Science in Christian Perspective



Mechanical Man:
A Christian Physiologist's Dilemma?

Department of Biology
Wheaton College
Wheaton, Illinois 60187

From: JASA 33 (December 1981): 202-207

The field of contemporary physiology is a mechanistic one. Christian theism maintains that man was created ex nihilo by a personal God. How can a Christian physiologist reconcile these positions? This paper surveys the historical roots of modern physiology, reviews the essential tenets of the Christian faith, and discusses a personal resolution of the apparent dilemma of mechanical man and personal Go& an understanding of the clockwork (physiological mechanisms) does not displace the necessity to understand man on other levels or explain his whole nature.

The Nature of Physiology

"The science of physiology . . . seeks to explain the underlying machinery of the life processes of the organism." Thus begins the first chapter of a famous physiology text, The Machinery of the Body, written about 30 years ago.1 The view of the human body as a machine is stated even more explicitly in the opening chapter of an excellent current text held in high esteem by physiologists: 

 The mechanist view of life holds that all phenomena, no matter how complex, are ultimately describable in terms of physical and chemical laws and that no "vital force" distinct from matter and energy is required to explain life ... Man ... is a machine-an enormously complex machine, but a machine, nevertheless.2

The hallmark of the study of physiology is the unravelling of the "how" of the operating parts. The physiologist
strives to explain, in physical and chemical terms, the mechanisms that operate in the living world. The field of contemporary physiology is therefore a mechanistic one. Physiologists reject as unscientific the tenets of vitalism: phenomena are only partly controlled by mechanical forces; they are in some measure self-determining. Vitalism ascribes the functions of a living organism to a "vital principle" distinct from chemical and physical forces.

An Historical Perspective of Physiology

History's first biologist and perhaps greatest philosopher, Aristotle, was a vitalist with a mechanistic streak.3 He analogized the source of motion or "prime mover" with energy and placed "form" and matter in constant interaction, as a mechanist might. At the same time, his vitalism

was etched in his belief in "causes" in nature, including the final cause or purpose in which the ends are actualized, a potential is achieved. (This "doctrine of final causes" part of vitalism is known as teleology). So, the roots of vitalism as well as mechanism can be traced to the Greek period.

Little was done in biology during the Roman period and the Middle Ages. Vitalism was the predominant philosophy. With the coming of the Renaissance and the invention of the printing press, the works of Aristotle resurfaced allid were among the first to be printed and distributed throughout Europe. Aristotle's influence was formidable. He was a systematist who tried to explain everything. He believed that the Creator (the "unmoved mover") made nothing in vain, that everything had a purpose which could be discovered and explained.

The adoption of Aristotle's methods characterized the Medieval spirit: the attempt to synthesize the rational with the Christian (or at least theistic) perspective. If man is rational, it is because God is rational.

Aristotle's explanations took the form of sweeping general theories, sometimes having no connection with experimental verification. And these theories were very strongly put. Consequently, as time passed, what started as theoretical explanation came to be accepted as proven fact. This was the horrible consequence of a highly theoretical approach: conjecture became dognia.4

Replacing the philosophy of Aristotle with empiricism was a most difficult task for the men of the scientific renaissance. The Belgian, Andre Vesal, dissected the human body and in 1543 described the formerly forbidden machine with an unprecedented thoroughness. In the 17th century William Harvey used a clever combination of observation and reasoning to argue that the blood circulated. Quantitative biology was born when he measured the cardiac output in animals. According to Coleman,4 because of Aristotle's strong influence, scientific investigation's pendulum swung radically to the opposite extreme, and emphasis on systematic theory was replaced by emphasis on experimentation. "Possibly, the swing . . . has been too extreme, allowing the emphasis on experimentation to remain in excess."4

Descartes, in the mid-17th century, went beyond Harvey's contention that the heart was a mechanical pump forcing blood through conduit vessels. Descartes believed the whole animal body was a machine, but that humans were more than animal machines because they had immortal souls. Descartes is credited with being the founder of mechanism in biology. He was a dualist, believing that human persons had both a physical and a spiritual nature, and he separated mind from matter. LaMettrie, a complete mechanist and materialist of the early 1700's, completely rejected the immortal soul of theologians and the vital force of life in his work L'Homme Machine (The Human Machine).

Probably the best example of an intense interest in experimentation is Claude Bernard, known as the father of experimental medicine. In the mid-19th century he described the importance of the concept of the constant internal environment.

To the present-day physiologist, the human body is a magnificent machine.

He fought systematic philosophy, pointing out that sweeping generalizations void of verification were totally valueless. He emphasized careful observation in both the clinical and laboratory setting. Most importantly, he distinguished between observation and experimentation. In the later process, an investigator repeatedly produces some disturbance and then expects to find a consistent response. Before Bernard's time, the life processes were thought to be fragile and composed of many fleeting manifestations somehow controlled by mysterious vital forces.4

Bernard believed that a given stimulus would always produce a given response, and therefore emphasized the value of laboratory experimentation and verification.

In the early part of the 20th century, Walter B. Cannon of Harvard extended Bernard's concept of the constant internal environment. In The Wisdom of the Body'5 he stressed that life is possible because stability is maintained by regulatory mechanisms. He gave us a most useful and significant conceptual term, still the keystone of today's physiology, when he wrote: "the coordinated physiological processes which maintain most of the steady states in the organism are so complex and so peculiar to living beingsinvolving, as they may, the brain and nerves, the heart, lungs, kidneys and spleen, all working cooperatively-that I have suggested a special designation for these states, homeostasis. "5

This survey of history has traced contemporary physiology's legacy. What does a physiologist do? Based upon what is currently known about the natural world, he asks: How does a muscle cell shorten, a neuron generate and propagate an impulse, the ear/brain hear? Beyond these considerations, in which the physiologist is a splitter, a dissecter, a "peeler away" of the covering and overlying in order to discover the fundamental mechanisms of function, he is a synthesizer. As he studies the mechanisms of life, he perceives that they are not isolated and autonomous. There is a relatedness among them and among the organs and systems in which they are found. There is feedback, control, preservation of constancy within the body as its mechanical components interact.

To the present-day physiologist, then, the human body is a magnificent machine. Dean Wooldridge states it succinctly in Mechanical Man6:

Thus we have failed to discover any aspect of fife-whether related to the origin of organisms, to their physical properties, to behavior, to intelligence, or to consciousness-whose explanation appears today to lie beyond the ultimate capabilities of physical science ... We seem justified in the broadest possible application of what may be called the central thesis of physical biology, that a single body of natural laws operating on a single set of material particles completely accounts for the origin and properties of living organisms as well as non-living aggregations of matter and man-made structures. Accordingly, man is essentially no more than a complex machine.

The Nature of Biblical Theism

Every person has a weltanschauung or world view. In James Sire's words, a world view is "a set of presuppositions ... which we hold ... about the basic make-up of our world."7 Until the end of the 17th century, the theistic world view was dominant. Arguments and debates in philosophy and science were conducted within the framework of theism.

Pertinent propositions of the theistic (Christian) world view' are:

1. God is infinite. He is prime reality, beyond measurement. 2. God is personal. He has personality.

3. God is transcendent and immanent. He is, beyond us and our world yet with us.

4. God is omniscient. He is all-knowing, the source of all knowledge.

5. God is sovereign. Nothing is beyond His authority and control. 6. God is good. Goodness is the essence of God's character, expressed in holiness and love.

7. God created the cosmos ex nihilo to operate with a uniformity of cause and effect in an open system.  

8. Man is created in the image of God. He therefore has personality, intelligence, morality and creativity.

9. History is linear, a meaningful sequence of events leading to the fulfillment of God's purposes for man.  

Christian theism maintains that the universe was created ex nihilo, from nothing, by a personal God who is good, all-powerful, and all-knowing. It is He who formed man to have God's image, and therefore to have intelligence, personality, and morality.

The Dilemma of the Christian Physiologist

The theistic world view was jolted with Copernicus' discovery that the earth (mankind) was not the center of the universe. Medieval reality was overturned. Newton showed that there were certain forces which govern the motions of particles that make up the universe. The mechanical nature of matter was quickly applied to man. As Matson states it in The Broken Image8:

The Copernican revolution ... dislodged man from the center of the universe; it remained for the Galilean-Newtonian revolution to remove him from the universe altogether ... and so, for purposes of science, [mart] was removed-except as insensitive body, or more accurately as mechanism. The consequences of this displacement have not yet, after three centuries, fully run their course.

A Christian theist believes that God created an ordered and orderly universe and created man in His own image to function as a person. Contemporary natural science views the cosmos as an intricate mechanism of cause-and-effect, a vast perpetual motion apparatus devoid of all purpose, and current physiology considers man to be "an enormously complex machine, but a machine, nevertheless."2

It is at once obvious that a physiologist who is a Christian, accepting and believing the essential tenets of biblical theism, will experience a tension as his faith and his "machine physiology" interact. Can he/she be genuinely true to Christianity and to physiology? Is resolution of this dilemma possible?

A Resolution

The naturalism of contemporary physiology claims that, " matter exists eternally and is all there is. God does not exist. Man is a complex machine. Personality is an interrelation of chemical and physical properties we do not yet fully understand."7 Rhodes' lists the names of the great men who gave birth to and nurtured the rise of modern science: Copernicus, Galileo, Kepler, Bacon, Descartes, Boyle, Faraday, Dalton, et al., and points out that all were devout Christians. He believes that the original dependence of science on Christian theology is illustrated in an examination of the presuppositions of modern science: belief in an orderly, regular, rational universe, that this orderliness is intelligible to the scientist, and that human reason is reliable. They justified their assumptions, says Rhodes, "on the basis of their belief in a personal, rational and dependable God."9

With a background like this, it would appear strange that modern science is so closely allied in the public mind with atheism or agnosticism. Rhodes believes the change came about as a result of the popularization and "explanation" of science by Fontenelle and his descendents of the philosophes movement of the 18th century. Quoting Butterfield in The Origins of Modern Science, Rhodes continues:

Many of the scientists of the 17th century had been pious Protestants and Catholics ... A skepticism which really had a literary genealogy combined to give the results of the 17th century scientific movement a bias which was rarely seen in the scientists themselves, and which Descartes would have repudiated?

I believe it is debatable as to who first promulgated the new religion of scientism, the belief that all truth is scientific truth and that the sciences give us our best shot at knowing "how things really are."10 However it began, scientism is with us today and is espoused by a majority of physiologists and other scientists.

Donald MacKay, a neurophysiologist and a Christian, is helpful as we seek a resolution to the dilemma of "physiology and Christianity." In The Clockwork Image he states:

Our working hypothesis is that the brain is capable of being studied as a mechanistic system. in order to explain human behaviour, chains of cause and effect can legitimately be sought and found in terms of physics, or physiology ... The last thing I want to suggest is that there is anything improper about a mechanistic approach as such . . . However . . . a mechanistic approach adopted for scientific purposes is being abused if it leads to ... machine mindedness.11

A danger with scientific models, therefore, is their universal application to explanations of everything. Scientific reductionism presupposes that the scientific model can be universally applied. MacKay calls this debunking of alternative explanations "nothing buttery." It is characterized by the notion that by reducing any phenomenon to its components you not only explain it, but explain it away:

Christians believed the world was created by God; Science (with a capital S) showed that 'really' it was 'nothing but' a fortuitous concourse of atoms. Christians thanked God for sending rain and daily bread; Science explained the agricultural cycle as 'nothing but' the workings of an intricate physical mechanism ... 11

MacKay hastens to point out that some Christian apologists, especially in the 18th and 19th centuries, asked for the trouble they received from science by posing "arguments for the existence of God" out of phenomena that they thought were beyond scientific explanation, thereby sharing in and encouraging the mistaken presupposition of the scientists.

The fallacy of scientific reductionism ("nothing buttery") is illustrated in this way by MacKay: Suppose an 
electrician were asked to describe an electric advertising bill-board. He proceeds to give a thorough description of the electrical circuitry so that the listeners understand precisely how each light bulb is activated. But then some one says to him that his technical description is incomplete because he did not mention the message of the advertisement. MacKay's point is that the electrician's account, in its own terms, is complete. What he has not accounted for is the thing as a whole. But this is outside of his terms of reference. MacKay says:

To me this is a helpful picture of the kind of connection there is between the scientific description of the universe and the Christian description. As a scientist, I have the job of helping to build in scientific language-at the scientific level-as complete a description of the pattern of physical events as I can, regarding no accessible events
as exempt from examination. As a Christian, I find that the very same pattern of events can bear an additional and vital significance as part of the activity of God himself.11

Science, including physiology, may be regarded as the in vestigation and communication of natural revelation.
Richard Bube, a Christian physicist, does not consider science to be an independent method of knowing God, but
rather a valid instrument in interpreting revelation.12 MacKay agrees. He believes that the freedom and autonomy of science is only methodological, not ontological.

Science is not an alternative to God as the source of truth, but a specialized way of gathering and discovering patterns in data which Christians believe to have one and the same Source. The discipline of science is autonomous in the sense that we need not have explicit theological convictions in order to practice it ... Whether it be true or false that all natural happenings have a mechanistic explanation, the notion says nothing-absolutely nothing-either for or against their continual dependence on God in the sense implied by biblical theism.11

The latter point is a significant thesis for Bube, who firmly believes that God is the reason everything exists and continues to do so. "The universe exists moment by moment only because of the creative and preserving power of God . . . If God were to 'turn Himself off,' everything would cease to exist! Without God there are no laws, no world, no us. Not only do we rely upon God as the Creator at the beginning ... we rely upon God constantly for our very existence. "13 Bube goes on to cite a number of scripture passages for this position. (Heb. 11:3; 1:3; Col. 1:17; Job 12:10; Acts 17:28; 1 Cor. 8:6).

Bube, like MacKay, believes further that there are levels at which a given situation can be described. Reality can be described on the levels of the physical sciences, biology, psychology, sociology, and theology. Every natural phenomenon can in principle be described on every level. An exhaustive description is one in which there are in principle no unknown or unknowable gaps, using only the particular categories of a given level. Complete knowledge requires an exhaustive description on every level.13

Is man only a complex machine? He is a complex machine. Every human activity is or may be ultimately physically describable. But these events can also be described in terms of the biological, psychological and social sciences, and ultimately, as Bube puts it, "in terms of that theology which relates the event and the man to God."13 Bube emphasizes that it is never the question of something happening, on one level exclusively (e.g. the physical), but of happening on every level simultaneously.

Michael Polanyi perceives that a machine is characterized by an operational principle, that is, the way its

David Bruce was born in Amherst, Ohio. He studied at Taylor University (B.A. and B.S. Ed., 1962) and Purdue University (M.S., 1965, Ph.D., 1968 - both in Physiology). During a recent leave from Wheaton College, where he is Professor of Biology, he engaged in research in the Department of Physiology and Pharmacology at the University of St. Andrews in Scotland. He has taught at DePaul University (1967), Purdue (1967-68), Seattle Pacific College (1968-74), and has been at Wheaton since 1974. He is currently Chairman of the Health Professions Committee at Wheaton, which coordinates the advising and recommending o fpre-medical and other students preparingfor the health professions. His research is in the physiology of hibernation (bats and ground squirrels), diving physiology (comparative and human), and other aspects of physiological adaptation to environment. He has published more than twenty technical articles in human and animal physiology.

components (organs) carry out their special function in working together for an overall operation that achieves the purpose of the machine. "The complete knowledge of a machine as an object tells us nothing about it as a machine."14 That is, a complete physical and chemical description cannot, in itself, allow us to recognize a machine. It can be recognized as such only by first guessing, a least approximately, what it's for and how it works.

For centuries past, the workings of life have been likened to the workings of machines and physiology has been seeking to interpret the organism as a complex network of mechanisms ... Any coherent way it benefits the organism is discovered ... Any description of such a system in terms of its physical-chemical topography is meaningless, except for the fact that the description covertly may recall the system's physiological interpretation-much as the topography of a machine is meaningless until we guess how the device works, and for what purpose.15

As a Christian physiologist, my task is to learn all I can about the clockwork of the body, while maintaining my perspective that man is not merely the sum of the mechanical parts.

When Polanyi brings in purpose, he raises the hackles of contemporary physiologists who shudder at its teleological implications. In the examples he chooses, reasons and causes are addressed. Polanyi contends that all physiology is teleological, that purpose is logically inherent in the conception of jointly-functioning organs." The physiologist responds by saying that he is concerned only with a mechanistic explanation. When he asks a student why the heart beats faster when he runs, he wants a detailed answer of the effects of blood chemistry on chemoreceptors whose afferent impulses activate cardiovascular centers in the central nervous system which in turn send efferent signals to the myocardium. He does not accept the answer: "So more blood and oxygen can get to my muscles." This recalls the levels-of-explanation issue raised earlier. "Teleology," said von Brucke, "is a lady without whom no biologist can live; yet he is ashamed to show himself in public with her."8

Bube is instructive at this point. He states that science is concerned primarily with the immediate or secondary causes of events. The biblical revelation speaks primarily of the ultimate causes of events.

Christians must not mistake science's preoccupation with immediate mechanisms as in itself a denial of the existence of ultimate causes . . . Scientists . . . must not mistake the preoccupation of Christian theology with ultimate causes as in itself a denial of the importance of immediate mechanisms.12

If man's structural and functional parts were completely described in terms of physics, would that mean that the whole man would then be described in terms of physics as he engages in interpersonal relationships? It is very probably true that every human experience has some physical, chemical (certainly physiological) counterpart in the body (especially the brain). The issue is whether everything about man is explained by a physical and chemical description. As Bube puts it,

Once these physical and chemical processes have been discovered, is there nothing else meaningful that can be said about the phenomena involved? . . . It is no longer necessary to debate whether man is a machine or a person created by God. Man can be understood only when described as a machine and as a person created by God, created with real personality in the image of a personal God but functioning on the biological, biochemical, and biophysical levels according to the laws that govern the rest of nature as well. 13

Science can never claim to be the only method of apprehending reality.9 As MacKay says, ". . we have in human nature a 'unity' which demands at least two levels of discussion: the level of the mechanical, appropriate for an  outside observer, and the level of the personal, appropriate  My from the inside standpoint of the agent himself .16 Langdon Gilkey speaks of the difference between the biophysical act of a human action and the reason for its occurrence.

Like the falling of a leaf, an act without purpose is "merely caused," the determined effect of a preceding physical event . . . Only where freedom and so the power of decision are assumed, only where a purpose is evident, does an action become meaningful to itself or to others as a human action ... Christian thought must accept the scientific method, which searches for the necessary interrelations between events, as a valid and important means for understanding the observable world around us. But Christianity can never accept science as a total view of finite reality ...17

Donald MacKay crystallizes the essential point of resolution emphasized in this paper. He writes:

Our nature has a multiplicity of complementary aspects, and no single account at one level of explanation can do full justice to all. In this sense man is indeed a mystery. Even to explain man's brain and body completely, if we could, in mechanistic terms, would not begin to dispose of the mystery which confronts us in the fact that, when all is said and done, here we are as cognitive agents who can contemplate the result. Where do we come into the mechanistic description? 11

In her article "The Man Who Is There,"18 Mary Jean Newton wonders if man is just a machine, or if there is something special in him that sets him apart from the rest of creation. She states that ultimately this question requires a faith response, because no one has yet found a way to prove conclusively to another person the truth of either alternative.

A Personal Application And Commitment

Is the dilemma resolvable for the Christian physiologist? Is man a machine? Or is there a reason, a purpose for human existence? I believe that man is a machine. As a physiologist I shall continue to study the parts, the mechanisms, and to teach my students about them. As a Christian, I believe that man is a personal agent, created by a personal God, and that man is to image God in all that he does. As a Christian physiologist, my task is to learn all I can about the clockwork of the body, while maintaining my perspective that man is not merely the sum of the mechanical parts. The central thesis of my attempt at resolution of the dilemma of the Christian physiologist is that a thorough description of man's physiology does not obviate the need for other levels of explanation of his whole nature. I would do my students a great disservice if I failed to help them learn all that is currently known about the mechanisms of the body and their interplay and control. I would do them a greater disservice if I persuaded them explicitly or tacitly to substitute the impersonal god of scientism for the personal God of creation as their ultimate motivator and raison detre.

I conclude with some final thoughts from MacKay:

. . . If we would understand what the Bible has to say about our human nature we must try to appreciate the wholeness of the biblical concept of man, as a unity of body, mind and spirit. There is absolutely no basis for the idea that the biblical doctrine, in all its fullness, raises any kind of barrier to the mechanistic explanation of human activity . . . The greatest educational need of our time [is] to restore wholeness to our view of life. The machine-image promises unification of a kind-but only at the cost of leaving out, as irrational and fragmentary oddities, those human questions and concerns and values which we feel most deeply . . . The only complete solvent of machine-mindedness, and the only perfect education for freedom, is in a proper conception of God as author of our whole lives, including the marvellously intricate mechanistic story that our science is uncovering.11

I firmly wish to be both a teacher and a student in that "freedom education" school.


1Carlson, A. J. and V. Johnson. 1948. The Machinery of the Body. 3rd ed. U. Chicago Press. pp. 4,5.

2Vander, A. J., J. H. Sherman and D. S. Luciano. 1980. Human Physiology - - The Mechanisms of Body Function. 3rd ed. McGraw-Hill. p. 9.

3Nicklanovich, M. D. 1973. From Cell To Philosopher. Prentice-Hall. p. 521.

4Coleman, T. G. 1975. "The Role of Theories in Biological Research," The Physiologist 18(4): 509-518.

5Cannon, W. B. 1932. The Wisdom of the Body. W. W. Norton Co. edition pub. 1963.

6Wooldridge, D. E. 1968. Mechanical Man. McGraw-Hill.

Sire, J. W. 1976. The Universe Next Door. InterVarsity Press.

8Matson, F. W. 1966. The Broken Image. Doubleday Anchor Books.

9Rhodes, F. H. T. 1965. "Christianity in a Mechanistic Universe," In Christianity In A Mechanistic Universe, D. M. MacKay ed. Inter-Varsity Fellowship/London.

10Evans, C. S. 1975. "Christian Perspectives on the Sciences of Man," unpub. paper from Faith-Learning Seminar, Wheaton College, Illinois. 

11MacKay, D. M. 1974. The Clockwork Image. InterVarsity Press.

12Bube, R. H. 1968. The Encounter Between Christianity and Science. W. B. Eerdmans.

13Bube, R. H. 1971 The Human Quest. Word Books.

Polanyi, M. 1958. Personal Knowledge. U. Chicago Press.

15Polanyi, M. 1968. "Life's Irreducible Structure," Science 160: 1308. Reprinted in J. Amer. Sci. Affil. 22(4): 123-131 (1970).

16MacKay, D. M. 1965. "Man as Mechanism," in Christianity In A Mechanistic Universe, D. M. MacKay ed. Inter-Varsity Fellowship/London.

17Gilkey, L. B. 1959. Maker Of Heaven and Earth. Doubleday & Co. p. 70.

18Newton, M. J. 1970. "The Man Who is There," J. Amer. Sci. Affil. 22(4): 145-147.