Untangling Evolution

Stephen M. Barr

Copyright (c) 1997 First Things 78 (December 1997): 14-17.

There’s no denying that historically evolution has been harmful to religious faith. It has contributed to undermining confidence in Scripture and to promoting a naturalistic view of man. In our own age, such atheists as Daniel Dennett, Richard Dawkins, Stephen Jay Gould, and Carl Sagan have claimed that natural selection destroys the Argument from Design and with it any reason to believe in God. But if we can set aside the historical effect of the theory of evolution—and set aside the theological meanderings of those who want to use the theory as a stick with which to beat religion—we can find that nothing in the theory itself creates intellectual difficulties for Christian or Jewish belief. Evolution raises important questions for faith, but not difficulties.

In The Blind Watchmaker, Dawkins argues that natural selection can give "design without design." The "watch" of the title refers to the famous argument of William Paley, and in this context stands for the intricate structures to be found in the biological world, which many think give proof of a divine Maker. There is no maker, says Dawkins, except the universe itself—his "blind watchmaker."

To eliminate design, as Dawkins would do, one must have some mechanism that produces form from formlessness, order from chaos. But no scientific explanation does this. Science explains order by deriving it from order. Consider the formation of crystals, an oft-cited example of the spontaneous emergence of order. The patterns exhibited by crystals are a reflection of underlying symmetries and principles of order that apply to the atoms themselves, to the space in which they move, and to the laws that govern their behavior. These, in turn, can be traced to deeper levels of physical law. No matter how profoundly one penetrates into the hidden workings of the world, it is not some formless flux that is encountered, but ever more remarkable and beautiful structure.

And this is just the point. To have evolution one must have a universe. And not just any universe will do. Rather, it is beginning to appear that the laws of nature must be carefully arranged. The facts of evolution, like the facts of reproduction, are no less astonishing for being natural. If they are natural we should be astonished at the laws of nature. What immortal hand or eye framed their fearful symmetry? Perhaps none, if the laws themselves also evolved by some process analogous to natural selection. But that would put us back where we started, since any such process must itself have been governed by laws of some kind.

The Argument from Design remains perfectly healthy, then, even if we concede to natural selection all that is claimed for it by the most naturalistic theory of evolution. But, as it happens, there is no reason to concede so much to it. It is far from clear that natural selection is really up to the job, not only of crafting complex organisms, but even of explaining what goes on in the simplest living cell, as the molecular biologist Michael J. Behe has amply demonstrated in his recent book, Darwin’s Black Box. Moreover, the times available for natural selection to have worked these wonders were far shorter than was commonly supposed. The Cambrian Explosion, that wild proliferation of new forms of life that occurred about 540 million years ago, took only a few million years. And it is now generally admitted that most species make their appearance in the fossil record quite suddenly, geologically speaking.

Unfortunately, many religious believers—and not only biblical literalists—have taken this argument one step further than it has to be or ought to be taken, to deny that life on earth has a common ancestry. I find this quite puzzling. If it can be shown that a reptile cannot evolve into a mammal or a fish into an amphibian by natural selection alone, then there must have been divine intervention. Nothing is added to the force of this argument by denying that the reptile or the fish did so evolve. The atheist is out on a limb, so why try to saw down the whole tree, especially against the grain of so much evidence?

The evidence for the common ancestry of life is very strong. To give some idea of what it is, I will simply list a few of the kinds of questions that common ancestry gives an answer to. Why is it that bats and whales have so much in common anatomically with mice and men? Why do virtually all vertebrate forelimbs have the same basic "pentadactyl" (five-fingered) design? (This is one of numerous examples of "homologous" structures exhibited by related species.) Why do some species of whales have vestigial and quite useless pelvic and leg bones, when they have no pelvises or legs? Why are all mammals native to Australia marsupials? Why is there a sequence of reptiles in the fossil record (the "therapsids") with a clear progression from reptilian to mammalian characteristics? Why does the record of life on earth show a clear trend towards greater complexity? Why is it found that the most ancient bird fossils are reptilian, and the most ancient whales have feet? Why do salamander embryos have gills and fins that they will never use?

The point in asking these and many similar questions is not only that common ancestry can answer them, but more significantly that no real answer on any other basis has been found to any of them. (There is certainly no theological explanation of why bats, humans, frogs, and lizards all have five fingers.)

Unanticipated discoveries in various fields have strengthened the case for common ancestry. The theory of plate tectonics and continental drift resolved a number of evolutionary puzzles (though some remain, such as the existence of the platyrrhine monkeys of South America). And dramatic confirmation has come from gene and protein sequencing. Particularly striking is the phenomenon of "molecular clocks." (This refers to data obtained by comparing certain proteins and nucleic acids in different species. It is found that the variation of these molecules from species to species over a vast taxonomic range exhibits patterns that are hard to explain unless one assumes that the molecular degree of difference between two species is in some cases a measure of the period of time that they have been evolving separately—that is, since they had a common ancestor.)

Let us suppose not only that evolution (that is, the common ancestry of all life on earth) is true, as I think the evidence shows, but that natural selection is a sufficient mechanism for it, which the evidence does not show. What difficulties would that create for religious belief? Unfortunately, the issues are sometimes clouded by a failure to make distinctions.

The critical distinction is between divine intervention and the other ways God acts. By "intervention" I mean something that goes beyond the order of nature, an effect produced by God in the world that contravenes either the laws of nature or the laws of probability. Intervention is not to be confused with providence. While faith tells us that all events are governed by providence, divine intervention is rare. Even events in which we think we can discern the hand of providence do not usually involve anything beyond what is naturally possible. A child’s voice in a garden is nothing extraordinary, and yet St. Augustine heard such a voice and it changed the course of history.

Creation means that God brings into existence all that is, and providence and design mean that He orders all that is. These concepts do not necessarily imply intervention. It is true that the account of the creation of plants and animals in Genesis is suggestive of intervention: there is no mention there of natural processes (unless they are hinted at when Genesis says that the earth and waters "brought forth" the various living creatures). But Genesis describes the creation of the sun and stars in a way that is even more suggestive of divine intervention. (The firmament does not "bring forth" the sun; God "sets" it there.) Yet modern astrophysics has an adequate naturalistic explanation of the formation of the sun and stars, which is not challenged even by most of those who question evolution.

The sun is an ordinary star, and there are many billions like it. But if the laws of nature were in certain respects even slightly different, no such stars would exist, and hence life as we know it would not exist either. Even apart from faith, therefore, we can recognize the role of providence and design in the existence of the sun and stars, although it is now clear that no intervention was required to produce them.

There are those who argue, nevertheless, that a consistent—or at least a full-blooded—theism requires intervention for the production of living things, since the alternative to intervention is a "naturalism" based on "blind forces" and "chance." "Naturalism" can be the denial that anything whatever goes beyond the nature of material things. Such naturalism denies a priori even the possibility of divine intervention, because it denies the existence of God. But not all naturalism is of this kind. There is also a naturalism whose opposite is the prescientific view of nature that one finds among primitive peoples. This naturalism is based on true progress in knowledge of the physical world. Science finds no signs of divine intervention in the realm of inanimate matter. In astrophysics, geology, chemistry, or plasma physics, for example, one does not encounter the miraculous.

In the human sphere things are different. Both faith and reason tell us that man has a spiritual soul, and therefore that purely naturalistic accounts of human realities are false. We believe, as well, that divine intervention has happened in human affairs, in particular in the miraculous events of salvation history.

Since the world of plants and animals is intermediate between the human and the inanimate, it is not obvious whether we should expect to find signs of intervention there. Ironically, there are stronger grounds for expecting it if human beings did evolve. If there had to be reptiles for there later to be men, then it would seem quite in character (if one may speak so) for God to have intervened to produce reptiles, by arranging, say, the necessary mutations or selective pressures.

On the other hand, one might expect no intervention in those parts of the biological world that do not involve man in any significant way. There is an excellent book called Evolution: A Theory in Crisis, which has deservedly become a classic of the anti-Darwinian literature. (It presents the arguments for evolution with exemplary fairness and honesty, and it should be noted that its author, Michael Denton, has since come to believe in evolution.) Among many other fascinating things, one can find in this book a discussion of the copulatory apparatus of the male dragonfly, which is apparently a prodigy of complexity and quite unique in the insect world. How, Denton asked, could such a thing have been produced by natural selection? That question is difficult to answer, but maybe no more so than the following one: Why would God, Who so rarely intervenes in nature, do so to produce a unique way for dragonflies to copulate?

A clergyman at a conference on the subject of creation, overhearing me pose this question, inquired with some slight sarcasm whether I had received any telegrams from the Almighty answering it. But I do not think it necessarily absurd to ask what God would be likely to do, for though God’s ways may often seem inexplicable to us, God is not arbitrary. I believe that Isaiah foretold future events. But I do not believe that Jeanne Dixon was able to do so. God’s interventions have followed a pattern, and Jeanne Dixon does not fit it. A presumption in favor of a natural explanation in a particular case, then, can be a result of theological considerations, rather than of atheistic or materialistic presuppositions.

There is much talk on both sides about "blind forces" in connection with evolution. But there is nothing in such an idea that should shock a Christian or Jew. It is not the forces of nature that see, but God. Indeed, it is precisely the blindness of nature that allows us to recognize that events must be guided by something beyond nature, by providence rather than by fate, or destiny, or occult forces. The blindness of nature argues against pantheism and all of nature-worship ancient and modern, not against theism. The idea that God works His will through blind agents is as biblical as the story of Joseph in the Old Testament. The notion of blind natural forces came not from a rejection of God, but of Aristotle, and in particular of his teleological physics. It was this that made modern science possible, and it did not result from a conflict between naturalism and supernaturalism, but from a conflict between two kinds of naturalism.

Similar ambiguities surround the notion of "chance." Evolutionists ascribe things to "random" mutations, and many feel that this in itself involves a denial of a rational cause or design. But the notions of chance, randomness, and probability are notoriously subtle. A simple example will illustrate this. It is well-known that the most common letter in English is "e," followed by "t," and then "a." These are statements about probabilities. As it happens, they hold true for the Gettysburg Address, as they do for most sufficiently long passages in English. But no one should doubt that Lincoln crafted this speech with great care, with every word—and consequently every letter—chosen to serve a purpose. By analogy, the fact that God’s providence extends to every event in the universe does not imply that notions of chance and probability will not apply to them. The mutations that led from the first single-celled creature to the genus Homo may have been chance events from a certain point of view, but as Pope John Paul II has said, every one of them was foreseen and willed by God. (I hasten to add that none of this is to suggest that it has been shown that random mutations and natural selection are sufficient as a mechanism of evolution. As of this moment, I would say, the arguments favor those who deny this.)

What troubles most people about evolution is its application to human beings. One reason is that some think it degrading to have apes as ancestors. But it is not obviously more dignified to have come directly from slime. A deeper reason is the discontinuity that we know to exist between human beings and the rest of creation—between spirit and matter. Yet it is hard to see that this is more of an issue for evolution than it is for human reproduction. We are in no position to observe the immediate antecedents of Adam, but we know that those of each human child today were a sperm and an egg, which are without doubt purely material in themselves.

The real question is whether man is more than a mere arrangement of atoms. If he is, then it would seem to matter little how those atoms came to be arranged as they are, whether by natural processes of evolution or reproduction, or by supernatural intervention. Pope John Paul II and Pope Pius XII have indicated the essential point: As long as we maintain the scriptural and philosophical truth that man has a spiritual nature, there can be nothing to fear in merely biological facts.

It is otherwise for the atheist. It is his faith that is at stake in this controversy, not ours. His faith requires that chance and natural law must be adequate to explain the facts of evolution. If they do not appear to be adequate, he must nevertheless insist that they are. It is for him, then, to dogmatize about strictly scientific matters, not for us. We can be content, and should be content, to be guided only by the evidence.

Stephen M. Barr is Associate Professor of Physics at the Bartol Research Institute, University of Delaware.