Human Beings Are
from International Philosophical Quarterly, 1997
The last few decades have made it clear that several ethical issues turn on the question of whether biological life is an essential and intrinsic aspect of a human person, or only an extrinsic instrument. This is quite obvious in the controversies concerning abortion and euthanasia. If the human person is not a particular type of organism, then one could hold that a human organism begins to exist at one time while the human person begins to exist at a later time. Conversely, if a human person is a particular type of organism, then whenever the human organism begins to exist that is the time that the human person begins to exist. Similarly, if a human person is a particular type of bodily being, a particular type of organism, then it makes no sense to say that, "Yes, that is the same living organism that used to be grandfather but that is not grandfather."
The relationship between the personal and the biological is also important for all of the issues in sexual ethics. Does sexual intercourse only symbolize a personal union? In that case the personal union itself would seem to be a purely spiritual reality, and demands on what structure the sexual act must take in order actually to symbolize union would have to be argued out extensively. If the biological is an intrinsic aspect of the human person, however, it might be that sexual intercourse does more, or can do more, than symbolize a union existing wholly in a different dimension of being; it may actualize or be an internal part of the union of bodily persons. In any case, the question of whether the bodily is something extrinsic associated with the human person, or the human person is a particular kind of bodily being, is a pivotal question for various ethical issues.
In this article I defend the position that human beings are living, bodily entities, that is, animals. The main argument I present is a development of Aquinas's argument against Plato's position on the relation of the soul to the body. The overall, main argument is as follows:
1. Sensing is a bodily act, that is, an act performed by a bodily entity making use of a bodily organ.
2. It is the same thing which senses and which understands.
3. Therefore, that which understands is a bodily entity, not a spiritual substance making use of the body.
Each of these steps in the argument will be explained more fully in this paper. The main development, however, will occur in providing support for the first premise, since substance dualists as well as proponents of the no-subject view (the position that the person is not a substance at all but a set of experiences united by memory and other psychological connections) typically deny that premise.
I. Main Challenges to Establishing the First Premise
To establish the first premise of the overall argument stated above, I shall begin with considering sensation in non-human animals. My argument to support the first premise will be that, first, sensation in non-human animals is an organic, bodily act. By this, I mean that it is an act performed by a bodily organism, an act intrinsically ordered to the survival or fulfillment of a bodily organism. Second, sensation in human beings is the same sort of act as sensation found in non-human animals. It will follow that sensation in human beings is an organic, bodily act.
I believe there are four theories which in various ways block acceptance of the proposition that sensation in non-human animals is an organic act. Two theories of material entities go against this proposition: mechanism and eventism (or process philosophy, the position that the ultimate entities are events rather than substances). And two theories of mind go against it: the no-subject view and substance dualism (that is, the identification of mind with an independent spiritual substance).
When we see a dog chase a rabbit or sniff out the place of a hidden bone, and observe that dogs have bodily structures similar to our eyes, ears, and noses, we understand that dogs see, hear and smell. But there are various ways of denying this position, linked with the theories mentioned above. First, someone might say that sensation is not a unitary action at all, but an aggregate of electrical and chemical reactions: a mechanist would take this sort of position. Second, someone might say that sensation is really a mental episode associated with the body: a proponent of the no-subject view might take this position. Third, someone might say that there really is no sensation in non-human animals; it only appears that way, they really are automata, as Descartes held. Fourth, someone might say that there is sensation in non-human animals but these animals are like Plato said humans are, namely, they have substantially distinct minds. So, to defend the first premise in the main argument stated above, we must defend the position that animals are enduring entities (against mechanism, eventism and the no-subject view), and the position that they really do sense (against the idea that they are automata), and the position that in them sensation is an organic act (against substance dualism).
II. Animals Are Enduring Agents
A mechanist holds that the dog is just an aggregate of smaller entities, perhaps molecules, and perhaps these molecules are aggregates of atoms, and so on. On this view, dogs and cats are only aggregates of smaller entities, and their actions are determined not by any intrinsic unitary direction but merely by the interaction of the smaller units. A proponent of this view might add that it is convenient to think of objects as unitary substances, but this convenience hardly translates into a truth descriptive of the world. This mechanistic view might then harmonize either with a functionalist view of the human mind or with the identification of the human self with a distinct substance as Platonists or Cartesians hold.
However, it is more than convenience that moves us to see dogs and cats as real substantial units rather than as mere aggregates, entia per accidens. Our viewing the
dog as a unit is similar, as Aristotle pointed out, to our viewing a house or other composite artificial objects as units. Why do we think of the boards and bricks of a house as one? Because we grasp a unity, a functional unity, in those materials. We understand that the materials of the house are all organized for the purpose of providing shelter and warmth. In this case the unity is extrinsic, or imposed from outside by human agency.
Analogously, when we see a dog chase a rabbit or come up to us drooping his head and wagging his tail, we apprehend a unity in the materials that go into the make-up of the dog. In the dog's chase of the rabbit we understand the canine feet and back and head as organized and directed to a single end, the catching of the rabbit. Even while the dog is sleeping, we understand the various parts of the dog--the cells, the tissues, the organs--as functional parts of a whole. Unlike the house, however, in this case the unity is from within.
The things around us, and most obviously the living things and animals, are really various types of agents. And agents endure. An agent is a source of regular actions and reactions. We observe recurrent and predictable actions and reactions; the source or center of such recurrent and predictable actions is a thing or agent. It is not reasonable to think of reality simply as events or as particles in random motion, because agents or natures are required to explain the recurrence of definite actions and reactions. We must think and act in relation to dogs as units, for example, because only in that way can we understand and predict the actions of the materials which together we refer to as a dog. The materials which together form a dog are in some ways similar to a multiplicity of chalk marks on a blackboard: why those bits of chalk dust are there can be explained mechanically, by reference to the properties of the chalk dust and the wood and other chemicals in the blackboard. But beyond that, there is an intelligibility in the chalk marks which can be understood only by grasping their unity, which allows them to express a meaning. Similarly, we cannot fully explain why the dog zigged and zagged exactly when he did without seeing the dog as a unitary agent, as an animal in pursuit of a prey. True, the motions of the parts of the dog can be explained on lower levels, that is, by reference to the smaller particles which go into the make-up of the dog. We can explain the dogs turning to the left by reference to muscle contractions, and these contractions can be explained as electrico-chemical reactions. But there is a unity in the zigging and zagging of a dog which can be understood only by seeing the materials in the make-up of the dog as parts of a single agent. But again unlike the house or chalk dust, here the unity is from within. It is the same with trees, and other composite substances.
Thus, the unity of the materials consists in their intrinsic organization. Dogs, cats, trees, and, on the lower level, molecules and even atoms, are composite units, understood as one in that they are distinct types of agents.
The position that animals and other entities are things or substances which persist through time is not an a priori necessary truth. It is not logically inconceivable that we could have a world with entities which do not persist at all, or for a very short time. The evidence that there are persisting substances, and that animals are persisting substances consists in all of the phenomena which show beyond reasonable doubt that animals and other entities are agents, and that they remain the same sort of agents, and numerically the same agents, throughout stretches of time. The actions initiated and sustained by animals--such actions as chasing prey, eating meals, mating--are actions which take time. To suppose that there are only events or experiences strung together in various ways is to lose sight of the fact that in countless cases an action and its structure is explained by the kind of agent that produced and sustained it. A dog will chase a rabbit, whereas a horse will not. This is partly because a dog is a carnivore while a horse is a herbivore. But this is most reasonably interpreted as meaning that a dog is a certain type of agent, that is, a persistent source of predictable actions and reactions--given certain circumstances this type of agent will act or react in certain ways.
This account of dogs and other animals is also challenged by Process philosophy, more specifically, the view I referred to above as eventism. Whitehead recognized that both difference and continuity must be included in our account of the realities we experience. But rather than locating the continuity in a persisting substrate, such as a substantial agent, he located it in the commonality of universal features. For example, an animal is not a persisting substance, but a society of events, and the continuity is the commonality of features shared by the series of events (which he calls actual occasions).
But the continuity which he recognized is in a series and so still calls for explanation. If the commonality is not intrinsically determined, then the regularity with which such continuous sequences occurs remains unexplained. If the explanandum remains the same throughout some stretch of time, then the explanans, to provide explanation, must also persist through time. That is, if what requires explanation is the order in a sequence of events spread throughout time, then the explanans must persist throughout that sequence. But the orders of sequences of events is precisely what requires explanation, especially on the level of living things.
So, it is reasonable to hold that the dog is a persisting organism. The dog chases the rabbit on Monday because the dog is a carnivore. The dog chases the rabbit on Tuesday because he is still a carnivore, and he remembers where he chased him on Monday. (This is shown by the fact that as he approaches the tree where he first saw the rabbit on Monday he begins to salivate and turn his head quickly in various directions.)
III. Animals Do Sense
Descarte denied that non-human animals sense. He held that animals are automata, that is, that they are like machines, mere aggregates. However, this position is untenable. Their movements are clearly specific by information obtained through sensation. They turn their heads in order to obtain sensations; they cry out apparently with pain when struck, groan or cry when apparently suffering from constant pain. Also, much of their behavior can be explained only by admitting that they remember and have images. Dogs which seem to be sleeping cry out or moan, clearly reacting to what they are dreaming. So, there is sensation in non-human animals; or at least sensation is associated with animals (perhaps occurring in the minds associated with them).
IV. Sensation in Non-human Animals is an Organic Act
Both Descartes and
The functional unity discussed above (in section II) in the body parts of the dog is intelligible only if it includes sensation. The zigging and zagging of the dog, which is why we rightly understand the dog as a unit to begin with, would be unintelligible unless the dog could sense. That is, the various bodily parts of the dog are reasonably understood as unified precisely as instruments or organs for acts of sensation. The parts of the dog are unified only as participating in the act of sensing an external object and reacting to it--only in this way is the scene understood as a dog chasing a rabbit coherent. And these unified actions are intelligible only as acts of sensation intrinsically ordered to the survival or perfection of the organism. So, sensing is an action done by the organism, and one in which the eyes and ears of the dog, for example, participate as intrinsic instruments or organs.
We can see this point in another way. Suppose sensation were not an organic act, an act intrinsically ordered to the survival and perfecting of the animal organism, but that it was, as Cartesians hold with respect to human sensation, an act performed by an immaterial substance associated with the dog's body. What would follow from that? If that were the case, then the bodily parts of what we call a "dog" would lack all intrinsic unity. One would have to analyze quite differently the scene which we now interpret as an action performed by the composite unit called a "dog." Its movement as well as its sensation would have to be viewed as performed by the dog-mind as a distinct agent. So, the dog's body would be an extrinsic instrument, somewhat as chalk is an extrinsic instrument for writing on a blackboard. But then, how would the dog's body be one? What intrinsic unity would the body parts have? The answer, I think, is that it would not be intrinsically one at all. It would be like the chalk dust, which is really an aggregate rather than something with intrinsic unity. But that brings us back to the excessive pluralism rejected earlier.
Again, if sensation in non-human animals were not an organic action then it would be, the way Descartes claimed sensation is in humans, an act performed by the animal's mind, upon the occasion of a change produced in the animal's body. Then the non-human animal's body would be an extrinsic instrument for the spiritual act of sensation. Now, this is initially plausible as an account of sensation in human beings, because they have a rich mental life and so one can abstract from various aspects of human living and think of sensation in human beings as serving only their mental life. But, this view is quite implausible when presented as an account of the sensations in non-human animals. If it were true, the animal's mental life would have to be the end or goal and its body would be an extrinsic instrument serving the animal-mind's needs. The animal-mind would have to have a life of its own, to which its body was an extrinsic instrument. But all of the evidence about non-human animals goes against this. In their case their sensations are subordinated to the survival and flourishing of the bodily organism rather than vice versa. Their mental life has no appearance of being contemplative. Rather, their mental life is regularly oriented toward obtaining food or mates or prey.
If we observe the body of any animal, we see various cells organized into tissues and the tissues organized into organs, and the organs into systems. These are reasonably viewed as parts of the organism insofar as each of these systems performs a function which supports the way of life of the organism as a whole. But consider the way of life of a wild animal, such as a lion or hyena. It is centered on hunting, and hunting cannot be done without sensation and perception. If we subtract from the lion his sensory functions then there simply is no lion at all. These functions are so inextricably bound up with the lion's life that the rest of the systems--the digestive, the circulatory, and so on--would be unintelligible without them. So, the bodily structures regularly exercised in sensation are clearly functionally parts of the lion as a whole. The conclusion is that in non-human animals sensation is an organic act.
V. Sensation in Human Beings is the Same Kind of Act as
Sensation in Non-human Animals
It is usually only when considering sensation in human beings that anyone is tempted to say that it is a purely spiritual act occasioned by changes in the body. And the reason why, as mentioned above, is that in human beings sensation often is subordinated to speculative understanding, that is, understanding pursued for its own sake. This is why I thought it helpful to begin with sensation in non-human animals. Once one grants that there really is sensation in non-human animals, it becomes clear that sensation in human beings is the same sort of act as sensation in non-human animals. There are the same type of bodily structures functioning as sense organs, the same type of nerve cells and organization in the brain relevant to sensory impulses. There are the same types of actions leading one to say that in both non-human animals and human beings their behavior is specified by sensory information in basically the same manner. Human beings do not usually chase rabbits, but they do sometimes chase dogs. It would be very odd if the zigging and zagging by the dog while he is chasing a rabbit was an entirely different kind of act than the zigging and zagging of the boy which is chasing the dog chasing the rabbit. Clearly, the chasing of a dog by a human is the same sort of act as the dog's chasing of a rabbit. Hence the argument which showed that the dog's sensation or perception is bodily applies equally to the sensation or perception performed by a human being.
VI. That Which Senses is the Same Thing as That Which Understands
The second premise in the main argument is: that which senses is the same thing as that which understands. Evidence for this proposition can be found by analyzing singular judgments. When one affirms, for example, that That is a tree, it is by ones understanding, or an intellectual act, that one apprehends what is meant by "tree" and apprehends objects as unitary, living things. Viewing such an affirmation or judgment as having a subject-predicate structure, we can say that the predicate of the judgment expressed here is grasped by ones understanding. The subject of the judgment, however, what one refers to by the word "That," is apprehended by sensation or perception. What one means by "That" is precisely that which is perceptually present to one. But, clearly, it must be the same thing which apprehends the predicate and the subject of a unitary judgment. So, it is the same thing, the same agent, which understands and which senses or perceives.
From these two points, the conclusion follows that what understands--what everyone concedes one refers to as I--is an animal.
1. Sensation in non-human animals is an organic act.
2. Sensation in humans in the same sort of act as sensation in non-human animals.
3. Therefore, sensation in humans in an organic act.
4. If sensation is an organic act, then what does the sensing is a bodily, organic being.
5. What senses is a bodily, organic being. (from 3 and 4)
6. The thing which senses is identical with the thing which understands.
7. The word "I" refers to the thing which understands.
8. Therefore, the word "I" refers to a bodily, organic being. (from 6 and 7)
Since organisms which sense are classified as animals, it follows that human beings are animals.
VII. Another Argument to Show that Sensation in
Human Beings is a Bodily Act
Another argument can be presented for the first premise of the main argument, namely, that sensation in human beings is a bodily act (#3 on the longer argument set out in the previous page. This argument moves from the object of the act to the nature of the act. What is sensed is never just a quality or quantity as it is in itself, but always a quality as it appears from this or that direction. For example, I do not simply see red or blue but a surface from this or that angle, that is, from the perspective of my eyes. The visual scene which I obtain of a house, for example, is necessarily from this or that perspective. Perspective is different from position. I can understand position mathematically, through coordinates, but perspective is something I can grasp only by experiencing it. I may know something about a perspective without actually seeing from it, but it is significant that I can do so only by imagining what it would look like to someone seeing it from that individual place.
So, what is seen--and the same is true analogously with the other senses--is internally characterized by spatial location. It is not just that what is known is a spatial location. Rather, what is known is the physical effect which the object has on the physical subject. That is, the very act of knowing itself seems to be characterized by spatial location. The facts about perspective are best explained by supposing that what we sense is neither a quality as it is in itself, nor something purely subjective, but something relative in this sense, namely, the thing in its physical action on ourselves. So, the subject which has the sensation is a bodily thing. What senses is not a mind associated with a body, but an animal. The rest of the argument continues as before.
VIII. On Human Intelligence
Some philosophers view understanding and even willing as so independent of sensation and the body that the result is that the principle of understanding and willing, the soul, must be conceived as complete of itself and without any intrinsic orientation to matter or the body. I believe it can be shown, however, that human intelligence has an intrinsic need and functional orientation to matter or the body. Showing this will answer an objection against the position that human beings are animals (namely, that this position leads to materialism, or that it ignores the transcendence of the intellect and will). It will also provide an additional argument for the position that human beings are animals; for if the most spiritual of human actions still require distinct bodily acts to attain their own goals then the principle of these acts must be understood as by nature a part.
The basic argument is again from Aquinas. The human soul is by nature a part, or an incomplete nature. Again, what a thing is is revealed in its actions. But the distinctive
actions of the human soul, such as understanding, have an intrinsic need for the actions of bodily parts. So, the principle of understanding (and willing) is by nature a part, or incomplete.
Some philosophers argue that the act of understanding, unlike sensation, is an act performed without a bodily organ. To establish whether they are right (as I think they are) would require another article. However, if human understanding is a purely spiritual act, an act performed without a bodily organ, nevertheless, it is naturally tied to sensation. Although it may not be contradictory to think that the act of understanding could occur in some instance without sense presentations, say, after death, we cannot really conceive of what that would be like. What we directly understand is always an intelligible content or pattern in a sense presentation. What we understand is not just occasioned by sense presentations, but is specified by them. This is shown by the fact that some sense presentations are appropriate for understanding a point while others are completely unhelpful. So, the sense presentation is more than a mere occasion for ones act of understanding, which might then be informed by something else. Rather, we intellectually grasp the point--when we do so directly--in the presentation of sense. After direct understandings, we can move on to understand by relation and analogy objects for which we do not have sense presentations. Also, while directly understanding an external, physical object, we are concomitantly (or reflexively) aware of our act of understanding. However, knowledge of our mental acts cannot be primary, but only concomitant to the primary and direct knowledge of material things. Our acts of understanding are always into sense presentations, or concomitant to, or by comparison or contrast with, what we first understand in sense presentations.
So, in the first place, this means that our intellect is by its nature oriented to sense presentations. The human intellect is not designed to turn away from matter in order to obtain its information elsewhere, as the Platonists and Cartesians hold. There is intelligibility in the material world, and it is that intelligibility which is proportionate to our human minds; our minds are not designed to turn away from or bypass the material world. So, the human intellect cannot naturally perform its function without the aid of the body, a need which manifests an incompleteness in what it is. The principle of human understanding is an incomplete nature.
Secondly, the human act of understanding is incomplete in that it is abstract. By understanding one directly grasps only a feature held in common by many things, abstracted from other features with which it is one in reality. For example, one directly understands such features as animal, human or triangular, whereas to know concrete animals, human beings and triangular things, one must exercise one's perception or imagination, as well as one's intellect. One must grasp those features as concretized in things; but to do that requires bodily perceptions, not just intellectual acts. All the human intellect by itself can grasp is an intelligible aspect of some thing. But to understand an abstract intelligible aspect of a thing just by itself is not to understand the thing in the manner in which it exists. To understand a thing in the manner in which it exists is to understand an intelligible aspect precisely as an aspect of a thing. But this involves a reference back to sense experience. For it is by sense experience that we are initially aware of the whole of which the intelligible aspect understood is an aspect. This occurs, of course, in intellectual acts of judgment.
This is not to say that every judgment is singular or that its evidence is narrowly perceptual. There are universal judgments and necessary ones for which the evidence is not just a perceptual link. Still, the abstract intelligible aspect must be conceived as joined to a thing or things, and the notion of a thing is dependent on our initial perceptual experience. Even when we refer to, and infer truths about, immaterial things, we do so by analogy with material things, and we conceive of them in the manner that is really only fitting to material things. (Thus, as Aquinas points out, our understanding and language about God are in certain respects unsuited to his non-material nature; the abstractive mode of our understanding fits material things, which exist as composites, not God who is not a composite.)
So, even though the act of understanding is done without a bodily organ, the human soul cannot complete its act--in the sense that it cannot succeed in understanding a thing in the manner in which it exists--by itself alone. This is an important point, because one cannot hold that the soul and the body constitute a single substance and, at the same time, that the soul is complete in its nature. So, although it can survive without the body (since it is possible for it perform some type of act without the body), it is intrinsically oriented to the body because its operations cannot attain their end without the aid of the body.
IX. On Privileged Access
One argument that moves many people to a dualist view is from the privileged access or privacy of our mental acts. How can sensory acts be bodily events when bodily events are open to public inspection, at least in principle, whereas my sensory acts are observable only by me? Other people can perhaps in some way observe me having a sensation but they cannot have my sensation. The essential argument would be: That to which one has privileged access is not identical with that to which there is public access; we have privileged access to our sensations as well as our thoughts and desires while there is public access to bodily acts; therefore sensations are not bodily or organic acts.
The difficulty is in the first premise. It is often the case that the same thing can be known in various ways. If A is known in one way and B is known in another, this does not mean that A is really distinct from B.
This really is the same mistake which Descartes made in his argument to identify the self with the mind, where he said that the fact that I can doubt the existence of the body but not the existence of the mind shows that the mind and the body are different things. But as Peter Geach points out, using a slightly different counterexample: a boy may doubt the existence of the postman while being certain of the existence of his father even though the two are identical. The moral is that the same reality may be apprehended in various ways; the diversity of apprehensions in no way proves the diversity of what is apprehended. One may apprehend a sensation from the standpoint of the one who is having the sensation, and one may apprehend the sensation from the standpoint of an external observer. The apprehensions differ, but only one thing is apprehended.
X. The Bodily Person and Intrinsic Value
In the introduction I suggested that there are significant ethical implications of the conclusion that biological life is an essential, intrinsic aspect of the human person. How this is so presents a puzzle. Biological facts just by themselves do not imply ethical conclusions, for the conclusion cannot contain more than is implicitly contained in the premises. That is, the naturalistic fallacy is indeed a fallacy. What, then, is the relationship between this factual conclusion and ethical positions?
When one chooses an action one chooses it for a reason, that is, for the sake of some good one thinks this action will help realize. That good may itself be a way of realizing some further good, and that good a means to another, and so on. But the chain of goods cannot be infinite. So, there must be some ultimate reasons for one's choices, some goods which one recognizes as reasons for choosing which need no further support, which are not mere means to some further good.
What is the character of these ultimate reasons, these ultimate goods? Such ultimate reasons must be reasons for oneself. That is, there must be in an object that which makes it suitable to oneself, or to the kind of agent one is. Conversely, there must be in oneself a natural interest or tendency toward that sort of object.
Of course, we have acquired tendencies as well as natural ones. Natural tendencies are those we have simply in virtue of the kind of thing we are. Acquired tendencies, on the other hand--for example, a taste for caviar, or for betting on races--can only be obtained by actions experiencing the objects of those acquired tendencies. But such actions are exercising pre-existing tendencies. So, acquired tendencies are determinations of natural tendencies. It remains that something can be an ultimate reason for acting only if one has a natural interest in the sort of object it is.
But that to which an agent has a natural interest or tendency must be the actualization or fulfillment of its natural potentialities. This is an essential proposition: If A naturally tends toward X, then X must be the actualization of the type of thing A is. X must be a something, a positive activity. If Y is the ceasing to be of A, for example, one would not think of it as the object of its tendency; rather, one would say that A is just short-lived, that it tends toward whatever it regularly attained prior to its ceasing to be. And X must be the actualization of a potentiality in A; the only actions to which A can naturally tend are those of which A is capable.
The self in whose fulfillment one is naturally interested, however, is not an isolated individual. One has various unions with other people, and so one is interested in the fulfillment not only of oneself as an individual but also in the fulfillment of all those with whom one is in communion--family, co-citizens, neighbors, ultimately, all persons. So, the fulfillment of other people naturally interests one; it is an improvement of one's condition since one is not an isolated individual but has various unities with other people. So, the ultimate reasons for choosing something consist in the prospects of an object to really fulfill oneself and others with whom one is in communion. In other words, every intrinsic good (ultimate reason for choosing) is an essential perfection of the self (oneself or other selves).
Now, this shows that every ultimate reason for acting, every basic good, is an intrinsic aspect of a human person. It does not show the converse, namely, that every intrinsic aspect of a human person is a basic good. Indeed, the converse is not true. There can be an entity composed of A and B where A is wholly instrumental, or merely instrumental, to B, or the whole A-B. For example, the heart is wholly instrumental to the animal. That is, bodily parts of a bodily entity can be instrumental to the bodily entity. However, could one say that the whole body of an animal is wholly instrumental to something else in or of the animal? If one could say that the whole body was instrumental to the mind, say, then it would have to be a dispensable part of the whole. Perhaps one could view it like the placenta a baby grows, or baby teeth, which serve a temporary function. But then, although one could still view the body as part of the whole human being, one would be forced to deny that the human being is an animal. One would be forced to view the human being as essentially a mind, even though its having a body would somehow be a dispensable but in some ways valuable part of it.
However, what we have shown above is that a human being is an animal, not a mind-cum-bodily-parts. The human agent which performs the various actions a human being performs is a living bodily, sensing being, that is, an animal.
What I am arguing is in some ways so obvious it is difficult to state. The perfection of S cannot consist in its ceasing to be S. If human persons are essentially animals, then their perfection cannot consist in their ceasing to be animals, for that would be their destruction. Moreover, if S is essentially an animal then the condition which is S's perfection must include S's being an animal. The perfection of an animal must include the well-being of its body; otherwise, the body is an appendage and what exists is not an animal. There can of course be internal ordering among the bodily parts of an animal, but to make the body as a whole merely an instrument in relation to another activity or to other activities, is implicitly to deny that the entity is essentially an animal. In general, then, one can say that any theory which implies that the body will not be a participant in the complete fulfillment of the human person implies a dualistic view of the human person and is therefore mistaken.
Suppose, then, someone holds that pleasant experience is the only intrinsic good. He holds that biological life is not itself a good but only a means for realizing pleasant experiences. This person is viewing pleasant experience as the only thing which in itself improves his condition. He identifies his condition as of the sort that can be improved only by an experience. Therefore he is viewing his condition as consisting only in consciousness. The same point applies to any view of what the intrinsic good is or intrinsic goods are. If the complete intrinsic good is identified with intellectual contemplation, then the human person is implicitly viewed as a non-material entity. The perfection of the human person, what is viewed as intrinsically (as opposed to merely instrumentally) good must include, although not be limited to, bodily perfection.
One might object that this argument presupposes a teleological view of human action. But suppose one holds that human action is not always for the sake of one's fulfillment. Suppose one holds a deontological ethical theory, and that in acting morally one acts, not for the sake of fulfillment, but to do one's duty, or to respond adequately to values, or from some other motive?
In this case one who does not include bodily fulfillment in what is intrinsically
good need not suppose dualism, even implicitly. However,
as a matter of psychology, whenever one chooses one does choose in order to improve one's
condition. One cannot choose otherwise, for
the objects one deliberates about and chooses must be objects one can choose, and
one can choose only what has a natural appeal to one.
So, deontological theories cannot actually prescribe choices of objects unrelated
(as such) to our fulfillment; therefore, they are in effect identifying the only
intrinsic human good with moral goodness. Thus, although such theories need not presuppose
dualism, their effect is dualist.
 See my Abortion and Unborn Human Life
(Washington, D.C.: Catholic University of America Press, 1996),
 See Germain Grisez, The Way of the Lord Jesus:
Vol 2, Living a Christian Life (Quincy, Ill.: Franciscan Press, 1993), 613-681; John
Finnis, "Law, Morality, and 'Sexual Orientation,'" Notre Dame Law Review
69 (1994), 1049-1076; Robert George and
 On the distinction between a composite substance and a mere aggregate, see Richard Connell, Substance and Modern Science (Houston, Texas: Center for Thomistic Studies, 1988), 3-39.
 Aristotle, Parts of Animals, I, 1 639b15-640a10; Metaphysics, Bk. VII, ch. 17.
 This is not to say that a world without substances is logically possible, but a world with substances whose duration was so short it was not detectable.
 Cf. Benedict Ashley, O.P., Theologies of the Body: Humanist and Christian (Braintree, Mass.: Pope John Center, 1985), 253-296; R. Harré and E.H. Madden, Causal Powers: A Theory of Natural Necessity (Tottawa, New Jersey: Rowman and Littlefield, 1975), 44-118; Ivor Leclerc, "The Problem of the Physical Existent," International Philosophical Quarterly 9 (1969), 40-62; Ivor Leclerq, The Philosophy of Nature (Washington, D.C.: Catholic University of America Press, 1986), 107-189.
 A. N. Whitehead, Process and Reality (New York: Macmillan, 1929), 34-35; 59-66, 240-248.
 Rene Descartes, Discourse on Method, 5; Replies to Objections, 4, 1.
 Rene Descartes, Meditations on First Philosophy,
 Cf. Peter Geach, What Do We Think With, in God and the Soul (New York: Schocken, 1969), 3-41; James Ross, Immaterial Aspects of Thought, Journal of Philosophy, 1992, 136-150; Mortimer Adler, Intellect: Mind Over Matter (New York: Macmillan, 1990), 41-54. In each case the argument is that understanding has a characteristic which is incompatible with being an act performed with a bodily organ. Geach argues that the basic act of understanding is atemporal (understanding is not a process which is itself extended in time). Adler defends the position that understanding has a universal as its direct object. And Ross argues that understanding can discern functions indiscernible to any material system (roughly, those which are, so far, extensionally equivalently and yet are intensionally distinct).
 It is important to see that, if human understanding is a purely spiritual act it still should not be thought of as an act "performed by the soul." Rather, the human being performs the acts of understanding, as it is the human being which performs the acts of sensing or walking. The difference would only be that sensing and walking are done with bodily organs and understanding is not. See especially Peter Geach's careful way of phrasing the question, in "What Do We Think With," op. cit.
 Cf. Bernard Lonergan, Insight, 3rd ed. (New York: Philosophical Library, 1970), 3-19.
 To his credit, Descartes wanted to hold that the body and the soul together make up one substance. However, he also held, and emphasized, a position incompatible with that, namely, that the soul is complete in its nature. For discussion and texts: Daisie Radner, "Descartes' Notion of the Unity of Mind and Body," Journal of the History of Philosophy 9 (1971), 159-170; Paul Hofffman, "The Unity of Descartes' Man," Philosophical Review 95 (1986) 339-392.
 Cf. Richard Swinburne, The Evolution of the Soul (Oxford: Oxford University Press, 1986), 45-61; Jerome Shaffer, Philosophy of Mind (Englewood Cliffs, N.J.: Prentice-Hall, 1968), 39-60.
 Rene Descartes, Meditations on First Philosophy, Meditation II.
 Peter Geach, God and the Soul, op. cit., p. 8.
 Cf. Alfonzo Gomez-Lobo, "Natural Law and Naturalism," Proceedings of the American Catholic Philosophical Association, 59 (1985), 232-249.
 This point is true of any agent, whether voluntary or not. For example, a plant grows, takes in nourishment and repairs damages to its structure. We say, then, that it is a unitary, living substance. To say this is to understand the various parts of the plant as organized toward an end, as an enduring source of regular activities and reactivities. Of course, many things also happen to the plant coming from outside. The wind blows the plant, a rabbit brushes against it breaking off one of its leaves. To understand a plant at all one must distinguish those activities (and reactivities) that come from within the plant from those that do not. The activities to which it internally tends must be viewed as actualizations of its potentialities. For that is what it means to say that the plant is the source of its regular activities and reactivities.
 This, by the way, is the reasoning behind Thomas Aquinas's remark that a person is not saved unless his body is saved, even if his soul has been saved, for, "Anima mea non est ego." ("My soul is not I.") Thomas Aquinas, Commentary on St. Paul's First Letter to the Corinthians, ch. 15, lect. 2, on verse 19, #924.