organism from a corpse (2014: 257).
In line with Lizza’s assessment of the situation, Joel Feinberg (2014) dedicates his short piece, ‘The Paradoxes of Potentiality,’ to highlighting the ‘slippery slope’ of decontextualized usages of potency. Feinberg says that sometimes it seems as if ‘anything at all can be potentially almost anything else at all!’ given a broad enough sense of potentiality (2014: 69). For example, dehydrated orange powder is intended to be potentially orange juice; it will actually become orange juice with the addition of water. But given other additions, the orange powder could also potentially become lemonade, poison, an orange cake, orange-colored building material ‘and so on, ad infinitum’ (2014: 69). Given this, Feinberg rightly notes that:
Clearly, some sort of line will have to be drawn between direct or proximate potentialities and indirect or remote ones; and however we draw this line, there will be borderline cases whose classification will seem uncertain or even arbitrary. Even though any X can become a Y provided only that it is combined with the necessary additional elements, a, b, c, d, and so forth, we cannot say of any given X that it is a ‘potential Y’ unless certain further—rather strict—conditions are met. (Otherwise the concept of potentiality, being universally and promiscuously applicable, will have no utility.) (2014: 69)
He suggests two possible criteria for narrowing the sense of potentiality to ‘proximate potentiality.’ First is the ‘causal importance’ of the additional elements that need to be added to a substance to actualize its potentiality. For example, the possibility of orange power becoming a building block is more remote than it becoming orange juice because the additional necessary elements of cement and water are importantly different from the qualities already inherent in the orange powder and thus are ‘causally crucial’ (2014: 70). However, as Feinberg notes, this criterion of causal importance is, in significant respects, relative to what one views as important. One’s view of an element’s importance can, for example, depend on the relative ease or accessibility of obtaining the addition. Because water is relatively easy to obtain in most circumstances, one might grant that orange powder is, in a strong sense, potentially orange juice. Under different conditions, however – for example, on a planet without water and no way to obtain it – the dehydrated powder seems to have less potential to become orange juice. This relativism within the sense of importance makes this criterion not very helpful. The second criterion that Feinberg identifies for something to have proximate potentiality is that of the “degree of deviation required from ‘the normal course of events’” (2014: 70). That is, a potentiality is proximate if, when nothing intentionally prevents it from actualizing its potential, it will. For example, a human embryo successfully implanted in a functioning womb will, in the normal course of events, become a child. On the other hand, an unfertilized ovum will not become an embryo or a human being unless something intentionally comes about to make this happen. For the second criterion of normal conditions necessary for proximate potentiality, Feinberg notes that what is ‘normal,’ like what is ‘important,’ is meaningful only within a specific context. This is important to highlight: potentiality is only relevant within a given background context. If that context is subject to change, rather than being permanent or stable relative to any given subject, then our meaning and use of potentiality might be subsequently skewed, perhaps to the point of uselessness. This conception of a normal state of affairs will be important in our discussion of the concept of nature in applications of potentiality.
Like Feinberg, Lizza highlights the importance of tethering the concept of potentiality to a context, but he furthers this analysis by arguing for the importance of actual or physical possibility. Relying on Edward Covey’s (1991) work, Lizza contrasts actual possibility with (3a) absolute or logical possibility (Lizza 2014: 257). As Feinberg’s analysis has highlighted, logical possibility makes the concept of potentiality so ‘promiscuous’ as to be useless — anything can be anything if we just change the relevant material conditions (2014: 73). So Lizza and Covey suggest that a more robust and useful sense of potentiality is ‘realistic’ or ‘actual’ possibility.
(3b) Actual Possibility
Lizza notes two aspects of the actual possibility. First ‘any sensible theory of potentiality must recognize that potentiality is at least dependent on certain internal factors, since those internal factors may affect whether a possibility is actual or not’ (2014: 258).9 But because ‘ascriptions of potentiality necessarily refer to possible future states of the entity,’ the actual extent of this potentiality is not solely comprised by these internal elements of the entity (Lizza 2014: 260; Covey 1991: 237). Thus, second, a subject’s potentiality must also ‘always be understood against a background of assumptions about the entity’s relation to the world and the possibility that it may be actualized’ (Lizza 2014: 260) Covey contrasts physical possibility and logical possibility in terms of ‘nomic regularities,’ which are defined as an event or state of affairs that comes about ‘in accordance with the laws of nature, given the initial state of affairs which actually obtains in the world’ (Covey 1991: 237). Covey illustrates this with Nicholas Rescher’s (1975) acorn example, in which it is logically possible for an acorn to develop into a pear tree, but obviously, given the current state of horticulture, this is not actually possible. Thus, Lizza’s account, like Feinberg’s, attempts to offer an answer to the problem of the promiscuousness of potentiality: in order to delineate a proximate, rather than a meaninglessly remote sense, of potentiality, we need to delineate both standard internal factors of the entity and a normal state of affairs in which the potentialities can be actualized. Lizza argues that actual possibility, with its two criteria of internal possibility and external plausibility, makes up a more robust conception of potentiality which can be ethically relevant in decision-making cases: ‘what is ethically significant about potentiality is not whether it is active or passive but whether there is an actual possibility for the potentiality to be realized’ (2014: 262).10
I take Lizza’s conception of actual possibility to be a refreshingly robust account of potentiality and a helpful move towards the realistic and concrete in the discussions of delineating cases of life and death. However, as Lizza and Freiburg both highlight, what is standard for a given subject and what is a normal state of affairs are meaningful only within a relevant or specific context. Any account of ‘normal’ that is untethered from a contextualizing framework is meaningless. I argue that although Lizza and Freiburg recognize the importance of contextualizing conditions to make the concept of potentiality more specific and meaningful, in order to properly contextualize potentiality, the most helpful framework may, in fact, be the original one: the Aristotelian account of nature. Before defending this claim, I would like to further clarify what I take to be an Aristotelian account of nature. Lizza, in defending actual possibility, favors expansive conditions, including what is made possible by technology and human choice, over an account of Aristotelian essences or natures, which appear essentially fixed and simply given. Although this is the standard account of Aristotelian essentialism, I do not think that this is the most accurate or helpful account.
In presenting an account of nature, it is necessary to simplify and limit the considerations of the interaction of secondary causes in the environment. However, we should not mistake a methodological principle of simplicity of explanation as a built-in feature of our metaphysics. In presenting a metaphysical framework such as Aristotle’s, we leave out secondary causes, interactions between causes, and contextualizing features, but this does not mean an Aristotelian account of nature is blind to the impact of those features on a natural entity’s potentiality. Within an Aristotelian account of nature, the subject’s environment can have an enormous impact on how that nature manifests and evolves. In an account of nature in which there is sensitivity to the environment and to the impact of secondary causes, there is a flexibility to how these causes work in conjunction with the subject’s biological givens in orienting a direction regarding its nature and ends. For example, human infants are born with flexible cartilage in multiple places rather than fully developed bones, which need to gradually ossify. This development is natural – it is part of their natural gestation and growth – but part of this process includes and is impacted by features of their environment, such as the food they eat, which can change the course of this development. When accurately understood, rather than caricatured, Aristotle’s metaphysics can ground a nuanced analyses that account for such complexities and complications.
Lizza’s focus on technology and free choice is an amplification of this sensitivity to the malleability of nature. He is wary of a strong account of nature as given because it seems to limit our possibilities to only what happens without human interaction and in the absence of a framework of human intentionality and choice. However, I take my account of nature to be sensitive to Lizza’s concern. An Aristotelian account of nature can and should be nuanced and sensitive to the malleability and possibility stemming from our human rational nature, including possibilities brought about through technology and choice.11 The fact that Aristotle’s framework does not explicitly address historically novel phenomena or possibilities, such as artificial organs, does not mean it cannot be effectively applied to these cases with appropriate analogical reasoning.
Although in its presentation, Aristotle abstracts from those secondary causes and their interaction with natural entities, in the borderline cases (so often the focus in the sphere of ethics), those secondary causes and specific features take on outsized relevance and would be important in our deliberations. An Aristotelian account of nature can be sensitive to these impacting causes: it is not a feature of the metaphysics but in its presentation or its theoretical account that we leave out complicating, secondary, reverberating features. My thesis is, in fact, in part, that a simplistic adoption of the Aristotelian framework, like that of Eberl and Shewmon, which abstracts too fully from the context of secondary causes, is unhelpful. A more flexible and nuanced account of nature is necessary in order for it to be effective, and in order for the concept of potentiality, in turn, to do any work.
III. Nature and Teleology: Context for an Aristotelian Potentiality
This section will argue for my own account of a more Aristotelian approach to contextualizing potentiality through its necessary background metaphysical commitments, namely a specified account of a teleological nature which can help further explain both the criterion of the subject’s internal characteristics and stability of the external environment from Lizza and Feinberg’s analysis. First, however, one element of Lizza’s account is worth addressing in detail in order to highlight how Aristotle’s conception of potentiality in the case of the human soul and its vivifying relation to the body might still be relevant for contemporary discussions, namely, Lizza’s notice of the spirituality of the Aristotelian soul. Lizza highlights that ‘[p]art of the difficulty in answering this question [of defining death and delineating cases of life and death] stems from the Aristotelian-inspired notion of potentiality that these authors rely on and that involves ensoulment’ (2014: 257). At play here is the notion of a spiritual soul, which informs the physical body. Lizza highlights that it is ‘the spiritual nature of the soul [which] makes it impossible to give a determinate answer to the borderline cases’ (2014: 257).
Initially, it might seem that Lizza brings up the spiritual element of the soul in order to critique an unwelcome addition of mysticism in conversations about medical practice. Although some might object to ‘soul talk’ on these grounds of ‘over spiritualization,’ I do not take Lizza’s critiques to amount to this, and I think this is for good reason. Aristotle’s account of the soul, unlike more recent interpretations of the soul, is exceptionally physiological. Although he holds that there is a purely immaterial mind, the majority of Aristotle’s treatment of the soul is in terms of the specific powers that vivify the various organs of living beings. In fact, Aristotle took his treatment of the soul to be part of natural philosophy, what we would today treat as biology. Thus, such superficial critiques of Aristotle’s account of the soul in light of its ‘spirituality’ overlook crucial interpretive aspects of Aristotle’s thought. But Lizza’s caution on spiritual grounds is via another route, namely, the inaccessibility of the soul because of its unobservability due to its formal immateriality. Lizza notes:
At work is a spiritual principle that informs physical bodies and gives them the potential they have. However, since souls or spiritual principles are not directly observable, any determinations of ensoulment and, therefore, active potentialities will be dependent on inferences from what is physically observable (2014: 258).
Because the soul itself and the potentialities of the soul are unobservable, our knowledge of them is only second-hand through their physical effects.
This is something that Aristotle highlights not only in his account of the potentialities of the soul but also in his analysis of the central features of human knowledge, which he works into his empirical methodology as a whole. The soul’s unobservability may be one reason Aristotle claims that any sure knowledge of the soul is ‘one of the most difficult things in the world to attain’ (402a10). In terms of the potentialities of the soul, the difficulty due to the immateriality of the soul is also linked to Aristotle’s interesting methodological remarks at the beginning of II.4 on the order of the inquiry. There, he says that if we are to understand what a particular power is,
vis what the thinking power is, or the perceptive, or the nutritive, we must go further back and first give an account of thinking or perceiving, for in the order of investigation, the question of what an agent does precedes the question, what enables it to do what it does (415a15-20).
That is, in order to understand the power or potentiality of a subject, we must first, in the order of discovery, investigate its corresponding activity or operation of that power. To understand a subject’s – say, a dog’s – potentiality for sight, we must be knowledgeable about the canine operation of seeing. Aristotle continues, ‘[i]f this is correct, we must on the same grounds go yet another step further back and have some clear view of the object of each; thus we must start with these objects, e.g., with food, with what is perceptible, or with what is intelligible’ (415a20-22). Thus, in order to understand the operation of canine sight, it is necessary to have knowledge, perhaps intimate knowledge, of the relevant objects of a dog’s vision.
This move from the powers through the operations to the objects is representative of a more general feature that Aristotle highlights throughout his account of human knowledge. At the foundation of Aristotle’s epistemology is the distinction between what is better known to us and what is better known in itself (415a20-22). Formal nature, causal powers, and potentialities, although more intelligible in themselves, are less observable and knowable to us and only become accessible to us through observation and abstraction from the effects of these powers.
This sensitivity in Aristotle to the order of knowledge and the dependency of our knowledge of potentiality on this chain from actuality to objects is important in our analysis of potentiality’s relevance in contemporary discussions. Specifically, the passage explaining the order of our knowledge of potentiality highlights that Aristotle was not unaware of the difficulty that Lizza brings up of gaining sure knowledge of potentiality because of its spiritual or unobservable nature.12 I take this passage as his recognition of that difficulty and his methodological solution to it. In the case of the soul, the potentialities only become known through their actual effects in the action of the body. Thus, it is extremely difficult to tell when the relevant potentialities are at hand without some background knowledge of the specific nature of the being, which determines its specific potentialities.
This brings us explicitly to my two recommendations of this paper. I take this passage, in a nuanced way, to highlight the necessity of an account of a specific and teleologically ordered nature. I do not take Aristotle’s recommendation that, in order to gain knowledge of something’s potentiality, one must have clear knowledge of that thing’s activity and knowledge of the object of that activity to denote potentialities, activities, and objects in general, but in their specificity. Specifically, potentialities and activities are relative to particular natures: to the different levels of souls instantiated in plants, animals, and humans, and to the specific different types of animal or plant nature. That is, I take Aristotle’s account of our knowledge of potentiality through a subject’s activity and the object of that activity to be necessarily relative to a given subject’s nature. The only way one can know a being’s unobservable potentiality is through an analysis of the subject’s relevant activities and objects, which, in turn, requires knowledge of that being’s specific nature. A full account of a being’s nature, which explains the being’s activities, objects, and potentialities, is one that involves an Aristotelian conception of teleology. I think that this conception of a teleological nature can give adequate robustness and concreteness to our conception of potentiality, which, though lacking in contemporary applications, is so prevalent in Aristotle’s account.
I think this is strengthened by the passage directly prior to the one I have just analyzed. In the last sentence of II.3, Aristotle claims, ‘it is evident that the way to give the most adequate definition of the soul is to see in the case of each of its forms for the most appropriate definition’ (415a13-14). That is, knowledge of the soul is most properly gained not through the general definition from II.1–2 but through a more detailed analysis of the specific nature of the souls of plants, animals, and humans. Similarly, knowledge of a being’s definition, and hence its relevant powers and actualities is not properly achieved in general, with a general notion of potentiality. Rather, something’s powers and activities are only properly known through a specific understanding of that being’s nature.
This is further highlighted in Aristotle’s explication of the two types of potentiality in De Anima 417a25-30:
But we must now distinguish different senses in which things can be said to be potential or actual.…We can speak of something as a knower either as when we say that man is a knower, meaning that man falls within the class of beings that know or have knowledge, or as when we are speaking of a man who possesses a knowledge of grammar; each of these has a potentiality, but not in the same way: the one because his kind or matter is such and such, the other because he can reflect when he wants to, if nothing external prevents him. And there is the man who is already reflecting — he is a knower in actuality, and in the most proper sense is knowing … Both the former are potential knowers.
This gives us the final sense of potentiality, which, although underused in analyzing cases of life and death in the current literature, is vitally important in returning to a more nature-specific and teleological use of potentiality.13
(4) First vs. Second Potentiality
As discussed above, Aristotle distinguishes two senses of actuality: the capacity for an action, such as having a body of knowledge and being able to think about it, and the actual operation of that action, such as reflecting. Corresponding to these two senses of actuality are two kinds of potentiality:
First Potentiality —> First Actuality/Second Potentiality —> Second Actuality
A subject has first potentiality for X if the subject has the nature or is part of a natural kind whose nature enables it to do X. A being has the second type of potentiality for X if it ‘possesses’ or is directly capable of actualizing this power. (In this sense, first actuality and second potentiality collapse into the same state). As Timothy Mosteller says, ‘[i]f nothing external prevents it from doing X’ (2005: 346; Aristotle 417a25). Again, we can use the example of knowledge: a human being, even in infancy, before there is any actual body of knowledge, possesses the first potentiality for knowledge because it is the type of being that has a rational soul, i.e., it has a human rational nature. A human would have the second potentiality for knowledge if they knew the subject matter of grammar and were able, on command, to recall and know grammatical truths. Mosteller notes the ontological dependence of the second potentiality on the first because ‘an entity cannot have potentialities that it is able to actualize by its own powers if it is not already the kind of thing that can actualize those potentialities’ (2005: 346). This is because the ‘essence’ or ‘natural kind-ness’ of the being in question is prior to and causal of the potentiality of that being. Aristotle is explicitly relying on his theory of natural kinds to explain his account of potentialities. As we can see from the example, a being only has the potential for certain activities because it has a specific type of nature.14
The account of a specified nature is intrinsically linked with the second feature of teleology. This nature, in Aristotle’s view, is necessarily teleological. It is ordered to a specific mode of proper functioning, which is relative to a given subject’s natural ends. That is, a nature that can give a meaningful context to the relevant senses of potentiality must be teleological in some sense because the telos or end of the natural subject will determine the ends to which the potentialities are ordered in the first place. In other words, potentialities are in their own nature teleological; they are potentialities for something, for a being’s natural activities. Thus, a rigorous account of potentiality has to include the subject’s nature and its natural ends because these are what determine the potentiality in the first place.15
Aristotle is clear on the teleological order of nature, specifically in the final casualty held by the soul: the soul is the source of movement, the end, and the essence of the living body (415b12). As its end and its formal nature, the soul is the final cause of the body,
for nature, like thought, always does whatever it does for the sake of something, which something is its end. To this, something corresponds in the case of animals, the soul, and in this, it follows the order of nature; all natural bodies are organs of the soul (415b15).
By this, I take Aristotle to mean that the soul, the first actuality of the being and the formal source of its specific nature, orients the natural ends and activities of that being. The specific animate and sensitive nature of a shark, for example, informs and orients a shark’s vision: its ability to see well in the low light of deep water is informed by its participation in its nature as an aquatic predator. In contrast, human vision, which is less adept in low light, seems to be informed by our social nature in line with our rationality: among higher mammals, humans have highly exposed whites of the eye, which allows for clear communication and social interaction through the clearly signaled direction of our gaze (Kano et al. 2022). The nature, i.e., the soul of the entity, teleologically orders and informs the organ’s activities and ways of life of the animate being and gives a context in which its second potentialities, both active and passive, can be better understood and assessed.
Thus, any discussion of an entity’s various modes of potentiality, be it actual, active, or strong, is, in fact, useless if the entity’s nature – which grounds any account of its potentialities – is unknown or undecided. It is knowledge of the subject’s teleological nature that grounds any account of its actual or active possibilities.16 The Aristotelian account of nature is fitted for the task of contextualizing and specifying our criterion of standard or normal for a given organism because it provides a model for distinguishing between what is essentially a subject’s nature and the physical organs and operations by which we know and define that nature.
Teleology in the Aristotelian worldview presumes actual possibility: since nature acts for an end and does nothing in vain, anything to which a natural being is teleologically oriented is, under normal conditions, an actual possibility. A teleological account of nature grounds our conception of actual possibility and furthers it through the specificity of the subject’s nature, which accounts for Lizza’s normal internal conditions while making them less situationally relative and more concrete and, thus, more practically helpful. Thus, if one takes an Aristotelian account of potentiality to be useful in delineating cases of life and death, one must buy into not only a realist account of actual possibility given a normal environment, but one must also grant on some level, an Aristotelian account of a teleological nature, which can determine the relevant powers and potentialities of the given subject. Lizza has highlighted the necessity of a more concrete and realistic account of potentiality in his call for actual rather than logical possibility and an account of normal internal features. I take my account to be in line with this move towards realism but to differ from Lizza in arguing the necessity of an account of nature that can ground and orient the normal features presumed by actual possibility in order for applications of potentiality to be meaningful.
IV. Suggestions for Application
Having argued for a more robust context in the Aristotelian framework for the conception of potentiality, I will briefly return to the case studies of defining death in medically complex cases in order to highlight how a nature-specific and teleological framework can help contextualize the conception of potentiality. However, as my aim in this essay was not to define the point of death or the beginning of life, my aim in returning to the specific medical case studies is not to argue for a specific answer to these ethical questions. Rather, in returning to these specific cases, I aim to make three framing suggestions stemming from my account of Aristotelian teleological nature.
First is to highlight that these borderline cases under discussion are inherently controversial precisely because, as Aristotle acknowledges, we only have visible effects rather than knowledge of the causes regarding whether an entity is in one condition or another or whether a substantial change in a subject’s nature has occurred. Because of this inherent epistemic difficulty, my first suggestion is that it might be ethically relevant to approach the delineation of borderline cases with an eye to expanding rather than limiting our conception of a living organism of a given species. Ethically, it seems more appropriate to air on the side of caution in cases where it is intrinsically difficult to delineate precisely whether a subject falls into the case of living human rather than trying to precisely restrict the status of human without full knowledge of the causes.
Second, I suggest that a renewed focus on the distinction between first and second potentiality is an overlooked yet foundational principle in these debates. As an example, I think that this distinction can bolster and ground Lizza’s critique of Eberl’s principle that ‘[i]f a person cannot actually perform his vital metabolic functions, then he is dead’ (Eberl 2008: 75). I agree with Lizza’s rejection of this claim and recognize the strength of his counterexamples: we do not think that someone in an iron lung or a bypass surgery patient is dead, even when they cannot independently perform metabolic functions. But Aristotle’s distinction between first and second potentiality is helpful here in underwriting an account of why these are genuine counterexamples. Eberl’s claim that one must be able to ‘actually perform’ their vital metabolic functions errs in focusing exclusively on the actualization of second potentiality and ignores Aristotle’s recognition that life is, in fact, a first actuality which grounds yet is distinct from the performance of specific second potentialities (2008: 75). This explains why someone can have first actuality, i.e., be a living entity of a certain nature, such as a human, without having a specific second actuality associated with that nature, i.e., without being able to express their rationality through verbal communication, or through actualizing their proper accident of risibility in laughter because of a physical disorder of their vocal cords. Thus, as in Aristotle’s example, just as we do not count sleeping people as dead even though they are not actualizing their human potentialities of intellect and will, in the second sense, so we would not count those metabolically sustained in some respects as dead either. In both cases, the subjects retain the capacity and actualization of other relevant vital human activities. Further, the artificially sustained subjects have the potentiality, in the second sense, of actualizing the artificially sustained capacities, given the removal of certain physical impediments.17 I take Lizza’s analysis to be bolstered and grounded by the formal account of first and second potentiality in De Anima.
Third, and finally, I suggest a response to Lizza’s assertion that if
an artificially sustained human organism with no brain function has the potential for intellect and will, then I see no non-arbitrary grounds for not attributing this same potential to an artificially sustained decapitated human organism, the cryopreserved body, or to even a corpse (2014: 251).
Lizza’s critique here is that the looser uses of potentiality either lower the criterion for being ‘potentially alive’ so much that it seems anything, including a corpse, could be alive, as in the case of Eberl, or they restrict the criterion for self-actualization as the basis for life so much that those on artificial life-support or awaiting bypass surgery would not count as alive, as in the case of Shewmon.18 I am willing to grant to Eberl that a cryopreserved body is potentially alive, having a weak sense of passive potentiality. Per suggestion one, it seems plausible and less problematic to ascribe life potentially to a cryopreserved body or to a brain-dead patient sustained through artificial means. Given this, how does an Aristotelian account respond to Lizza’s challenge that if we grant life to those sustained artificially, on what grounds do we deny life to an artificially sustained decapitated subject, or even to a corpse if there is such a widened sense of potentiality?
I argue that according to an Aristotelian account, the artificially sustained decapitated human organism is not alive, even though an artificially sustained brain-dead person is alive.19 In the case of the artificially sustained decapitated subject, although some organs might be alive through being artificially sustained,20 the person as a substantial unity is not alive, having absolutely no potentiality for intellect and will because they lack the organs necessary to ground that potentiality.21 If an organism is decapitated and does not have an organ necessary to ground the activities, intellect, and will – namely, the brain – then there is no way on the Aristotelian account that organisms, even one that is organically integrated by artificial sustainment, could be said to be able to fulfill potentialities that a human person should have. This is because, on the Aristotelian account, without an organ there would be no potentiality for the exercise of that organ or any activities dependent on it.22
Here, it is important to highlight that in Aristotle’s account of the soul, the organs that underlie the powers are central in specifying nature and are crucial components specifying and orienting the powers towards their ends.23 Without the linking element of an existing organ grounding an activity essential to the nature of the subject, there cannot be any potentiality for that activity because a capacity stemming from the soul is only enacted or performed by the subject through the particular features of the organ. In the case of a decapitated human body, there is an absolute absence of the organ necessary for rationality, which entails that the organism can no longer be regarded as having the capacity to perform human-specific functions, even in principle, while a brain-dead body still possesses the physical organ even if its functions are damaged. The organs serve as a critical link between the potentialities as such and their actualization. Thus, the presence of a brain, even one whose capacities are damaged, is necessary for the integration of the soul and its body.
Granted that a decapitated organism, without the organ that can ground the relevant potentiality for human function, is not a living human, on what grounds do we grant that an artificial sustained brain-dead is still a living human? Here my account of the integration of the levels of powers is important for understanding why, on the Aristotelian account, there may not be a substantial change in the kind of entity with the loss of higher powers. With this account of integrated powers, all of the powers of the entity, not just the highest ones, are teleologically oriented to and manifestations of the specific nature of the entity. The powers are specified within the nature of the entity they participate in. Thus, although a loss of the highest, species-defining powers – in the human case, intellect and will – is significant, this does not immediately entail a change in species, or a substantial change, on the Aristotelian account. If an artificially sustained brain-dead human is alive in a nutritive sense, although it lacks the second actuality of its intellect and will, the integrated account of the powers of the soul point to the entity’s remaining not only alive but also human in a strong sense, because all the lower powers which are still actualized, are still the human nutritive powers.24 If an entity, even if sustained through technology, retains the human nutritive powers and is alive, then it is human; even the higher-order actualities are not able to be enacted. Thus, Aristotle’s framework gives us the ability to recognize a loss of some potentialities without necessarily a change in the nature of the thing. An entity can have second potentiality without second actuality, and if an entity retains second potentiality, they must remain linked to the first potentiality, i.e., they must remain in the same species.25
V. Conclusion
I have argued that in order to return in a more robust way an Aristotelian conception of potentiality which can escape the arbitrariness and ad hoc issues arising from contemporary applications, one must grant a metaphysical framework in which the concept of potentiality can have a robust explanatory role. This framework concerns the Aristotelian teleological nature. My analysis responds to that of Feinberg and Lizza, who argued for the insufficiency of the current uses of potentiality in favor of a more realistic conception of actual potentiality and who highlighted the importance of the subject’s context of both normal internal features and a normal external environment for delineating the relevant senses of potentiality. I have argued that the insufficiency of potentiality that Lizza and Feinberg cite is, in fact, due to a lack of an Aristotelian context of a teleological nature: it is this Aristotelian framework of the subject’s teleological nature directing the subject’s potentiality which can provide an answer to Feinberg and Lizza’s critiques in a more robust way. Although I grant that the conceptions of both teleology and nature have received substantial objections from evolutionary accounts of human development and philosophical deconstructionist views, my account does not intend to defend or rebuff broader philosophical systems. It is only intended to show that if one wants to employ an account of potentiality, one needs to take into account some sense of nature that grounds those potentialities and a teleological end to which those potentialities are ordered.
Notes
[1] Although the specific case studies in this paper focus on the example of human life and death, I take my recommendation to apply more broadly to include ethical cases involving non-human animals.
[2] Substances are most properly natural beings, although artifacts might also count as substances in a weaker sense. Translations of Arisotle throughout are from The Complete Works of Aristotle Barnes, (1985).
[3] Note that by ‘potentially alive,’ I take Aristotle to mean not that the body is actually dead and potentially alive but that the body, in reference to the soul, is potential since the soul, as form, is what actually vivifies it, and also the body has a specific capacity for life and hence is organic whatever relevant sense of the term that designates for the different types of life.
[4] For examples of the integration of the soul’s powers, see Shields (2009: 306) and Matthen (2014: 43).
[6] Eberl also highlights that the relevant sense of potentiality for rational ensoulment ‘refers to something’s capacity to be in a certain way, as opposed to merely the possibility of its becoming something’ (2008: 66–67. Emphasis in original). For more on this see Witt (1995: 264).
[7] Shewmon defines active potentiality as the ‘capacity to develop the capacity for X,’ noting that ‘to develop’ should not be understood in the overly restrictive sense of being entirely spontaneous but should accommodate instances ‘where external elimination of some impediment is required for the development to proceed.’ (2010: 272)
[8] In contrast, van Inwagen, uses a laxer criterion that does not involve the power of self-motion, which Lizza also argues against (1995: 146–147; Lizza, 2014: 254).
[9] An example of these internal factors which is extremely relevant in ethical discussions of potentiality in beginning-of-life cases is Jim Stone’s (1987) analysis of whether the potentiality of a genetically defective human embryo is at all different from the potentiality of a non-defective or normal healthy. He argues that the relevant sense of potentiality is different based on this difference in internal factors.
[10] Lizza includes as relevant for the determination of actual possibility not only the current physical features of an organism and the given regularities of the external physical environment but also the ‘external understanding’ of the organism by humans, alternations in their capacities through technology, and the broader ‘nomic regularities,’ the ‘cultural’ world (2014: 268).
[11] I think it is also helpful to note that the Aristotelian framework of nature obviously works best with natural subjects and that artificial entities, such as organs created for testing or other artificial or quasi-natural subjects brought about through technological advancements, will have only analogous roles within the Aristotelian framework.
[12] Lennox discusses additional difficulties posed by the immateriality of the rational soul (2019: 100).
[13] For an example of contemporary use of this distinction in applying potentiality to complex cases of life and death, specifically in the case of headless clones see Timothy Mosteller (2005).
[14] This mirrors the point we saw in the case of the lower powers of the soul being incorporated into the higher powers, in that the way the dog sees is informed by its sensitive soul and its nature.
[15] For a detailed analysis of Aristotle’s conception of the teleological relationship between matter and substance in terms of the potentiality of the matter being actualized by the substance, see Johansen (2012a; 2012b).
[16] I do not here undertake to define any given being’s nature, with its relevant telos, features, and operations: this is a job for the biologist and anthropologist; rather, my claim here is that this account of a being’s nature is prior causally to any account of its potentialities and is a necessary prior framework for our ethical deliberations.
[17] One possible objection against this view is that all of the individuals in the controversial cases may be described as members of the human species. Just as preserved butterfly specimens in a museum clearly are members of their species, the artificially sustained decapitated human organism, the cryopreserved body, and the human corpses should be considered members of the human species, thus making the appeal to natural kinds unhelpful. In response, Aristotle’s position in De Anima II.3 is helpful: ‘Suppose that the eye were an animal – sight would have been its soul, for sight is the substance or essence of the eye which corresponds to the formula, the eye being merely the matter of seeing; when seeing is removed the eye is no longer an eye, except in name – it is no more a real eye than the eye of a statue or of a painted figure’ (412b17-22). That is, dead members of a natural kind are members of their species ‘in name only’ since they lack not only the functions and potentialities that living individuals of those species have, but critically, because they lack the principle of being for their kind, namely the soul. Thus, the question metaphysically hinges on the existence of a soul animating the body and only epistemically hinges on what physical features and functions a being displays to alert us to its ensoulment and, thus, its qualification as a member of the kind.
[18] For reference, I take it that on the Aristotelian picture, a corpse is, by definition, the limit case, in which by whatever acceptable methods, it has been determined that the body is no longer vivified, actualized, or organically integrated through the soul. For more on the methods and difficulty of delineating death, see Lizza (2006).
[19] Thus, while granting along with Eberl that a cryopreserved body is potentially alive, having a weak sense of passive potentiality, per suggestion one, I disagree with Eberl’s further conclusion that an artificially sustained brain-dead human body is no longer a living human being.
[20] I think the question of whether organs might count as substances in some derivative sense on the Aristotelian account is an interesting one for this debate, which I will not address here.
[21] Aristotle is clear that nous or rationality does not have a bodily organ. However, it also seems clear that the activity of the intellect is dependent on bodily organs, most notably the brain, for prior activities of imagination and sense processing on which the intellectual activities depend. Thus, an incapacitation of the organ of the brain will have the immediate and direct consequences of impending the activities of imagination and the downstream and indirect consequence of impeding the activities of the intellect.
[22] Here, my view disagrees with that of Shewmon, who argues that the decapitated human body is a living human being. Although, Shewmon might argue that given the specifically human nutritive activity that persists in the artificially sustained decapitated body (albeit through artificial support) we have reason to think that it is a living human being, this view overlooks the centrality of the organs in grounding the relevant capacities.
[23] The role and the centrality of the organs as a medium between the potencies, or powers of the soul and their actualization on Aristotle’s account is an area which merits further examination.
[24] On my interpretation of Aristotle’s account of the souls’ powers, there are no generic nutritive or sensitive powers as such. Nutritive powers are importantly most proper to plants and sensitive powers to animals because, in each case, these powers define the species as its highest powers. But this does not entail that the powers are generic or that if a human has only the vegetative powers, they are then a plant. Rather, the human nutritive powers are precisely human.
[25] There might be relevant differences between this analysis of the loss of powers, and the cases which Lizza highlights regarding the sufficiency of specifically human capacities for ascribing realistic potential for intellect and will in cases of the development of these powers. While this discussion emphasizes the teleological orientation of these given capacities, as indicative of actual possibility, Lizza’s argument highlights that such capacities alone do not guarantee the development of intellect and will in individuals, for example, in cases such as anencephalic fetuses or other beings that exhibit deformations incompatible with their kind’s normal potentialities. My aim is not to resolve the ethical grounds or implications at stake, which is the focus of Lizza’s analysis, although of course the case studies are ethically charged: I do not take it that my discussion has resolved the significant ethical implications regarding how we interpret potentiality in Aristotelian terms, but only to have argued that a metaphysical framework needed to understand and employ an Aristotelian conception of potentiality: my suggestion is that a teleologically grounded one is necessary. Moreover, I take it that there are remaining differences between my account and Lizza’s account of ‘actual’ potentiality, in addition to the relevant differences in their focus noted above. Thus, this issue is worthy of further scholarly investigation, as it has important implications for both the understanding of potentiality and the ethical considerations within the Aristotelian framework.
Acknowledgements
I would like to thank two anonymous referees at Metaphysics for their comments and suggestions. I would also like to gratefully acknowledge the Paul Schmitt Foundation for their support of the open-access publication of several articles on Aristotle’s De Anima submitted in response to an associated Call for Papers. The Paul Schmitt Foundation’s support was used to cover the Article Processing Charge for these articles.
Competing Interests
The author has no competing interests to declare.