Il dibattito sul disegno (o progetto) intelligente, nella sua forma filosoficamente più sofisticata, chiama in causa una ormai consolidata - anche se non del tutto omogenea - tradizione filosofica, il naturalismo, che esclude qualsiasi valore conoscitivo a spiegazioni che invocano interventi soprannaturali,o divini, all'interno della scienza. Creando uno iato "epistemologico" pressochè incolmabile fra teologia e scienza, il naturalismo - la posizione che vorremmo sostenere e argomentare in questo scenario - sostiene infatti l'assoluta neutralità della ricerca scientifica rispetto alle credenze religiose e alle questioni di fede. Nel caso del darwinismo, il naturalismo è stato recentemente attaccato sul piano politico e ideologico, ci sembra interessante riportare la discussione sul piano filosofico.

In questo saggio ormai "classico" di Alvin Plantinga, pubblicato per la prima volta in Facets of Faith and Science (vol. 1, ed. J. van der Meer, Lanham, MA: University Press of America, 1996, pp. 177-221), l'affermazione della non neutralità religiosa della scienza diviene il punto di partenza per recuperare una concezione del naturalismo scientifico compatibile con le istanze della metafisica e della religione, che Plantinga fa risalire a Pierre Duhem e che costituisce a suo avviso la premessa del dialogo - o dello scontro - tra scienza e fede o, per dirla con Plantinga, tra la Civitas Dei e la Civitas Hominum di agostiniana memoria.
Pubblichiamo qui un estratto del saggio di Plantinga (a cura di Margherita Di Stasio) che contiene le parti più rilevanti per il dibattito in corso su Rescogitans (e che potete comunque leggere anche nella sua versione integrale), con l'intento di aprire una discussione su uno dei nodi teorici a nostro avviso più interessanti di una controversia che tende molto spesso ad assumere toni spiacevolmente dogmatici e ideologici.

Republished whit author's permission from Facets of Faith and Science, vol. 1, ed. J. van der Meer (Lanham, MA: University Press of America, 1996), pp. 177-221.

And I must express our thanks to Professor Plantinga for his usual kindness.(M.D.S)

Methodological Naturalism?

by Alvin Plantinga

Unmatched for sweep and eloquence, St. Augustine's De Civitas Dei is a magnificently powerful expression of a view of human history that has been taken up by a host of later Christians.^[1] According to that view, human history involves a struggle, a contest, a battle between what he calls the Civitas Dei, the City of God, on the one hand, and, on the other, the City of the World or the City of Man. The former is devoted to the worship and service of the Lord; the latter serves quite a different master. Augustine believes that all of human history is be understood in terms of this struggle, and nearly any cultural endeavor of any size or significance is involved in it. Now modern natural science is an enormously important aspect of contemporary intellectual life. There are of course those naysayers who see in it no more than technology, no more than a means of serving such practical ends as fighting disease and building bridges or space vehicles. But surely they are wrong. Science has indeed done these important things, but it has done more: it has also given us powerful insights into ourselves and into the world God has created. Science has transformed our intellectual landscape; it is difficult even to imagine what our intellectual life would be without it. If we follow Augustine, we should therefore expect that science too plays an important role in the contest he describes.

According to an idea widely popular ever since the Enlightenment, however, science (at least when properly pursued) is a cool, reasoned, wholly dispassionate^[2] attempt to figure out the truth about ourselves and our world, entirely independent of ideology, or moral convictions, or religious or theological commitments. Of course this picture has lately developed some cracks. It is very much worth noting, however, that 16 centuries ago Augustine provided the materials for seeing that this common conception can't really be correct. It would be excessively naive to think that contemporary science is religiously and theologically neutral, standing serenely above that Augustinian struggle and wholly irrelevant to it. Perhaps parts of science are like that: the size and shape of the earth and its distance from the sun, the periodic table of elements, the proof of the Pythagorean Theorem--these are all in a sensible sense religiously neutral. But many other areas of science are very different; they are obviously and deeply involved in this clash between opposed world views. There is no neat recipe for telling which parts of science are neutral with respect to this contest and which not, and of course what we have here is a continuum rather than a simple distinction. But here is a rough rule of thumb: the relevance of a bit of science to this contest depends upon how closely that bit is involved in the attempt to come to understand ourselves as human beings. Perhaps there is also another variable: how ''theoretical' the bit in question is, in the sense of being directed at understanding as opposed to control.

It would be of great interest to explore this area further, to try to say precisely what I mean in saying that science isn't religiously neutral, to see in exactly what ways Christianity bears on the understanding and practice of the many relevantly different sciences and parts of science. The first is not the focus of this paper, however; and the second question (of course) requires vastly more knowledge of science than I can muster. That is a question not just for philosophers, but for the Christian community of scientists and philosophers working together. What I shall do instead is vastly more programmatic. First, I shall point to three examples of the religious non-neutrality of scientific claims or hypotheses. I shall then argue that a Christian academic and scientific community ought to pursue science in its own way, starting from and taking for granted what we know as Christians. (This suggestion suffers from the considerable disadvantage of being at present both unpopular and heretical; I shall argue, however, that it also has the considerable advantage of being correct.) Now one objection to this suggestion is enshrined in the dictum that science done properly necessarily involves "methodological naturalism" or (as Basil Willey calls it) "provisional atheism."^[3] This is the idea that science, properly so-called, cannot involve religious belief or commitment. My main aim in this paper is to explore, understand, discuss, and evaluate this claim and the arguments for it. I am painfully aware that what I have to say is tentative and incomplete, no more than a series of suggestions for research programs in Christian philosophy.

I Is Science Religiously Neutral? Three Examples

A. Simon and Altruism

[...]

B. The Grand Evolutionary Myth

Since I have dealt with this example elsewhere (in the essanys referred to in footnote 4) I can be brief here. Consider The Grand Evolutionary Myth (GEM). According to this story, organic life somehow arose from non living matter by way of purely natural means and by virtue of the workings of the fundamental regularities of physics and chemistry. Once life began, all the vast profusion of contemporary flora and fauna arose from those early ancestors by way of common descent. The enormous contemporary variety of life arose, basically, through natural selection operating on such sources of genetic variability as random genetic mutation, genetic drift and the like. I call this story a myth not because I do not believe it (although I do not believe it) but because it plays a certain kind of quasi-religious role in contemporary culture: it is a shared way of understanding ourselves at the deep level of religion, a deep interpretation of ourselves to ourselves, a way of telling us why we are here, where we come from, and where we are going.

Now it is certainly possible--epistemically possible,^[8] anyway,--that GEM is true; it certainly seems that God could have done things in this way. Certain parts of this story, however, are, to say the least, epistemically shaky. For example, we hardly have so much as decent hints as to how life could have arisen from inorganic matter just by way of the regularities known to physics and chemistry.^[9] (Darwin found this question deeply troubling;^[10] at present the problem is enormously more difficult than it was in Darwin's day, now that some of the stunning complexity of even the simplest forms of life has been revealed.^[11]) No doubt God could have done things that way if he had chosen to; but at present it looks as if he didn't choose to.

So suppose we separate off this thesis about the origin of life. Suppose we use the term 'evolution' to denote the much weaker claim that all contemporary forms of life are genealogically related. According to this claim, you and the flowers in your garden share common ancestors, though we may have to go back quite a ways to find them. Many contemporary experts and spokespersons--Francisco Ayala, Richard Dawkins, Stephen Gould, William Provine, and Philip Spieth, for example--unite in declaring that evolution is no mere theory, but established fact. According to them, this story is not just a virtual certainty, but a real certainty.^[12] Now why do they think so? Given the spotty character of the evidence--for example, a fossil record displaying sudden appearance and subsequent stasis and few if any genuine examples of macroevolution, no satisfactory account of a mechanism by which the whole process could have happened, and the like^[13]--these claims of certainty seem at best wildly excessive. The answer can be seen, I think, when we realize that what you properly think about these claims of certainty depends in part on how you think about theism. If you reject theism in favor of naturalism, this evolutionary story is the only game in town, the only visible answer to the question "Where did all this enormous variety of flora and fauna come from? How did it all get here?" Even if the fossil record is at best spotty and at worst disconfirming, this story is the only answer on offer (from a naturalistic perspective) to these questions.

From a theistic or Christian perspective, however, things are much less frantic. The theist knows that God created the heavens and the earth and all that they contain; she knows, therefore, that in one way or another God has created all the vast diversity of contemporary plant and animal life. But of course she isn't thereby committed to any particular way in which God did this. He could have done it by broadly evolutionary means; but on the other hand he could have done it in some totally different way. For example, he could have done it by directly creating certain kinds of creatures--human beings, or bacteria, or for that matter sparrows^[14] and houseflies--as many Christians over the centuries have thought. Alternatively, he could have done it the way Augustine suggests: by implanting seeds, potentialities of various kinds in the world, so that the various kinds of creatures would later arise, although not by way of genealogical interrelatedness. Both of these suggestions are incompatible with the evolutionary story.

A Christian therefore has a certain freedom denied her naturalist counterpart: she can follow the evidence^[15] where it leads. If it seems to suggest that God did something special in creating human beings (in such a way that they are not genealogically related to the rest of creation^[16]) or reptiles or whatever, then there is nothing to prevent her from believing that God did just that. Perhaps the point here can be put like this: the epistemic probability of the whole grand evolutionary story is quite different for the theist and for the naturalist. The probability of this story with respect to the evidence together with the views a theist typically holds, is much lower than its probability with respect to evidence together with the views the naturalist typically holds. So the way in which the theory of evolution is not religiously neutral is not, as with Simon's explanation of Mother Teresa, that it is straightforwardly incompatible with Christian teaching; it is rather that the view in question is much more probable with respect to naturalism and the evidence than it is with respect to theism and that evidence.

There is a connected issue in the same area, but with a different twist. Prominent writers in the scientific community--for example, Dawkins, Futuyma, Gould, Provine, Simpson, and others--unite in declaring that evolutionary biology shows that there is a substantial element of randomness or chance involved in the origin and development of the human species; therefore, human beings (so they claim) have not been designed by God or anyone else. Gould writes: "Before Darwin, we thought that a benevolent God had created us." After Darwin, though, says Gould, we realize that "No intervening spirit watches lovingly over the affairs of nature (though Newton's clock-winding god might have set up the machinery at the beginning of time and then let it run). No vital forces propel evolutionary change. And whatever we think of God, his existence is not manifest in the products of nature." Gould's sentiments are stated more clearly by Futuyma:

By coupling undirected, purposeless variation to the blind, uncaring process of natural selection Darwin made theological or spiritual explanations of the life processes superfluous. Together with Marx's materialistic theory of history and society and Freud's attribution of human behavior to processes over which we have little control, Darwin's theory of evolution was a crucial plank in the platform of mechanism and materialism--of much of science, in short--that has since been the stage of most Western thought.^[17]

Clearer yet, perhaps, is George Gaylord Simpson:

Although many details remain to be worked out, it is already evident that all the objective phenomena of the history of life can be explained by purely naturalistic or, in a proper sense of the sometimes abused word, materialistic factors. They are readily explicable on the basis of differential reproduction in populations (the main factor in the modern conception of natural selection) and of the mainly random interplay of the known processes of heredity. . . . Man is the result of a purposeless and natural process that did not have him in mind.^[18]

The same claim is made by Richard Dawkins:

All appearances to the contrary, the only watchmaker in nature is the blind forces of physics, albeit deployed in a very special way. A true watchmaker has foresight: he designs his cogs and springs, and plans their interconnections, with a future purpose in his mind's eye. Natural selection, the blind, unconscious automatic process which Darwin discovered, and which we now know is the explanation for the existence and apparently purposeful form of all life, has no purpose in mind. It has no mind and no mind's eye. It does not plan for the future. It has no vision, no foresight, no sight at all. If it can be said to play the role of watchmaker in nature, it is the blind watchmaker.^[19]

These writers, therefore, unite in declaring that modern evolutionary thought has shown or given us reason to believe that human beings are, in an important way, merely accidental; there wasn't any plan, any foresight, any mind, any mind's eye involved in their coming into being. But of course no Christian theist could take that seriously for a moment. Human beings have been created, and created in the image of God. No doubt God could have created us via evolutionary processes; if he did it that way, however, then he must have guided, orchestrated, directed the processes by which he brought about his designs.

Now again (as with Simon) we might say that strictly speaking, when these people make such declarations, they are neither speaking as scientists nor doing science. They are instead commenting on science, drawing conclusions from scientific results--conclusions that don't follow from the scientific results themselves, requiring extra and extrascientific (perhaps philosophical) premises. Perhaps this is true, although it has become increasingly difficult to draw a sharp line between science and such other activities as philosophical reflection on science. Whether or not what we have here is science strictly so-called, however, isn't really the important question for my present purposes. Whether or not what we have here is science or only parascience, we have deep involvement with the spiritual struggle Augustine points out; in either case that involvement must be noted and dealt with by the Christian intellectual community, and in particular by the part of the Christian intellectual community involved in the science in question.

C. Cosmic Fine-Tuning

[...]

II Weak Arguments for Methodological Naturalism

Now in view of these examples and many others like them (together with broader Augustinian considerations), the natural thing to think is that (in principle, at any rate) the Christian scholarly community should do science, or parts of science, in its own way and from its own perspective. What the Christian community really needs is a science that takes into account what we know as Christians. Indeed, this seems the rational thing in any event; surely the rational thing is to use all that you know in trying to understand a given phenomenon. But then in coming to a scientific understanding of hostility, or aggression, for example, shouldn't Christian psychologists make use of the notion of sin? In trying to achieve scientific understanding of love in its many and protean manifestations, for example, or play, or music, or humor, or our sense of adventure, shouldn't we also use what we know about human beings being created in the image of God, who is himself the very source of love, beauty and the like? And the same for morality? Consider that enormous, and impressive, and disastrous Bolshevik experiment of the 20th century, perhaps the outstanding feature of the 20th century political landscape: in coming to a scientific understanding of it, shouldn't Christians use all that they know about human beings, including what they know by faith?

True: there could be practical obstacles standing in the way of doing this; but in principle, and abstracting from these practical difficulties (which in any event may be more bark than bite), the right way for the Christian community to attain scientific understanding of, say, the way human beings are and behave, would be to start from what we know about human beings, including what we know by way of faith. Hence the sorts of hypotheses we investigate might very well involve such facts (as the Christian thinks) as that we human beings have been created by God in his image, and have fallen into sin. These 'religious' ideas might take a place in our science by way of explicitly entering various hypotheses. They might also play other roles: for example they might be part of the background information with respect to which we evaluate the various scientific hypotheses and myths that come our way.

I say this is the natural thing to think: oddly enough, however, the denial of this claim is widely taken for granted; as a matter of fact, it has achieved the status of philosophical orthodoxy. Among those who object to this claim are Christian thinkers with impressive credentials. Thus Ernan McMullin:

But, of course, methodological naturalism does not restrict our study of nature; it just lays down which sort of study qualifies as scientific. If someone wants to pursue another approach to nature--and there are many others--the methodological naturalist has no reason to object. Scientists have to proceed in this way; the methodology of natural science gives no purchase on the claim that a particular event or type of event is to be explained by invoking God's creative action directly.

Part of the problem, of course, is to see more clearly what this methodological naturalism is. Precisely what does it come to? Does it involve an embargo only on such claims as that a particular event is to be explained by invoking God's creative action directly, without the employment of 'secondary causes'? Does it also proscribe invoking God's indirect creative action in explaining something scientifically? Does it pertain only to scientific explanations, but not to other scientific assertions and claims? Does it also preclude using claims about God's creative action, or other religious claims as part of the background information with respect to which one tries to assess the probability of a proposed scientific explanation or account? We shall have to look into these matters later. At the moment however, I want to look into a different question: what reason is there for accepting the claim that science does indeed involve such a methodological naturalism, however exactly we construe the latter? I shall examine some proposed reasons for this claim and find them wanting. In part III, I shall then argue that nevertheless a couple of very sensible reasons lie behind at least part of this claim. These reasons, however, do not support the suggestion that science is religiously neutral.

Well then, what underlies the idea that science in some way necessarily involves this principle of methodological naturalism? First, and perhaps most important: this conception of science is an integral and venerable part of the whole conception of faith and reason we have inherited from the Enlightenment. I don't have the space to treat this topic with anything like the fullness it deserves; but the central idea, here, is that science is objective, public, sharable, publicly verifiable, and equally available to anyone, whatever their religious or metaphysical proclivities. We may be Buddhist, Hindu, Protestant, Catholic, Muslim, Jew, Bahai, none of the above: the findings of science hold equally for all of us. This is because proper science, as seen by the Enlightenment, is restricted to the deliverances of reason and sense (perception) which are the same for all people. Religion, on the other hand, is private, subjective, and obviously subject to considerable individual differences. But then if science is indeed public and sharable by all, then of course one can't properly pursue it by starting from some bit of religious belief or dogma.

One root of this way of thinking about science is a consequence of the modern foundationalism stemming from Descartes and perhaps even more importantly, Locke. Modern classical foundationalism has come in for a lot of criticism lately, and I do not propose to add my voice to the howling mob.^[37] And since the classical foundationalism upon which methodological naturalism is based has run aground, I shall instead consider some more local, less grand and cosmic reasons for accepting methodological naturalism.

A. Methodological Naturalism is True By Definition

[...]

B. "Functional Integrity" Requires Methodological Naturalism?

[...]

III Two Stronger Arguments for methodological naturalism

These arguments, therefore, are not very convincing; but there are two quite different, and I think, stronger arguments or lines of reasoning for embracing methodological naturalism in the practice of science. The first of these really deserves a paper all to itself; here, unfortunately, I shall have to give it relatively short shrift.

A. Duhemian Science

We can approach this argument by thinking about some striking passages in Pierre Duhem's The Aim and Structure of Physical Theory.^[54] Duhem was both a serious Catholic and a serious scientist; he was accused (as he thought) by Abel Rey^[55] of allowing his religious and metaphysical views as a Christian to enter his physics in an improper way. Duhem repudiated this suggestion, claiming that his Christianity didn't enter his physics in an improper way, because it didn't enter his physics in any way at all.^[56] Furthermore, he thought the correct or proper way to pursue physical theory was the way in which he had in fact done it; physical theory should be completely independent of religious or metaphysical views or commitments. Why did he think so?

For two reasons. First, he thought religion bore little relevance to physical theory: "Was it not a glaring fact to us, as to any man of good sense, that the object and nature of physical theory are things foreign to religious doctrines and without any contact with them?" (p. 278).

But there is something else, and something perhaps deeper. Although Duhem may have thought that religious doctrines had little to do with physical theory, he didn't at all think the same thing about metaphysical doctrines. In fact he believed that metaphysical doctrines had often entered deeply into physical theory. Many theoretical physicists, as he saw it, took it that the principal aim of physics is to explain observable phenomena. Explanation is a slippery notion and a complex phenomenon; but here at any rate the relevant variety of explanation involves giving an account of the phenomena, the appearances, in terms of the nature or constitution of the underlying material reality. He goes on (pp. 10 - 18) to give a striking illustration, recounting how atomists, Aristotelians, Newtonians, and Cartesians differ in the explanations or accounts they give of the phenomena of magnetism: atomists give the requisite explanation, naturally enough, in terms of atoms; Cartesians in terms of pure extensions; and Aristotelians in terms of matter and form. The differences among these explanations, he says, are metaphysical; they pertain to the ultimate nature or constitution of matter. But of course if the aim is to explain the phenomena in terms of the ultimate nature or constitution of matter, then it is crucially important to get the latter right, to get the right answer to the metaphysical question "What is the nature or constitution of matter?" In this way, he says, physical theory is subordinated to metaphysics: "Therefore, if the aim of physical theories is to explain experimental laws, theoretical physics is not an autonomous science; it is subordinate to metaphysics" (p. 10 (Duhem's emphasis)).

Well, what's the matter with that? The problem, says Duhem, is that if you think of physics in this way, then your estimate of the worth of a physical theory will depend upon the metaphysics you adopt. Physical theory will be dependent upon metaphysics in such a way that someone who doesn't accept the metaphysics involved in a given physical theory can't accept the physical theory either. And the problem with that is that the disagreements that run riot in metaphysics will ingress into physics, so that the latter cannot be an activity we can all work at together, regardless of our metaphysical views:

Now to make physical theories depend on metaphysics is surely not the way to let them enjoy the privilege of universal consent. . . . . If theoretical physics is subordinated to metaphysics, the divisions separating the diverse metaphysical systems will extend into the domain of physics. A physical theory reputed to be satisfactory by the sectarians of one metaphysical school will be rejected by the partisans of another school.

Duhem goes on to quote Christian Huygens, who, as an 'atomist' rejected Newton's idea of action at a distance: "So far as concerns the cause of the tides given by Mr. Newton, I am far from satisfied, nor do I feel happy about any of his other theories built on his principle of attraction, which to me appears absurd."^[57] He also quotes Descartes' comments on a work by Roberval^[58] who put forth a theory of universal gravitation well before Newton:

Nothing is more absurd than the assumption added to the foregoing: the author assumes that a certain property is inherent in each of the parts of the world's matter and that, by the force of this property, the parts are carried toward one another and attract each other. He also assumes that a like property inheres in each part of the earth considered in relation with the other parts of the earth, and that this property does not in any way disturb the preceding one. In order to understand this, we must not only assume that each material particle is animated, and even animated by a large number of diverse souls that do not disturb each other, but also that these souls of material particles are endowed with knowledge of a truly divine sort, so that they may know without any medium what takes place at very great distances and act accordingly.^[59]

The point Duhem makes is that if a physical theorist employs metaphysical assumptions and notions that are not accepted by other workers in the fields, and employs them in such a way that those who don't accept them can't accept his physical theory, then to that extent his work cannot be accepted by those others; and to that extent the cooperation important to science will be compromised. He therefore proposes a conception of science (of physics in particular) according to which the latter is independent of metaphysics:

. . . I have denied metaphysical doctrines the right to testify for or against any physical theory. . . . . Whatever I have said of the method by which physics proceeds, or the nature and scope that we must attribute to the theories it constructs, does not in any way prejudice either the metaphysical doctrines or religious beliefs of anyone who accepts my words. The believer and the nonbeliever may both work in common accord for the progress of physical science such as I have tried to define it (p. 274-75).

So here we have another argument for methodological naturalism, and a simple, commonsense one at that: it is important that we all--Christian, naturalist, creative anti-realist, whatever--be able to work at physics and the other sciences together and cooperatively; therefore we shouldn't employ, in science, views, commitments and assumptions only some of us accept--that is, we shouldn't employ them in a way that would make the bit of science in question unacceptable or less acceptable to someone who didn't share the commitment or assumption in question.^[60] But then we can't employ (in that way) such ideas as that the world and things therein have been designed and created by God. Proper science, insofar as it is to be common to all of us, will have to eschew any dependence upon metaphysical and religious views held by only some of us; therefore we should endorse methodological naturalism. We do not, of course, have to be metaphysical naturalists in order to pursue Duhemian science; but if science is to be properly universal, it can't employ assumptions or commitments that are not universally shared.

This is an appealing argument for methodological naturalism. It is pragmatic, not principial: it is a good thing to do science together; we should therefore maximize the possibility of cooperation and cooperative inquiry wherever possible; therefore we should not propose, in science, theories essentially involving beliefs that are not common to us all. "When we regard a physical theory as a hypothetical explanation of material reality, we make it dependent on metaphysics. In that way, far from giving it a form to which the greatest number of minds can give their assent, we limit its acceptance to those who acknowledge the philosophy it insists on." So we should adopt a sort of positivist (in the old sense), metaphysically noncommittal, conception of science. Science, properly done, will neither make metaphysical or religious assumptions nor have metaphysical or religious consequences.

This simplicity, to be sure, is a bit deceptive. What is really important for commonality is not the absence, from science, of hypotheses referring to God, or of metaphysics as such, or other philosophical ideas, but rather the absence of views or assumptions that divide us. If there are certain metaphysical views we all share, then there would be no reason, from this point of view, for banning those metaphysical views from science. (Thus Duhem's reason for thinking science should abstain from metaphysics is quite different from Bas van Fraassen's, whose views bear some resemblance to his.) So far as Duhem's suggestion goes, science can employ any universally accepted proposition or assumption whatever, even if in fact it is a piece of metaphysics or theology.^[61] Perhaps it is metaphysics, on some accounts anyway, to suppose that there has really been a past, or really are material objects that exist independently of human thought. If these are assumptions we all or nearly all make, then from this perspective, they can be included in science.

What sorts of propositions are they, that nearly everyone party to the scientific enterprise accepts? Here we see a link between Duhem and van Fraassen--and also, of course, a connection with the idea that science is empirical science; science is in some special way related to the deliverances of experience, in particular the deliverances of sense. And the deliverances of sense are not, for the most part, loci of disagreement among us. In this neighborhood there is much to be said and no space to say it: I shall say just the following. Perhaps observation is, as many have told us, in some sense 'theory-laden'; but it doesn't follow that it is theory-laden in such a way as to destroy commonality. Barring exceptional circumstances, all will agree, presumably, that the pointer is between the 5 and 6 (rather than, say, the 1 and 2). Further, the theory with which observation is laden needn't in every case be such as to divide us. Still further, even where it does divide us (where, for example, the realist claims to see the trail of the electron in the cloud chamber and the empiricist sees no such thing) attention to the way in which a term like 'see' gets analogically extended can often defuse the alleged disagreement as to what gets seen.

So propositions whose truth can be determined by observation will be among those admissible to science from this perspective. Of course science employs more: it also employs the deliverances of reason, logic and mathematics--where, once more, there is little disagreement. Still other propositions are widely accepted and employed in science, although they aren't determinable by observation and go beyond logic and mathematics. We suppose it reasonable to assume that the regularities that obtain in our cosmic neighborhood also obtain in regions of the universe spatiotemporally more remote from us; we suppose that the future will resemble the past in a way that is extremely hard to state but nonetheless real. (We don't feel obliged to repeat the experiment tomorrow, on the grounds that things might change overnight.) We also assume that various inductive policies are likely to work, that simple explanations (again, in a sense that is extraordinarily hard to explain) are to be preferred to complex one, and so on.

According to this attractive Duhemian ideal, then, science is to be a common enterprise and is to employ (in the sense mentioned above) only propositions that are common to all or nearly all those party to it. Duhemian science, you might say, would be public science; it would be maximally inclusive and wholly neutral with respect to the world-view differences that separate us. And of course there are whole vast stretches of our cognitive economy where these world-view considerations do indeed seem to be wholly irrelevant. Anyone with decent eyesight will see that the pointer points to 7; metaphysical or theological differences have nothing to do with it. The same will hold, presumably, for a measurement of the distance from Earth to Jupiter. Anybody will see that a contradiction can't be true; again, it doesn't matter whether you are theist, or an anti-realist or a naturalist, or whatever. The same will go for a deduction of Cantor's Theorem from the axioms of ordinary set theory. (Of course disagreement may break out about those axioms.)

Duhemian science, obviously enough, would involve methodological naturalism: no hypotheses involving God or sin, or what one knows by special revelation will enter essentially into the constitution of such science. But it is crucially important to see methodological naturalism will be just one small part of a much more inclusive constraint: not only won't science, so conceived, employ hypotheses about God, it also won't employ any hypotheses whose cogency involves or presupposes metaphysical naturalism. Nor will it employ assumptions like those, for example, that seem to underlie much cognitive science. For example, it couldn't properly assume that mind-body dualism is false, or that human beings are material objects; these are metaphysical assumptions that divide us. Nor could it employ the deterministic assumptions that seem to underlie much social science; these beliefs also relevantly divide us. Further, many assumptions about the proper function of human beings and their faculties would have to be proscribed: for example, Simonian assumptions about what is and isn't rational, and Piagettian claims about what a properly functioning 12 year old will or won't believe, and the assumption widely current in scientific study of religion that serious religious belief must be a manifestation of pathology or invincible ignorance. Duhemian science would also proscribe the idea that the Theory of Common Ancestry is certain, as well as the idea, widely expressed by writers on evolution, that the randomness or chance involved in genetic variation is such as to preclude human beings' having been designed--by God or anyone else. It would also exclude McMullin's Principle of Indifference, and perhaps much more--perhaps some principles from psychology, from sociology, from economics, and so on. Instead of speaking of 'methodological naturalism', therefore, perhaps we should speak of 'methodological neutralism', or maybe 'metaphysical neutralism'.

Duhemian science, therefore, is maximally inclusive; we can all do it together and agree on its results. But what about those who, like Simon, for example, think it is important also to do a sort of human science which starts, not from methodological naturalism, but from metaphysical naturalism? And what about those who, like the atomists, Cartesians and Aristotelians think it is important to pursue a sort of science in which the aim is successful explanation in terms of underlying unobservable realities? And what about Christians or theists, who propose to investigate human reality employing all that they know, including what they know as Christians or theists? So far as Duhem's claims go, there is nothing improper about any of this. Should we call this kind of activity 'science'; does it deserve that honorific term? There is no reason in Duhem for a negative answer. It is important, to be sure, to see that science of this sort isn't Duhemian science and doesn't have the claim to universal assent enjoyed by the latter; but of course that is nothing against it. According to the fuller Duhemian picture, then, we would all work together on Duhemian science; but each of the groups involved--naturalists and theists, for example, but perhaps others as well--could then go on to incorporate Duhemian science into a fuller context that includes the metaphysical or religious principles specific to that group. Call this broader science 'Augustinian science'. Of course the motivation for doing this will vary enormously from area to area. Physics, and chemistry are overwhelmingly Duhemian^[62] (of course the same might not be true for philosophy of physics); here perhaps Augustinian science would be for the most part otiose. The same goes for biological sciences: surely much that goes on there could be thought of as Duhemian science. On the other hand, there are also non-Duhemian elements in the neighborhood, such as those declarations of certainty and the claims that evolutionary biology shows that human and other forms of life must be seen as a result of chance (and hence can't be thought of as designed). In the human sciences, however, vast stretches are clearly non-Duhemian; it is in these areas that Augustinian science would be most relevant and important.

So return to our central question: should the Christian scientific community observe the constraints of methodological naturalism? So far as this argument is concerned, the answer seems to be: yes, of course, in those areas where Duhemian science is possible and valuable. But nothing here suggests that the Christian scientific community should not also engage in non-Duhemian Augustinian science where that is relevant. There is nothing here to suggest that if it ain't Duhemian, it ain't science.

B. Science Stoppers?

There is still another reason for methodological naturalism; this one too is common sense simplicity itself. God has created this whole wonderful and awful (both taken in their etymological senses) world of ours. One of the things we want to do as his creatures is to understand the world he has made, see (to the extent that we can) how it is made, what its structure is, how it works. This is not, of course, the only thing God's children must do with the world; we must also appreciate it, care for it, love it, thank the Lord for it, and see his hand in it. But understanding it is valuable, and so is understanding it in a theoretical way. One way of understanding something is to see how it is made, how it is put together, and how it works. That is what goes on in natural science. The object of this science is nature; for Christians, its aim (one of its aims) is to see what the structure of this world is and how it works; this is a way of appreciating God's creation, and part of what it is to exercise the image of God in which we have been created.

But there will be little advance along this front if, in answer to the question, Why does so and so work the way it does? or What is the explanation of so and so? we regularly and often reply "Because God did it that way" or "Because it pleased God that it should be like that." This will often^[63] be true, but it is not the sort of answer we want at that juncture. It goes without saying that God has in one way or another brought it about that the universe displays the character it does; but what we want to know in science are the answers to questions like "What is this made out of? What is its structure? How does it work?" How is it connected with other parts of God's creation? Claims to the effect that God has done this or that (created life, or created human life) directly are in a sense science stoppers. If this claim is true, then presumably we can't go on to learn something further about how it was done or how the phenomenon in question works; if God did it directly, there will be nothing further to find out. How does it happen that there is such a thing as light? Well, God said, "Let there be light" and there was light. This is of course true, and of enormous importance, but it taken as science it isn't helpful; it doesn't help us find out more about light, what its physical character is, how it is related to other things, and the like. Ascribing something to the direct action of God tends to cut off further inquiry.

Of course this is a reason for only part of methodological naturalism. There are several different ways in which Christianity might enter into the texture of science: (1) stating and employing hypotheses according to which God does things directly, of course, but also (2) stating and employing hypotheses according to which he does something indirectly; further, there is (3) evaluating theories with respect to background information that includes Christian theism; still further, there is (4) employing such propositions as human beings have been created in God's image, either directly or as background, and (5) doing the same for such doctrines as that of original sin, which don't involve any direct mention of God at all, and (6) deciding what needs explanation by way referring to that same background. The considerations cited in the last paragraph are at best a reason for a proscription of (1).

But they aren't even much of a reason for that. The claim that God has directly created life (for example) may be a science stopper; it doesn't follow that God didn't directly create life. Obviously we have no guarantee that God has done everything by way of employing secondary causes, or in such a way as to encourage further scientific inquiry, or for our convenience as scientists, or for the benefit of the NSF Clearly we can't sensibly insist in advance that whatever we are confronted with is to be explained in terms of something else God did; he must have done some things directly. It would be very much worth knowing (if possible) which things he did do directly; to know this would be an important part of a serious and profound knowledge of the universe. The fact that such claims are science stoppers means that as a general rule they won't be helpful; it doesn't mean that they are never true, and it doesn't mean that they can never be part of a proper scientific theory. (And of course it doesn't even bear on the others ways in which Christianity or Christian theism can be relevant to science.) It is a giant and unwarranted step from the recognition that claims of direct divine activity are science stoppers to the insistence that science must pretend that the created universe is just there, refusing to recognize that it is indeed created.

So there is little to be said for methodological naturalism. Taken at its best, it tells us only that Duhemian science must be metaphysically neutral and that claims of direct divine action will not ordinarily make for good science. And even in these two cases, what we have reason for is not a principled proscription but a general counsel that in some circumstances is quite clearly inapplicable. There is no reason to proscribe questions like: did God create life specially?; there is no reason why such a question can't be investigated empirically;^[64] and there is no reason to proscribe in advance an affirmative answer.

Christian thought (particularly since the High Middle Ages) as opposed to Greek (and in particular Aristotelian^[65] thought) contains a strong tendency to see the world as through and through contingent. The world need not have existed; that is, God need not have created it. The world need not have had just the structure it does have; that is, God could have created it differently. This sense of the contingency of nature has been one important source of the emphasis upon the empirical character of modern science. As a sort of rough rule of thumb, we can say that it is by reason, by a priori thought, that we learn of what cannot be otherwise; it is by the senses, by way of a posteriori inquiry that we learn about what is contingent.^[66] But the world as God created it is full of contingencies. Therefore we don't merely think about it in our armchairs, trying to infer from first principles how many teeth there are in a horse's mouth; instead we take a look. The same should go for the question how God acts in the world: here we should rely less upon a priori theology and more upon empirical inquiry. We have no good grounds for insisting that God must do things one specific way; so far as we can see, he is free to do things in many different ways. So perhaps he did create human life specially: or perhaps he has done other things specially. We can't properly rule this out in advance by way of appeal to speculative theology; we should look and see.

My main point, therefore, can be summarized as follows. According to Augustine, Kuyper, and many others human history is dominated by a battle, a contest between the Civitas Dei and the City of Man. It is part of the task of the Christian academic community is to discern the limits and lineaments of this contest, to see how it plays out in intellectual life generally, and to pursue the various areas of intellectual life as citizens of the Civitas Dei. This naturally suggests pursuing science using all that we know: what we know about God as well as what we know about his creation, and what we know by faith as well as what we know in other ways. That natural suggestion is proscribed by the principle of Methodological Naturalism. methodological naturalism, however, though widely accepted and indeed exalted, has little to be said for it; when examined cooly in the light of day, the arguments for it seem weak indeed. We should therefore reject it, taken in its full generality. Perhaps we should join others in Duhemian science; but we should also pursue our own Augustinian science.

By way of conclusion, I call attention to something else John Stek has said:

Theology must take account of all that humanity comes to know about the world, and science must equally take account of all that we come to know about God. In fact, we cannot, without denying our being and vocation as stewards, pursue theology without bringing to that study all that we know about the world, nor can we, without denying our being and vocation as stewards, pursue science without bringing to that study all that we know about God.^[67]

Just so.

^[1]For example, many Reformed Christians follow Abraham Kuyper in holding that intellectual endeavor in general and natural science in particular are not independent of religious commitment. Perhaps the credit for this idea should go not to Augustine, but to Tertullian. Tertullian has suffered from a bad press; one of his major emphases, however, is that scholarship, intellectual endeavor, is not religiously neutral.

^[2]The idea is not, of course, that a scientist won't be passionate either about science generally, or his favorite theories, or his reputation; it is rather that none of these properly enters into the evaluation of a scientific theory or explanation.

^[3]"Science must be provisionally atheistic or cease to be itself." "Darwin's Place in the History of Thought" in M. Banton, (ed) Darwinism and the Study of Society (Chicago: Quadrangle Books, l961). Willey does not mean, of course, that one who proceeds in this way is properly accused of atheism. In the same way, to call this procedure or proscription 'methodological naturalism' is not to imply that one who proceeds in this way is really a naturalist. (See Ernan McMullin's "Plantinga's Defense of Special Creation", Christian Scholar's Review (Sept. 1991), p. 57.

^[8]Here I leave to one side the teachings of early Genesis, since I am not sure just how those teachings bear on the issue at hand. See my "Evolution, Neutrality, and Antecedent Probability," p. 94.

^[9]In 1952 Stanley Miller, a graduate student in the laboratory of Harold Urey showed that certain amino acids could arise under what may have been the conditions of earth before life; this generated a fervent but temporary burst of dithyrambic optimism. The optimism dissipated when the enormous distance between amino acids and the simplest forms of life sank in, and when there was little or no progress in showing how that distance could have been traversed. See in particular Robert Shapiro, Origins (New York: Summit Books, l986) and Thaxton, Charles, Walter Bradley,and Roger Olsen. The Mystery of Life's Origins (New York: Philosophical Library, 1984).

^[10]"It is mere rubbish, thinking at present of the origin of life; one might as well think of the origin of matter." Letter from Darwin to Hooker, The Life and Letters of Charles Darwin, vol. 2, ed. Francis Darwin (New York: Appleton, 1967), p. 202.

^[11]See The Mystery of Life's Origin, by Charles Thaxton, Walter Bradley and Roger Olsen (New York: Philosophical Library, 1984); Origins, by Robert Shapiro (New York: Summit Books, 1986); Evolution, Thermodynamics, and Information: Extending the Darwinian Program, by Jeffrey S. Wicken (New York: Oxford University Press, 1987); Seven Clues to the Origin of Life (Cambridge: Cambridge University Press, 1985) and Genetic Takeover and the Mineral Origins of Life, (Cambridge: Cambridge University Press, 1985) by A. G. Cairns-Smith; and Origins of Life, by Freeman Dyson (Cambridge: Cambridge University Press, 1985); see also the relevant chapters of Michael Denton, Evolution: A Theory in Crisis (London: Burnet Books, 1985).

^[12]Evolution, says Francisco J. Ayala, is as certain as "the roundness of the earth, the motions of the planets, and the molecular constitution of matter." "The Theory of Evolution: Recent Successes and Challenges", in Evolution and Creation, ed. Ernan McMullin (Notre Dame: University of Notre Dame Press, l985), p. 60. According to Stephen J. Gould, evolution is an established fact, not a mere theory; and no sensible person who was acquainted with the evidence could demur. "Evolution as Fact and Theory" in Hen's Teeth and Horse's Toes (New York: W.W. Norton and Company, l980), pp. 254-55. According to Richard Dawkins, the theory of evolution is as certainly true as that the earth goes around the sun. This astronomical comparison apparently suggests itself to many; in "Evolutionary Biology and the Study of Human Nature" (presented at a consultation on Cosmology and Theology Sponsored by the Presbyterian (USA) Church in Dec., l987) Philip Spieth claims that "A century and a quarter after the publication of The Origin of Species, biologists can say with confidence that universal genealogical relatedness is a conclusion of science that is as firmly established as the revolution of the earth about the sun". And Michael Ruse adds his nuanced and modulated view that "evolution is Fact, Fact, Fact!"

^[13]See the essays referred to in footnote 4.

^[14]According to Jesus, God remembers each and every sparrow (Luke 12:6); might he not have been minded to create the first of them specially?

^[15]And of course part of the evidence, for a Christian, will be the Biblical evidence. I myself think that the Biblical evidence for a special creation of human beings is fairly strong.

^[16]Of course it is possible both that God did something special in creating human beings and that they are genealogically related to the rest of the living world.

^[17]Douglas Futuyma, Evolutionary Biology, (2nd edition, 1986) p. 3.

^[18]George Gaylord Simpson, The Meaning of Evolution (rev. ed., 1967) pp. 344-45.

^[19]The Blind Watchmaker (London and New York: W.W. Norton & Co., 1986) p. 5.

^[37]I've argued elsewhere that one condition of rationality laid down by modern classical foundationalism is in fact self-referentially incoherent. See, e.g., "Reason and Belief in God", in Faith and Rationality, ed. A. Plantinga and N. Wolterstorff (Notre Dame: University of Notre Dame Press), 1983, pp. 60 ff.

^[54] Trans. Philip P. Wiener, foreword by Prince Louis de Broglie (Princeton: Princeton University Press, 1954). The book was first published in 1906.

^[55]"La Philosophie scientifique de M. Duhem" Revue de Métaphysique et de Morale, XII (July, 1904), 699ff.

^[56]See the appendix to The Aim and Structure of Physical Theory, which is entitled "Physics of a Believer" and is a reprint of Duhem's reply to Rey; it was originally published in the Annales de Philosophie chrétienne Vol I (Oct. and Nov.) 1905, pp. 44ff. and 133ff.

^[57]Huygens to G. W. Leibniz, Nov. 18, 1690, Oeuvres complètes de Huygens, Correspondence, 10 volumes (The Hague, 1638-1695) ix, 52. Quoted by Duhem.

^[58]Aristarchi Samii, De mundi systemate, partibus et motibus ejusdem, liber singularis (Paris, 1643).

^[59]Descartes to Mersenne, in Correspondence, ed. Tannery and Adam Letter (1893) Clxxx p. 396.

^[60]This wouldn't preclude, of course, employing such ideas in theories proposed, not as true, but only as empirically adequate.

^[61]It isn't clear to me whether Duhem himself proposes that physics shouldn't involve any metaphysics, or whether he things only that it shouldn't involve divisive metaphysics. He tends to write as if it is the former he has in mind; but his arguments support only the latter.

^[62]The Principle of Indifference (above, p. 00018) is non-Duhemian, but it isn't easy to find other examples. (I am assuming that interpretations of quantum mechanics (as opposed to quantum mechanics itself) belong to philosophy rather than physics.)

^[63]Though not always: if the question is Why was there such a thing as WW II? the answer is not Because it pleased God to do things that way. God of course permitted the Second World War to take place; but it wasn't pleasing to him.

^[64]Why couldn't a scientist think as follows? God has created the world, and of course has created everything in it directly or indirectly. After a great deal of study, we can't see how he created some phenomenon P (life, for example) indirectly; thus probably he has created it directly.

^[65]See Posterior Analytics, Bk. I, 1-2, 4, where Aristotle declares that scientia is a matter of seeing what necessarily follows from what one sees to be necessarily true. (Of course Aristotle's own practice is not always easy to square with this suggestion.)

^[66]Of course this is at best a rough and general characterization: we can obviously learn of necessities a posteriori (for example by using computers to prove complicated theorems) and perhaps also of contingencies a priori. This question of the connection between the a priori and the necessary, on the one hand, and the contingent and the a posteriori on the other (the question of the relation between the a priori / a posteriori distinction and the necessary/contingent distinction) is as deep as it is fascinating.

^[67]Loc. Cit., p. 260-261.