Library: Modern Documents: Keith Augustine: Book Review: Whatever Happened to the Soul? (2000)

Book Review: Whatever Happened to the Soul?

by Keith Augustine

Book Review: Warren S. Brown, Nancey Murphy, and H. Newton Malony, eds. 1998. Whatever Happened to the Soul? Scientific and Theological Portraits of Human Nature. Minneapolis: Fortress Press. 243 pp.

According to the back cover of the paperback edition, Whatever Happened to the Soul? "strives for greater consonance between contemporary science and Christian faith." This is not surprising when the preface reveals that the authors were supported by a grant from the John Templeton Foundation. Nonbelievers can take some consolation in the fact that historically in the "war between science and religion" the "reconciliation" has always fallen on the side of science with theologians scrambling to redefine their faith in order to make it compatible with new scientific evidence, and this book is no exception. That we never see the reverse--scientists scrambling over the latest theological speculation--illustrates the authoritative dominance of science over religious belief in the modern world. Scientific explanations of phenomena have been so successful that today believers are trying to develop scientifically-informed theologies. The authors of the present volume, for example, write: "We have written from the perspective that views soul as a functional capacity of a complex physical organism, rather than a separate spiritual essence that somehow inhabits a body. We have adopted this position because we believe it is the best way to incorporate and reconcile all the various sources of available data" (xiii). In other words, the accumulated scientific evidence available to us today strongly suggests that the soul--conceived of as a separable immaterial mind inhabiting the body[1]--does not exist.

Evolution and Human Nature

In Chapter 2, "Human Nature: One Evolutionist's View," Francisco J. Ayala draws a distinction between biological evolution, which all organisms share, and cultural evolution--the "transmission of information by a teaching-learning process" (38) which occurs independently of genetic change and is supposedly a uniquely human phenomenon[2] (at least on this planet). While it is clear that Ayala is primarily concerned with highlighting features which uniquely distinguish human beings from other animals, Ayala's description of the evolutionary lineage which led to human beings is completely consistent with a naturalistic account of human origins. The mere fact that one can list features which uniquely characterize modern humans does not show that Homo sapiens occupy a special place in the animal kingdom[3] since many organisms have special features which uniquely characterize them. If the difference between humans and animals is only one of degree--as evolution implies--then human beings should not expect to have any special relationship with the Creator of the universe beyond the relationship that the Creator would have with any other organism. Nor should a Creator, if he exists, have any special plans for human beings over other organisms. In fact, if we take the account of human evolution developed by modern biologists seriously, modern humans came perilously close to extinction about 70,000 years ago. Were it not for accidental mutations which gave modern Homo sapiens an adaptive advantage over their competitors, it may well have been the modern humans who went extinct rather than the Neanderthals. Thus evolution does seem to undermine the special role that Christianity attributes to human beings in the grand scheme of things.

Surprisingly, there is no hint of any need or desire on Ayala's part to insert the guiding hand of God anywhere in the evolutionary process. For example, while commenting on what distinguishes human beings from other animals, Ayala writes: "It was the appearance of culture as a superorganic form of adaptation that made humankind the most successful species" (39). Later, he writes: "[B]iological adaptation depends on the accidental availability of a favorable mutation" [emphasis mine] (39). Since cultural adaptation cannot arise without the requisite biological adaptation which makes it possible and the biological aspect is determined by natural selection interacting with random mutations, Ayala presents an account of human evolution devoid of any notion of purpose or design which one would expect from a theistic evolutionist.

Ayala also presents a discussion of evolution and the development of ethical systems where he emphasizes that ethical systems are primarily cultural products rather than genetically-innate behavioral rules that have been selected for by evolution. His discussion of ethics is centered around why human beings develop ethical systems but it does not imply the objectivity of any of our ethical systems. In fact, if ethical systems developed in a way analogous to the way languages developed, as Ayala maintains (p. 42), then picking any ethical norm over any other would be just as arbitrary as picking English over French. It is surprising that none of the authors attempt to present a brief defense of moral realism given its importance in Christian theology and the implication of moral skepticism in Ayala's account of the development of ethical systems.

The Evidence From Neuroscience

As one would expect from its title--"Brain, Mind, and Behavior"--Chapter 4 is the most important chapter in the entire book. It begins with a brief historical account of the development of neuroscience to the present day and then illustrates the overwhelming evidence for the dependence of consciousness on the brain by considering localization studies of brain functions, split-brain surgery and hemispheric specialization, various mental deficiencies tied to brain lesions or brain damage, and the effects of brain damage on personality traits and social behavior. Malcolm Jeeves' historical overview of the development of neuroscience ends with a brief consideration of a very famous and dramatic example of mind-brain dependence:

In 1848, a 25-year old foreman, Phineas Gage ... accidentally prematurely exploded a charge which sent a tamping iron through Gage's left cheek, piercing his skull, traversing the front of his brain and exiting at high speed from the top of his head.... His employers described how, before the accident he was efficient and capable, but afterward his personality had clearly undergone a dramatic change. Not only was he feckless and irresponsible, his likes and dislikes, his aspirations, his ethics and morals, were altered. Such findings suggested that ... there may be systems in the human brain, which, if damaged, may alter the personal and social dimensions of normal life (77-78).

In Chapter 6, "Nonreductive Physicalism: Philosophical Issues," Nancey Murphy conceives of physicalism [4]--the position that only physical matter is needed to account for everything encountered in nature--as the "research program" of the neurosciences. For neuroscience, physicalism entails that mental phenomena can be accounted for in terms of brain function. In Imre Lakatos' philosophy of science, a research program is a model which explains known phenomena and (hopefully) predicts the occurrence of novel phenomena. Research programs which generate novel predictions are progressive programs, whereas those which fail to generate novel predictions are considered degenerating[5]. The ability of a program to generate predictions which are later confirmed is an important mark of scientific progress. Murphy writes: "Insofar as researchers ... make progress in explaining 'mental' phenomena, the program as a whole is making empirical progress and its core thesis [physicalism] is thereby corroborated" (140). Murphy continues: "I find brain localization studies to be some of the most impressive pieces of evidence for the physicalist program. Besides simply locating and modeling mental processes as previously understood, these studies sometimes improve our understanding of the mental processes themselves" (140). The enormous success of physicalism as a research program and the complete absence of a rival research program in psychology based on dualism illustrates the level of corroboration that physicalism has received from neuroscience. There is simply no ongoing research correlating mental states to the states of an immaterial spiritual substance. That this is so is no accident; rather, it is indicative that dualism is a degenerative research program--a scientific dead end as useless today as an Earth-centered model of the solar system.

The ability to localize mental traits to specific areas of the brain provides strong evidence that mental phenomena are generated by the brain itself, rather than by an immaterial soul which merely uses the brain to control the body. Nevertheless, Murphy concedes that such evidence does not constitute proof that dualism is false because mental traits could merely be correlated with certain areas of the brain. Why they would be so correlated must be a great mystery to dualists who think that the mind can exist almost completely intact in the absence of a brain, as if thinking, remembering, and perceiving would be unaffected by the disintegration of the brain and sense organs. Furthermore, certain types of well-established phenomena, such as the creation of two separate streams of consciousness operating simultaneously in one body in split-brain patients (who have had the corpus callosum connecting the left and right hemispheres of the brain severed), cannot be accounted for on dualism[6]. If the mind was an indivisible immaterial substance that could exist independently of the brain then we should not be able to create two minds simply by severing the corpus collosum. Nor should the mind be directly affected by any tampering with the brain. If Cartesian dualism were true the only affect that brain damage could have would be to incapacitate the ability of the mind (or soul) to control the body, but the mind itself would remain intact. We have an enormous amount of evidence that this is false--changes in the brain result in changes in mental states themselves. The specific evidence from neuroscience, as well as the general success of physicalism and the corresponding failure of dualism as research programs, provides sufficiently strong evidence--even if not irrefutable proof--to make physicalism by far the best explanation of the evidence at hand.

Nonreductive Physicalism

In contrast to the mind-body dualism inherent in traditional Christian theology, the authors of Whatever Happened to the Soul? vie for a position known as nonreductive physicalism. According to nonreductive physicalism, a person is a physical organism that possesses higher-level mental traits which emerge from, but are not reducible to, complex lower-level physical processes in the brain. This position is characterized as nonreductive physicalism because the physical organism, it is argued, cannot be completely explained in scientific terms. In the first chapter Nancey Murphy succinctly explains what nonreductive physicalism entails for the mind-body problem: "[T]here are no 'mental' events that are without a physical realization in the brain, yet neurophysiological analysis will never give an adequate account of those events" (26). In Chapter 5, "Cognitive Contributions to Soul," Warren Brown argues along similar lines that mental states are emergent properties of the brain which arise when the functional organization of the brain reaches a certain level of complexity. On Brown's account, mental states depend on brain states (i.e., cannot exist without them) but cannot be explained in terms of (that is, reduced to) the physical properties of the brain. Nonreductive physicalism is also called property dualism because it contends that there is only one sort of substance in the natural world--physical matter--but that substance can have both physical and (irreducibly nonphysical) mental properties.

Nonreductive physicalism has become the dominant position in the contemporary philosophy of mind. The most poignant reason for adopting nonreductive physicalism is the subjective character of our mental states. Reductive physicalism requires us to say that qualia--the experiential "feels" of mental states, such as the painfulness of a pain or the "redness" of the sight of a red object--are identical to or one and the same as some physical properties of the brain. The problem is that physical properties such as mass are inherently objective or public, whereas mental properties are (or at least appear to be) inherently subjective or accessible only to the person who has them. It is extremely difficult to imagine how an experiential feature like "redness" can be identical to a physical property of neurons like electrical conductivity. Thus there is a strong case that mental properties cannot be identical to any physical properties (such as those of neurons) because mental states are inherently subjective and thus irreducibly nonphysical.

Ironically, none of the contributors to Whatever Happened to the Soul? present the well-known and forceful argument for nonreductive physicalism given above. In fact, the authors do not present any arguments for nonreductive physicalism over the reductive variety. I regard this as a major deficiency given that the central aim of this book is to present a defense of nonreductive physicalism. It is also surprising given that the contributors explicitly state that (1) reductive physicalism is incompatible with their theological beliefs and (2) the evidence from neuroscience is just as compatible with reductive physicalism as it is with nonreductive physicalism. On empirical grounds alone, one could accept either position and yet which option one chooses is the difference between deciding that the contributors' theological beliefs are incoherent and deciding that they are tenable. One would think that the authors would want to supplement their empirical arguments for physicalism in general with philosophical arguments for nonreductive physicalism in particular. The contributors seem content with presenting empirical support for physicalism and then opting for the nonreductive variety simply because it is the weakest version of physicalism compatible with the evidence. While this is an acceptable way of presenting the options, the authors could have provided a much stronger case by taking advantage of several lines of argument for nonreductive physicalism that have been developed in the rich philosophical literature available to them.

While none of the authors present an argument for nonreductive physicalism, Nancey Murphy does argue that one can consistently reject mental reductionism and still be a physicalist. In Chapter 6 Murphy presents her own definition of the relation thought to hold between mental and physical states--supervenience. In the philosophy of mind, to say that a mental state is supervenient on a brain state typically means that a mental state is dependent on and determined by a brain state. A common way of illustrating this is to say that two worlds could not be identical in all physical respects and yet differ in some mental respect[7]. On Murphy's definition of supervenience, a mental state is instantiated by a brain state only because some other specific circumstance obtains which binds the mental state to the brain state. In Murphy's example of supervenience in a different context, the message "I'm home" supervenes on my lights being on only if I've made a prior agreement with you that I'll send the message that I'm home by turning on the lights. This prior agreement is the specific circumstance which binds the message to the lights. Turning on the lights causes the message to be sent to you only because of this specific circumstance. I could make a prior agreement that I'll leave the lights on only when I'm not home, and the same physical state will instantiate a different message: lights on will mean "I'm not home." By changing the circumstance, there is a difference on a higher level even though nothing else on the lower level has changed[8]. This means that the same brain state can instantiate different mental states under different circumstances. The fact that one could use "shades up" instead of "lights on" to convey the same message also shows that the same mental state can be instantiated by different physical systems--e.g., human brains, extraterrestrial brains, or advanced computers--or by different physical states of the same system. Murphy's promising solution suggests that supervenient relations do not reduce to identity relations and thus nonreductive physicalists can consistently claim that mental states are not identical to brain states.

Mental Causation

The characterization of nonreductive physicalism outlined above is a very plausible account of the mind-body relationship. However, so far I have omitted one feature of the authors' version of nonreductive physicalism that is very problematic: top-down causation. Top-down causation (or mental causation) refers to the controversial ability of mental states to cause changes in brain states. Warren Brown claims that emergent properties exhibit top-down causation in Chapter 5 while Nancey Murphey concludes in Chapter 6 that higher-level mental states are not causally determined by lower-level brain states. Brown asserts that mental processes "determine the course of the neurophysiological systems that instantiate them" (102). However, it seems far more likely that neurophysiological systems determine the course of the mental processes they instantiate, not the other way around; this would explain why, for example, brain damage severely handicaps one's cognitive abilities while brain development increases mental competence. In a footnote (#8, p. 102-3) Brown contends that this position does not imply that there is nonbiological interference in brain processes but rather that brain processes are influenced by the pattern of activity of the information being processed. Since information-processing is a brain process, to say that the brain's pattern of activity influences brain processes is redundant--it is as uninformative as saying that the pattern of electrical activity in a circuit influences the circuit's electrical processes.

If all influences on the brain are biological, as Brown maintains, and all biological influences are physical, then it follows that all influences on the brain are physical--that is, there are only physical causes of brain states. Since mental states are irreducibly nonphysical on nonreductive physicalism, mental states cannot be the cause of any brain states. All causes are still on the physical level of description, so there is no real top-down causation. The supervenience of the mental on the physical entails that fixing lower-level physical properties also fixes one's mental properties--but this implies that mental properties make no independent causal contribution to brain processes. In Murphy's example of supervenience, for example, the message "I'm home" is not an independent cause of anything. Turning on the lights combined with the information conveyed by telling you what "lights on" means is sufficient to cause you to recognize the message "I'm home." The supervenient message is not itself a cause distinct from the act of turning on the lights or the act of telling you what "lights on" means; rather, it emerges from the combination of the two. Thus the notion of emergent or supervenient causation seems to be incoherent.

In order for the mental properties of the brain to influence the brain's physical properties there would have to be nonphysical interference in brain processes causing the brain to function differently than it would in the absence of such interference. But there cannot be such interference if, as most physicalists maintain, the physical world is a closed system where every caused physical event has a physical cause[9]. Moreover, such nonphysical interference in the workings of the brain is highly unlikely because mental causation would constantly be at work whenever we made a decision to act in any way and this nonphysical interference would be very noticable to neuroscientists studying active brain states. That there is no good evidence for such prevalent interference strongly suggests that only physical causes are operative in the brain. Given the causal closure of the physical and the nature of supervenience, a plausible form of nonreductive physicalism would therefore insist that mental properties are simply nonphysical byproducts of physical brain states. These mental byproducts would be epiphenomenal in the sense that they would have no causal power of their own. This conclusion may be at odds with the common belief that we (our mental selves) control our actions, but there are good reasons for thinking that this belief is false.

Free Will

Murphy and Brown want to have their cake and eat it to: they accept the overwhelming evidence from neuroscience that mental states depend on brain states and yet deny that brain states determine the mental states that they instantiate. I suspect that they do this because they think it leaves room for a robust kind of free will where agents can act as independent causes of the brain states which in turn cause our actions. This kind of free will seems necessary if one accepts Christian tenets about morality, justice, and salvation. The problem is that our mental states are determined by the brain's physical properties. Because we cannot choose the physical properties of our brains we cannot really choose our own mental states[10] or our actions. It is an interesting fact that this point is uncontroversial when we are talking about a patient suffering from psychosis due to a chemical imbalance in the brain but resisted when we are talking about people with normally functioning brains. What differentiates the psychotic from the mentally-healthy individual is the difference in the physical properties of their brains. The way a mentally-healthy person reasons about situations and decides what courses of action to take are just as determined by his normally-functioning brain as the psychotic's reasoning and decision-making are determined by his malfunctioning brain. This raises some interesting questions about moral responsibility. If a psychotic becomes a serial killer due to a chemical imbalance in his brain, does this exempt him from responsibility for his actions? If so, where do we draw the line for when brain states exempt someone from moral responsibility since all of our actions are ultimately determined by our brain states? Does this exempt all of us from moral responsibility? Unfortunately, none of the contributors address such questions.

Murphy's brief treatment of free will in Chapter 6 is disappointing--she presents no defense of the claim that "we could have done otherwise" than the behavior determined by our brain states. Malcolm Jeeves' thoughtful discussion of free will in Chapter 4, however, is much more promising. Jeeves wisely dismisses dubious arguments that quantum indeterminacy leaves room for robust free will. He points out that quantum effects are quite negligible on the level of neurons, that overall brain function is based on large networks of neurons and thus the unpredictable behavior of a single neuron would make little difference in the brain as a whole, and that the random fluctuations associated with quantum indeterminacy are minute compared to thermodynamic fluctuations or fluctuations in the blood supply to the brain. This latter point is especially poignant because even if quantum fluctuations did occur at the level of neurons their effects would be "drowned out" by the much larger deterministic sorts of bodily fluctuations. Jeeves wraps up his discussion of quantum indeterminacy by pointing out that, rather than finding a place for free will, indeterminacy could be used to excuse a person of responsibility for his actions.

While Jeeves only alludes to this point, one can easily see why quantum indeterminacy provides no special place for free will. Determinism is the position that all events--including human actions--are determined by the causes that preceded them. Indeterminism holds that some events are not determined by prior causes but rather occur randomly and unpredictably with no causes at all. If any of our actions occur randomly, without cause, then those actions are not under our control. If we set up a machine to "decide" whether or not to shoot someone based on the results of a random number generator (odds meaning shoot, evens meaning do not shoot) we would not say that the machine "freely chose" its action or was responsible for it. For this reason we cannot use quantum indeterminacy to provide free will or assign responsibility for human actions. The emerging picture strongly implies that we cannot choose otherwise than we do whether or not determinism is true. By all indications, a robust, counter-causal sort of free will is an illusion: Either human actions are completely determined by prior causes or they occasionally occur randomly for no reason at all.

It is important to realize that this conclusion follows even if we assume that physicalism is false. We do not have to assume that the causes of our actions are physical causes in order for determinism to be true (and thus for robust free will to be an illusion). If interactionist dualism were true and (nonphysical) mental events caused other mental events and physical events, we would still have cognitive determinism: Every mental event would have prior causes and thus be determined by those causes. We choose certain courses of action over others for reasons (biologically-determined reasons on physicalism): we may perceive one course of action to be the best way for us to achieve our ends and more immediate concerns like fending off starvation may compel us to choose one way rather than another. Even if mentality plays a causal role in the physical chain of events which includes our actions, our actions are still determined precisely because something causes them to occur. So again, our actions are either completely determined by prior causes or they just occur, uncaused, for no reason at all.

According to soft determinism, we could have done otherwise than we did if we had chosen to do otherwise and were unrestrained by external forces in acting on those choices. This very plausible position is a compromise: it renders free will compatible with determinism but does so by weakening the meaning of "free will" (compared to its traditional meaning)[11]. The real question, then, is whether we could have chosen to act otherwise than we did choose for any of our past actions. It seems that an affirmative answer is required to make sense of essential Christian doctrines where people are held morally responsible for their actions[12] and where one's actions determine the state of one's existence after death. However, it seems unlikely that we can choose to make different choices than we do in fact make. Our decision to act is based on how we reason about the best way to fulfill our desires, the desires that we have, and which of our conflicting desires happens to be strongest. How we reason is based on our limited experience, so we cannot be faulted for miscalculating or being oblivious to certain consequences of an action. Nor can we be faulted for having the desires that we have since we do not choose them. We are compelled to make the choices that we do by circumstances--the circumstances that confront us immediately, how we think about how to deal with them, and the desires that we have. Because we do not have control over any of the factors which determine the actions that we take, we do not have control over any of our actions.

Despite these very persuasive reasons for denying that a robust, counter-causal sort of free will exists, Jeeves claims that to believe "that the common human experience of freedom to choose is an illusion is blatantly unscientific special pleading. It amounts to sweeping universally shared and agreed empirical data under the carpet" (95). While such an ardent defense of robust free will is understandable given its importance in Christian theology, this characterization of the issues is not quite accurate. What is at stake here is not universally-shared data, but universally-held intuitions about the choices we make, intuitions which could be as wrong as those which would lead us to believe that it is impossible to bend space or slow down time. While Jeeves does reiterate an argument for free will made by Donald MacKay based on the unpredictability of a subject's behavior once a prediction about the subject's behavior is made known to the subject, it is far from clear that MacKay's hypothetical scenario shows that one's choices are not entirely causally determined.

Jeeves wraps up his subsection on free will by endorsing a form of indeterminism: "It is at the level of our conscious experience that there is indeterminacy, irrespective of any indeterminacy at the level of the brain" (97). To his credit, Jeeves recognizes that the physical indeterminism exhibited in quantum mechanics has nothing to do with the notion of free will. However, he fails to recognize that indeterminism on the cognitive level fares no better. As explained earlier, if our actions are not determined by psychological processes such as how we reason or what desires we have[13], then our actions occur randomly and are not in our control. If there was indeterminism on the cognitive level then our mental states could not act as causes of our behavior because our actions would have no causes.

Physicalism and Religious Experience

In a subsection of Chapter 6 titled "A Nonreductive-Physicalist Account of Religious Experience," Nancey Murphy argues that religious experiences can still be genuine experiences of a transcendental reality even if human beings do not possess an immaterial soul. In order to do this, Murphy needs to show that physicalism can account for mystical experiences in terms of brain processes without portraying such experiences as nothing but the effects of brain processes. To show that religious or mystical experiences are more than brain processes (in a way that dreams are not) one needs to show that such experiences are actually caused by God. Ironically, Murphy explicitly realizes that she needs such an account of divine action but never even outlines one. The fact that Murphy made no attempt to give an account of divine action was disappointing given how (self-admittedly) important it is to her project. Everything Murphy said in this subsection is consistent with religious experiences being nothing more than unusual mental phenomena.

Murphy failed to even hint at any good reasons for positing God or other spiritual entities to explain mystical experiences. Furthermore, if such experiences occur in purely physical beings entirely due to brain events, one wonders how God could cause such experiences. There are two problems here: (1) how a nonphysical entity like God could be the cause of any physical events and (2) how we could know that God caused an event. The first problem is illustrated by the difficulty of imagining how a purely physical human organism, lacking an immaterial soul or perceptual faculties beyond those provided by physical sense organs, could "perceive" God or be the recipient of revelatory knowledge from God. By what mechanism does God infuse our brains with knowledge of himself? How could a purely immaterial or bodiless entity like God, who occupies no physical space and exists outside of time, affect firings between the synaptic pathways in our brains? As for the second problem, without an account of divine action we cannot say which mystical experiences are delusional and which are genuine. Without a nonarbitrary way of deciding this (i.e., without appealing to one's own religious prejudices in order to favor certain mystical experiences over others) we have no good grounds for holding that mystical experiences are anything more than interesting psychological phenomena like dreams or feelings of déjà vu.

Murphy provides no grounds for distinguishing between mystical experiences caused by God and those solely caused by unusual brain states induced by, for example, the physiological effects of fasting or sensory deprivation. There is simply no way to know when we should attribute such experiences to supernatural causes and when we should seek naturalistic explanations. Moreover, the presence of a successful naturalistic explanation of a mystical experience--such as a diagnosis of temporal lobe epilepsy--would not be sufficient to rule out the possibility of divine action since one could claim that God is "working through" this disorder to provide knowledge about himself to the mystic. These considerations indicate that the notion of divine action is so vague and uninformative that we could not have knowledge of divine action even if it occurred. Thus religious experiences do not justify the belief that God is the cause of those experiences anymore than feelings of déjà vu justify the belief that one has lived in a new place before in a past life.

Christianity and Human Nature

Chapters 7 and 8 argue that biblical sources do not posit the existence of a separate, immaterial soul which harbors a person's personality and survives bodily death. It is well-known among scholars that early Christians posited a physical resurrection of the body without subscribing to a belief in an immortal soul, despite the stubborn persistence of the doctrine of the immortality of the soul in "pop" Christianity today. The idea of a separable immaterial soul inhabiting the body was first developed by the Greek philosopher Plato and incorporated into Christian theology largely due to the influence of St. Augustine. Augustine wrote just before the fall of Rome and became the last word on many subjects in Christian theology throughout the Middle Ages until the Renaissance, by which time dualism was deeply entrenched in Christian theology despite its Platonic origins. In the first chapter Nancey Murphy points out that a brief survey of the theological literature of the twentieth century shows a diminishing interest in Platonic dualism. Early on, the Platonic account of a person as a soul was supplanted by accounts which insisted that a complete person was a body-soul unity even though the soul could exist temporarily in a disembodied state while awaiting a physical resurrection of the body. Today many theologians accept a completely physicalistic account where a person is in essence a physical body. In fact, a brief survey of the content of contemporary philosophy of religion journals shows an avid interest among Christian philosophers in defending the idea of bodily resurrection without assuming the existence of a soul in order to guarantee that the "transformed" resurrected body is the same person as the person who had an "organic" body before death.

While belief in a separable immaterial soul may not be essential to Christianity, the belief is so widespread that most people who believe in life after death, regardless of their religious affiliation, posit the existence of an immaterial soul which functions as the vehicle by which human beings can attain immortality. Although many academic Christian philosophers now eschew Platonic dualism, its influence among Christians--both Protestant and Catholic--is still quite strong. I suspect that many Christians would feel quite uneasy about accepting the resurrection of the body if immediately after death one ceased to exist. One probable reason many Christians still cling to the idea of a soul is that they do not want to stake their everlasting life on something as tenuous as God's will. After all, if God exists he seems rather indifferent to the fate of sentient beings on this side of life since he fails to intervene to prevent excessive amounts of unnecessary and often horrific suffering[14] so prevalent that even the most sheltered individual cannot fail to notice it. But if human beings are in essence indestructible immaterial souls then our immortality is guaranteed by our nature, even if it turns out that God does not exist or does not plan to resurrect us. Furthermore, immortality of the soul--despite all the evidence against it--is still far more plausible on empirical grounds than the belief that our physical bodies will ultimately be reconstituted despite decay, cremation, and reabsorption into other organisms.

Conclusion

The authors of this volume attempt to show that the central tenets of the Christian faith (which includes belief in the resurrection of the body) are compatible with scientific findings. However, even if they have succeeded in doing so they have made little progress since a lack of conflict between a belief system (such as astrology) and science does not establish the validity of the belief system in question. For many contemporary philosophers and scientists, it is a sufficient case against Christianity that we have no good reasons (e.g., no compelling empirical evidence) to accept Christian doctrines in the first place. Atheism is justified by the simple fact that invoking the God hypothesis is unnecessary for explaining the world around us.

Although physicalism does not logically entail atheism (since physicalism applies to nature and God exists outside of nature), it renders accounts of the world which appeal to supernatural forces obsolete because nothing beyond nature is required to explain the natural world if physicalism is true. If human beings evolved from other organisms and are different from them only in degree--as evolution implies--and physiological psychology reveals that we have no substantial soul that makes us different in kind from other animals, then we seem to be nothing more than highly complex animals. If this is so human beings probably have no special place in the universe and thus no personal relationship with its creator.

Furthermore, physicalism provides a persuasive (though by no means conclusive) inductive argument against the existence of God. The contributors' conclusion that "there are no 'mental' events that are without a physical realization in the brain" (26) implies that mental states cannot exist in the absence of physical arrangements of matter. If all known cases of mental activity require a physical basis then there are probably no disembodied minds. But God is a disembodied mind. Therefore, God probably does not exist. As Jeff Lowder puts it in The Empirical Case for Metaphysical Naturalism, "if nothing mental happens without something physical happening, that is evidence against both the existence of souls and the existence of any being who is supposed to have a disembodied mind, including God." This conclusion can be resisted by maintaining that it only follows for minds that exist within nature, whereas God exists outside of space and time. However, since the only minds that we know exist are physically embodied, it is much more plausible that disembodied minds simply do not exist.

Endnotes

[1] One of the main philosophical objections to dualism has been the difficulty in conceiving how a nonphysical mind could interact with or inhabit a body since--by definition--it does not occupy space. Although the main reason for the decline of dualism has been the overwhelming neuroscientific evidence against it, the theory of relativity also provides a strong argument against dualism. According to dualism, the mind exists in time (since mental states change) but not in space (since it is nonphysical). According to relativity theory, however, space and time are just different aspects of a single, unified space-time. If we take relativity theory seriously--and there are good empirical reasons for doing so--any entity which exists in time must also exist in space and vice versa. Alternative accounts which posit the existence of a physical astral body occupying space escape this argument but are highly implausible since such an entity should be detectable yet has never been detected.

[2] As Paul Murray has pointed out, animal studies have actually shown that the "transmission of information by a teaching-learning process" is not a uniquely human trait. Whale songs (which vary between pods), predatory hunting strategies, and cases where a species' young learn which foods to eat by example all exhibit cultural evolution in nonhuman animals. Donald Morgan has also noted experiments where chimpanzees have learned sign language from their parents (who in turn had been taught by humans) and where parrots have learned to count, identify the colors and shapes of various objects, and use a small-vocabulary language appropriately. These findings undermine Ayala's contention that there is a sharp division between biology and culture which signals a significant difference between human beings and other animals.

[3] As implied by the Christian doctrine that human beings are made in the image of God whereas other animals are not.

[4] Also called materialism.

[5] For an interesting application of Lakatos' criteria for measuring scientific progress, see Susan Blackmore's "Unrepeatability: Parapsychology's Only Finding" in The Repeatability Problem in Parapsychology edited by B. Shapin and L. Coly (Parapsychology Foundation, 1985).

[6] See The Scientific Case Against Immortality for a survey of the neuroscientific evidence against dualism.

[7] This is called global supervenience.

[8] One might think that this implies that there could be a mental difference between two worlds that are identical in all physical respects, which is a negation of global supervenience. However, the same brain state can instantiate different mental states only when the physical circumstances change, so the two worlds would not be identical in all physical respects. In this example, nothing about the physical state of the lights has changed, but my prior communication to you (a physical act) about what "lights on" means has. The overall implication is that mental states cannot be explained in terms of the physical properties of brain states just as the message that I'm home cannot be explained in terms of the physical properties of the circuitry and lights.

[9] This assumption is often called the causal closure of the physical or the causal completeness of physics. The qualifier "caused" is included here because some quantum events--such as radioactive decay and the creation of virtual particle-antiparticle pairs in a vacuum--have no causes at all. Because significant causal indeterminism is limited to the subatomic realm, every physical event on the level of neurons is still completely determined by its previous causes.

[10] We can control our mental states by changing the physical properties of our brains, as in the case of schizophrenics who lead normal lives by taking medication. I mean that we cannot simply decide or will what mental state we are in.

[11] One problem with soft determinism is the question of whether it simply collapses into hard determinism (the position that free will and determinism are incompatible and determinism is true) since both sorts of determinists deny the existence of free will in the traditional, counter-causal sense. It is unlikely, for example, that a hard determinist would deny a claim as innocuous as "I could have done otherwise if I had so chosen"--hence the possibility that soft determinism and hard determinism are really the same position, the two differing only in their definition of free will. There is another sense, however, in which the two positions differ: hard determinists tend to conclude that we are not morally responsible for our actions because determinism is true, whereas soft determinists tend to argue that we cannot be held morally responsible for our actions unless determinism is true. The hard determinist conclusion is supported by the fact that we do not have control over the causes of our actions. On the other hand, the soft determinist position is supported by the fact that we do not control our actions if they are uncaused random events and thus moral responsibility can only be assigned to persons in virtue of their causal involvement in producing an action.

[12] "Actions" referring not only to one's behavior toward others but also to one's decisions--such as one's decision to accept or reject Jesus as one's personal savior--which may also be necessary on a Christian account for one to achieve salvation and a desirable existence in an afterlife.

[13] If we assume that mental properties have no causal power, our actions would be determined by the brain processes which generate our psychological states. Our actions would not be determined by our mental states themselves since our mental states never enter the physical causal chain where our actions occur.

[14] Unnecessary especially to animals and mentally-challenged individuals incapable of receiving the positive character-building benefits that supposedly balance or outweigh the negative effects of suffering.