Dialogue
Plantinga's Defense of Special Creation
University of Notre Dame
Notre Dame IN 46556
Christian Scholars Review XXI:1 (September 1991):
55-79.
Used by Permission
My colleague, Alvin Plantinga, bids the reader of his essay, "When faith and reason clash: Evolution and the Bible," to take his spirited defense of special creation "with a grain of salt." Perhaps he will forgive me if I take it seriously, because I think that this is how many readers would take it, in the context of the continuing controversies about "creation science."
1. Theistic science
His thesis in regard to evolution is that, for the Christian, the claim that God created mankind, as well as many kinds of plants and animals, separately and specially, is more probable than the claim of common ancestry that is central to the theory of evolution. And his larger context is that of an exhortation to Christian intellectuals to join battle against "the forces of unbelief," particularly in academia, instead of always yielding to "the word of the experts." These intellectuals must be brought to "discern the religious and ideological connections... [they must not] automatically take the word of the experts, because their word might be dead wrong from a Christian standpoint." The implication that worries me is that Christian intellectuals should ally themselves with the critics of evolution, despite the almost universal support it has among experts in the relevant fields of natural science.
The "science" these Christian intellectuals profess will not be of the usual naturalist sort. Their account of the origin of species, for instance, will be at odds with that given by Darwin, on grounds that are distinctively Christian in content. Despite the fact that claims such as these on the part of the Christian depend on what he or she knows "by faith, by way of revelation," Plantinga believes that they can appropriately be called science, and he suggests as labels for them "theistic science" or "Christian science." An important function of this broader knowledge would be revisionary. He reminds us that "Scripture can correct current science," in regard to whether or not, for example, the universe originated at a particular moment in the past.
Plantinga's "theistic science" bears some similarity to the "creation science" that has commanded the headlines in the U.S. so often in recent decades. Like creation scientists, he maintains that the best explanation of the origin of "many kinds of plants and animals" is an interruption in the ordinary course of natural process, a moment when God treats "what he has created in a way different from the way in which he ordinarily treats it." Like them, he relies on a critique of the theory of evolution, pointing to what he regards as fundamental shortcomings in the Darwinian project of explaining new species by means of natural selection, and emphasizing recent criticisms of one or other facet of the synthetic theory from within the scientific community itself. Like them, he calls for a struggle against prevailing scientific orthodoxy, one which may pit the teachers of Christian youth against the "experts."
But the differences between them are obvious.1 Most creation-scientists believe in a "young earth" dating back only a few thousand years, and attempt to undermine the many arguments that can be brought against this view. Plantinga allows "the evidence for an old earth to be strong and the warrant for the view that the Lord teaches that the earth is young to be relatively weak." The creation scientists argue for a whole series of related cosmological theses (that stars and galaxies do not change, that the history of the earth is dominated by the occurrence of catastrophe, and so forth); Plantinga focuses on the single issue of the origins of the kinds of living things, and especially of humankind. And he is in the end more concerned to combat the claims of certainty made by the evolutionists than he is to argue that the Christian is irrevocably committed against a full evolutionary account of origins. He allows (which the creation-scientists, I suspect, would not) that as evolutionary science advances, his own present estimate that special creation is more likely might have to give way.
The creation-scientists attempt to detach their arguments from any sort of reliance on Scripture, or more generally, from theological considerations, whereas Plantinga appeals explicitly to the Scriptural understanding of the manner of God's action in the world. The former make a heroic attempt to qualify their creationism as "scientific," in what they take to be the conventional sense of that term. Their effort, I think it is fair to say, was hopeless right from the start. But it may have been prompted as much by political necessity as by strength of conviction regarding the purely scientific merits of their arguments. The creationists would undoubtedly have preferred to defend a view more explicitly based on the Bible, but the exigencies of the constitutional restrictions on what may be taught in Plantinga's Defense of Special Creation the public schools of the U.S. prevented this. The scientists among them would have wanted to shore up their case with various consonances between the catastrophism of their young-earth account and the geological record. But the inspiration for their account lay, and clearly had to lie, in the Bible. Trying to fudge this, though understandable in the circumstances, proved a disastrous strategy.
Plantinga offers a far more consistent theme. True, his "theistic science" will not pass constitutional muster, so it will not serve the purposes for which creation-science was originally advanced. But that not an argument against it; it is merely a consequence of the unique situation of public education in the U.S., a situation that imposes losses as well as gains. I do not think, however, that "theistic science" should be described as science It lacks the universality of science, as that term has been understood in the Western tradition. It also lacks the sort of warrant that has gradually come to characterize natural science, one that points to systematic observation, generalization, and the testing of explanatory hypothesis. It appeals to a specifically Christian belief, one that lays no claim to assent from a Hindu or an agnostic. It requires faith, and faith (we are told) is a gift, a grace, from God. To use the term "science" in this context seems dangerously misleading; it encourages expectations that cannot be fulfilled, in the interests of adopting a label generally regarded as honorific.
Plantinga objects to the sort of "methodological naturalism" that would deny the label "science" to any explanation of natural process that invokes the special action of God; indeed, he characterizes it, in Basil Willey's phrase, as "provisional atheism." "Is there really any compelling or even decent reason for thus restricting our study of nature?" he asks. 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 to be explained by invoking God's creative action directly. Calling this methodological naturalism is simply a way of drawing attention to the fact that it is a way of characterizing a particular methodology, no more. In particular, it is not an ontological claim about what sort of agency is or is not possible. Dubbing it "provisional atheism" seems to me objectionable; the scientist who does not include God's direct action among the alternatives he or she should test scientifically when attempting to explain some phenomenon is surely not to be accused of atheism!
Let me make myself clear. I do not object (as the concluding section of this essay will make clear) to the use of theological considerations in the service of a larger and more comprehensive world-view in which natural science is only one factor. I would be willing to use the term "knowledge" in an extended sense here (though I am well aware of some old and intricate issues about how faith and knowledge are to be related).2 But I would not be willing to use the term "science," in this context. Nor do I think it necessary to do so in order to convey the respectability of the claim being made: that theology may appropriately modulate other parts of a person's belief-system, including those deriving from science. I would be much more restrictive than Plantinga is, however, in allowing for the situation he describes as "Scripture correcting current science," But before we come to our differences, it may be worth laying out first the large areas where he and I agree.
2. Points of agreement
What really galls Plantinga. are the views of people like Dawkins and Provine who not only insist that evolution is a proven "fact," but suppose that this somehow undercuts the reasonableness of any sort of belief in a Creator. Their argument hinges on the notion of design. The role of the Creator in traditional religious belief was that of Designer; the success of the theory of evolution has shown that design is unnecessary. Hence, there is no longer any valid reason to be a theist. In a recent review of a history of the creationist debate in the U.S., Provine lays out this case, and concludes that Christian belief can be made compatible with evolutionary biology only by supposing that God "works through the laws of nature" instead of actively steering biological process by way of miraculous intervention. But this view of God, he says, is "worthless," and "equivalent to atheism."3 (On this last point, Plantinga and he might not be so far apart!) He chides scientists for publicly denying, presumably on pragmatic grounds, that evolution and Christian belief are incompatible; they must, he says, know this to be nonsense.
Plantinga puts his finger on an important point when he notes that for someone who does not believe in God, evolution is some form or other is the only possible answer to the question of origins. Prior to the publication of The Origin of Species in 1859, the argument from design was part of biological science itself. The founders of physico-theology two centuries earlier, naturalists like John Ray and William Derham, had shown the pervasive presence in Nature of means-end relationships, the apparently purposive adjusting of structure and instinctive behavior to the welfare of each kind of organism. Someone who rejected the idea of God had, therefore, to face some awkward problems in explaining some of the most obvious features of the living world; it seemed as though science itself testified to the existence of God.4
Darwin changed all this. He made it possible to reconcile atheism with biological science; from then onwards, the fortunes of atheism as a form of intellectual belief would depend upon the fortunes of the theory of evolution. No wonder, then, that evolution became a crucial "myth" (as Plantinga puts it) of our secular culture, replacing for many the Christian myth as "a shared way of understanding ourselves at [lie deep level of religion."5 No wonder also that an attack on the credentials of evolutionary theory would so often evoke from its defenders a reaction reminiscent in its ferocity of the response to heresy in other days.
Is evolution fact or theory? No other question has divided the two sides in the creation-science controversy more sharply. Plantinga notes that someone who denies the existence of a Creator is left with no other option for explaining the origin of living things than an evolutionary-type account. It thus, equivalently, becomes "fact" not just because of the strength of the scientific evidence in its favor but because for the at least no other explanation is open. On the other side, the believer in God is going to resent this use of the word, "fact," because it seems to exclude in principle the possibility of a Divine intervention, and hence by implication, the possibility of the existence of a Creator. "Fact" seems to convey not just the assurance of a well-supported theory, but the certainty that no other explanation is open.
The debate may often, Therefore, be something other than it seems. Instead of being just a disagreement about the weight to be accorded to a particularly complex scientific theory in the light of the evidence available, the debate may conceal a far more fundamental religious difference, each side appearing to the other to call into question an article of faith. To religious believers, calling the assertion of common ancestry a "fact" appears to violate good scientific usage; no matter how well-supported a theory may be (they argue), it remains a theory. To non-believers, the phrase "merely a theory" comes as a provocation, because it suggests a substantial doubt about a claim that appears to them as being beyond question, a doubt prompted furthermore in their view by an illegitimate intrusion of religious belief.
At one level, then, Plantinga's essay can be read as a plea for a more informed understanding of the real nature of the creation-science debate, and a more sympathetic appreciation oi what led the proponents of creation-science to take the stand they did. Even their defense of a "young" earth (the major point of disagreement between his view and theirs) ought not (he says) be regarded as "silly or irrational." One need not be "a fanatic, or a Flat Earther, or an ignorant Fundamentalist" to hold such a view. The claim that the earth is ancient is neither obvious nor inevitable; it has to be argued for, and disagreement may, therefore, easily occur.
Plantinga is right, to my mind, to see more in the creation-science debate than evolutionary scientists (or the media) have been wont to allow. And the sort of challenge he offers to the defenders of evolution, though it is not new, could serve the purposes of science in the long run if it forced a clarification and strengthening of argument on the other side, or if it punctured the sometimes troubling smugness that experts tend to display when dealing with outsiders. Plantinga leans too far in the other direction, however. The charitable reading of creation-science that he urges could easily mislead. A claim does not have to be obvious or inevitable for its rejection to connote fanaticism or ignorance. If the indirect evidence for the great age of the earth is overwhelming (Plantinga himself allows that it is "strong"), if its denial would call into question some of the best-supported theoretical findings of an array of natural sciences (cosmology, astrophysics, geology, biology), then one is entitled to issue a severe judgment oil the challenger. Perusal of works like that of Morris would lead one to suspect that no matter how strong the scientific case were in favor of an ancient earth, it would make no difference to their authors. Their implicit commitment to a literalist interpretation of Genesis is such that it blocks a genuinely rational assessment of the alternative. The term, "fanatic," is a notoriously difficult one to apply fairly, because it conveys moral, as well as epistemic, disapprobation. But I would be willing to defend its appropriateness to such expositions of creation-science as that of Morris.
What bothers Plantinga, I suspect, about the use of the term here, is that from his point of view the creation-scientist's heart is in the right place, even if perhaps his head isn't. Anyone who stands up for "sola Scriptura" in the modern world, even in contexts as unpromising as the debate about the age of the earth, ought not (he seems to suggest) simply be dismissed. Creation-scientists may be wrong in holding that the earth is only a few thousand years old, but their "motivation for making this claim ought be regarded with sympathy by their fellow-Christians, I would disagree, but it is because of a deeper disagreement about the merits of the "sola Scriptura" premis and of the remaining major theses of creation-science. Though I would not be as harsh on the creation-scientist as leading evolutionists have been, I would, as a Christian, want to register disapproval of creation-science at least as strong as theirs, though for reasons that go beyond theirs. These reasons will become clear, I hope, in what I have to say about Plantinga's analysis of what happens when "faith and reason clash."
3. Galileo and Genesis
In his Letter to the Grand Duchess Christina (1615), Galileo gave the most extended account that anyone perhaps had written up to that time of how the Christian should proceed when an apparent conflict between science and Scripture arises. Aided, doubtless, by some of his theologian-friends, he drew upon Augustine, Jerome, Aquinas, and an impressive array of other authorities, in order to show that the use made of Scripture by those who opposed the Copernican theory was illegitimate.6 There may be some lessons to be drawn from this historic document in the context of the Darwinian debate, apart from tile obvious one of the embarrassment that the Church would later suffer because of its ill-advised attempt to make the geocentric cosmology of the Old Testament authors a matter, equivalently, of Christian faith.
What, then, did Galileo hold about the bearing of the Scriptures on our knowledge of the natural world? It does not take long for he reader to discover that two radically different principles are proposed in different parts of the Letter, and to realize that Galileo almost certainly was not aware o, the resulting incoherence.7 On the one hand, he cites Augustine in support of the traditional view that in cases of apparent conflict, the literal interpretation of Scripture is to be maintained, unless the opposing scientific claim can be demonstrated. In that case, theologians must look for an alternative reading of the Scriptural passage(s), sinceit is a first principle that faith and natural reason cannot really be in conflict. However, the straightforward interpretation of Scripture is to be preferred in cases where the scientific claim has something less than "necessary demonstration" in its support, because of the inherently greater authority to be attached to the word of God.8
On the other hand, Galileo also argues that one should not look to Scripture for knowledge of the natural world: the function of the Bible is to teach us how to go to heaven, not how the heavens go, in the aphorism attributed to Baronius. God has given us reason and the senses to enable us to come to understand the world around us. Attempting to teach the underlying structures of natural process would have baffled the readers of Scripture and defeated its obvious purpose. Galileo produced a number of convergent lines of argument to the effect that Scripture is simply not relevant to the concerns of the sciences to begin with.
The implications of these two quite different hermeneutic principles were, of course, altogether different for the resolution of the Copernican debate.9 But that is not my concern here. More to my purpose is to note that the first principle has one quite disastrous consequence: it sets theologians evaluating the validity of the arguments of the natural philosophers, and natural philosophers defending themselves by composing theological tracts. Either way, there will be immediate charges of trespass. The theologian challenges the force of technical scientific argument; scientists urge their own readings of Scripture or their own theories as to how Scripture, in general, should be read. In both cases, the professionals are going to respond, quite predictably: what right have you to intrude in a domain where you lack the credentials to speak with authority? The assessment of theory strength is not a simple matter of logic and rule but requires a long familiarity with the procedures, presuppositions, and prior successes of a network of connected domains, and a trained skill in the assessment of particular types of argument.
Transposing from the Galilean to the Darwinian debate demands some care, yet there are obvious morals to be drawn. Neither of Galileo's principles is entirely adequate for regulating disputes of this general kind. One ought not require that a scientific case be demonstrative before it have any standing in the face of an apparently contrary Scriptural assertion. On the other hand, one cannot (as Plantinga correctly says) simply rule out conflicts of this kind by laying down that Christian doctrine can have no implications for matters that fall under scientific jurisdiction. Galileo was right to maintain that the Bible was not intended as (in part) a manual of natural knowledge. The biblical writers simply made use of the language and the cosmological beliefs of their own day while telling the story of human salvation. But that story itself does require certain presuppositions about human nature, about freedom and moral responsibility, for example, that would clash with psychological theories affirming the unreality of our claim to freedom of moral action. So it is not as though the two domains are, in principle, so safely walled off from one another that no conflict can possibly arise.
Nevertheless, Scripture scholars would be in a large measure of agreement today that the domain of such potential conflict is quite limited. In particular, the creation narratives of the first two chapters of Genesis are not to be read as literal history. The points they are making lie deeper and can only be reliably discerned by investigating the wider literary context of that day, on the one hand, and the later theological appropriations of those narratives, on the other.10 It is not as though the texts are to be taken literally unless and until a conclusive scientific account of origins can be constructed. Rather, no likelihood is to be attached in the first place to the literal construal of the story, say, of the separate creation of the animals. To interpret it literally or quasi-literally is to misunderstand the point hat the writers of those narratives were trying to make, the great majority of contemporary Scripture scholars would agree.11
An interesting feature of Plantinga's argument is that lie explicitly brackets the reference to Genesis that one would expect to find, given the primacy he accords to Scripture. Did he originally plan to return to the text of Genesis at the end of his paper to clinch his case? ("Suppose we temporarily set to one side the evidence, whatever exactly it is, from early Genesis.") I kept waiting for him to turn finally to the biblical narratives of creation as the strongest reason for distrusting the evolutionary story. Historically, these narratives provided the main warrant for the traditional Christian belief that God intervened in a special way to bring to be the first members in the lineage of each natural kind. Those who, like Plantinga, have urged the superiority of special creation over evolution have almost always relied upon a direct appeal to Genesis, unless (as we have seen) they were prevented, as the recent creation-science advocates were, by political constraints.
Plantinga is under no such constraints, however. Since he evidently believes that a case can be made for special creation without any overt appeal to Genesis, he may have felt it better to avoid the controversies that surround the literalist approach to the Genesis text. He already has the scientists on his hands. Why open a second front and take on the theologians too? There is no rhetorical advantage to be gained by making explicit that he can expect little support for the thesis of special creation on the part of contemporary biblical scholars.
Despite his silence in regard to Genesis, I do not think that a linkage between his argument and the more traditional Genesis-based argument can be denied. Without the latter, would anyone think it a priori more likely that the God of the salvation story would intervene to originate natural kinds instead of allowing them to appear gradually and in a "natural" way? And if biblical theologians are right in holding that the cosmological references in the Old Testament ought be understood as conveying fundamental theological truths about the dependence of the natural and human worlds on their Creator, rather than explaining how exactly these worlds first took shape, then perhaps one ought be just as wary of drawing a cosmological moral from the salvation story as a whole as from the controversial passages in Genesis.
What must be disputed, to my mind, is a modern analogue of the first of Galileo's principles,12 which would, equivalently, reaffirm the presumption that the biblical text was partially intended as a cosmology, so that in cases of apparent conflict between the biblical and current scientific accounts we should evaluate the strength of the scientific account as a means of deciding which of the two competitors" to accept. Plantinga proposes such a "balancing of likelihoods" methodology: a literalist understanding of God's making of the ancestors of the main natural kinds, he concludes, should be preferred unless and until a far stronger case can be made for the evolutionary alternative.
What I am urging is that it is potentially destructive (as the Galileo case amply shows) to treat the biblical and the scientific as competitors in the realm of cosmological explanation. The cosmological implications (if any) of the Scripture story are to be discovered by theological study, not be assessing the credentials of the supposedly competing scientific account. Even if the theory of evolution could be entirely dismissed on scientific grounds, this would not of itself give us any warrant for supposing that the biblical account of origins ought, therefore, be taken literally. It might well be that, in the absence of a plausible evolutionary account the only reasonable alternative for the Christian would be something like special creation. But even this would not warrant the supposition this creation, in the literal sense, is what we ought properly infer from the biblical texts, whether the accounts of Creation in Genesis, or the story of Israel leading up to the coming of Christ. The interpretation of these texts is primarily a hermeneutic problem for the theologian; criticism of supposedly competing scientific theories will rarely be relevant.13
Where the theologian is unsure of the best interpretation to give a text, it is not inappropriate, of course, to take into account that some of the possible interpretations may be closed off by the findings of the natural or social sciences. But even in such a case (as Augustine's own practice might easily be made to illustrate) primary weight should be given to the hermaneutic issue as to what the disputed text was originally intended to convey and the theological issue of what the tradition has made of it. This way of handling relationships between Scripture and the sciences does not close them off from one another entirely, as we have already seen. But it encourages us to resist the temptation to construe the two as normally belonging to the same order of explanation or historical claim. As an illustration of how Scripture could "correct current science," Plantinga remarks: "If, for example, current science were to return to the view that the world beginning, and in infinitely old, then current science would be wrong."14 I do not believe that Scripture does prescribe that the universe ha a beginning in time, in some specific technical sense of the term, "time"; the point of the Creation narratives is the dependence of the world on God's creative act, to my mind, not that it all began at a finite time in the past.15 A world that has always existed would still require a Creator.
4. The Thesis of Common Ancestry
Plantinga. dismisses the evidence ordinarily presented in support of what he calls the Thesis of Common Ancestry (TCA) as inconclusive, after a rather cursory review. His conclusion: "It isn't particularly likely, give in the Christian faith and the biological evidence, that God created all the flora and fauna by way of some mechanism involving common ancestry." Though my "disagreement with him centers especially on the conclusion he draws from Christian faith in regard to the antecedent likelihood of special creation, I am going to spend some time on the scientific issues first. The credentials of a thesis encompassing as much of past and present as TCA does cannot, of course, be dealt with satisfactorily in a few pages. 16 This is particularly true when these credentials are being denied, contrary to the firm conviction of the great majority of those professionally engaged in the many scientific fields involved.
Though a full-scale defence of TCA cannot be attempted here, and would in any event be beyond my competence, it may be worthwhile to indicate how in a general way such a defence might proceed.17 First, an important distinction, one alluded to by Plantinga. TCA is a historical claim that the kinds of living things originated somehow from one another. On the other hand, the various theories of evolution are an attempt to explain how that could have occurred.18 The dominant theory of evolution at the present time is the so-called "modern synthesis," associated with such figures as Simpson, Dobzhansky, and Mayr. It has its critics: Goldschmidt and Schindewolf a generation ago, for example, Gould and Kimura today. Though all of these have found fault with the Darwinism of the modern synthesis and have proposed alternatives to it, none would for a moment question TCA. Their confidence in TCA does not depend, then, on a similar degree of confidence in the explanatory adequacy of a specifically Darwinian account of the origin of species. Is it, perhaps, that they implicitly reject God's existence, and thus TCA is for them (in Plantinga's phrase) "the only game in town"? I don't think it is quite as simple as this, although the implicit setting aside of a theistic alternative obviously could play a role.
Much of the evidence for TCA functions independently of the detail of any specific evolutionary theory. Plantinga mentions three such categories of evidence, so I will confine myself to those. There is the fossil record which has already yielded innumerable sequences of extinct forms, where the development of specific anatomical features can be traced in detail through the rock-layers.
Paleontologists have traced the development of eyes in no less than forty independent animal lineages ("lineages" being determined by overall morphological similarities).19 They continue to uncover stage after stage in crucial "linking" forms, such as the therapsids, for example, the forms that relate reptiles with the earliest mammals. In cases like these (and there are a lot of them), paleontologists can point to a variety of morphological features that gradually shift over time, retaining a basic likeness (a so-called Bauplan) throughout. Gould's objection regarding the rarity of transitional forms (quoted by Plantinga) has to be taken in context. Gould would not deny the morphological continuities of the fossil record; like thousands of other researchers he has given too much of his time to tracing these continuities for him to underrate their significance. What he would say (and what many defenders of the modern synthesis would now be disposed to admit) is that species often make their appearance in the record without the prior gradual sequence of modifications one would have expected from the traditional gradualist Darwinian standpoint. But this leaves untouched the implications, overall, of the fossil record for TCA. It does, of course, affect the sort of theory that could account for the sequence found in the record20 which might confuse, since non-Darwinian explanations of common ancestry have, of course, also been proposed. And he says that TCA "is what one most naturally thinks of as the Theory of Evolution." What he may mean here is that TCA is theoretical and it implicitly involves evolution in some guise. But it is preferable, I would suggest, not to equate TCA and "the Theory of Evolution" because for most readers "the" theory of evolution is Darwin's.
Instead of scrutinizing the fossil record, we might look to the living forms around us, and there discover all sorts of homologies and peculiar features of geographical distribution, which are best understood in terms of TCA. Tire arguments here are long familiar and I will not daily on them. But there is a further category of evidence which has taken on a great deal of importance in the last twenty years. This comes from molecular biology.21 Comparison of the DNA, as well as of the proteins for which DNA codes, between different types of organisms shows that there are striking similarities in chemical composition between them. Cytochrome C, for example, found in all animals, is involved in cell respiration. It contains 104 amino-acids, in a sequence which is invariable for any given species. For humans and rhesus monkeys, the sequence is identical except in one position; for horses and donkeys the sequence also differs in only one position. But for humans and horses, the difference is 12; for monkeys and horses, the difference is 11. If instead of cytochrome C another homologous protein is chosen, similar (though not necessarily identical) results are found. These very numerous resemblances and differences between the macromolecules carrying hereditary information can be explained by supposing a very slow rate of change in the chemical sequences constituting these molecules, and thus a relationship of common descent among the organisms themselves. Thus, the "molecular" differences between any two species become (on this hypothesis) a rough indication of how long since the ancestors of these species diverged; rather more securely, one can infer the relative order of branching between three or more species; one can infer whether A branched from B before C did. What is impressive here is the coherence of the results given by examining many different macromolecules in this light.
But much more impressive is that these results conform reasonably well with the findings of both paleontology and comparative anatomy in regard to the ancestral relations between species, the postulated tree of descent that had already been worked out in some detail in these other disciplines. The fit, as one would expect, is not exact in each case in regard to the "closeness" between the species, but it is nevertheless quite good. When a single explanatory hypothesis (TCA) underlies the binding together of three domains so diverse in character, we have the sort of consilience that carries more weight with scientists that does, perhaps, underlay another virtue of theory.
It should be underlined that specific theories of evolution are not yet involved . The support given TCA by these diverse types of evidence does not depend any particular explanatory account of how species-change takes place. One could reject natural selection as the primary agent of evolutionary change, for examiple, and still find this argument for TCA convincing.22 Of course, a satisfactory explanatory account of how evolutionary change occurred would greatly strengthen the case for TCA. But in the light of the continuing debates about the adequacy of this or that feature of the neo-Darwinian model, it is important to us that there is a vast body of evidence for common descent that does not depend for its logical force on the further issue of how exactly the transitions from life-form to another came about. Fix missing words in the next paragraph!
Plantinga raises one objection that bears on TCA directly. Does there not seem to be an "envelope of limited variability" surrounding each species, so that a deviation of more than a small amount from the central species-norm leads to sterility? Would one not expect to find evidence of new species now and then appearing in the present (or perhaps being deliberately produced) if TCA is true? The first and simplest response is to note that in the plant d (in the forest, for example) new species have indeed been observed. And production of fertile hybrids is an important part of agricultural research. The y of populations of microorganisms to alter their structures quite basically relatively short times under the challenge of antibiotics is all too well-known. Defenders of the modern synthesis themselves insist on the extraordinary lity of the genotype, in the animal realm particularly; this stability is essential e maintenance of species differences, and some progress has been made rd an understanding of its molecular basis in the constellations of genes.
TCA does not require rapid change. The presumption is that the kind of species-change that would sustain TCA could take thousands of generations to accomplish. The rate of change required (as has been shown in detail in recent studies in population genetics) is far too slow for the sort of direct evidence to accumulate that Plantinga is asking for. But even more fundamentally, there are serious problems with the species concept itself, the concept underlying this objection. Ought it, for example, be based on the morphological difference (of the kind that paleontologists or comparative anatomists can attest to), or ought it be based on interbreeding boundaries (as naturalists have long preferred to maintain)?23 If we were to find the fossil remains of animals as different as a St. Bernard and a Chihuahua in the rock strata, we should assuradly label them as different species. But if we adopt the biological species concept according to which "species are groups of interbreeding natural populations that are reproductively isolated from other such groups,"24 how are we to apply this to populations that are widely separated in space or time? Mayr emphasizes that such application always involves complex and indirect forms of inference.25 The moral is not that the species-concept is so ambiguous as to be unusable, but only that such notions as species-change are far more difficult to handle than at first sight they seem to be. And more specifically, the claim that an "envelope of limited variability" surrounds each species has no precise empirical foundation.
I suspect that in the end this claim simply begs the question against TCA. It asserts that the sort of change TCA would require does not occur. But this is just the issue, and this is what is challenged by the three kinds of evidence described above, all of them pointing to TCA as the most reasonable explanation. What does Plantinga make of these? He deals with them, to my mind, in a quite unsatisfactory way: "Well, what would prevent [God] from using similar structures?", referring to the argument from homologies; and: "As for the similarity in the biochemistry of all life, this is reasonably probable on the hypothesis of special creation." Any attempt to reconstruct the past on the basis of traces found in the present can, of course, always be met with the objection: but God could have disposed matters so as to make it look as though it happened that way, even though it didn't. If TCA is correct, one would expect the sort of coherences that molecular biology is now turning up in such abundance. I can see no reason whatever to suppose that the hypothesis of special creation would antecedently have led us to expect this same range of evidence. Recalling the lines of a famous debate long ago about fossils, the God of the Christian tradition is surely not one who would deceive us by strewing around what would amount to misleading clues!
Let me stress once again the criterion of consilience. Evidence from three quite disparate domains supports a single coherent view of the sequence of branchings and extinctions that underlie TCA. If TCA is false, if in fact the different kinds of organisms do not share a common ancestry, this consilience goes entirely unexplained. It is all very well to say: "but God could have...." This hypothesis leaves the consilience exhibited by TCA an extraordinary coincidence. So it is not as though allowing the theistic alternative into the range of possible explanations alters the balance of probability drastically, as Plantinga supposes. TCA is, of course, an hypothesis, as any reconstruction of the past must be. But it remains by far the best-supported response, even for the theist, to the fast-multiplying evidence available to us.
5. Theories of evolution
What about the objections to the neo-Darwinian theory of evolution, as such, as distinct from TCA? Plantinga outlines a familiar objection to any theory which relies on natural selection as the primary mechanism of evolutionary change. There is no plausible evolutionary pathway (he argues) linking an eyeless organism, say, with an organism possessing the complex structures of the mammalian eye, such that every single stage along the way can be shown to be adlaptively advantageous. This is the oldest of objections to Darwin's theory; it was the primary criticism raised by Mivart in his Genesis of Species (1871). Darwin's own first response was to emphasize that his theory did not rely on natural selection alone.26
Among the other processes that he proposed, one in particular is still emphasized: change of function, where a structure that originally developed because of the adaptive advantage offered by one particular function takes on (especially under the impact of change of habitat or the like) a new function. Another process whose importance has only recently come to be recognized is genetic drift. In the isolated and often small populations that furnish the likeliest starting-point for the speciation-process, there can be a sort of genetic random sampling error that eventually marks off the smaller population from the parent population. And there can be "hitchhiker" effects of all sorts due to genetic linkage. These
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that the processes responsible for the origin of the main phyla are not well understood.31 Their explanatory model has already been substantially reshaped over the last fifty years, while retaining the original emphasis on the transformative powers of selection operating on individual differences. Undoubtedly, more such reshaping lies ahead. Like any other active scientific theory, the modern synthesis is incomplete, but its exponents argue, in great detail, that there are no in-principle barriers to its continued successful extension to the difficult cases. A minority has proposed that a more radical transformation is needed, one which abandons either the gradualism or the heavy reliance on selection that have marked the Darwinian approach.32 The most extreme view is represented by Michael Denton, who argues that all current theories of evolution are in principle inadequate to handle macroevolution, and that we have to await another quite different sort of theory.
Where does the burden of proof lie in a matter of this sort? The claim that principles of a broadly Darwinian sort are capable of explaining the origins of the diversity of the living world rests on the successes of the theory to date. These are very considerable; they span many fields and have shown intricate linkages between those fields. In particular, the theory has shown an extraordinary fertility as it has been extended into new domains; even when it has encountered anomalies, it has shown the capacity to overcome these in creative ways that are clearly not ad hoc.33 This is the sort of thing that impresses those who are actually in touch with the detail of this research. And it gives a prima facie case for supposing that the theory can be further extended to contexts not yet successfully treated. But, of course, this cannot in the strong sense be proved; it can only be made seem more (or less) plausible.
On the other side is the claim that theories of a Darwinian type are in principle incapable of handling certain classes of data: gaps in the fossil record, the origin of complex organs like the eye, the origin of the broad divisions of the living world (the phyla), or the like. Claims of this sort are hard to establish because they cannot anticipate the trajectory that the theory itself may follow as it is reworked in the light of new challenge. (Could the changes of the last century leading up to the modern synthesis have been foreseen?) This is not to: ay that such claims can never be established, or at least shown to be strongly supported. So it is not that the burden of proof falls to one side rather than the other. Rather, it is a matter of weighing up the merits of the cise on each side, and making some kind of comparative assessment, informed by parallels from the earlier history of science, and a very detailed knowledge of the history and contemporary situation of the various fields where the evolutionary paradigm is applied.
Plantinga formulates a second sort of objection to theories of evolution in general: they can never tell the whole story of the genetic changes involved, the rates of mutation, the links between gene adaptation, and so forth: "Hence we don't really know whether evolution is so much as biologically possible." But first of all, evolutionary explanation begins at the level of the biological individual and the population, not the gene; natural selection operates oil adaptations of whose genetic basis we may be (and usually are) entirely unaware. And the explanation is none the less real for that. But, more important, evolutionary explanation is of its nature historical, and historical explanation is not like explanation in physics or chemistry. It deals with the singular and the unrepeatable; it is thus necessarily incomplete. One must be careful to apply the appropriate criteria when assessing the merits of a particular explanation. An evolutionary explanation can never be better than plausible; the real problem lies in discriminating between different degrees of plausibility. The dangers of settling for a very weak sort of plausibility are real (Gould's "just so" stories). But the dangers of requiring too strong a degree of confirmation before allowing any standing to an evolutionary explanation ("Hence we don't really know...") are just as great.
The presumed inadequacy of current theories of evolution is part of what leads Plantinga to propose his own alternative. What exactly is it? Is it that God brought to be in a miraculous way each of the millions of species that have existed since life first appeared on earth? More than 99.99% of these are now extinct. May one ask why God would have created them? The thesis that Plantinga deems more probable than TCA is simply that "God created mankind, as well as many kinds of plants and animals, separately and specially." Perhaps he means that God just created the phyla (including the ones that have gone extinct?). As we have seen, it is the manner in which the major divisions of tile living world came to be that has provided the theory of evolution with its largest challenge. But why not all species? How is Plantinga to decide just which thesis is more probable than TCA? Presumably by checking to see what evolutionary theory has, in his view, been able to explain successfully. And then whatever is left over, God is more likely to have brought about miraculously.
God of the gaps? It certainly sounds like that. Whatever science cannot currently explain, or, more exactly, whatever one can make a case for holding that science could never in principle explain, is to be deemed the "special" work of God. One is reminded of eighteenth century natural theology. But Plantinga's intent is not apologetic, as that of natural theology was. It is not that he is using the supposed gaps in evolutionary explanation to support belief in the existence of a God who could plug the gaps. Rather, he considers it antecedently probable that God would intervene in ways like this; his critique of evolutionary theory is intended to locate the spots at which He is most likely to have intervened. Whenever evolutionary theory is unable to explain in a totally convincing way the origins of a particular kind, the hand of God is to be seen at work.
Plantinga claims that the Christian believer "has a freedom not available to the naturalist," because he or she is "free to look at the evidence ... and follow where it leads." This might be correct if he were to hold only that the believer holds open an extra alternative that allows him or her to be more critical of the shortcomings of the scientific theory. But he holds something much stronger than that: there is an antecedent likelihood of "special" intervention of this kind in cosmic process, and hence unless the scientist has a strong case, the hypothesis of Divine intervention has to be allowed the higher likelihood. Recall the two hermeneutic principles sketched by Galileo: the "confrontation" principle suggests that unless a clear case can be made for the scientific theory, the theological alternative should take preference. I am not sure that this does in the end allow the Christian believer more freedom than the naturalist. But whatever of that, it certainly ensures conflict; it is likely to maximize the strain between faith and reason.
6. The integrity of God's natural world
Plantinga's argument relies first and foremost on the premise that God's special" intervention in cosmic process is antecedently probable. Here is where he and I really part ways. My view would be that from the theological and philosophical standpoints, such intervention is, if anything, antecedently improbable. Plantinga builds his case by recalling that "according to Scripture, [God] has often intervened in the working of his cosmos." And the examples he gives are the miracles of Scripture and the life, death, and resurrection of Jesus Christ. I want to recall here a set of old and valuable distinctions between nature and supernature, between the order of nature and the order of grace, between cosmic history and salvation history. The train of events linking Abraham to Christ is not to be considered an analogue for God's relationship to His creation generally. The Incarnation and what led up to it was unique in its manifestation of God's creative power and His loving concern for His universe. To overcome the consequences of human freedom, a different sort of action on God's part was required, a transformative action culminating in the promise of resurrection for the children of God, something that (despite the immortality claims of the Greek philosophers) lies altogether outside the bounds of nature.
The story of salvation is a story about men and women, about the burden and the promise of being human. It is not about plants and animals; it provides no warrant whatever for supposing that God would have brought the ancestors of the various kinds of plants and animals to be outside the ordinary order of nature. The story of salvation does bear on the origin of the first humans. If Plantinga were merely to say that God somehow "leant" into cosmic history at the advent of the human, Scripture would clearly be on his side.How this "leaning" is to be interpreted is, of course, another matter.34 But his claim is a much stronger one.
To carry the argument a stage further: what would the eloquent texts of Genesis, Job, Isaiah and the Psalms lead one to expect? What have theologians made of these texts? This is obviously a theme that far transcends the compass of an essay such as this one. I can make a couple of simple points. The Creator whose powers are gradually revealed in these texts is omnipotent and all-wise, far beyond the reach of human reckoning. His Providence extends to all His creatures; they are all part of His single plan, only a fragment of which we know, and that darkly. Would such a Being be likely to "intervene" in His creation in the way that Plantinga describes? (I am uncomfortable with this language of "likelihood" in regard to God's action, as though we were somehow capable of catching the Creator of the galactic universe in the nets of our calculations. But let that be.) If one can use the language of antecedent probability at all here, it surely must point in the opposite direction.
St. Augustine is the most significant guide, perhaps, to the proper theological response to this question. He was the first to weave from biblical texts and his own best understanding of the Church's tradition the full doctrine of creation exnihilo, as Christians understand it today. And in the De Genesi ad litteram, his commentary on the very texts in Genesis where the writer speaks of the coming to be of the plant and animal world on the fifth and sixth "Days" of Creation, he enunciated the famous theory of the rationes serninales, the seed-principles which God brings into being in the first moment of creation, and out of which the kinds of living things will, each in its own time, appear.35 The "days," said Augustine, must be interpreted metaphorically as indefinite periods of time. And instead of God inserting new kinds of plants and animals ready-made, as it were, into a preexistent world, He must be thought of as creating in that very first moment the potencies for all the kinds of living things that would come later, including the human body itself:
In the seed, then, there was invisibly present all that would develop in time into a tree. And in this same way we must picture the world, when God made all things together, as having had all things which were made in it and with it when day was made. rhis includes not only the heavens with sun, moon, and stars ... but also the beings which water and earth contained in potency and in their causes, before they came forth in tile course of time.36
Augustine, for one, would not have attributed an antecedent probability to God's "intervening" to bring the first kinds of plants and animals abruptly to be, rather than having them develop in the gradual way that seeds do.
But what are we to make of Plantinga's objection that having life coming gradually to be according to the normal regularities of natural process is "semideistic," that it attributes too much autonomy to the natural world? He says:
God could have accomplished this creating in a thousand different ways. It was entirely within his power to create life in a way corresponding to the Grand Evolutionary Scenario ... to create matter ... together with laws for its behavior, in such a way that the inevitable37 outcome of matter's working according to these laws would be first, life's coming into existence three or four billion years ago, and then the various higher forms of life, culminating as we like to think, in humankind. This is a semi-deistic view of God and his workings.
He contrasts this alternative with the one he favors:
Perhaps these laws are not such that given enough time, life would automatically emerge. Perhaps he did something different and special in the creation of life. Perhaps he did something different and special in creating the various kinds of animals and plants.
His characterization of the first alternative as "semi-deistic" is intended to validate the second alternative as the appropriate one for the Christian to choose. But why should the first alternative be regarded as semi-deistic? He allows that it was within God's power to bring about cosmic evolution, but then asserts that to say He did in fact fashion the world in this way would be semi-deistic. This is puzzling. It would be semi-deistic in an extended sense perhaps, if we already knew that God had intervened in bringing to be some kinds of plants and animals, in which case the "Grand Evolutionary scenario" would attribute a greater degree of autonomy to the natural world than would be warranted. But this is exactly what we don't know. And to assume that we do know it would beg the question.
The problem may lie in the use of the label, "semi-deistic." A semi-deist, Plantinga remarks, could go so far as to allow that God "starts everything off," and "constantly sustains the world in existence," and even maintain that "any given causal transaction in the universe requires specific divine concurrent activity." All this would, apparently, not be enough to make such a view orthodox from the Christian standpoint. What more could be needed? Defining God's relationship with the natural order in terms of creation, conservation, and concursus, has after all been standard among Christian theologians since the Middle Ages. Perhaps what still needs to be made explicit is that God could also, if He so chose, relate to His creation in a different way, ii the dramatic mode of a grace that overcomes nature and of wonders that draw attention to His covenant with Israel and ultimately to the person of Jesus. The possibility of such an "intrusion" on God's part into human history, of a mode of action that lies beyond nature, must not be excluded in advance, must indeed be affirmed. I take it that the denial that such a mode of action is possible on the part of the Being who creates and may even also conserve and concur is what constitutes semi-deism, in Plantinga's sense of that term.
But someone who asserts that the evolutionary account of origins is the best supported one is not necessarily a semi-deist in this sense. Some defenders of evolution-notably those who deny the existence of a Creator and are, therefore, not deists of any sort-would, of course, exclude special creation in this in principle way. But there is no intrinsic connection whatever between the claim that God did, in fact, choose to work through evolutionary means and the far stronger claim that He could not have done otherwise. Nor, of course, is there any reason why someone who defends the evolutionary account of origin should go on to deny that God might intervene in the later human story in the way that Christians believe Him to have done.
In sum, then, at least four alternatives would have to be taken into account here. There are those who defend the evolutionary account of origins, and, rejecting the existence of God, would (if pressed) say that life could not possibly have come to be except through evolution. There may be those who maintain that God created, conserves, and concurs in the activity of the universe, but that He could not "intervene" in its history to bring new kin& of animals and plants to be, for example. These (if there are any such) are the semi-deists Plantinga describes. Then there are those who prefer the evolutionary account of origins on the grounds of evidence that this is in fact most probably ne way it happened, but are perfectly willing to allow that it was within the Creator's power to speed up the story by special creation of ancestral kinds of plants and animals, even though (in their view) this was not what He did. This is a view that a great many Christians from Darwin's day to our own have defended; it is the view I am proposing here. It is not semi-deistic. And finally, there is the option of special creation: that God did, in fact, intervene by bringing various kinds of living things suddenly to be.
When Plantinga presents two alternatives only, the second being that God might "perhaps" have intervened as defenders of special creation believe He did, he must be supposing that the other alternative, the "Grand Evolutionary scenario," is one that excludes such a "perhaps," i.e., that excludes, in principle, the possibility that God could have intervened in the natural order. What I am challenging is this supposition. The Thesis of Common Ancestry can claim, as we have seen, an impressive body of evidence in its own fight. It need not rely on, nor does it entail any in-principle claim about what God could or could not do.38
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finally, how should the Christian regard this thesis? Perhaps better, since ! evidently "distinctive threads in the tapestry of Christianity," in Planvocative metaphor, how might someone respond who sees in the Chris//ine of creation an affirmation of the integrity of the natural order? TCA i cousinship extending across the entire living world, the sort of coherLeibniz once argued) that one might expect in the work of an all-powerful vise Creator. The "seeds," in Augustine's happy metaphor, have been ~m the beginning; the universe has in itself the capacity to become what tined it from the beginning to be as a human abode, and for all we know 3e.
When Augustine proposed a developmental cosmology long ago, there was :he natural science of his day to support such a venture. Now that has What was speculative and not quite coherent has been transformed, the labors of countless workers in a variety of different scientific fields. ows the Christian to fill out the metaphysics of creation in a way that (I am ~d) Augustine and Aquinas would have welcomed. No longer need one that God added plants here and animals there. Though He could have the evidence is mounting that the resources of His original creation were t for the generation of the successive orders of complexity that make up Id.
s, common ancestry gives a meaning to the history of life that it previRed. In another perspective, this history now appears as preparation. The
~ world is for them no more than temporal succession. Things do not have natures fy their actions; rather, the fact that they act according to certain norms must be ttributed to God's intentions. There is no reason why God should not, for example, make new kinds of plants and animals appear, if He so wishes; since there is no zature, God is committed only to the reasonable stability of (more or less) regular n on which human life depends. The issue that separated the nominalists from the an defenders of real causation in nature is brought out very well in the essay by eddoso cited by Plantinga: "Medieval Aristotelianism and the Case against Secausation in Nature," in Divine and Hwnan Action, ed. T. V. Morris, Ithaca: Cornell y Press, 1988.
is perspective, the issue of "special creation" comes to be posed in a quite different i view which affirms the sufficiency of the natural order for bringing about the f life might be dubbed by the occasionalist as "semi-deist." When I read the h in which Plantinga says that someone who maintains that God creates, conid concurs in the activity of, the universe is "semi-deistic," my first reaction was to hat this committed him to occasionalism, since it is only from the occasionalist ve that this view of Gud's relationship with the natural order would be classed as ist." But Plantinga is quite evidently not an occasionalist; his treatment of natural nplies that he believes in the operation of secondary causation in nature. Thus, I .imed in the discussion above that Plantinga must have had something else in mely, the openness of creation to a supernatural order of grace and miracle. Ily, the occasionalist would be likely to believe that special creation is antecedently bable, and (in Berkeley's version, at least) might tend to question a theory, like the evolution, which depends on the reality of such causes as genetic mutation.
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uncountable species that flourished and vanished have left a trace of themselves in us. The vast stretches of evolutionary time no longer seem quite so terrifying. Scripture traces the preparation for the coming of Christ back through Abraham to Adam. Is it too fanciful to suggest that natural science now allows us to extend the story indefinitely further back? When Christ took on human nature, the DNA that made him son of Mary may have linked him to a more ancient heritage stretching far beyond Adam to the shallows of unimaginably ancient seas. And so, in the Incarnation, it would not have been just human nature that was joined to the Divine, but in a less direct but no less real sense all those myriad organisms that had unknowingly over the eons shaped the way for the coming of the human.39
Anthropocentric? But of course: the story of the Incarnation is anthropocentric. Reconcilable with the evolutionary story as that is told in terms of chance events and blind alleys? I believe so, but to argue it would require another essay. Unique? Quite possibly not: other stories may be unfolding in very different ways in other parts of this capacious universe of ours. Terminal? Not necessarily: we have no idea what lies ahead for humankind. The transformations that made us what we are may not yet be ended. Antecedently probable from a Christian perspective? I will have to leave that to the reader.
Notes
1The most obvious difference scarcely needs be stated. Plantinga is one of the most highly respected philosophers in the U.S., justly renowned for the quality of his scholarship and the care and rigor of his arguments. I bracket him here with the creation-science group, incongruous as such an association may seem, only because of the broad similarity of their theses in regard to special creation. I very much fear that this similarity may be sufficient to encourage creation-scientists to co-opt his essay to their own purposes.
2For a taxonomy of the ways in which faith and knowledge have been related by different Christian thinkers, see James Kellenberger, Religious Discovery, Faith, and Knowledge, Englewood Cliffs N.J.: Prentice-Hall, 1972, chap. 10.
3William B. Provine, review of Trial and Error: The American Controversy over Creation and
Evolution, Academe, 73 (1),1987, 50-52.4See McMullin, "The Rise and Fall of Physico-theology," section 4 of "Natural Science and
Belief in a Creator", in Physics, Philosophy, and Theology, ed. R. J. Russell et al., Rome: Vatican Observatory Press, 1988, 63-67.5Plantinga is using the term "myth" here in a technical sense, he reminds us, one that
should not of itself be made to connote falsity or fiction.6Maurice Finocchiaro provides a new translation of the Letter in his The Galileo Affair, Berkeley: University of California Press, 1989, pp. 87-118.
7Galileo introduces one further way of dealing with tensions between Scripture and natural science, suggesting that the biblical authors accommodated themselves to their hearers. This does not, in practice, reduce to either of the principles above. The notion of accommodation had already been hinted at by theologians as diverse as Thomas Aquinas and John Calvin. But this is not the place for an exhaustive analysis of the logical complexities of the famous Letter. See my "Galileo as a Theologian," Fremantle Lecture, Oxford, 1983 (unpublished), and jean Dietz Moss, "Galileo's Letter to Christina: Some Rhetorical Considerations," Renaissance Quarterly, 36, 1983, 547-576.
8Finocchiaro, The Galileo Affair, p. 94.
9See my Introduction to Galileo, Man of Science, New York: Basic Books, 1967, pp. 33-35.
10There is an abundant literature on this topic. See, for example, Robert Clifford S.J., Creation in the Hebrew Bible," in Physics, Philosophy, and Theology: A Common Quest for Understanding, ed. R. J. Russell, W. R. Stoeger and G. V. Coyne S.J., Notre Dame: University of Notre Dame Press, 1988, 151-170; Dianne Bergant CSA and Carroll Stuhimueller CP, "Creation according to the Old Testament," in Evolution and Creation, ed. E. McMullin, Notre Dame: University of Notre Dame Press, 1985,153-175; Bernhard W. Anderson, "The Earth is the Lord's: An Essay on the Biblical Doctrine of Creation," in Is God a Creationist? ed. I. M. Frye, New York: Scribner, 1983,176-196.
11There is a larger issue here of deciding on the proper approach to Scripture generally. Plantinga characterizes the Reformed Christian as one who takes "Scripture to be a special revelation from God himself." Thus, for example, the story of Abraham, including the details of where he lived and journeyed and how he came to father a son, becomes a matter for history in the modem sense of that term, to be construed (in Plantinga's view) as having the standing of science. There is an implicit literalist presumption here that an Unreformed Christian like myself, someone unsympathetic, that is, to the constraints of the "sola scriptura" maxim, would surely question. But to debate this would lead us far afield indeed.
12
131n his Letter to Christina, Galileo cited Augustine to warn against the dangers of opposing "unbelievers" (read: experts) on the basis of inadequate scientific knowledge (Finocchiaro, The Galileo Affair, p. 112). 1 suppose that this is what worries me most about the strategy Plantinga urges on his Christian readers. Though he stresses the importance of scholarship and the patient effort to understand, the reader who proceeds on his advice to do battle with defenders of evolution all too easily risks causing the sort of "laughter" that Augustine deplores, because of its negative effects on the credibility of the Christian message generally.
14As an illustration of how complex the notion of temporal beginnings has become, the Hawking model does not imply that the universe is infinitely old (as that phrase would ordinarily be understood) but rather that as we trace time backwards to the Big Bang, the normal concept of time may break down as we approach the initial singularity some fifteen
billion years ago. The history of "real time" (as Hawking calls it) would still be finite in the same terms as before, as he explicitly points out (A Brief History of Time, New York: Bantam Books, 1988, p. 138).15The question of whether or not the time elapsed in cosmic history is finite or infinite depends, in part, on the choice of physical process on which to base the time-scale, particularly on whether it is cyclic or continuous. The question of the finitude or infinity of past time, so much debated by medieval philosophers and theologians, cannot straightforwardly be answered in absolute terms. The notion of time-measurement is far more complex and theory-dependent than earlier discussions allowed. But the theological point of the biblical account of creation remains untouched by technical developments such as this. See McMullin, "How Should Cosmology Relate to Theology?" in The Sciences and Theology in the Twentieth Century, ed. A. R. Peacocke, Notre Dame: University of Notre Dame Press, 1981, p. 35.
16As Plantinga himself recognizes: "There isn't the space here for more than the merest hand waving... " But when the stakes are as high as they become by the end of his essay, one may fairly question whether hand waving is likely to be enough.
171 would like to acknowledge my debt to the many who in discussion have helped me overcome the bafflement that evolutionary theory induces in the non-expert. In particular, my thanks go to Phil Sloan, Bill Charlesworth, Francisco Ayala, Bob Richards, and John Beatty.
18Plantinga distinguishes between the Thesis of Common Ancestry and the attempt to explain common ancestry by some mechanism or other. But he calls the latter "Darwinism,"
19See L. von Salvini-Plawen and E. Mayr, "On the Evolution of Photo-receptors and Eyes," Evolutionary Biology, 10, 1977, 207-263.
201n his most recent discussion of the relation between microevolution and macroevolution, Mayr writes: "Almost every careful analysis of fossil sequences has revealed that a multiplication of species does not take place through a gradual splitting of single lineages into two and their subsequent divergence but rather through the sudden appearance of a new species. Early paleontologists interpreted this as evidence for instantaneous sympatric speciation [speciation over a single area], but it is now rather generally recognized that the new species had originated somewhere in a peripheral isolate and had subsequently spread to the area where it is suddenly found in the fossil record. The parental species which had budded off the neospecies showed virtually no change during this period. The punctuation is thus caused by a localized event in an isolated founder population, while the main species displays no significant change" (Toward a New Philosophy of Biology, Cambridge, Mass.: Harvard University Press, 1988, p. 415). This theory of allopatric speciation (speciation involving a second-in this case a geographically isolated but adjoining-territory) allows Mayr to modify the gradualism of the original Darwinian proposal, while retaining the basic Darwinian mode of explanation and avoiding the (to him) objectionable "punctual" events of the Gould-Eldredge scenario. But the debate is by no means closed.
21For a brief review of this evidence, see Francisco Ayala, "The Theory of Evolution: Recent Successes," in Evolution and Creation, ed. E. McMullin, 59-90.
22 In this regard, the position adopted by Michael Denton, perhaps the most sweeping critic of evolutionary theory now writing, is quite puzzling. On the one hand, he finds the sort of sentience described above altogether remarkable: "It became increasingly apparent as and more sequences are accumulated that the differences between organisms at a molecular level corresponded to a large extent with their differences at a morphological level; and that all the classes traditionally identified by morphological criteria could also be detected by comparing their protein sequences.... The divisions turned out to be more mathematically perfect than even the most die-hard typologists would have predicted" (Evolution: Theory in Crisis, Bethesda, Md.: Adler and Adler, 1986, pp. 276, 278). But the distances between the molecular sequences characteristic of different species can only be explained (he argues) by postulating a remarkably uniform "molecular clock" marking the rate of change in the constituents of particular kinds of molecules (and varying from one kind to another), and such a "clock" (he maintains) is impossible to understand on neo-Darwinian principles. What would seem, at best, to follow from this is that neo-Darwinian theory can't explain the uniformity of the postulated "clock." But he assumes that he has also justified TCA, while providing no hint himself as to how the correspondences he finds so remarkable might be explained by something other than common ancestry.23These are only two of the many possibilities. There is an enormous literature on this topic. See, for example, the papers gathered in Section VII of Conceptual Issues in Evolutionary Biology, ed. Elliott Sober, Cambridge, Mass.: MIT Press, 1984, and E. Mayr, Animial Species and Evolution, Cambridge, Mass.: Harvard University Press, 1963, 400-423.
24Mayr, Toward A New Philosophy of Biology (TNPB), p. 318.
25A further problem is suggested by the notion of a "natural" population. Reproductive isolation in the animal world is due, in the first instance, to behavioral barriers, which are the main isolating mechanisms (Mayr, TNPB, p. 320). Under artificial circumstances, such barriers can be overcome, but this will not necessarily give rise to new biological species. Likewise, deliberate interbreeding to produce new varieties of domestic dog, for example, will not produce a natural population with its own behavioral barriers to outbreeding.
261ndeed, he showed some uncharacteristic indignation in his comment in the last edition of the Origin of Species (1872): "As my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of that work, and subsequently, I placed in a most conspicuous position-namely, at the close of the Introduction-the following words: 'I am convinced that natural selection has been the main but not exclusive means of modification.' This has been of no avail. Great is the power of misrepresentation" (p. 395).
27For a useful review, from the
point of view of the modern synthesis, see E. Mayr, "The Emergence of Evolutionary Novelties," in Evolution after Darwin, vol. 1: The Evolution of Life, ed. Sol Tax, Chicago: University of Chicago Press, 1960, 349-380.28Mayr, for instance, repudiates what he calls "selectionist extremism," and says that 11 much of the phenotype is a b
y-product of the evolutionary past, tolterated by natural selection but not necessarily produced under current conditions.... The mere fact of the vast reproductive surplus in each generation, together with the genetic uniqueness of each individual in sexually reproducing species, makes the importance of selection inescapable. This conclusion, however, does not in the least exclude the probability that random events also affect changes of survival aikd of the successful reproduction of an individual. The modern theory thus permits the inclusion of random events among the causes of evolutionary change. Such a pluralistic approach is surely more realistic than any one-sided extremism" (TNPB, pp. 136,140). Still, he also wants to say that the modern synthesis for which he is perhaps the leading spokesman "was a reaffirmation of the Darwinian formulation that all adaptive evolutionary change ii due to the directing force of natural selection on abundantly available variation" (TNPB, p. 527; emphasis mine).29See S. J. Gould and R. Lewortin, "The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the A
daptationist Programme," Proc. Royal Society London, B205, 1979, 581-598. 0ne such problem is that a mutation affecting the phenotype in a major way would require co-ordinated change in hundreds of genes; another is that a macro-mutation in a single individual would not be enough, in a sexually reproducing species, to establish a new kind right away. The role of mutations in evolutionary change is much less dramatic than is often conveyed in popular accounts; they serve mainly to augment the stock of variations in a population upon which recombination can work. (Recombination is the blending of fraternal and maternal DNA in each new biological individual in a sexually reproducing species; it is responsible for the fact that each such individual is different from all others.)311n the early stages of life's development on earth, sixty or seventy different phyla (morphological types) developed, most of which became extinct. Not a single new phylum has originated since the Cambrian period, more than four hundred million years ago. It would seem that the genetic structures of this early period were not as fixed as they later became. Selection may thus have had fewer constraints then than later on when highly cohesive genotypes developed; the rate of species-change might thus have been quite rapid, lowering the chances of an adequate fossil record of the changes.
32The differences between the "punctuated equilibrium" model of Gould and Eldredge and the standard one of the modem synthesis are not nearly as great as was originally claimed. In particular, Gould's original assertion that only a "non-Darwinian" theory could handle the evidence from the fossil record was quite clearly based on a very narrow construal of what ought to count as "Darwinian." Mayr has to my mind convincingly shown that Gould's own model is compatible with Darwinian principles (TNPB, chapter 26).
33Denton's comparison of the modern synthesis to late Ptolemaic astronomy with its profusion of epicycles, and his conclusion that it is a paradigm in crisis (Evolution, chapter 15) cannot, I think, be sustained. The crucial disagreement between us would be as to what constitutes and ad hoc modification (what he, oddly, calls a "tautology").
311n the early stages of life's development on earth, sixty or seventy different phyla (morphological types) developed, most of which became extinct. Not a single new phylum has originated since the Cambrian period, more than four hundred million years ago. It would seem that the genetic structures of this early period were not as fixed as they later became. Selection may thus have had fewer constraints then than later on when highly cohesive genotypes developed; the rate of species-change might thus have been quite rapid, lowering the chances of an adequate fossil record of the changes.
32The differences between the "punctuated equilibrium" model of Gould and Eldredge and the standard one of the modem synthesis are not nearly as great as was originally claimed. In particular, Gould's original assertion that only a "non-Darwinian" theory could handle the evidence from the fossil record was quite clearly based on a very narrow construal of what ought to count as "Darwinian." Mayr has to my mind convincingly shown that Gould's own model is compatible with Darwinian principles (TNPB, chapter 26).
33Denton's comparison of the modern synthesis to late Ptolemaic astronomy with its profusion of epicycles, and his conclusion that it is a paradigm in crisis (Evolution, chapter 15) cannot, I think, be sustained. The crucial disagreement between us would be as to what constitutes and ad hoc modification (what he, oddly, calls a "tautology").
34"God fashioned man from the dust of the earth and breathed into his nostrils the breath of life" (Genesis 2, 7). The "fashioning" here could be that of a billion years of evolutionary preparation of that "dust" to form a being that for the first time could freely affirm or freely deny his Maker. Pius XII in his encyclical Humani Generis (1951) allowed that such an evolutionary origin of the human body was an acceptable reading of the Genesis text. But he added that the human soul could not be so understood; it had to be specially "infused" by God, presumably not just in the case of the first humans, but all humans since. Many theologians today would find the Platonic-sounding dualism underlying this assertion troubling. The uniqueness of God's covenant with men and women and of the promise of resurrection does not require that there be a naturally immortal soul, distinct in its genesis and history from its "attendant" body. But it is unnecessary to develop this issue here, since Plantinga's challenge extends to the evolutionary account of the plant and animal worlds, and not simply of the human.
35For a full discussion, see "Augustine's 'seed principles,"' section 4 of my Introduction to Evolution and Creation, 11-16.36The Literal Meaning of Genesis, 2 vols., translated by J. H. Taylor, New York: Newman, 1982, V, 23; p. 175 (Translation slightly modified.).
37"Inevitable" is a word that defenders of evolution, whether theists or not, would be uneasy with. it suggests that the evolutionary process is at least in a general way deterministic or predictable. But this is just what nearly all theorists of evolution would deny.
38There is one further perspective on this matter of semi-deism that I have deliberately set
aside above. The occasionalists of the fourteenth century maintained that God is the only cause, strictly speaking, of what happens in the world. What appears to be causal actionmore of 38
39Though the alert reader will have caught echoes of the theology (not the biology; see section 5 above) of Teilhard de Chardin, the affinities with the Christology of Karl Rahner are more immediate perhaps. See, for example, his "Christology within an Evolutionary View of the World," Theological Investigations, Baltimore: Helicon, vol. 5, pp. 157-191