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Aquinas versus Locke and Descartes on the Human Person and End-of-Life Ethics

J.P. Moreland and Stan Wallace, International Philosophical Quarterly (Vol. XXXV, No. 3 Issue No. 139 Sep. 1995).

During the last decade or so, there has been a growing body of literature about various topics in end-of-life ethics. And while there is no clear agreement about a number of issues in this literature, nevertheless, there is something of a consensus that has emerged, perhaps unconsciously and implicitly at times, regarding how to view a cluster of crucial metaphysical themes relevant to the ethical issues just mentioned — the nature of personhood, humanness, and personal identity. In our view, this consensus approach to these three themes is Cartesian and Lockean in spirit. Often conspicuous by its absence, especially outside Catholic circles, is any discussion of Thomistic insights into these metaphysical desiderata, much less an acceptance of them. This tendency is egregious and contributes to a way of framing certain ethical issues that determines their resolution from the beginning.

In light of this problem, we have a twofold purpose in mind for what follows. First, we shall clarify the views of Thomas Aquinas regarding the human person and compare them briefly with the Cartesian/Lockean position insofar as that position has been appropriated by those working in the mainstream of contemporary ethical reflection. Secondly, we will select certain contemporary philosophical problems central to end-of-life ethics and show how the Thomist view solves them differently and more adequately than the Cartesian/Lockean approach. With this in mind, we will first overview Aquinas’ approach to humanness, personhood, and the human person, then briefly sketch out the thinking of Locke and Descartes on these ideas insofar as their doctrines are informing the contemporary debate, and, finally, offer a comparison of how these different ways of thinking solve three problems of interest for contemporary ethical dialogue.

I. Thomas Aquinas on Personhood and Humanness

Aquinas gives attention to issues of philosophical anthropology primarily in: Commentary on the Sentences 1; Summa Contra Gentiles 11, 58-90; Disputed Questions on the Soul; Exposition of Aristotle on the Soul; and Summa Theologiae la. 75-102.

Aquinas defines the soul as the substantial form of the body—"if any definition covers all types of ‘souls’ it will be this: the soul is the primary actuality of a physical bodily organism.”1 He further states that "the soul is a substance in the manner of a form that determines or characterizes a particular sort of body."2 It is this substantial form which, when united with the body, makes one substance — the individual human person. This may be better understood by analyzing his ontology of form, matter, and the relationship obtaining between the two.

The distinction between substantial form and body derives from Aquinas’ metaphysical distinction between matter and form, which he developed largely from Aristotle. Concerning all physical entities there are two dimensions: matter and form. Matter is not to be conceived of physically per se (i.e., as an independently existing raw material yet to be formed), but rather as that which has the potentiality to be actualized into an existent entity. It is thus termed prime matter. "Matter is that which is not as such a ‘particular thing,’ but is in mere potency to become a ‘particular thing.’ "3 It is that which is common to all material things and which is formed into different entities by the second element—the substantial form.

Form is the inherent principle which makes the existent entity what it is. It is logically prior to and actualizes its matter. Aquinas states: "Matter, then, differs from form in this, that it is a potential being; form is the ‘entelechy’ or actuality that renders matter actual; and the compound is the resulting actual being."4 He also writes: ‘Form is that by which a ‘particular thing’ actually exists. And the compound is ‘the particular thing’ itself."5 The form then, when combined with prime matter, becomes the existent entity. But just as prime matter cannot exist apart from form, form is never existent apart from instantiation in matter (except the human soul, which can exist disembodied in the intermediate state). Though it is logically prior to matter, it cannot exist temporally prior. Aquinas says that "no form as such is complete in kind; completeness in this sense belongs only to the substance composed of form and matter."6 Thus, concerning physical entities, to be (to have physical existence) is to be an instantiated form. This combination of form and matter creates the substance—the individual entity.

We may now go on and apply this understanding of form’s relationship to matter to the question of the human person’s essential composition. As an entity in the physical world, it follows that the human person must be defined as a deep unity of form and matter. The human’s form is his essence or substantial soul that actualizes matter to become his body. According to Aquinas, "the soul is a substance in the manner of a form that determines or characterizes a particular sort of body."7 The result of this union is the existence of the individual person. The type of essence (soul) instantiated defines what type of entity the particular entity is—it defines, in other words, the natural kind to which the individual belongs.

Aquinas further elucidates how this instantiation of form in matter brings individual human persons, not identical beings, into existence. He argues that individuation is a necessary result of the form being instantiated in matter; the act of instantiation individuates the form, resulting in individual beings. This act of instantiation produces an individual with a suchness (the form or natural kind), and also a thisness — this specific instantiation. It is important to emphasize that matter per se most likely does not individuate for Aquinas, since matter qua prime matter has no actuality, but only potentiality. Rather, individuation occurs via the act of the form being instantiated in matter, as a result of the form’s capacity to actualize the potentiality of matter.

This can also be understood along the lines of Aquinas’ doctrine of existence and essence, which is related to the form/matter distinction. Essence is what a thing is — its form — and existence is that a thing is — the individual instantiation or act of existence. Again, though the essence is logically prior to the existence in the sense that it defines the type of existence obtained, it is not temporally prior. Therefore, as all (finite) substances are a combination of form and matter it can also be said that they are a combination of essence and existence.

Aquinas’ emphasis on the one individual substance produced by the union of form and matter differs significantly from Cartesian dualism. Put briefly, Cartesian dualism views a human as a being composed of two ontologically distinct substances—a spiritual substance (the soul now taken to be the mind) and a physical substance (the body). Moreover, the mind alone constitutes the essence of the individual and the body in no way partakes of this essence. Descartes states: "For in my opinion nothing without which a thing can still exist is comprised in its essence, and although mind belongs to the essence of man, to be united to a human body is in the proper sense no part of the essence of mind."8

On the other hand, Thomistic dualism logically excludes the possibility of the body existing qua human body without a soul informing it. Thus, any notion of a human being composed of two individual substances is rejected. Aquinas writes: "We must not think, therefore, of the soul and body as though the body had its own form making it a body, to which a soul is super-added, making it a living body; but rather that the body gets its being and its life from the soul."9

Given Aquinas’ ontology that a form must necessarily be instantiated in an existent physical entity (except for the intermediate state), for the human body to have existence logically prior to the addition of the soul, the body would already have to have a separate form for it to exist before being attached to the soul. But if this were true, man would have two forms—the form of the body before the soul and the additional form of the soul. Yet for Aquinas this is impossible, since the soul gives the entity complete being; and were the body to have a form without the soul, it would already have complete being, and thus when the soul is added there would be two complete beings.

There are two other features of the Thomistic view of substance that are crucial to our topic. For Aquinas, a substance is a unity of capacities. Now, capacities come in hierarchies. There are first-order capacities, second-order capacities to have these first-order capacities, and so on, until ultimate capacities are reached. For example, if I can speak English but not Russian, then I have the first-order capacity for English as well as the second-order capacity to have this first-order capacity (which I have already developed). I also have the second-order capacity to have the capacity to speak Russian, but I lack the first-order capacity to do so.

Higher order capacities are realized by the development of lower order capacities under them. An acorn has the ultimate capacity to draw nourishment from the soil, but this can be actualized and unfolded only by developing the lower capacity to have a root system, then by developing the still lower capacities of the root system, and so on. When a substance has a defect (e.g., a child is color blind), it does not lose its ultimate capacities. Rather, it lacks some lower order capacity it needs for the ultimate capacity to be realized.

A substance’s capacities culminate in a set of its ultimate capacities which are possessed by it solely in virtue of the substance belonging to its natural kind; e.g., Smith’s ultimate capacities are his because he belongs to the natural kind "being human." A substance’s inner nature is its ordered structural unity of ultimate capacities. A substance cannot change in its ultimate capacities; that is, it cannot lose its ultimate nature and continue to exist. Smith may replace his skin color from exposure to the sun and still exist, but if he loses his humanness, his inner nature of ultimate capacities that constitutes being human, then Smith ceases to exist.

From the Thomist perspective, the fact that substances contain a hierarchy of capacities makes ambiguous the notion that a human being has lost such and such a capacity. Most advocates of the contemporary Lockean and Cartesian perspective miss this point. They seem to assume that if a first (or lower) order capacity is gone, then the person is not present. But this simply does not follow because the human person, constituted by a set of ultimate capacities definitive of the person’s nature, can still be present even if a lower order capacity is absent through defect.

Finally, sometimes properties relate to each other as does genus to species. Here are some genus/species relationships: being a color/being red, being a shape being square, and, according to Aquinas, being a person/being a human. Aquinas follows Boethius in defining a person as "an individual substance of a rational nature."10 He claims that "person" signifies the genus of rational substances." The species is a way by which the genus exists. Being red, square, or human are ways that being colored, shaped, or a person exist in individual things.

Before we turn to a brief snapshot of Locke and Descartes, it may be helpful to offer four points of summary about Aquinas’ view of personhood, humanness, and the human person. First, the individuated human soul is the form of the body and stands to that body in a deep, intimate way. And the unity and species specific kinds of properties, parts, and capacities possessed by the body are due to the soul that informs it, and the properties, parts, and capacities of that body stand in internal relations to each other as functional entities within a metaphysically prior whole. This is what is meant by saying that the soul stands to the body in a "deep" or "intimate" way or that the unity among the properties, parts, and capacities of the body is a deep kind of unity. The soul has a natural exigency for the body, and the body’s structure and functioning are grounded in and a reflection of the internal capacities of the soul. Moreover, the properties, parts, and capacities of the body stand in internal relations to each other, and those parts and capacities are aspects of a whole that is ontologically prior to them, in that those parts and capacities are what they are in virtue of the whole of which they are aspects.

Second, the individual human person contains a unity of capacities that come in a hierarchy such that its ultimate capacities constitute its inner nature and are possessed solely by virtue of membership in the natural kind "human being." Third, the personhood/humanness relation is one of genus/species and is not a supervenience relation in which personhood supervenes upon a properly structured, functioning human being. Thus, for Aquinas, there is no such thing as a human non-person any more than there can be a red non-colored thing. Fourth, while the soul has a natural exigency for the body, nevertheless, the individual human being is identical with the soul that can have a body (since personal identity is maintained in a disembodied state). And the soul is the ground, not only of mental functioning, but also of biological functioning. It is because the human person is present in the body that it still functions both as a holistic unity and as a distinctively human body.

II. Humanness and Personhood in Locke and Descartes

Our survey of Locke and Descartes will be brief for two reasons. First, most people are familiar with their thought because the contemporary consensus mentioned at the beginning of the article is an exemplification of it even if unconsciously. Second, only a few parts of Locke’s and Descartes’ views are relevant to our topic.

With regard to Locke, though he was somewhat inconsistent, the standard way to understand him is to note that he distinguished the identity of being a man (human) that consists in the "continuity" of a living organized body from the identity of a person that consists in the "continuity" of consciousness and psychological traits, especially memory.l2 It is important to note that, for Locke, continuity of a person is not continuity of a substance that has consciousness, but of consciousness itself. This means that personhood and humanness have very different criteria of identity and that the person is to be understood independently of both humanness per se and the body. Moreover, the body, for Locke, is a certain kind of biological organization and is to be characterized independently of the person. On this view, the person is associated with mental functioning (especially memory) and not with the biological functioning and organization of the human body.

In a similar vein, Descartes’ entire project in the Meditations on First Philosophy was to argue that we have a clear and distinct idea of both matter and mind and that the two types of entities are utterly different. Whatever we experience as being in us and can be conceived of as existing in wholly inanimate bodies must be attributed solely to the body. And what cannot be conceived in any way as capable of belonging to a body must be attributed to the soul. Specifically, three Cartesian ideas have carried over into the contemporary perspective.13 First, the entire human being is a property-thing and not a substance. The body and soul are two distinct substances linked through an external relation of cause and effect. Second, the person is to be associated with mental functioning and the various modes of thinking broadly conceived. The individual human soul is not related to the biological functions of the body.14 Third, the human body, due to its materiality and to the mechanistic causality that, according to Descartes, pervades it, should be understood independently of its being en-soured by an individual person.

It may be helpful at this point to illustrate how the Lockean and Cartesian perspectives of the person have taken center stage in current end-of-life ethics. To do this, consider the claims of Robert N. Wennberg who is a paradigm case of the tendencies in view.15 He summarizes his own view in this way: "I argued that what is of special value about human life is personal consciousness, which makes it possible for the individual to participate in God’s creative and redemptive purposes for human beings; biological human life is valuable because it sustains and makes possible personal consciousness, but where there is only biological or somatic human life, that special value no longer attaches to the individual, and biological or somatic death may be allowed to proceed unimpeded."16

Regarding personal identity, Wennberg says that "When an individual becomes permanently unconscious, the person has passed out of existence, even if biological life continues. There cannot be a person where there is neither the capacity for having mental states nor even the potentiality for developing that capacity."17 Elsewhere he says that "psychic life is what is essentially significant about human beings."18 It becomes clear that personal identity is constituted by continuity of consciousness or the developed capacity of consciousness, e.g., of personality, agency, memory, purposeful action, social interaction, sentience, thought, will, and emotional states.

Humanness, however, is merely a biological notion. To be a human is simply to have "human organic life" or "biological human life" and to be a "human biological organism."19 Wennberg explicitly claims that to be a human is merely to fall under a biological classification, viz., Homo sapiens.20 Thus, biology (and, perhaps, chemistry and physics) exhausts what it is to be human.

Finally, with regard to personhood itself and its relation to humanness, the paradigm case of a person, for Wennberg, is an adult human being, i.e., a creature with the developed capacities to think, will, feel, and have agency.21 Both the soul and personhood are properties (or sets of properties and the capacities for them) that supervene upon human biological life. It is possible to be a human non-person when psychic death occurs and there is irreversible loss of the capacities of consciousness cited above. In cases like this, there is a human present because human biological life continues, but the person has ceased to be. In general, being human is neither necessary nor sufficient for personhood.22

We have seen the differences regarding personal identity, personhood, and humanness between the view of Aquinas and the views of Locke and Descartes. In order more fully to appreciate their differences, let us look at how each view treats a specific set of problems.

III. Three Areas of Comparison

The first major area of difference between the Thomist and the Cartesian perspectives consists in their treatment of the body/soul relation and the problem of interaction. This problem is a difficulty for both views and each may have the resources for handling it. But, in our view, the Thomist position is superior in this regard. For one thing, a standard dualist response to the problem of interaction is to claim: (1) we have enough evidence that interaction takes place between mind and body that even in the absence of a view as lo how (or where) such interaction occurs, we are still justified in believing in that interaction; and (2) the "how" question (given the difference between mind and matter, how can such interaction take place) is inappropriate here because, for any causally interacting entities A and B, such a question is a request for a description of an intervening mechanism between A and B, and since the interaction between mind and body is immediate and direct, a how question does not arise.23

Now, this response seems to be a good line of argumentation for the dualist to adopt. The Thomist view, however, makes this approach more natural and convincing than the Cartesian position. For the latter, mind and matter are two very different substances, each complete in its own right, connected by an external causal relation. It could be argued that interaction seems a bit ad hoc in light of the natures of the two interacting entities.

By contrast, the Thomist view offers two important things left out of the Cartesian picture. First, the soul is taken to have a natural exigency for a body, that is, part of the very nature of the soul is its natural, built-in tendency to form and interact with a body. For Descartes, the soul by nature is indifferent to the body. Second, on Aquinas’ view, the body itself is what it is because the soul formed it and grounds its structure. The body’s structure reflects the internal structural order of capacities within the soul. If the body already requires an interacting soul to exist in the first place, subsequent interaction is relatively unproblematic. The Thomist view depicts this subsequent interaction such that physical operations of the body are like tools or instrumental causes the soul uses to carry out its activities and which can, in turn, limit and specify the precise nature and direction of those activities.

It could be objected that the Thomist picture begs the question here and merely relocates the problem of interaction rather than solving it by simply claiming that the soul’s exigency is just the sort of thing that makes interaction natural in the first place and which makes the body dependent on the soul’s functioning. But this objection is inadequate and does not capture the precise nature of the superiority of the Thomist view to the Cartesian picture. On any dualist interaction model, sooner or later, causal interaction must be taken to be direct, basic, and fundamental. This is just the way causation itself works. The real issue is to come up with a model of mind or soul and body in which such interaction is more natural and less ad hoc.

In this regard, the Thomist model of the soul is like standard responses to Bradley’s famous regress argument against relations.24 According to Bradley, if two entities a and b need some relation R to ground their relatedness, then there will need to be two further relations, R* and R**, to relate a and b to R, respectively, and so on to infinity. The proper response to Bradley is to say that the regress does not get going because it is just the nature of relations that they can relate relate without first having themselves to be related to those relate. In the same way, the Thomist affirms that it is just the nature of the soul to have an exigency to form and interact with a body. It is easier to see how this could be the case for a Thomist soul than for a Cartesian mind.

The problem of causal pairing is a second way to show the superiority of the Thomist view regarding the body/soul relation and interaction. The problem has been addressed by John Foster, a Cartesian dualist.25 Normally, says Foster, when two events are causally related, they are so by virtue of the way they fall under some natural law due to their non-causal properties and relations. For example, the event of a metal expanding due to the event of its being heated can be explained in a standard covering-law type way.

Foster, however, claims that this model breaks down when it comes to the following case: suppose two brains cause two parallel mental events but the psycho-physical laws (granting for the sake of argument that there are such) plus non-causal factors (e.g., initial conditions) will not decide which mental event goes with which brain. Suppose B is the event of Smith’s brain being in state 4> at t and E is a mental event of type ~P which occurs in Smith’s mind tAo second later as a direct causal result of B (B causes E). What psycho-physical law could account for this causal episode? Foster invites us to consider L’: whenever a brain is in tP, a mental event of kind ~P will occur ‘/to second later. Unfortunately as Foster points out, this will not work for the following reason. If we have a parallel case occurring in Jones (B’ causes E’), then L’ cannot rule out B causing E’ or B’ causing E. What about L2: whenever brain x is in 4>, a mental event of kind ~P will occur in ‘Ao second in that mind which x embodies. Foster claims that this account is circular and rejects it for that reason. It spells out causation in terms of embodiment, but embodiment must be spelled out in whole or in part in terms of causation. At least part of what makes a particular brain x the brain of a particular subject y is that things are psychophysically arranged in a way which gives x and x alone the capacity to have a direct causal influence on y and on y alone and vice versa.

As a Cartesian interactionist, Foster’s conclusion to this problem is to claim that even in the physical realm there are cases where fundamental laws do not adequately account for causal pairing (e.g., two spheres of metal type k produce simultaneous, exactly similar flashes, but a causal law plus non-causal factors do not determine the correct causal pairings). Thus, causal relations cannot be wholly accounted for in terms of non-causal properties and laws.

Now, the main problem with Foster’s analysis of this problem resides in the inadequacy of his Cartesianism expressed in his rejection of L2 above. According to Foster, the fundamental way that the embodiment of mind by brain has to be spelled out is by means of (efficient) causation. Indeed, this must be the correct answer if one is confined within Cartesian dualism. But why limit one’s substance dualism to the Cartesian version? In fact, it is quite easy to see that causal interaction is not the correct way to analyze the fundamental relationship between mind (or soul) and body because a counter-example can be given that shows that direct causal interaction is not sufficient for individuation and embodiment.

Consider a case of demon possession. Even if such cases are not real (and we do not wish to deny their reality), still, there is a possible world in which Smith is possessed by a demon such that the demon can have direct causal interaction both with Smith’s brain and with Smith’s mental life. In a case like this, we have direct causal interaction, but the causal influencer (the demon) is neither the entity nor the only entity that is individuated in union with Smith’s brain.

The Thomist view can both embrace L2 and handle the demon possession case. Regarding the former, Aquinas depicts the soul as being "in" the body in the sense that it is diffused throughout the body and is fully present in each part as the essence and unifier of that body. And the body is "in" the soul in that the soul is the seat of the body and the body is formed by the soul as an expression of the inner structure of capacities of the soul itself. Thus, embodiment can be analyzed in L2 along the lines of the ownership relation and the two ways of "being in" just mentioned. This avoids circularity. With regard to the demon case, the demon and the soul can exert direct causation on the brain, but the soul and not the demon is the essence and owner of the body. By grounding the body/ soul relation more deeply than causation, the demon case can be handled.

Our analysis of the problem of interaction lends support to the idea that the body/soul relation is metaphysically deeper and more intimate on the Thomist view. As mentioned earlier, on the Thomist view, the body is grounded in and is a reflection of the internal structure of the soul that owns, underlies, and has a natural exigency for it. The soul is not related to the body merely by means of an external relation (causal or otherwise) that connects two independent entities. This fact leads to a second area of comparison: different ways of understanding the human person and the relation between the human person and biological functioning. The contemporary Cartesian and Lockean perspective, as illustrated by Wennberg, analyzes being human as a mere biological notion unrelated to personhood. The human body is a physical object, described in terms of chemistry, physics, and (perhaps) biological categories, and thus, the functioning human body is unrelated to the existence of the person that may or may not be present in that body.

On the Thomist view, the human person is present if and only if the human soul is present; and if the human body is functioning as a biological unity, then the human person is still present because the soul is the ground of that functioning. The point is not that the human body functions as a unity extensively because the soul could still be present even if some of the body parts were dysfunctional or gone entirely. Nor does the soul’s presence mean that the body will not need external aid (e.g., a respirator) to function in certain ways. But ff there is reason to believe that there is still unified organic life exemplified by a body, then the Thomist perspective will see the human person as still being present.

As an application of these differences, if we limit ourselves to the present debate about whole versus higher brain criteria for death, the Thomist will tend to prefer the former and the Cartesian and Lockean will prefer the latter. This is because the former go beyond mental functioning in their understanding of human personhood and include biological functioning as well. The Thomist will want to know what it is that gives organic unity to the human body and grounds its species-specific principle of individuation, capacities, and properties.26 By contrast, the Cartesian and Lockean will tie personhood into various criteria expressing different aspects of mental life.27 Our purpose here is not to argue for the Thomist perspective but merely to show how it is relevant to the issue before us. If this is the case, then more attention should be given to it when these issues are debated.

A final area of comparison between the two perspectives is closely related to the second one: the possibility of potential persons and human non-persons. For the Thomist, a genus and a species in the category of substance are not degreed properties. That is, they are either fully predicable of an entity or they are absent. They do not come in degrees. An entity either is or is not a human person or some other type of person. Thus, statements like the following one by Lawrence Becker to the effect that the notion of being a potential human (or person) or of becoming more and more of a human (or person) represent a deep metaphysical misunderstanding: "Human fetal development is a process analogous to metamorphosis, and just as it makes good sense to speak of butterfly eggs, larvae and pupae as distinct from the butterflies they become (to say that they are not butterflies) so too it makes sense to say that human eggs, embryos, and fetuses are distinct from the human beings they become—they are not human beings, only human becomings."28

From the Thomist perspective, this line of thought mistakenly identifies a thing’s essence or natural kind with an adult member of that kind, and this mistake is rooted in a failure to treat living organisms in general, and humans in particular, as genuine substances with natures constituted by a non-degreed genus and species that define its natural kind. By contrast, the Cartesian and Lockean perspective need not treat humanness or personhood as a degreed property, but such a view is allowed by this approach as is the notion of a potential person, because the standard properties associated with personhood (e.g., self-awareness, ability to use language, etc.) are, in fact, degreed properties.

Moreover, since the Thomist analysis of the personhood/humanness relation treats it as a genus/species relation, then the following implication arises. Just as there can be colored things that are not red things but not vice versa, so there can be persons that are not humans (e.g., angels, Martians) but not vice-versa. For the Thomist, it is impossible for there to be a human non-person. By contrast, the contemporary Lockean and Cartesian viewpoint treats the personhood/ humanness relation as a supervenience relation in which the former supervenes on a properly functioning biological human life capable of sustaining psychic functioning.

There are different understandings of supervenience.29 But a generally accepted understanding of it for properties runs as follows: property P supervenes on property Q just in case (1) P and Q are completely distinct properties in that neither P nor Q enters into the very being or constitution of the other; (2) P is ontologically dependent on and determined by Q; (3) the relation between P and Q is non-reductive; (4) for any possible world in which some entity x exists, if x has Q that is sufficient for its having P, i.e., there cannot be two entities alike in having Q but differing with respect to R An entity cannot change in respect to P, cease to be P, or become more or less P without changing in respect to Q.

The important thing to note here is that the Lockean and Cartesian appropriation of the supervenience relation makes personhood dependent upon humanness, not vice versa as is the case in the Thomist view, and this fact makes possible the existence of human non-persons.

Our purpose in presenting these three areas of contrast has been to show just how the two views will differ regarding the topics of relevance in each area, and to argue that the Thomist view is the superior one. In the process, we have seen the differences between the Thomist view and the Lockean and Cartesian perspective regarding issues of importance for end-of-life ethics: the nature of the human person and the proper analysis of humanness, personhood, and personal identity.

We have tried to show that the Thomist view is worthy of more consideration than it is currently receiving. Irrespective of this, however, the fact is that a number of thinkers still embrace the Thomist perspective. And if it is, indeed, true that much contemporary ethical discussion of end-of-life issues takes place without due consideration of the Thomist perspective, then that discussion will tend to be one-sided and impoverished. Moreover, if philosophers have some responsibility to train health care professionals in the art of bioethical decision-making, and since most of those professionals have little or no familiarity with the history of philosophy or the metaphysics that underlies different ethical positions, then by interacting more directly with the Thomist position, we can do a better job of enr


1 Thomas Aquinas, Commentary on Aristotle’s De Anima, trans. K. Foster et al (London: Kegan Paul, 1951), 11.1.233.

2 Ibid., 221

3 Ibid., 215.

4 Ibid.

5 Ibid.

6 Ibid., 213.

7 Ibid., 221.

8 Rene Descartes .`Reply to the Fourth Set of Objections,” reprinted in Descartes’ Philosophical Writings, trans. and ed. E. Anscombe and P Geach, intro. A. Koyre (Indianapolis: Bobbs-Merrill, 1971).

9 Exposition of Aristotle on the Soul, II.1.225.

10 Thomas Aquinas, Summa Theologiae t, q. 29, a. 1, obj. 1.

11 Summa Theologiae 1. q. 29, a. 2.

12 John Locke, "Of Identity and Diversity," An Essay Concerning Human Understanding, Bk. 2, ch. 27.

13 These perspectives are rooted in Descartes specific notions of a substance and of substance dualism. We are not claiming that most contemporary discussions of end-of life ethics require Cartesian dualism. Our point is that regardless of the further question of the reduction of mind to matter in standard ways, the Cartesian influence is seen in the way to be mentioned here.

14 In 1648 in a letter to Princess Elizabeth entitled Description of "The Human Body and of all its Functions", Descartes revised his views somewhat, but he still maintains that all the major bodily functions are independent of the soul and only the function of thought (both its actions and passions) is to be attributed to the soul. At other times, Descartes hesitated to isolate the soul and body as completely as would seem to be implied in his overall metaphysical views. He writes: Nature also teaches me by these sensations of pain, hunger, thirst, etc., that I am not only lodged in my body as a pilot in a vessel, but that I am very closely united to it, and so to speak so intermingled with it that I seem to compose with it one whole. See Meditations on First Philosophy: Meditation VI.

15 Cf. Robert N. Wennberg, Terminal Choices: Euthanasia, Suicide, and the Right To Die (Grand Rapids: Eerdmans. 1989); Life in the Balance (Grand Rapids: Eerdmans, 1985).

16 Terminal Choices. p. 176

17 Ibid., p. 159.

18 Ibid., p. 160. Life. pp. 31-46. Here Wennberg confuses what is distinctive with what is essential.

19 Terminal Choices. pp. 159, 168.

20 Life, pp. 27, 28. 34, 124-25. On page 124 Wennberg falsely implies that traditional sanctity of life advocates identify being human with falling under the biological classification Homo sapiens. But this is not so because traditionalists view humanness as a theological and metaphysical notion that goes beyond biology.

21 Life pp. 33, 36. 42,127.

22 Terminal Choices, pp. 159, 161, 163, 165, 169; Life, pp. 43-44. 117-19,130.

23 Cf. Mark Bedau. Cartesian Interactionism, in Mid~ esr Studies in Philosophy X: Studies U2 The Philosophy of Mind, ed. Peter A. French, Theodore E. Uehling. Ir., and Howard K. Wettstein (Minnesota: Univ. of Minnesota Press, 1986). pp. 483-502.

24 E H. Bradley, Appearance and Reality (Oxford: Oxford Univ. Press, 1897h pp. 27-28.

25 See John Foster, "A Defense of Dualism,” in The Case for Dualism (Charlottesville: Univ. of Virginia Press, 1989), pp. 13-15. Our disagreement with Foster is not with his substance dualism, but with the Cartesian as opposed to Thomist way of expressing that dualism.

26 It is important to note that DNA cannot solve this problem because a DNA molecule has the same features possessed by the human body in this regard: it is a multiplicity in need of organic unification and it has a distinctively human set of capacities and properties owned by and grounded in the human soul. For more on this, see Richard Connell, Substance and Modern Science (Notre Dar.1e: Univ. of Notre Dame Press, 1988).

27 Cartesian dualist Richard Swinburne argues that persons still exist while asleep in that the sleeping body will again by normal processes (or by events like being shaken) give rise to a conscious life which is the life of the person existing before sleep. He adds to this the idea that a person still exists while the soul is not functioning just in case normal bodily processes or available artificial techniques will in a fairly speedy way restore or give rise to functioning. See Richard Swinburne, The Evolution of the Soul (Oxford: Clarendon Press, 1986), pp. 176-79. Note that the soul’s functioning is spelled out strictly in terms of mental functioning (e.g., having desires, thoughts, beliefs, volitions, sensations). Absent is the soul’s role in sustaining bodily functioning. It would appear that this omission is what gives Swinburne’s discussion an aura of arbitrariness, which he himself acknowledges.

28 Lawrence Becker, “Human Being: The Boundaries of the Concept," in What Is a Person. ed. Michael F. Goodman (New Jersey: Humana Press, 1988), p. 60.

29 See Kim, "Supervenience,” in Handbook of Metaphysics and Ontology, ed. Hans Burkhardt and Barry Smith (Munich: Philosophia Verlag, 1991),11, 877-79.

30 We would like to thank R. Douglas Geivett and Dennis Monokroussos for their helpful comments on an earlier draft of this article.