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ST. THOMAS AQUINAS AND THE NATURAL LAW TRADITIONContemporary Perspectives
The Catholic University of America PressCopyright © 2004 The Catholic University of America Press
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Chapter OneTHE ANTHROPOLOGICAL FOUNDATIONS OF THE NATURAL LAW
A Thomistic Engagement with Modern Science
Benedict M. Ashley, O.P.
The nature-nurture debate goes on acrimoniously today among experts in different fields. Thus E.O. Wilson, the sociobiologist, tries to explain human behavior by evolutionary genetics, while another expert, Richard C. Lewontin, denounces sociobiology as a pseudoscience. The debate usually ends with the banal agreement that nature and nurture "interact" in such a complex way that no workable criteria can be found to determine their respective contributions to human behavior. This agreement, however, does not put an end to the controversy. Why this impasse? The term "nature" is inescapable in science since by "science" we mean natural science not the sciences of pure mathematics, ethics, theology, and so on. We also speak of natural laws and we distinguish artificial objects or artifacts made by humans from natural objects.
Moreover, reliable criteria are used by scientists to distinguish whether an observed phenomenon can or cannot be explained by natural law. Thus scientists measure Newton's natural law of gravitation by observing the mutual attraction of massive bodies. In practice this is quite difficult because gravity is a very weak force and the observations can be easily disturbed by chance influences. Yet no one doubts that it is possible with proper ingenuity to devise methods that will determine gravitational force to a high degree of accuracy. Thus all of scientific knowledge depends on observations, sometimes requiring elaborate techniques, by which "natural" events are distinguished from those that are by chance or due to artificial human intervention. Thus "nature" is that uniform or regular behavior that things are observed to exhibit when isolated from the interventions of chance or deliberate human design.
If we understand the term "nature" as does physics, there is, in principle, no difficulty in separating what is natural in human behavior from what is not. All that is necessary is to observe human behavior and then leave out all features of that behavior that are not universal, regular, and uniform. When this is attempted, of course, it becomes obvious that human behavior is so variable that much of it cannot be considered "natural" and therefore has to be ascribed to chance or artifice. But there is a verifiable residue of features common to all human beings. If there were not, it would be meaningless to speak of the species Homo sapiens.
Nor does the vast number of exceptions that can be cited to any such generalizations about human nature undermine their scientific validity. Even the law of gravitation appears to have many exceptions—for example, a leaf in the wind or a balloon rises not falls. But when we find an exception we look for some element of chance, for example, the current of air that strikes the leaf, or the human artifice that made the balloon and filled it with helium, that accounts for these exceptions; we do not abandon the law of falling bodies. Thus it would seem that the nature-nurture controversy is solvable in principle if not always in practice. The more and more precise observations we make of human behavior, the clearer and more certain it will become what is human nature as distinct from the results of "nurture" or, to use another term, "culture" and chance.
But how are to we to distinguish between "culture" and "chance"? The reality of "chance" was rejected by the deterministic science of the nineteenth century. It believed Laplace's claim that if he knew the exact condition of the universe at a given moment he could infallibly predict its whole future. Today the quantum and chaos theories have made that mechanist claim absurd. The natural laws of quantum physics do not predict the exact future of a material entity but only provide a range of probabilities as to its behavior. Such laws give an appearance of determinism that increases with the average behavior of the entities involved, but it never rules out highly improbable events. Chaos theory states that very small variations in the initial conditions of natural processes, perhaps even ones so small as to be undetectable, can make a huge difference in the ultimate outcome of the process. It also reveals that what at first appear to be purely random processes, that is, ones determined by chance, when sufficiently repeated converge on certain definite results that manifest previously hidden natural determinisms. For example, the swing of a pendulum is actually quite random, yet if sustained for many swings it averages out sufficiently that it can serve as a regular measure of time and thus manifests Newton's law of gravity.
Hence chance cannot be eliminated from our explanations of what we observe in the natural world but is implied by the very fact of the reality of natural laws. Nature and chance are distinguishable but inextricably linked together. Thus Stephen Jay Gould can say that Darwinian biological evolution, the natural process that today is taken as the foundation of all biological science, is largely a matter of chance. We can reconstruct the history of the emergence of a species using various natural laws, but we cannot eliminate the element of chance. The reality of chance does not contradict natural law, since by chance we mean that one thing acting lawfully according to its nature interferes with the behavior of another thing acting lawfully according to its nature. Experiments used to measure the law of gravitational attraction between two massive bodies are never quite precise because they may be interfered with by slight convection currents in the air of the laboratory, a vibration from a passing truck outside the laboratory, or other factors.
Of course, it is possible that there may be still a third law that regulates the interference of the two other agencies in a uniform manner. If this is the case we have a complex system of causes. There is, however, no scientific evidence whatsoever that our universe is a system of a kind that is so tightly regulated by some single law that this eliminates all chance events. The only reason to suppose that it is would be to satisfy a determinist prejudice like that of Laplace. But not only is that concession to determinism unnecessary for the advance of science, but it has actually proved an obstacle to that advance, as Einstein's bias for determinism for a while blocked the acceptance of the Copenhagen interpretation of quantum phenomena.
The same goes for the concept of the "artificial," or free, man-made, element in explaining our observations of the world. Of course some have thought that if we knew human nature and the situations in which humans are placed well enough we could predict their future behavior. They have tried to find "laws of history." But now that chance has been shown to play a large part in the history of the universe, how can we suppose that human history is any more deterministic? In fact observation of human behavior in comparison with the behavior of those hominoid animals closest to us in evolutionary descent quickly reveals that besides deterministic laws and chance concurrences free choice enters human behavior. The very notion of "culture" implies that the human animal is highly inventive.
To be inventive means to be able to consider alternative possibilities and to choose among them to find the appropriate means to a given end. This is what is meant by the term "freedom." Therefore, the debate between nature and nurture is precisely about the relative degree in which nature—and the element of chance in nature—contributes to explaining human behavior and the degree that human freedom contributes to it. This interlinking of freedom and nature, like the linking of nature and chance, does not contradict the deterministic or natural aspect of human behavior but complements it. For example, a characteristic feature of human culture is language, yet linguistics shows us how intertwined are psychological laws and human free invention in human speech. All normal human infants have a remarkable facility in learning the language of their parents and the language they learn is determined by the culture of their parents. But this language changes a bit every day by the invention of new words or new usages of words. Thus the historic variety of human languages is immense; today it is about six thousand.
I have gone into all this at some length to show that to talk about a "natural law" requires the well-defined concept of "nature" and of "chance" and to talk about the "natural moral law" requires also the concept of "freedom." The reason that in today's culture the traditional concept of "natural moral law," so basic to the value systems out of which modern society grew, is today so often rejected, is that these concepts are confused and their interrelationships misconstrued.
Aquinas's Anthropology or Theory of Human Nature
St. Thomas Aquinas can be of help to us today in trying to recover the sense of the "natural moral law" because he so carefully analyzed the distinctions between and the relationships of nature, chance, and freedom neglected in much current ethical debates. Aquinas's anthropology is genuinely empirical, that is, based on an analysis of human behavior as we observe it. He lacked, of course, much of the vast store of information now available in biology, anthropology, psychology, and sociology. No doubt, if he had been faced with this knowledge explosion, he might have been as confused as we often are. But the very paucity of his data forced him to subject it to a foundational analysis. Today it is too often overlooked that when we use a telescope or a microscope we have to interpret and validate what we see through them by its broad conformity with what we see with our naked eye. The same goes for the kind of anthropological and psychological data that we can now gather by traveling around the globe or compiling clinical histories. An outside observer has special difficulties in accurately perceiving what is going on in a foreign culture. A clinician knows that the way people behave in his office may not reveal how they behave in their families.
Aquinas carefully analyzed for us the knowledge we can acquire in daily life prior to any special technique of observation. His results, therefore, have the special value of not being colored by current ideologies, but at the same time they must not be taken for anything but an extremely broad outline that must always be filled in with much more detail as our study of human nature advances.
Approaching human nature in this outlining and naïve way, we recognize that we are living things, animals, and very remarkable animals indeed, precisely in that we have an invented culture marked by social communication through a true language that contains abstract concepts. St. Thomas did not begin, as did Plato of old or most modern philosophers since Descartes, with introspection into our self-consciousness and then attempt to deduce the other marks of human nature and our relation to our environment from a cogito ergo sum. As an Aristotleian in his epistemology, Aquinas held that nothing is more mysterious and obscure than our self-consciousness, our inner life. Since we ought to always go from what is more knowable to what is less knowable, the right way to study human nature is to begin with the objects that form our environment, including in particular other human beings that we can touch, see, hear, and smell. From what we can observe about such sensed objects and their behaviors little by little we can come to understand something about our inner life in its obscure mystery. Thus Aquinas would never have accepted Descartes's dualistic account of the human person. Although we are composed of a spiritual soul and a material body, these are correlative, like the organization of a system and its parts. We can only know the system if we know the parts, yet we cannot understand the parts except insofar as they function within the system as a whole.
Taking this approach to human nature, Aquinas concluded that there is a human species all members of which are essentially alike, although in secondary ways they can differ very much, for example, in gender and in maturity, while remaining essentially the same. The best view of human nature will be achieved only if we give special attention to normal and mature specimens. As regards gender, this means considering both man and woman in their complementary relation, and as regards maturation, it is necessary to consider human life from conception to death and on into eternity. Many variations in humanity, however, are irrelevant in exploring human nature, for example, that of skin color or education or of customary habits peculiar to this or that place or time. It is by looking to what is universal and specific that we will come closer to what is natural to human beings.
The fact of human language and the special form of family life and the larger social life that is characteristic of the human animal Aquinas finds as the clue to understanding what is most specific and unique to human nature and thus explanatory of the particular kind of animal body that we possess. This specific ability that marks out the human species is its power of abstract thought manifested in human language. From this power also flows human freedom, the possibility of free choice and of morality, and therefore the power of human society to invent a culture and its artificial technology. Today careful study of animal behavior has shown that some apes have the capacity not only to learn new behaviors but to transmit them to future generations in a sort of culture, that they have a kind of language and can learn better communications, and that they can not only use but invent tools. Of course Aquinas probably knew that birds build nests, and bees hives, and that apes can wield a stick as a weapon. Today we are beginning to think that the Neanderthals had stone tools and used fire, yet may not yet have been able to speak, and were genetically not of our human species.
Such findings, however, are not surprising once we have admitted with Pope John Paul II that humans came to be through biological evolution. In an evolutionary process some lower form of life must very closely approximate the next higher form of life. Yet there is a critical point at which a new species originates, marked by some new specific trait that has previously had only analogous approximations, first sketches as it were. Again, what is specific to humans, according to Aquinas, is not just any kind of language, nor any kind of transmitted learning, nor any kind of use or invention of tools, but the capability of abstract thought and the power of free choice that it makes possible. Nothing we know about past or living hominoids unequivocally manifests such an ability to think abstractly and choose freely, yet we can observe such activities emerge in every growing human child in normal health.
If Aquinas was right in concluding from these observations that what specifies human nature is intelligence and free will, the question arises of the relation of these abilities to the fact that we are also obviously animals, living by the powers of nutrition and reproduction possessed also by plants, and subject to the laws of physics that govern inanimate substances. Aquinas knew far less than we do about human anatomy, physiology, and genetics. He even followed Aristotle's erroneous opinion that seems today absurd, although it was based on Greek medical science, that the primary organ of the body is the heart rather than, as we know it to be, the brain. Yet we can follow Aquinas's view that the special traits of the human body are appropriate to a kind of organism whose behavior is intelligent and free and able to control its environment. He notes that the human hand with its opposable thumb and ability to make very finely controlled movements is just the kind of instrument an intelligent animal needs. Today we can explain the anatomy and physiology of the body and in particular the brain in vast detail in view of its evolutionary adaptation to serve intelligent life and that by developing modern science and technology can now exercise such remarkable control over its physical environment.
Excerpted from ST. THOMAS AQUINAS AND THE NATURAL LAW TRADITION Copyright © 2004 by The Catholic University of America Press. Excerpted by permission of The Catholic University of America Press. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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