As a longtime fan of Stephen Jay Gould, I could hardly resist attending his lecture on immortality at the Harvard Divinity School. (The lecture is a semi-annual affair, in which luminaries from various disciplines are invited to address the ever-popular topic of our prospects after death. Previous speakers have included William James and Josiah Royce.) What would the eminent geologist and neo-Darwinian venture to say on a topic so far outside his ordinarily naturalistic concerns? It seemed that obvious at the outset that two time-honored approaches were available to him: one, critique the notion of immortality as wishful thinking, not to be countenanced by those of a scientific frame of mind; the other, to declare that science and religion are not in conflict, since they don't share any aims, methods, or domains of discourse to provide the basis for disagreement. In his witty and engaging talk Gould took the second approach, arguing that since religious claims–such as the existence of an immortal soul–are not testable hypotheses, they cannot be challenged by science.

It seemed logical, Gould admitted, that having taken this position, he would have nothing further to offer on the topic of immortality. But, not wanting to disappoint us, he managed to say a good deal over the next hour and a half which applied his expertise on evolution to a pair of related questions. First, was the concept of immortality directly selected for by evolutionary mechanisms, that is, did it have survival value leading to the reproductive success of those individuals who may have "carried" it? Second, given that some theological schemes of trans-personal immortality, like that of Teilhard de Chardin, are based in the notion of progressive evolution towards some collective and eternal "supermind", is there any indication that evolution has teleological characteristics?

Because I want to return to the issue of what might be called the "commensurability" of science and religion, I will give just the briefest account of Gould's persuasive answers to these questions. (His responses are recurring themes in many of his articles and books, for those who want to pursue them further.) On the first, Gould argued that the concept of immortality originated well after the appearance of our species, and so was not directly selected for by biological evolutionary mechanisms. The physical basis of our ability to form such abstract concepts–the brain–was indeed selected, but for its advantages in dealing with far more concrete problems than the existence of the soul. The marvelous fact is that the neural architecture conferred on us by the exigencies of natural selection allows, as an "unintended" and "unnecessary" spin off, the ability to elaborate all the intricacies of philosophy and theology, including that most intriguing issue, our fate after death.

As for teleology in evolution, Gould showed that there is no evidence at all that later creatures are necessarily more complex, better adapted, or in any sense "improvements" upon earlier creatures. Given that many significant shifts in organic design were precipitated by geological events and chance mutations which might well have turned out differently, there is no teleological necessity attached to our being the species we are now, nor is it inevitable that the complexification of adaptive strategies will continue. As Gould put it, if you rewound the tape of history and played it again, we would most likely not be here, and other species, with very different features, would be exploiting very different ecological niches. If there is no evidence of progress in evolution, then mystics such as Teilhard cannot legitimately avail themselves of scientific backing when they try to extend accepted evolutionary theory into a teleological scheme which guarantees eternal life.

At the end of his talk Gould answered some questions from the audience, a few of which readdressed the possibility of conflict between religion and science. But he adamantly stuck to his initial position: science deals in empirical matters, religion does not, thus they cannot be in conflict. Pressed at one point on the existence of an immortal soul, Gould admitted that he had his own private suspicions on the matter, but that these suspicions were not grounded in his scientific views. The further question then arises (and unfortunately did not get asked) : On what grounds do his suspicions rest? If one does not base a critique of religious claims on science, then according to what criteria are they to be evaluated?

Gould's contention that science and religion represent separate domains, that they are basically incommensurable, seems to leave us at a loss. Must we enter the world of theology in order to assess a religious belief in the existence of the soul, or rely simply on our intuitive, off the cuff responses to the issue? If a claim that the soul exists is indeed not empirically based, but simply a profession of personal faith or institutional dogma, does this require us to leave such a claim unchallenged by science? I think Gould was being too meek (or perhaps too diplomatic) in his refusal to attack, on scientific grounds, the religious belief in an immortal soul. My reason for this is simple: religion and science inhabit the same, single world about which they assert mutually incompatible propositions. Since their respective claims cannot both be true, they are in conflict, and insofar as we sympathize with the scientific perspective we shouldn't refrain from declaring its position on these issues. But, I will argue as my main thesis, there may be no third perspective independent of religion or science which can decide where our sympathies should lie. The way of faith and the way of evidence meet and do battle on a field unrefereed by any higher criteria which either side can appeal to. Thus our choice between them may be more a function of cultural indoctrination and educational emphasis rather than the outcome of reasoned argument. Nevertheless, at the end of this essay I will try to balance this rather skeptical conclusion by showing that there may be good pragmatic reasons to favor one over the other.

First, it is important to see that science and religion do share a domain of discourse in that their opposing claims refer to the same world. If the theologian should argue against this assertion and say that the soul exists in a utterly separate realm, then he would have to admit the absurdity of any religiously based injunctions concerning our earthly lives. To have significance for us, the spiritual world must intersect at some point with the material world, in which case, at the point of intersection they are part of the same world. The monistic assumption that all phenomena are interconnected elements of a single universe is, of course, the working hypothesis of science and a fundamental tenet of naturalism. But even the most devout spiritualists must accede to some overlap in the material and spiritual domains, otherwise they risk defining their practices as irrelevant.

Given this basic aspect of commensurability, let us next assume that Gould is correct in asserting that the religious claim of the soul's existence is an untestable, non-evidential matter of faith. Such faith is based, perhaps, on personal revelation and introspection, emotional necessity, Biblical inerrancy, or authoritarian tradition. Thus when we ask those who believe in the soul to give their reasons they answer "I have no scientifically acceptable evidence; I just believe it because the Bible tells me so, because it's obvious we have them, because without them life would be meaningless and we'd just be robots", etc... Note that although they make no appeal to evidence (by hypothesis) they do have a belief about this world, namely that it contains souls. The soul, although it may be an ethereal and invisible essence, nevertheless exists here and now.

This is an ontological claim about the world we all live in and so it inevitably affects us, whether it be very slightly as we idly peruse a Jehovah's Witness pamphlet, or more dramatically if as Catholics we anticipate eternal damnation for our sins. Even if the belief in the soul is ordinarily independent of material or experimental evidence, the ramifications of such a belief are quite real, and not inconsiderable. This means that the debate over its existence need not be empty philosophizing, but represents a conflict between fundamentally different world views with correspondingly different material and social consequences. Examples of the impact of religion on public policy are not difficult to find: attempts to restrict abortion and birth control, to limit the right to refuse medical treatment, to prevent the teaching of evolution, and to curtail the range of artistic and sexual expression are just a few. The recent threats of excommunication to enforce compliance with orthodox Catholic views are obvious efforts to gain political leverage by taking advantage of the belief in a soul. Given the very real, and not always beneficial, effect of some spiritual beliefs in everyday life, science should not abdicate its role in countering religious claims simply because they are not empirically testable. To do so would leave the ideological influence of religion unchallenged by one of its strongest competitors. Since there is only one world to know, live in, and preserve, science must try to make the case for a naturalistic view of this world, even if that view denies some cherished beliefs.

The scientist, in making such a case, and faced with a simple tenet of faith that the soul exists, cannot argue directly against the "true believer". Such a believer rejects the necessity for evidence and so is not moved by the demand for it. But the scientist can, and should–for the benefit of persuading those still susceptible to argument–make the counterclaim that the soul does not exist, on the basis that there is no evidence to warrant the assertion that it does.

Although there may be no hope of convincing an avowed "non-empiricist", there is obviously a fundamental dispute between religion and science about what really exists. This dispute, it will be seen, stems partially from their respective stances about what constitutes legitimate grounds for belief. The "credo" of religion permits ontologies untethered to systematic observation, while the methods of science require that ontological claims be consistent with most of the intersubjective evidence. To argue against the soul, then, is really to argue (among other things) for a certain framework of justification for belief. The conflict between science and religion about the existence of the soul is real enough since they can't both be right, and in this sense they are commensurable. But a substantive debate over what exists cannot be joined until there is agreement on the prior issue of what counts as legitimate grounds for belief. It is here, I think, where the contrast between science and religion is most stark, and where it is most difficult to discover something in common that could provide the basis for argument.

One approach might be to recognize that beliefs, whether supported by evidence or faith, and quite apart from their ultimate truth, serve a pragmatic function in dealing with human needs. Could we not then compare how well faith-based beliefs and scientific theories each work to address these needs, and see if one proves superior? If we could show that faith fails where science succeeds then this might induce the true believer to question the value of non-evidential claims and their associated ontologies.

The difficulty with this is that the needs traditionally addressed in the realm of faith are not usually conceded to be needs which science could fulfill. Satisfactory solutions to "ultimate" questions such as the purpose and meaning of life, the fate of the individual after death, and the basis for ethical conduct are normally considered the province of religious tradition. Science, for most of us, does not provide answers to such questions, nor can it console us in times of suffering the way religion can: by positing a next world in which our pain will be redeemed, all our questions answered. Science can tell us the how, but not the why; it can offer means, but not ends; it can solve any number of practical problems but is largely silent about the issues that lie at the heart of the human condition. Given that religion and science seem to address very different needs it is difficult to compare them on the basis of the pragmatic value of their respective beliefs. Science cannot attack the non-empirical faith in the soul on grounds that it doesn't "work" because, for many people, it works quite well in solving some rather important problems.

If the belief in the soul cannot be simply dismissed as useless conceptual baggage then how should I, the good empiricist, go about justifying my skepticism regarding it? Can I resort to anything beyond my commitment to science? On what grounds could I say to the true believer, "You know, you really ought to consider the lack of scientific evidence for your position"?

Before tackling this question we must raise the possibility that my skepticism about the soul is not scientific but simply "agnostic": perhaps I simply don't believe, one way or the other, in the existence or non-existence of the soul. Or perhaps I am a "true believer" but with an opinion which contradicts the spiritualist: I have an unshakable faith, having nothing whatever to do with evidence, that the soul doesn't exist. But if I am naturalistically inclined are these likely responses? Hardly, since they go against the grain of my world view, which takes as primary the evidence of my senses, the importance of intersubjective agreement, and the global unity of phenomena. The scientific and naturalistic impulse is to connect the most disparate realms of existence into a coherent whole, thus it is highly improbable that I would set aside questions about the soul either as undecidable (despite the lack of any evidence that it exists) or as decidable by radically different criteria. Thus my skepticism will most likely be scientific skepticism, whatever the question. For this reason I doubt that, despite his disclaimer, Gould's doubts about the soul's existence stemmed from any other source than his scientific habit of mind.

Of course, some scientists do compartmentalize their stances on central metaphysical issues, taking some things on faith, some on evidence. An interesting question is how they decide which beliefs are granted immunity from the evidential requirement. What is special about traditional religious concerns which tends to exempt them, even in the opinion of some scientists, from empirical investigation? The obvious answer seems to be that faith-based responses to certain questions are simply more emotionally satisfying; they give comfort and hope in a way science cannot. This puts the burden on science to show why anyone should bother to adopt a consistent and uncompartmentalized empiricist stance. To return to our example, how are we to justify our scientific skepticism with regard to the soul?

As I said earlier, this is really to ask that we justify the requirement that a belief in the soul should have some backing in evidence. Since the history of successful science is (very roughly) one of observation, hypothesis, prediction, and further observation, the central role of evidence within science itself is well accepted. The requirement of evidence is part of a process which leads to the most simple, unified, and predictive theories. It is the ordering and explaining of evidence–the appearance of the world to us–which is the scientific project par excellence. Theories unite appearances into coherent, lawful, and universal wholes which further appearances will, it is hoped, confirm (tentatively) or disconfirm. Since there is no experimental evidence that the soul exists, and since it cannot play an explanatory or predictive role in any scientific hypothesis, there are no grounds for granting it a place in a theoretical ontology. Its non-existence is strongly presumed among scientists, at least outside of church.

Asking that a belief in the soul be backed by evidence is simply to apply empiricism outside the normal realm of science, to what is usually a question decided by religious tradition or personal introspection. It is to follow the impulse towards cognitive unification into a realm which traditionally has been hotly defended against empirical investigation. What could induce those committed to protecting the spiritual domain from science to reassess their loyalties? Since, as we have seen, the answers given by faith to personal existential and metaphysical questions work well for many, the scientist cannot pitch the demand for evidence strictly on the basis of utility. She can, however, make an appeal to however much of the scientific impulse which her religious opponents possess. It might run as follows: "Do you find a dissonance between your everyday beliefs and your religious convictions, especially in the way these beliefs are justified? Is cognitive consistency and a potentially unified view of all existence important to you? If so, then look to evidence to decide the traditional metaphysical questions, not faith."

Such an appeal assumes that true believers are sometimes rational in the commonsense way that is the starting point of science, that they form some of their beliefs on the basis of objective evidence, collective agreement, and overall coherence. Even the most ardent spiritualists must be responsive to the material world on its own, empirical terms. In matters of faith, however, their beliefs are not similarly grounded, with the result that they use two very different epistemic strategies in justifying beliefs. Like the scientist who "compartmentalizes", the spiritualist might come to recognize and feel discomfort about this feature of his cognitive life, and seek to redress the inconsistency. I suspect that this sort of dissonance has indeed been the spur for many "conversions" from religious to more naturalistic world views.

But, of course, epistemic consistency is not necessarily important to everyone; there is no law, conventional or natural, which requires it. Many people are quite content to deal with earthly matters on grounds of evidence, and spiritual matters on grounds of authority, revelation, positive thinking, and so on, in which case the impasse still confronts us. How do we convince them that they ought to justify central beliefs, such as the existence of the soul, on the same basis as their everyday beliefs about cars, jobs, politicians, unicorns and the tooth fairy?

At this point, I must confess I am pessimistic about discovering a compelling argument which might persuade the committed spiritualist to adopt a wholly naturalistic stance. If appeals to cognitive consistency and unity don't work, and if the belief in an immortal soul has an important function in someone's cognitive economy, then faith may well continue unperturbed. Although I consider commonsense to be the start of scientific empiricism, the argument could be put that it is equally commonsensical to use both evidence and faith at will, depending on what works. Why do we need evidence for all beliefs, when some of them get along just fine without it and are a great comfort to boot? Isn't it rational for us to do what works?

If we define rationality, liberally, as a cognitive enterprise which aids the achievement of a given end, then faith-based beliefs can indeed be considered rational, even though from an empirical standpoint they deal in non-entities. The goals of many, (but certainly not all) religions and New Age philosophies involve the dissemination of doctrines which attempt to satisfy deep needs of existential security, meaning, and identity. The defence of such systems against the demand for evidence requires that their tenets be transmitted by tradition and scriptural authority, and the personal nature of the needs addressed almost guarantees that these tenets will gain confirmation from biased introspection and wishful thinking. But if no better alternative is available then it is difficult to fault the faith-based response to existential questions as irrational. Given the circumstances of many people's lives, it may make good pragmatic sense to reject the demand for evidence and rely on a faith that promises salvation, if not in this world, then in the next.

The rationality of science is in service to very different goals and so consists of correspondingly different cognitive strategies. The grand project, that of constructing a cumulatively more inclusive and coherent picture of reality, has little directly to do with personal security, or with ultimate concerns of identity, death, and the source of good and evil. Of course its specific applications can have much to do with the alleviation of human suffering, but generally it is impersonal, seeking to flesh out and possibly complete, as philosopher Thomas Nagel characterizes it, "the view from nowhere". This austere objectivity demands that the criteria for truth lie outside any single individual's perception, opinion, or experimental report, and that even the most central beliefs of current scientific orthodoxy be held as mutable. The requirement of intersubjective evidence insures that beliefs will be responsive to collective perception and experiment, and this responsiveness in turn means that scientific theories and ontologies may change radically in the light of new findings.

Given the disparity in goals and cognitive strategies, it is no wonder that science and religion, although they exist in and make claims about the same world, have difficulty finding common ground. Each can justify itself by its own lights, by success in its particular projects, but in deciding between them what could serve as a standard? (Must we decide between them at all? Apparently we must, since this choice can determine our stance on many important issues.) If they are to be compared and weighed against one another, it must be as human activities which share some motives, aims, or methods, for there is not, I think, a larger cognitive perspective which could demonstrate that one is the "best" approach to every problem or show, as a matter of principle, where we should apply one and not the other. Philosophy may seem a possible candidate for such a perspective, but philosophy is not itself an agreed upon platform which provides ready-made criteria to judge such issues. Rather, like science, it is a process of open-ended inquiry. Philosophy can ask the question of whether and how to choose evidence or faith, along with their radically different pictures of the world, but it cannot readily answer it.

Our allegiance to religion or science is ordinarily determined not by philosophical inquiry, I suggest, but simply by the fact that each of us grows up in a particular culture, whether it be religious, scientific, or a mixture of the two. Gould, and others like him, will probably decide the question of the soul on empirical grounds because their rigorously cultivated world view, with its high value on cognitive unity, pretty much demands it. Those brought up within a strong religious tradition, or susceptible to comforting systems of beliefs with little or no evidential support, will decide by checking their catechism or following their intuitions. Since science cannot categorically disprove the existence of the soul, but only cite lack of evidence for it, those unimpressed by the demand for evidence will happily take advantage of this apparent failing and postulate whatever they please. Unless the demand for evidence is backed up by appealing to something that true believers already believe in, it will cut no ice with them. But part of the culture of faith is the gut feeling that revelation and authority alone are sufficient grounds for belief, that we need not consider what science has to say. Thus there is no obvious point within science (or philosophy) from which to justify, to the true believer, the epistemic austerity of naturalism.

As someone engaged in the cause of popularizing science and naturalism, I find it difficult to admit that there may be no knock-down argument which might win converts to the consistent application of evidence to central beliefs. To me it seems obvious that truth and observation are necessary partners, at least when considering matters of fact. But for many, there are fundamental "facts" about what exists which have nothing to do with observation, and there is nothing I can say which would convince them otherwise. The prospect looms, therefore, of two cultures, fighting over the same bit of ontological turf, but without enough in common to ever decide the contest. Such a picture has its own sort of melancholy appeal, if one likes perpetual combat.

Retiring from this arena, I will propose a different sort of solution which may yet afford the naturalist some satisfaction. In this essay I have stressed the point that the respective ontologies of science and faith are driven by different strategies of justifying belief, and that these strategies in turn are driven by different pragmatic concerns. But, since we are all human beings, it is likely that we will share many, if not all, of these concerns as we make our way through life. The scientist, when not engaged in the grand project of unifying knowledge (or more likely the lesser project of getting funded for research), faces the same existential questions that religion has staked out as its special domain. And of course we grant the theologian, the devout layperson, and the New Age acolyte at least a modicum of the intellectual curiosity and desire for cognitive consistency exemplified by science.

If scientists face existential dilemmas with the cognitive predispositions typical of their profession, then should we suppose that they are necessarily at a disadvantage compared to those whose ontologies are unrestricted by the requirements of evidence? Put another way, can scientists and (more broadly) naturalists satisfactorily address "ultimate" concerns without resorting to the sort of compartmentalization which makes them Easter Christians and Passover Jews? If so, then perhaps a case can still be made for the global application of the naturalistic stance, on the grounds that it can beat, or at least match, religion at its own game. Perhaps we need not inflate our claims about what exists in the world in order to meet our personal needs for existential security, a stable identity, and a source of basic values. If this be the case, then we can argue against a belief in the soul on the grounds that it is pragmatically unnecessary: Occam's razor in a different context.

I believe that we can successfully address ultimate concerns within an empirically restricted, naturalistic ontology, but space prohibits a complete consideration of this issue here (see Spirituality Without Faith for this). Instead, I will return briefly to the question of the soul, and show with this example how staying true to naturalism might work as well or better than faith as a pragmatic strategy.

Suppose we reject–on grounds of insufficient evidence, predictive failure, and general fuzziness–any belief in a soul or other immutable, personal essence which could survive after death. As naturalists, our penchant for cognitive consistency blocks what philosopher Paul Kurtz calls the "transcendental temptation", so we face death without the reassurance that any trace of what we are will continue. The question then arises: what kind of consolation for this ultimate loss can there be? Is there any sort of security, any deep connection with something more permanent in a world without souls?

The answer is in the straightforward recognition of the fact that in dispensing with the soul, we dispense with the metaphysical culprit that got us into existential trouble in the first place. Without the soul we find that our being organic, evolutionary creations places us firmly within the majestic sweep of natural history. Without it to confuse us into thinking that we are alien wretches thrown into a hostile universe, we can see our limited life spans as the expression of a marvelously intricate combination of physical law and singular contingency, as interlocked pieces of a much larger, self-organizing design. The soul was perhaps "invented" to allay our unavoidable, biologically programmed fear of death, but once invented it forced a split between the natural and the spiritual. It is this split, I think, that is the primary source of our existential insecurity, and it entails all the cognitive dissonance, compartmentalization, and self-deception of having two sorts of beliefs, one sort backed by evidence, another backed by revelation and scriptural authority.

The realization that we don't exist as spiritual essences removes the conceptual and emotional barrier between ourselves and our natural heritage; it shows us our true home, and allows a satisfying, but not trivial, cognitive consistency. My personal extinction is the end of this organically contrived point of view, but not the end of the ongoing project of "point of view-ness" that has arisen spontaneously in the world. The basic fact of awareness–that general capacity which underlies the particularities of my character and memory–is re-expressed in each consciousness which has the privilege and peril of discovering itself awake in a largely unsentient universe. Discarding the notion of a surviving personal essence allows the unproblematic conjoining of the individual and the surround, not in the sense of mystical union, but in the material, concrete sense of a flower in a field. The flower's shoots and blossoms are the biologically transformed elements of the field, and when it dies its elements in turn are incorporated into other life forms. There is no ultimate security for individuals, but without the soul to separate us from nature, we discover our place as temporary configurations in the field of organic and physical existence, and as such we are not just individuals, but part of the continuing pattern.

Such might be the naturalist's consolation in the face of death. But is this better than what faith can offer? If we genuinely believe the whole religious picture of God-soul-eternal peace then it's likely we will find more emotional security than the hard-headed naturalist, since under these beliefs the individual is preserved in some form. But if we find ourselves, as many do, half in one camp and half in the other, the transcendental temptation offered by the soul might be overcome by the allure of cognitive consistency and the sort of identification with natural patterns I outlined above. (Perhaps some would deem such identification yet another way of giving in to the temptation. If so, I admit to being insufficiently hard-headed.) Although we probably cannot beat religion by converting the true believer, we can at least show that the restricted ontology and evidential empiricism that characterize science need not impoverish our response to life's fundamental questions.

Of course I have only dealt here with one such question, so it would be impertinent to claim that I have established a watertight case for a globally naturalistic outlook. But I hope that eventually the gulf between the impersonal project of gathering objective knowledge and the personal desire to discover a fulfilling existential place in the world may be bridged by showing the pragmatic value of a naturalistic view of ourselves. This is not to suggest that in adopting a global naturalism we would go about our lives checking each and every one of our beliefs against the latest scientific developments. Most of the time we live at a level of practical decision-making and ordinary enjoyments, where cosmic questions and fundamental ontologies have little bearing. Nor is it to suggest that quantitative scientific truths are the only truths: the phenomenology and behavior of the individual, as well as the dynamics of groups, may prove irreducible to the hard sciences, at least for any practical purposes. But naturalism can supply a "deep background" for our rational superstructure, underpinning a sure sense of being at home in the universe, and allowing the enthusiastic pursuit of our human projects without the need to deny that we and our works are ephemeral.

It is as a successful and satisfying culture of beliefs - not as an argument from secure and universally agreed upon premises - that naturalism will take hold, competing against traditional, faith-based ideologies as a response to the human condition. This response can involve our most sophisticated social and intellectual resources but need not ignore the personal existential predicament. Showing the power of such a view would still not establish it as the only choice, since there is no a priori standard which rules out faith and its expanded ontologies as illegitimate. Although faith, tradition, authority, and revelation will continue to meet certain needs, for many these needs can be met equally well by hewing to the evidential requirement for central beliefs. There are considerable emotional satisfactions to be had within naturalism, and I would call them spiritual satisfactions were not that characterization too freighted with dualism. No matter - they are no less real for want of a name.

©  Thomas W. Clark