In these topics we will examine the history of conceptions of the human makeup as they arose in ancient philosophy and religion -- primarily in Christianity, but also with a few notes about Jewish developments. We also examine new issues that arose in the modern period, especially as a result of scientific and philosophical developments. Whereas body-soul dualism had become the majority view by the end of the middle ages, in the modern period there has been growing interest in physicalist accounts. Currently, localization studies by contemporary neuroscientists--that is, finding specific regions or distributed systems in the brain associated with particular cognitive and emotional functions--provide some of the most compelling evidence that it is the brain, rather than a mind or soul, that is responsible for these capacities. In other words, the current trend in neuroscience is pointing us towards a reductive physicalist account of the human.
In addition, we will consider whether a nonreductive physicalist account of the person is in conflict with essential Christian (and Jewish) teachings. To this end, we will examine recent developments in biblical studies and consider some of the implications of a physicalist account of the person for theology.
Other sections will investigate the philosophical question of reductionism. If mental events are essentially products of the brain, and if we assume that brain events are determined by natural laws, then how can we maintain views of human freedom and responsibility? This is still an open question, but it will be valuable to consider some of the resources available for addressing the problem.
Finally, we will consider some of the practical implications of the intellectual changes we have surveyed.
Are human beings composed of two parts, a material body and a nonmaterial soul, or are human beings purely physical beings? This question reflects a deep, but often unspoken, conflict within our culture over views of the very nature of humans. The first of these views is called dualism (body-soul dualism or mind-body dualism), and the second is here called physicalism. While this question is an old one, going back nearly to the beginning of Western intellectual history, it is becoming more prominent at the present time, due to developments in the cognitive and neurosciences. While many religious believers hold a dualist view, these scientific developments make it less and less plausible that we need the concept of an immaterial mind or soul to account for human capacities and behavior.
Within the physicalist camp there is another important distinction between reductionist and nonreductionist views. Thus, we can distinguish between "reductive physicalism" and "nonreductive physicalism." The reductive physicalist says that humans are purely physical beings and thus all of our thoughts, emotions, and experiences are nothing but brain states. For example, the laws of neurobiology could, in principle, explain all of human life, including rationality, morality, and even religion. The nonreductive physicalist, in contrast, says "yes," humans are purely physical, but this leads us to recognize that it is our brains (in our bodies and in social relationships) that enable us to think, to make moral choices, and even relate to God. Thus, the nonreductive physicalist position is equally opposed to dualism and to reductive physicalism.
While many conservative believers worry about conflicts between religion and science, it is more often argued that religious belief and science are so different they cannot possibly relate, either positively or negatively. However, this brief survey shows that concepts of human nature in our culture are the product of both religion and science, as well as philosophy. Presently, there are conflicting views on the nature of a person. Thus a dialogue between science and religion can help provide timely clarification of these issues.
One of the most important sources for Western views of the nature of the human being is ancient Greek philosophy, especially Plato (427-347 BCE) and Aristotle (384-322 BCE).
According to Plato's dualist view, a human being is a soul imprisoned temporarily in a body. The soul is immaterial and eternal, and accounts for human consciousness. Plato believed the soul to have three `parts': 1.) reason; 2.) the spirited element, which initiates action; 3.) and the drives and appetites.
Plato's dualist conception of the person fits well with his dualist conception of reality in general. Beside this imperfect and corruptible physical world, there is the transcendent realm of the Forms or Ideas, which is perfect and eternal. According to Plato, the soul's true home is in the realm of the Forms.
Plato's philosophy had a significant impact on the development of early Christian thought, largely through the Neoplatonists who elaborated his ideas and incorporated them into religious systems. Augustine (354-430 CE), who has been called the most influential theologian since the Apostle Paul, made great use of Neoplatonist philosophy for treating theological issues. However, Augustine was compelled to make some modifications to the Platonic conception of the soul. According to Augustine, a human being is a rational soul using a mortal and material body, so it is not imprisoned in the body. Like Plato, Augustine's view of the soul is tri-partite, but there are some slight differences between the two thinkers. Whereas Plato saw reason as the highest attribute, Augustine thought that the will was the highest or dominant aspect. Finally, while the soul is immortal for Augustine, it does not exist eternally before incarnation, as it does for Plato.
In contrast to Plato, the Greek philosoher Aristotle thought of the soul not so much as an entity, but more as a life principle--the aspect of the person that provides the powers or attributes characteristic of the human being. Therefore, plants and animals have souls as wellthat is, nutritive and sensitive souls.Our souls incorporate the nutritive and sensitive powers, but also include rational powers. Because the soul is a principle of the functioning body, it dies with the body (although Aristotle speculated that perhaps some aspect of rationality survives death).
Aristotle's conception of the soul and body also fits well into his general conception of reality. All material things are comprised of matter and form. The form is an immanent principle that gives things their essential characteristics and powers. So the soul is but one type of form.
In general, what we see in Greek philosophical speculation is the recognition that human beings have some remarkable capabilities all their own (such as doing mathematics and philosophy) and others that they share with animals (sensation).
Thomas Aquinas (1225-74), the most influential of Catholic theologians, developed a largely Aristotelian conception of the person, but he also needed to make some qualifications. While he believed Aristotle's philosophy helped Christians to appreciate Christian teaching on the resurrection of the body, he still believed that Christian doctrine required an immortal soul to which the body would be restored at the general resurrection. Thus, he argued (and not very cogently) that Aristotle was wrong about the mortality of human souls.
Aquinas theoretical approach to the nature of the soul was to ask, first, in what kinds of activities do people engage. Then, he identified the kinds of operative powers needed to explain such actions. Finally, he concluded as to the sort of entity needed to account for all of these powers. The activities that he recognized included the biological functions of growth, assimilation of food, and reproduction. A higher set of activities included sensation, emotional responses to perceptions, and locomotion. But the highest faculties of all were the cognitive functions of understanding, judging, and reasoning -- along with the ability to be attracted to the objects of the understanding (will). This latter faculty is what accounts for human moral capacities, as well as for the attraction to God.
We can see that medieval theology drew on the prior Greek speculations. It did not seem possible to attribute human powers to the body, so theories were developed about an additional component of the person to account for them, e.g., the soul. Further, since living persons can perform the human capabilities and corpses cannot, the soul was also taken to be the life principle.
Over the course of the modern period (ca 1650-1950) a variety of reasons have emerged for rejecting the sorts of dualism separating body, mind, and soul. These reasons encompass theological, philosophical, and scientific considerations. Theological reasons include: (1) the claim that dualism is not biblical and that theology ought to reject Greek conceptions in favor of the original Hebraic conceptions of the Bible; (2) the related claim that resurrection of the body (rather than immortality of the soul) was the original Christian account of life after death; and (3) the claim that dualism has led to an un-Christian depreciation of the physical creation.
There have always been philosophical problems connected with the concept of the soul. For example, Plato said that the body could not affect the soul. If this is so, then how could the senses provide it with perceptual knowledge? In the modern period, the problems have become acute, leading most philosophers and many theologians to conclude that a different account of the nature of the human being is required.
The philosophical reasons for this change have largely to do with the difficulties (or impossibility) of explaining how a nonmaterial entity could interact with a material body. In addition, these problems have been exacerbated by a variety of scientific developments.
Rene Descartes (1596-1650) is considered the first modern philosopher, and he has had a tremendous impact on all later conceptions of the person. Descartes distinguished two basic kinds of created realities: (1) extended substance, meaning all material things, and (2) thinking substance, including angels and human minds. (Note in Descartes the shift in terminology from `souls' to `minds.' These concepts overlapped for ancient and medieval thinkers, and English-language philosophy has generally used the term 'mind' rather than 'soul.').
The problem of mind-body interaction suddenly became more difficult in the Modern period because a version of atomism came to replace Aristotelian conceptions of matter. In Aristotle's theory, matter and form were correlative, with form being the active principle and matter being the passive. So the soul, as one type of form, was conceived exactly as that which animated, or moved, the body. In the early modern scientific conception of matter, especially as developed by Isaac Newton, matter was also seen as inert, or passive. But matter in Newton's conception, rather than being moved by immanent forms, was moved by external, physical forces. This raised a dilemma: if we maintain the immateriality of mind, then there is no way to account for its supposed ability to move the body. Alternatively, if we interpret it as some kind of physical force, its effects ought to be measurable and quantifiable, just like any other force in nature. However, no "psychic force" is yet explained or accounted for in modern physics. To solve this dilemma, a variety of philosophical theories have been tried. For instance, "psycho-physical parallelism" holds that mental events and physical events occur in parallel chains, only appearing to interact causally because of a pre-established harmony. And, "epiphenomenalism" claims that brain events cause mental events, but mental events have no causal effects of their own. Psycho-physical parallelism has had very few supporters. Epiphenomenalism is problematic because it simply denies that the mental, qua mental, makes any difference in the world. Both of these theories see brain events -- which are presumably governed by the laws of neuroscience, and ultimately by the laws of physics as making things happen. This leads to the problem of what it means for a physical (brain) event to cause a mental event.
These problems have led most secular philosophers to conclude that we are better off not postulating minds as entities at all. We may speak, instead, of mental events, but these are still identical with physical (brain) events, in some way. That is, we call them mental events as we experience them `within'; physical as we imagine a neuroscientist looking at the brain from without.
As we have seen, early modern science's new conception of matter created philosophical problems for mind-body dualism. Many philosophers have judged these problems to be insoluble, and this, in turn, has led to a wholesale rejection of the concept of a substantial mind.
Recent science has shown the fruitfulness of taking the brain to be the seat of all those mental faculties medieval thinkers, such as Thomas Aquinas, had attributed to the soul. Therefore, we consider here a variety of results from neuroscience which make it appear that the various human capacities once attributed to the soul are better understood as capacities of the human brain.
One sort of research concerns the localizing of various cognitive and affective functions in specific regions or distributed systems of the brain. This research began by studying victims of brain damage, correlating lost faculties with localized damage discovered during autopsies. With the development of CAT scans (computerized axial tomography), it has become possible to study correlations between structural abnormalities and the behavior of people while they are alive. Further, MRI scans (magnetic resonance imaging) now provide quite detailed pictures of the brain, more easily revealing locations of brain damage. And PET scans (positron emission tomography) allow research correlating localized brain activity with the performance of specialized cognitive tasks.
These varied techniques have allowed for the localization of a vast array of cognitive functions. To show the extent to which current science now studies the capacities once attributed to the soul, let us consider in more detail the account developed by Thomas Aquinas of the hierarchically ordered faculties, or powers, of the soul.
The `lowest' powers of the human soul, shared with plants and animals, are the vegetative faculties of nutrition, growth, and reproduction. All of these processes are now fairly well understood in biological terms, especially since the discovery of DNA. The brain is significantly involved here, in that neurochemicals play a large role in appetite and sex drive; while pituitary hormones control growth.
Next higher are the sensitive faculties, shared with animals but not plants. They include the exterior senses of sight, hearing, smell, taste, and touch, as well as the four "interior senses," called sensus communis, phantasia (imagination)R, vis aestimativa, and vis memorativa (memory). The sensus communis is the faculty that distinguishes and collates data from the exterior senses. An example of this faculty would be associating the bark and the brownness of the fur with the same dog. The vis aestimativa allows for apprehensions that go beyond sensory perception. Here, an example would be apprehending the fact that something is useful or useless; friendly or unfriendly. This sensitive level of the soul also provides for the power of locomotion and for lower aspects of appetite -- the ability to be attracted to sensible objects. This appetitive faculty is further subdivided between a simple tendency toward or away what is sensed as good or evil, and a more complex inclination to meet bodily needs or threats with appropriate responses: attack, avoidance, or acquiescence. Together, these appetitive faculties (all still at the sensitive level) provide for eleven kinds of emotion: love, desire, delight, hate, aversion, sorrow, fear, daring, hope, despair, and anger.
Locomotion is now known to be controlled by the motor cortex -- running across the top of the brain -- and by the efferent nervous system.
Great progress has been made in tracing the processes involved in sensation. For example, signals are transmitted from two different kinds of light-sensitive cells in the retina, through a series of processors, and on to the visual cortex. Smell involves the sending of signals from six different kinds of receptor cells to the olfactory lobes.
The task Aquinas assigned to the "interior sense" sensus communis -- the ability to synthesize input from the various external senses -- is now studied by neuroscientists as "the binding problem."
The "interior sense" of memory, identified by Aquinas, has also been researched a great deal. Long-term memory is now understood to arise from patterns of connections within the neural network. Short-term memory is believed to be enabled by a system of "recurrent pathways," such that information is processed, recycled, and then fed into the process again. The hippocampus is involved in converting short-term into long-term memory, but how this happens is not yet known.
One of the most interesting findings involves the localization of specific sorts of memory. Paul Churchland presents a map of the brain showing regions involved in language memory, with different locations being responsible for verb access, proper name access, common noun access, and color terms. The parietal lobes are an example, as they are involved in our memory of faces.
PET scans make it possible to record localized elevations of neuronal activity. Paul Churchland reports an experiment in which his wife, Patricia, was asked to perform a task involving her visual imagination. The activity in her visual cortex was elevated exactly during the time she was doing the exercise, but not to the same extent as when she received external visual stimulation. Paul Churchland hypothesizes that visual imagination involves the systematic stimulation of the visual cortex "by way of recurrent axonal pathways descending from elsewhere in the brain."
The vis aestimativa of Aquinas included the ability to distinguish between the friendly and the unfriendly, the useful and the useless. One clear instance of this is our ability to read others' emotions. While there does not seem to be a single location responsible for this capacity, there are patients whose brain damage has resulted in its loss. For instance, Churchland describes the patient "Boswell," who suffers from extensive lesions to the frontal pole of both temporal lobes, and to the underpart of the frontal cortex. One, among many, of his mental deficits is the inability to perceive emotion. Churchland reports:
I watched as Boswell was shown a series of dramatic posters advertising sundry Hollywood movies. He was asked to say what was going on in each. One of them showed a man and a woman, in close portrait, confronting one another angrily. The man's mouth was open in a plainly hostile shout. Boswell, without evident discomfort or dismay, explained that the man appeared to be singing to the woman.
The sensitive appetite postulated by Aquinas was responsible for emotions such as desire, delight, sorrow, and despair. Studies of the etiology of mental illnesses involving inappropriate affect have shown a significant role for neurotransmitters such as serotonin.
The rational faculties described by Aquinas are distinctively human: passive and active intellect and will. The will is a higher appetitive faculty whose object is the good. Since God is ultimate goodness, this faculty is ultimately directed toward God. The two faculties of the intellect enable abstraction, grasping or comprehending the abstracted universals, judging, and remembering. Morality is a function of attraction to the good, combined with rational judgment in reference to what the good truly consists.
These higher mental faculties Aquinas attributed to the rational soul are further from being understood. However, all of them involve language. Even if we do not understand how these mental faculties depend on brain functioning, we know that they do because of the close association of linguistic abilities with specific brain areas, especially Wernicke's area and Broca's area.
To review, a variety of results make it appear that the various human capacities Aquinas had attributed to the soul are better understood as capacities of the human brain. In fact, these capacities are attributable to specific regions of the brain.
These conclusions are not uncontroversial. First, there is the argument within neuroscience over specialization versus globalism. That is, many would argue that each of the mental capacities listed above is much more a result of global functioning of the brain, not localized functioning. We need not get into this argument; all that needs to be pointed out is that the regions cited above are involved in the specified functions, since all we know is that, if a region is damaged by illness or injury, a corresponding function is lost. Second, there are still some philosophers and scientists who maintain a dualist account of the mind and brain. They point out that however precise science may become in associating mental functions with the brain, science will never prove it is the brain performing the functions. It may simply be the case that functions performed by an independently existing mind, or soul, are just highly correlated with brain functions.
For Aquinas, the rational appetitive function was the ground of moral behavior. In his fascinating book, Descartes' Error, Antonio Damasio reports a famous case of brain damage caused by a metal rod driven through the skull of a railway employee, named Phineas Gage. Gage recovered almost entirely from his physical disabilities, except for loss of sight in one eye. It is surprising, of course, that Gage survived such a traumatic event at all, but more surprising is the fact that his personality was completely changed as a result of the accident. Gage's doctor describes how "the equilibrium or balance, so to speak, between his intellectual faculty and animal propensities" had been destroyed. The changes became apparent as soon as the acute phase of brain injury subsided. He was now "fitful, irreverent, indulging at times in the grossest profanity which was not previously his custom, manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires, at times perniciously obstinate, yet capricious and vacillating, devising many plans of future operation, which are no sooner arranged than they are abandoned. . . ." .
These new personality traits contrasted sharply with the "temperate habits" and "considerable energy of character" Phineas Gage was known to have possessed before the accident. Previously, he had "a well balanced mind and was looked upon by those who knew him as a shrewd, small businessman, very energetic and persistent in executing all his plans of action." So radical was the change in him that friends and acquaintances could hardly recognize the man. They noted sadly that "Gage was no longer Gage." So different a man was he that his employers had to let him go shortly after he returned to work. The problem was not lack of physical ability or skill; it was his new character.
Damasio uses this story to introduce his research on brain localization. That is, by a careful analysis of Gage's skull, Damasio has been able to determine exactly which parts of the brain were destroyed by the iron rod. He infers from this and other similar cases that specific regions are essential to the sort of practical reasoning Gage became incapable of performing. To return to Aquinas's language, Gage lost his ability to be attracted to the Good.
It is now widely agreed that the predominant understanding of the human being in the Hebrew scriptures is holistic and nonreductive physicalist. Jewish scholar Neil Gillman writes:
Biblical anthropology knows nothing of this dualistic picture of a person which claims that a human being is a composite of two entities, a material body and a spiritual or non-material soul. . . .
The [Hebrew] Bible, in contrast, portrays each human as a single entity, clothed in clay-like flesh which is animated or vivified by a life-giving spark or impulse variously called ruah, nefesh, neshamah, or nishmat hayyim. . . .
In the later tradition, these terms came to be understood as synonymous with the Greek "soul." But this identification is not in the Bible.
For example, nefesh first meant neck or throat; by extension it signified a living being. Neshamah and ruah both mean breath or wind. Since death is the going out of the breath, it was possible to identify "something that goes out when one dies" with Plato's soul.
There is somewhat less agreement on New Testament conceptions of human nature. Most scholars now agree that the New Testament generally supports a holistic and nonreductive physicalist account of the person. However, some argue that the New Testament presupposes dualism, since there are a few passages appearing to support a doctrine of "the intermediate state." This intermediate state, it is said, assures Christians that between death and the general resurrection they survive to await judgment. Therefore, the person must be "constructed in such a way that at death it can `come apart,' with the conscious personal part continuing to exist while the organism disintegrates." Some of the biblical texts cited to support this are Matthew 10:28; Matthew 27:50; Luke 16:19-31; Luke 23:42-43; John 12:25; 1 Peter. 3:19-20; and Revelations 6:9-11. Several questions have to be settled in regard to these texts and their relevance for the "intermediate state." Again, one question concerns translation. For example, when it is said of Jesus in Mt. 27:50 that he "gave up his spirit," is this to be taken literally, or as a metaphorical way of saying that he died?
Second, Christians have had to distinguish between the teaching of Scripture and the assumptions, concepts, and theories of the time they were used to convey the teachings. In other words, it is common to speak of God's revelation being accommodated to the thought-forms of the ancient cultures. An important example is the use of -- or accommodation to -- ancient cosmology throughout the Old Testament, as when Isaiah says that God will gather Israel and Judah from "the four corners of the earth" (Isaiah 11:12). So if it is shown that the New Testament speaks of an intermediate state -- or otherwise presumes some sort of dualism -- an important question to raise is whether this is biblical teaching or merely accommodation to the thought of the times. That is, we have to ask whether metaphorical language was used to convey theological truths that could not have been conveyed very well in other thought-forms at the time.
It may be most accurate to say that the New Testament has no explicit teaching on this issue. Rather, various New Testament writers assumed one or another conception of the constitution of the human being in order to teach about other issues concerning the relation of humans to one another, to the rest of creation, and to God.
Critical church history in the Modern period has recognized significant doctrinal developments. These developments, largely revolving around semantic difficulties in language translations, have had a strong bearing on how we have come to our own human makeup. One important aspect is the recognition of the Hellenization of Christian thought -- the `translation' of doctrines into the thought-forms and language of Greek culture. This process, already begun in New Testament times, accelerated in the Patristic era and continued at least until the Reformation.
One response to this recognition was a call to purify theology of its Greek accretions, and to return to the original Hebraic understanding of Jesus and his significance. This movement has led to questions over whether body-soul dualism was in fact biblical teaching. That is, whether both Old and New Testament conceptions of the person have been distorted by the translation of the original Hebrew and Greek into modern languages, and the modern interpretation of those scriptures in accordance with dualistic philosophies.
Nonetheless, Christian theologians such as Augustine soon adopted the dualist picture of human nature, and this came to be the most common Christian view until the present century.
The doctrine of the intermediate state continues to be a critical issue for some Christians. Historically, Thomas Aquinas went to great lengths to make room in his theology for such a doctrine, and it was made official for Catholicism by the Fifth Lateran Council in 1513. Calvin seems to have settled the issue for members of the Reformed tradition. His work Psychopannychia (1542) was written against other reformers who were teaching, either that the soul simply dies with the death of the body, or that it goes into an unconscious "sleep" between death and the general resurrection. Despite the fact that psychopannychia literally means a watchful or sentient "wake" of the soul -- ordinarily used to designate a position such as Calvin's own -- Calvin's treatise has, instead, been applied to his opponents.
Early psychopannychists included Luther, Michael Servetus, and Carlstadt, as well as a variety of lesser-known Radical Reformers, such as Westerburg; some were banished or put to death for their support of this position.
Finally, is there any meaning to the question of an intermediate state? If God is not `in time'; perhaps those who are with God after death are therefore not in time, either. Thus, we may not know what it means to distinguish between immediate resurrection and resurrection after a period of waiting.
A theological issue, then, the intermediate state concerns the relation between anthropology and the doctrine of salvation. Critics of dualism claim that it fosters an overly-narrow conception of salvation, as merely saving souls for the after-life. They argue that a more biblical -- and generally more adequate -- account of salvation involves saving the whole person. Further, this alternative account is as much a this-worldly concern as a concern for the final state. It can be argued that the conception of salvation as "getting to heaven" is a Neoplatonic idea, closely related to Plato's view that the proper abode of the soul is the realm of the Forms. It is important to emphasize that the original Christian account of hope for life after death was the expectation that all would enjoy the resurrection of the body. Wolfhart Pannenberg proposes that a more authentic Christian view involves the ultimate transformation of the entire cosmos, similar to the transformation that Jesus' body has already undergone in the Resurrection.
Beginning around the second century BCE, there were two independent developments in Jewish thought concerning the afterlife. Prior to that point, the Jewish tradition had taken death to be the final end of human life. One development was the expectation of bodily resurrection at the end of time. The other was the adoption of a dualist account of the person, according to which the soul survives the death of the body. Neil Gillman says:
In their original form, the two doctrines of the resurrection of the body and the immortality of the soul appear independent of each other. One knows nothing of bodies, the other knows nothing of souls. One ascribes personal identity to the body; the other, to the soul. One teaches that at the end of time, the body will be revived. The other insists that the soul is immortal and needs no revival.
However, Rabbinic Judaism (from around 200 CE) conflated these traditions, teaching that the soul leaves the body at death but receives a resurrected body at some later time.
Neil Gillman points out that while many Jews since the Enlightenment have given up all concepts of life after death, there is a current movement within Judaism to recapture the doctrine of bodily resurrection (rather than immortality of the soul). Gillman asks:
[W]hy stress bodily resurrection rather than immortality of the soul? For many reasons: Because the notion of immortality tends to deny the reality of death, of God's power to take my life and to restore it; because the doctrine of immortality implies that my body is less precious, important, even "pure," while resurrection affirms that my body is not less God's creation and is both necessary and good; because the notion of a bodiless soul runs counter to my experience of myself and of others; because immortality implies the absorption of my soul into an All-Soul thus denying my individuality; and because resurrection affirms the significance of society.
One powerful reason for holding to mind-body, or body-soul, dualism in the modern period is that the major perceived alternative has been a reductive physicalist account, which seems to imply determinism. Therefore, it is important in theological discussions to distinguish between reductive and nonreductive versions of physicalism. To see the difference, consider a recent finding by V.S. Ramachandran at the University of California, San Diego. Ramachandran and his research team studied patients suffering from temporal lobe epilepsy. It has long been known that such patients often experience intense mystical and religious experiences. This recent study involved testing patients' involuntary responses to a series of test words about sex, violence, and religion. This was done by measuring the electrical conductivity of their skin, a standard measure of emotional response. The result was that the test group showed a stronger response to the religious language than did a group of "normally" religious people and a neutral control group. This led to speculation that the temporal lobe is part of the neural machinery involved in religious experience.
Now, what further conclusions are to be drawn from such claims? One commentator says "there is the quandary whether the [brain] created God or whether God created the [brain]." Others say "these studies do not in any way negate the validity of religious experience or God." A reductionist response to this research would affirm that religious experience is nothing but a neurological event in the temporal lobe. However, to see why this is not the only (or even the most likely) interpretation, consider a parallel case. As described above, neuroscientists have done a great deal to explain the processes involved in visual perception. When these neural pathways are mapped out, it becomes possible to question whether objects in the external world produce visual images in the brain, or whether the brain produces the (apparent) objects in the external world.
Just as it is possible to distinguish between visual perception and visual imagination, similarly it is possible to make a distinction between authentic religious experience and experiences that are merely psychological and/or neurological phenomena. Religious believers have established communal procedures for "testing" religious experience for authenticity. These tests include consistency with Scripture or earlier teaching, and whether the experience fits into the life story of the individual and the community. For example, does it lead to an increase in the "fruits of the Spirit," such as love, joy, and peace?
The issue of reduction versus nonreduction can be stated this way. Is it possible to identify mental states with brain states, while avoiding the implication that mental life is totally determined by physical laws? If such determinism cannot be avoided, then human freedom is an illusion. As such, we are deceived about the aspects of our humanity we hold most dear; religious faith, love, morality, and intellectual endeavors are merely the outworking of blind laws of physics. The reductionist says these experiences are nothing but brain states. The nonreductive physicalist says, instead, that the brain (or the brain in the body and in social relations) is the means which make these experiences of God and other humans possible for a physical creature.
Both Judaism and Christianity apparently began with a concept of human nature that comes closer to contemporary nonreductive physicalism than to Platonic dualism. But, both made accommodations to a prevailing dualistic philosophy, and combined a doctrine of the immortality of the soul with a doctrine of the resurrection of the body. The pressing question now, concerns whether to return to those earlier nonreductive physicalist accounts of human nature, as many Christian theologians have urged throughout this century.
If a nonreductive physicalist view of the person is acceptable theologically and biblically, as well as scientifically and philosophically, a variety of consequences follow in the fields of ethics, spiritual development, medicine, and psychotherapy.
For example, many arguments against abortion depend on when the human soul is presumed to appear. If the soul is present from the moment of conception, then abortion at any stage of pregnancy is full-scale murder. This argument no longer makes sense with a nonreductive physicalist account of the person, in which there is no soul upon which one's humanity depends. Similar sorts of issues arise with regard to euthanasia. It is certainly true that the concept of the soul has been valuable for ethical purposes; it needs to be shown that equally powerful arguments can be constructed using the nonreductive physicalist account of personhood. For example, Jesus' injunction to care for the "least of the brethren" (Matthew 25:40) can be applied supremely to children before they are born, as well as to the elderly at the end of their life. Notice that in Jesus' parable the emphasis is not on saving the souls of those who are in distress, but rather, on meeting their bodily needs for food, water, clothing, and companionship.
Spiritual formation throughout most of Christian history has presupposed a Platonic conception of the person. It has often been understood, for instance, that "mortification of the flesh" is necessary for the flourishing of the soul. It is likely that a nonreductive physicalist account of the person will lead to healthier and more effective approaches to spiritual life.
Psychotherapists have already come to realize the dependence of psychological health on physical health, such as when a serious illness leads to depression. Equally important is the less-frequently recognized dependence of physical health on psychological and spiritual factors. This includes, for example, the role of stress (a psychological factor) in causing ulcers, high blood pressure, and other psychosomatic ailments. Spiritual factors, such as resentment resulting from an inability to forgive others, also play a significant role in affecting one's physical health. Increasingly, studies are finding that prayer and church attendance are associated with better health. A nonreductive physicalist conception of the person can be expected to promote a more integrative practice in a variety of health-care professions. That is, it will not be possible to compartmentalize the person and to conclude that physicians treat only physical illnesses, psychologists only mental illnesses, and pastoral counselors only spiritual ills.