The Grand Coherence, Chapter 8: Biology and Christianity

This post is part of the book The Grand Coherence: A Modern Defense of Christianity. For all the links in the book, see this introductory post.

We're now ready to wrestle with one of the greatest challenges to the Christian faith in modern times. When the famous memoirist Henry Adams (1838-1918) was young, he prayed, he went to church, he had clergymen in his family, and religiosity, albeit only of a “mild deist” sort, was normal in his elite Bostonian social circle. Long afterwards, he wrote that “of all the conditions of his youth which afterwards puzzled the grown-up man, this disappearance of religion puzzled him most” (The Education of Henry Adams, chapter 2). 

He was not alone, though. Many went the same way in the wake of the 1859 publication of Charles Darwin’s Origin of Species. A mild deism made a lot of sense in the 1840s, for if you weren't adventurous enough to believe in miracles, there was still a vast amount of order and design in living nature, which had to be explained somehow, and for which science had no explanation. Darwin supplied an ingenious and impressive story of how life came to be which did not rely on God, and thereafter, atheism seemed the most rational option for those who find miracles distasteful. There have been religious declines and religious revivals since then, but Darwinian evolution has persistently been a force tugging minds away from religion, and for recent champions of atheism such as Daniel Dennett (1942-) and Richard Dawkins (1941-), Darwinian evolution is the bastion of truth from which they launch their sorties against faith.

First, let's see what Darwin got right.

Charles Darwin’s great accomplishment was to explain why living creatures are adapted to their environments. In so doing, he transformed our understanding of the natural world by eliminating, or at least marginalizing, the Aristotelian notion of telos. Usually translated as “final cause,” telos could be variously rendered into English as purpose, function, goal, fulfillment, perfection, flourishing or even happiness, depending on context and with appropriate qualifications. Teleology was crucial to the way medievals understood the world, but it didn't fit into a modern scientific worldview. Darwin showed how it could be dispensed with, and replaced with a new kind of reasoning, which might be described as reasoning from ecological equilibrium.

Aristotle was a philosopher of enormous range, but above all, he was interested in biology. He thought it evident that purpose is important in understanding the biological world, so he made telos the most important of four kinds of “causes” that govern our world. For Aristotle, it is a general principle that nature is pervaded by telos, and he thought it is the telos of a stone to fall, or of a planet to move along a certain path through the night sky, in the same way that it is the telos of an acorn to become an oak. Since Aristotle was the single most influential philosopher in Western civilization for much of the next two thousand years, this teleological thinking became very widespread. 

From the 17th century on, a new post-Aristotelian style of science swept through the Western mind, which displaced the old final causes with more exact and ubiquitous efficient causes, and saw a more lawlike and deterministic order in the physical universe, with less room for purposes to play a role. Telos no longer fit. And yet the whole biological world was evidently thick with functions and purposes. For a while, “natural theology” flourished, and the purposiveness that obviously pervades living nature was taken as indicative that a creative, personal God had purposefully created living nature, but that didn't really answer all the questions. Darwin changed that by elucidating how the continuous operation of natural selection, cogently labeled “survival of the fittest” by Darwinist thinker Herbert Spencer, ensures that creatures must perform some ecological function efficiently, and the parts of a creature must serve some purpose, for them to survive and reproduce. It dovetailed nicely with the new physics, and Darwin’s new theory quickly became the dominant paradigm in biology.

It works like this. At any given time, there is some variation among the members of any given species. Not all specimens survive, not all of those that survive reproduce, and some of those that reproduce have a lot more offspring than others. So each generation of a species may be different from the last. And it will be, unless the population is optimized in a particular way to make the gene pool stable. Odd, maladaptive features will be bred out of a population. Traits that are definitely superior will become universal over time. Minority traits can retain market share if they are beneficial when rare. A well-adapted species can retain some variety, but everything about it has a purpose in one sense, while in another sense, purpose isn’t at work as a causal factor. The appearance of purpose springs from the nature of equilibrium.

Richard Dawkins’ famous book The Selfish Gene, to which my thought is much indebted, supplies a brilliant metaphor for understanding how ecological equilibrium maintains itself and shapes the biological world. Genes, a loose term for the minimum functional units of DNA, are in constant competition with each other, as they continue from generation to generation through the bodies of organisms that carry them. They are naturally immortal, cycling through the transient, disposable “somas” (bodies) of individual organisms, and using them as instruments for their own perpetuation. Organisms are sometimes therefore instinctively altruistic, most notably to kin, but the genes are ruthlessly “selfish,” in the sense that the ways they shape human instinct, when not merely accidental, are always narrowly oriented towards their own survival. 

Together, these selfish genes comprise the gene pool. From an evolutionary perspective, the species almost is the gene pool, or at least, the continuity and stability of the species depends on the continuity and stability of its gene pool. Some genes will be more common than others, but each gene must tend to maintain its market share, large or small, from generation to generation. If that’s not the case, the species will change over time as evolution selects for some genes and against others. The species is stable to the extent that the gene pool is in equilibrium.

The stability of a species depends, among other things, on its being adapted to its environment. If it is poorly adapted, it may still survive, but it will come under strong selective pressure to become better adapted. The gene pool will shift over time, as some genes contribute to flourishing, and tend to multiply, while others detract from it, and tend to die out. The gene pool may allow for tremendous variety within a species, as we observe in the case of dogs. It is assumed that at some point divergent populations would lose the ability to interbreed and produce fertile offspring, thereby forming separate species, though as far as I've been able to discover, such “speciation” has not been observed in experimental settings for sexually reproducing biota. What applies to species applies loosely to whole ecosystems. All the gene pools of the various species are stable, and the populations are relatively stable, and the ecosystem is a great equilibrium, which would probably persist for thousands or millions of years if not interfered with. Evolutionary competition keeps the system in balance. That’s why we can anticipate that a country’s landscape will be similar if we come back to it after many years or centuries, even if none of the specific organisms are still living.

Darwinian evolution rendered the Aristotelian idea of telos somewhat obsolete. Before Darwin, teleology was needed to explain the orderliness of life and the pervasiveness of evident purpose in the biological world. After Darwin, telos could disappear from the scientist’s explanatory toolkit, a pleasing simplification of metaphysics. Adaptation, not telos, explained the variety of creatures in nature, and their stability. It wasn’t some mysterious telos keeping them fixed, but ecological equilibrium. However they came about, species had to be a certain way in order to survive. Genes in the gene pool are in competitive equilibrium, reproducing themselves from one generation to the next just enough, on average, to retain their market share, and so the gene pool persists, and with it, the species. This kind of reasoning from ecological equilibrium has come to pervade modern biology. It allows biologists to fully appreciate the pervasive presence of purpose in living nature without making purpose a fundamental causal factor in nature. Purpose is a causal factor in a way. It does make sense to say, and is true in a sense, that a bird has wings for the purpose of flying. But that only means that it’s an ecological equilibrium for birds to have wings because wings that confer the power of flight facilitate the survival and reproduction of birds, and that has long enabled flying bird populations to persist in nature in ecological niches where non-flying birds could not. Purpose is an emergent property, explained by the more fundamental fact of ecological equilibrium. 

I will lean heavily on the concept of the selfish genes and the method of reasoning from ecological equilibrium when I make the case for Christian sexual ethics in chapters 11, 12, and 13.

Unfortunately, the useful practice of reasoning from ecological equilibrium as a way to understand the forms taken by life has been, from Darwin down, all mixed up with a wildly overambitious and downright fanciful story about natural history, called the theory of evolution.

The theory of evolution does not consist only or mainly in the claim that species change over time due to natural selection. It is the claim that all life on earth, or in the universe, emerged in no other way than through evolutionary processes of natural selection and mutation. All the seeming design of the living world emerged originally, by this account, accidentally, but because life forms self-replicate, and some self-replicate more than others, lucky accidents were preserved, giving rise to the whole cornucopia of fascinating designs that the biosphere presents for our wonder, gratitude, and use. 

Let's consider how a theory like this ought to be tested. What would it take for us to really be able to claim to know that Darwinian evolutionary mechanisms are powerful enough to have generated the vast, dazzling, magnificent, bewildering, ingenious, exquisite array of life as we know it? What evidence would we need to be sure that that's what really happened?

Well, first, it would be nice to have DNA from all the biota that ever lived, and living specimens of at least most of them. Let’s call them the Universal DNA Library and the Universal Zoo. And don’t let the word “zoo” make us forget that it includes plants, fungi, bacteria, and so on.

Of course, to keep specimens alive in the Universal Zoo at all, you would need to know something about the habitat, behavior, and diet of all these organisms. 

But you’d want to know a lot more about the habitat than just enough to keep them alive, because you’d need to know what selective pressures the species faced. So let’s assume you know at least what species lived side by side over any part of their range at any time in history, and something about the temperature, weather, landscape, and nutrient or chemical environments of the places where each organism had historically lived. 

You would need to thoroughly understand how the features of each organism made it well adapted to its environment.

Next, you would need to form a comprehensive system of hypotheses about ancestry linking all the creatures. For any creature X, you would have a hypothesis “X descended from Y, which descended from Z…, [and many more steps]... which descended from Q, the organism that emerged spontaneously from the prebiotic soup.” Then you would need to test all these hypotheses.

How would you test the hypotheses? Well, first, you would also need to know a lot about the population history of each species. How many of them lived, overall and in particular environments and historical periods?

Now comes the hard part. 

For each link between an ancestral species and a descendant species, you would have to settle whether the change from ancestor to descendant could realistically have happened by chance mutation and natural selection, in one or more steps. 

To do that, you would first need to catalog all the relevant differences between the ancestor and descendant species. Any changes in the genome that play any causal role in useful adaptations by the descendant that would have helped it survive would need to be explained. Because, in this scenario, the Universal Zoo is complete, you wouldn’t have to worry about intermediate creatures between ancestors and descendant species. If any such evolutionarily stable and populous creatures existed, they’d be in the Zoo themselves. The changes from immediate ancestors to immediate descendants would be the minimum evolutionary steps, which, if they occurred naturally by Darwinian processes, would need to have happened by chance mutation.

The next step would require great skill in the science of probability. For each useful change, you would need to calculate (a) the probability that it would occur, and (b) the probability that, having occurred once, it would be preserved in the population long enough to propagate through it. That gives you the number, so to speak, of sides on the dice that each species would have to roll in order to make the proposed evolutionary step. The historic population of the species in key adaptive windows is the number of rolls allowed. Then you could calculate the odds that a given evolutionary step could be successfully taken.

For example, suppose you want to know whether fish X could have evolved feature Y, maybe a different kind of fin, by chance, thereby turning into fish Z. To find out, you'd need to know (a) how many of fish X there were, (b) how often feature Y would appear by chance mutation, and (c) how likely a fish X newly endowed with feature Y would be to survive and reproduce enough to propagate feature Y and form species Z. If (a) is 10 million, and (b) is 1 million, then:

P(Y)=1-(999999/1000000)^10000000=99.9955%

where P(Y) is the probability that feature Y would emerge spontaneously in these conditions. We'd still need to check its likelihood of surviving, but so far, the proposed evolutionary step passes the probability test. By contrast, if there were 10 million specimens and the odds of Y per specimen are 1 in 100 million, then the odds become:

P(Y)=1-(99999999/100000000)^10000000=9.516%

This is not so good, and starts to jeopardize the theory that feature Y evolved, and by extension the theory of evolution in general, of which the evolution of feature Y is a part.

It could get worse. Suppose the odds of feature Y per specimen are just 1 in 100 trillion, and there were just 100,000 specimens of fish X. Now P(Y) is just 1 in 1 billion, or in other words, it’s essentially impossible. The theory that Y emerged by chance would seem to need to be abandoned. And with it, seemingly, falls the entire theory of evolution, since if any feature must have emerged other than by chance, the claim that all of life emerged only by chance is false.

Now, it seems a lot to ask that every link in the vast evolutionary chain should pass this probability test, and the whole theory should be abandoned if even one link fails. Is there a way out of this exorbitant requirement?

There is, sort of. At any rate, there is a nuance that must be introduced here, which tends to mitigate the probability challenge. We must distinguish complexity from specified complexity. The concept is easiest to introduce using random number sequences. 

Suppose I roll a die ten times and get 4, 2, 6, 3, 1, 1, 2, 6, 1, 3. There’s nothing odd about that. That looks pretty random, and random is what we would expect. 

But now suppose that just before I rolled, someone claiming a clairvoyant knowledge of the future wrote down on a paper the numbers “4, 2, 6, 3, 1, 1, 2, 6, 1, 3” and added, “Those are the numbers you’re about to roll on this die.” That would be very odd indeed. Either he really is clairvoyant, or he’s rigged up a pretty impressive hoax.

What’s the difference? 

In the first scenario, the particular sequence of numbers was complex in a way, but there was nothing specified about it. Almost 6^10 other sequences of numbers would have been equally good examples of the thing it represents, which is mere randomness. So we can readily accept that it emerged by chance. It would be odd and silly to be impressed on the grounds that that specific sequence was ex ante improbable. The only cogent characterization of what happened was that a die was thrown ten times and a random series of numbers appeared. And that wasn’t improbable ex ante, at all.

But in the second case, that sequence of numbers has been clearly specified as uniquely important. The cogent characterization of it is “the exact sequence predicted by the claimed clairvoyant.” As such, it is unique, and it was very improbable ex ante, indeed, prohibitively improbable, under the usual assumption that where a die comes down is random and unforeseeable. It proves there was something else going on. 

Now, what if I roll a die ten times and get 1 every time. Intuitively, this would be very odd and surprising. But why? No one predicted it. It wasn’t specified in that way. But it seems improbable because it exhibits a very striking pattern. The cogent characterization is probably not “ten ones in a row,” because the specific number doesn’t matter. I would doubtless have been just as struck by rolling ten twos or ten sixes. Perhaps it’s “ten of the same number,” or merely “a very clear numerical pattern.” The point is that there is a clear pattern where there shouldn’t have been one. A mere random series of numbers was overwhelmingly probable, yet somehow failed to occur. To settle the ex ante improbability of that, you’d first need to pick among various plausible candidates for the cogent characterization of the realized outcome. Or maybe you’d construct some kind of weighted average across these characterizations. Whatever you did would certainly confirm your intuition about the vast improbability of the roll.

The concept of specified complexity, easiest to make clear in dice game examples, is important to understanding the whole nature of science, but especially, in assessing the probability of Darwinian evolution.

Specifically, thinking about the probability of an evolutionary step in terms of specified complexity lowers the probability hurdle, because fin type Y might be just one of many fin types that would have been just as impressive and useful, so the emergence of fin type Y has an element of innocuous randomness in it that makes it less improbable. Suppose that alongside fin type Y, which emerged, there were the possibilities of fin types Y1, Y2, …, Y1000, all of which would have been equally impressive and useful, though noticeably different. In that case, the cogent characterization of P(Y) might be, not “the odds that fish X would evolve fin type Y,” but “the odds that fish X would evolve a fin type from the set Y, Y1, Y2, …, Y1000.” And that might often rescue evolution from a charge of prohibitive improbability, albeit at the cost of requiring a very high degree of biological imagination on the part of evolutionary theorists, as they spin out counterfactual possibilities of how life might have developed otherwise.

Now, my tentative feeling is that if this kind of analysis could be done, the evolution of life as we know it only by chance mutation and natural selection would turn out to be prohibitively improbable. But my tentative feeling should carry very little weight.

The important thing, rather, is that we don’t have the Universal Zoo, or the Universal DNA Library, or a thorough, tried and tested model of the probability distribution of mutations, or a comprehensive set of hypotheses about ancestor-descendant relationships, or the population histories of all species. We have impressions in old rocks, made by some hard body parts, dated by difficult and fallible chronometric exercises, used as the basis for uncertain reconstructions of what must be a tiny fraction of all the organisms that have lived on Earth. And we have no DNA of anything that lived much more than a million years ago. I have tried to imagine what information would be needed to do a thorough, responsible assessment of whether the emergence of all life through evolution was effectively possible, that is, not prohibitively improbable. The information we actually have falls very, very far short of that. 

Richard Dawkins, the author of The Selfish Gene mentioned above, has another well titled book called Climbing Mount Improbable which may come closest to meeting the challenge of being a probabilistic audit of the theory of evolution. Yet it doesn't come close at all. Dawkins starts with another brilliant metaphor. He uses the symbol of a towering mountain to represent the complexity of life as we know it. On one side, the mountain’s face is a sheer cliff, far too high and steep to be climbed, and some mountaineers are standing beneath it and claiming that the summit will never be reached. But just go round to the other side, and you'll find a gently ascending slope. Dawkins claims that the evolution of life is like that, full of complexity that couldn't possibly have emerged by chance leaps, but which could be and was achieved in non-obvious gradual ways. But he doesn't remotely prove that Mount Improbable has this odd shape. The book is a fascinating tour of life, and full of interesting speculations about how flight might have evolved, how elephants’ trunks might have evolved, how walking might have evolved, and so on. But the book offers little or no evidence that the proposed evolutionary pathways were actually traveled by historical life. Never, except maybe in one case, does he offer any rigorous quantitative evidence that the evolutionary pathways actually occurred, or could have occurred. 

That one case is spiderwebs. Dawkins describes the spider’s problem in great detail: the need for a net large and strong and just yielding enough without being bouncy, with the spider being close enough to its prey but far enough from its predators. Then he cites computer simulations that seem to show something like the emergence of web patterns a little like those of natural spiders. With a good deal more honing, this simulation-based argument might actually establish that evolutionary mechanisms suffice to account for spiderweb designs. So the spiderweb simulations come close to being a good example of one drop of the kind of evidence that, if we had an ocean of such evidence, would begin to make evolution a well-substantiated theory deserving of belief. 

But several biologists have conducted partial probabilistic audits from the other side, and proclaimed that it fails, and that therefore evolution, as a comprehensive theory of the origins of life, can't be true. For example, Michael Behe, author of Darwin’s Black Box (2001), The Edge of Evolution (2007), and Darwin Devolves (2019), takes the probabilistic mindset to complex features of living things, assesses the adequacy of Darwinian mechanisms to explain them, and finds they come up far short. Likewise, Stephen C. Meyer, author of the 2009 book Signature in the Cell, focuses on the origins of life, for which the Darwinian theory of evolution doesn’t work as an explanation, since natural selection can only operate after living things capable of metabolism and self-replication have occurred. He argues that the minimum viable living system would be prohibitively unlikely to emerge by chance, and therefore must have been intelligently designed. William Dembski, a master of probability theory, has helped these evolution skeptics formulate their arguments and become another champion of the emerging school of thought.

These thinkers are often called the “intelligent design” school, and I’ll follow suit, though the label highlights the major fault of thinkers whom in many ways I greatly admire. From the failure of evolution to explain life, they tend to pivot to the conclusion that life was intelligently designed, while still saying that they are doing science. This confusingly mixes up a factual dispute with a merely semantic one. Scientists tend to think that the exclusion of the supernatural from their theories is part of what it means to be a scientist. This can be called “methodological naturalism,” which is separate from the doctrinal naturalism that I’ve been calling “scientific materialism.” Science hasn’t always meant that, and there was a time when science freely borrowed ideas from theology and philosophy, but it’s reasonable to use the term “science” now as its practitioners and probably the public now understand the term. It would be clarifying if intelligent design advocates framed their conclusions: “we have revealed permanent limits on what science can know about the origins and development of life, but also, by the way, we’re pretty sure we do know a way forward in understanding life, though it’s not conventionally scientific.” Instead, they tend to mix up scientific evolution skepticism with philosophical advocacy for intelligent design, while claiming or at least not explicitly relinquishing scientific credentials for their intellectual enterprise as a whole. 

I would prefer to accept the mainstream definition of science, and say that the intelligent design school is strictly scientific, and quite persuasive, in their evolution skepticism, but step outside the limits of science when they advocate intelligent design. The atheist philosopher Thomas Nagel, in his book Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False, takes a similar line, separating the negative arguments of the intelligent design school against evolution, which he agrees with, from the theistic conclusions, which he rejects. By contrast, I agree with the intelligent design conclusion, but I wouldn’t characterize it as scientific. The scientific pretensions of the intelligent design advocates are in some cases    politically motivated, since voters in the US who want alternatives to evolution taught in schools have often found themselves overruled by judges who claim that it’s unconstitutional to teach “religion” in school, but permissible to teach “science.”

Another semantic disagreement that I have with intelligent design advocates concerns the term “irreducible complexity,” as used by Michael Behe for features of life to which there is no probabilistically tenable evolutionary pathway. I find this term clumsy because the complexity in question is reducible in a way. DNA is dissolvable into nucleotides, and proteins into amino acids, which in turn consist of atoms. There’s nothing supernatural or magical about those molecules from day to day, as the term suggests to my imagination. A more descriptive phrase for what Behe means would be “evolutionarily unattainable complexity,” but I’ll use Behe’s phrase since mine is unfamiliar and unwieldy.

Substantively, I can't independently confirm that the intelligent design thinkers have done their anti-evolutionist calculations right, though my intuition is strongly supportive. At any rate, I can see that they're framing the right questions, and the mainstream biological establishment, which is still dogmatically committed to Darwinian evolution, should respond by conducting its own probabilistic audits and seeing if it can get the opposite result. Dawkins tried to do this, sort of, in Climbing Mount Improbable, though not very successfully. Others could try to do better. Instead, the intelligent design critique of evolution has generally been scorned and then ignored, its questions misunderstood, ridiculed and delegitimized, rather than answered. For biologists have many practical things to do, curing diseases and improving crops and educating the public and whatnot, and since evolution has worked its way into routine biological language in a way that makes it seem indispensable, they get very annoyed when the central tenet of the field is attacked. 

The apparent but illusory indispensability of Darwinian evolution to biology is well illustrated by the way that, in biological writing, the phrase “have evolved” tends to appear whenever a striking and useful feature of a life form is described. All it really means is that a feature is adaptive. Probably not once in all of biology does it signify that a specific, detailed process by which a feature evolved from known past features of ancestor organisms has been thoroughly audited and found not to be prohibitively improbable. And yet it's true in a way, as biologists sometimes say, that all of modern biology depends on the theory of evolution. A Darwinian style of reasoning pervades biology, and is very useful. But the validity of such reasoning doesn't depend on the truth of the theory of evolution as a complete account of the origins of life. A modest notion of Darwinian ecological equilibrium, such as I outlined at the beginning of this chapter, is quite sufficient to supply an epistemic warrant for the kind of practical Darwinian reasoning that pervades biology and supplies testable hypotheses to help interpret living nature.

Biologists sometimes appeal to the authority of tradition, and pontificate impressively that Darwin’s theory of evolution has been believed by most biologists for 150 years. But the theory’s durability, in striking contrast with the vast changes that have occurred in more evidence-rich scientific fields, doesn’t show that we know enough to prove Darwinian evolution true, but that we know too little to prove it false.

There is a kind of blind spot in the scientific method here, because it encourages scientists to make hypotheses and test them, but it doesn’t have a good way to guard against hypotheses that are excessively elastic. The philosopher of science Karl Popper tried to fix this blind spot by making “falsifiability,” the production of risky predictions that might fail and thereby prove the theory false, the criterion of whether a field of study is a science or not. His hero, Albert Einstein, passed the falsifiability test with flying colors when he made specific predictions from his general theory of relativity, about the bending of light, and declared that, if the predictions were not confirmed, the theory would need to be abandoned. Many scientific theories, like the law of gravity, or principles in electromagnetism and chemistry, are abundantly falsifiable. Gravity, for example, could be falsified at any moment by any object randomly floating free of the ground, except that doesn't happen, because the theory of gravity is true. By Popper’s account, real sciences pass the falsifiability test, and falsifiability is the distinguishing mark of real sciences.

What about evolution? Does it pass the falsifiability test? What facts would prove it wrong? It's not easy to say. If paleontologists find an old specimen that seems like the ancestor of a modern animal, that is taken as corroboration of the theory of evolution. But if old specimens seem to be the ancestors of no modern animal, that is no evidence against evolution. Presumably, those creatures went extinct somewhere along the way. And what if a modern animal seems to have no ancestors in the fossil record? That isn't really a strike against the theory of evolution, because it's well understood that most creatures don't get fossilized, and conditions may simply not have been propitious for the fossilization of those ancestors. The relationship of evolution to evidence has a kind of “heads I win, tails you lose” character. At the worst, new fossil evidence might add no particular corroboration to the theory of evolution. It can't refute it.

Yet there is one way that evolution should be vulnerable to falsification, namely by a probabilistic audit. It might be discovered that the ratio of the improbability of certain favorable mutations to the opportunities the history of life has afforded for such mutations to occur and be preserved is such that the emergence of those mutations by chance is prohibitively improbable. And that is just how the intelligent design school claims they have falsified it. What could falsify evolution is if there were just too much complexity for the proposed evolutionary mechanisms to have brought it about, and that is just how intelligent design champions claim they have refuted evolution already. Whether evolution deserves to be considered scientific in Karl Popper’s sense depends on whether the biological establishment can really rise to the challenge and commit themselves implacably to abandoning the theory of evolution unless they can succeed in refuting the probabilistic calculations of the intelligent design school, rather than keep trying to marginalize and silence the challengers.

Now, readers will probably have noticed that there is an intriguing parallel between physics and biology with respect to intelligent design. In both fields, features of nature have been found that would just be too unlikely to occur by chance. Intelligent design, though not exactly a scientific hypothesis, seems to some to be the only explanation that can rescue science from a cul-de-sac of intolerable oddity. 

Yet from there, things have played out differently. Physicists have offered the multiverse and the anthropic principle as an explanatory alternative to the intelligent design conclusion, but they don’t seem very fond of it, and its scientific credentials are very dubious, so the state of play seems like a respectful stalemate, with the theistic view of the Big Bang enjoying a comfortable tolerance without being accorded scientific legitimacy, as if physics says that it isn’t science, exactly, but it might well be true. By contrast, biologists do like their theory of evolution very much, and furiously defend it against the intruders. 

But if intelligent design is plausible in physics, then it’s only fair to grant that it’s plausible in biology. If you’re not willing to accept the multiverse fantasy, but you do want a coherent worldview, you might reasonably conclude that theism is unavoidable. And if God caused the Big Bang, there’s no reason He should have stopped there. To judge from His fine tuning of the universe to make stars and galaxies, He seems to like intricacy and variety. Why should He not have intervened on a favorite planet to make still more intricacy and variety there? God could have arranged for naturalistic evolution to occur by setting initial conditions and then standing aside, leaving it up to chance. But maybe chance-based processes like evolution wouldn't have generated as much interesting and beautiful complexity as God wanted, so He intervened to add more of it. He wanted His living designs to last for a while, so He made them in ecological equilibrium, just as painters paint in oil. But, by this account, mere ecological equilibrium is a constraint on but not a determinant of the inventory of designs nature sustains. That would make evolutionary biology a bit like a school of artistic criticism that tried to explain all great paintings entirely from the chemical properties of the oil base of the paint. (To this metaphor we will return.) Since either of these theories, purely chance-based evolution, or an evolution with intermittent infusions of intelligent design by God, might have occurred, we need to look to evidence to help us decide. If the evidence appears to show that mere chance-based evolution was prohibitively improbable, then we don't need to sit around waiting for the evidence to say something different. We can conclude that probably the Big Bang Causer of 13.8 billion years ago stuck around and became the Life Shaper of the past is 3.8 billion years or so.

So far my critiques have addressed the theory of evolution as a whole, but I should mention that human evolution poses special problems. These problems have a moral aspect. If you think humans evolved from animals, it follows very naturally that the great moral distinction we make between animals and people is connected with that evolution. It would seem likely, too, that the processes that differentiated us from the beasts have proceeded further in some humans than others. That can lead to the disastrous conclusion, thoroughly put into practice by the Nazi regime of Adolf Hitler, that some people are more like animals than people, and can be treated like animals, killed, enslaved, and so forth. 

But human evolution isn't just morally problematic but also implausible. Humans have glorious powers of language and abstract reasoning and art that set them dazzlingly apart from all beasts. Evolutionists are compelled by their faith to believe that this incredible transformation took place gradually, by natural, chance-based processes, and there have been dark speculations about “cave men” and “ape-men” and “the missing link,” but there's no empirical warrant at all for the idea that the distinctive human faculties emerged gradually. Anyone who is open-minded about divine intervention in the cosmos would surely conclude that the emergence of humans is probably one of these moments of special creation.

I will make no comment in this book about the historicity of the Garden of Eden, a topic about which I have no insight. As a parable of the human condition, though, it is very shrewd and penetrating. It explains, in what I would call a mythic fashion (but true tales can also mean in the way that myths mean, symbolically and imaginatively, so this is not a comment on its status as fact or fiction), some very mysterious, important, and stubborn truths about human nature. Our vast powers of reasoning and artistry are, according to Genesis, the legacy of our having been made “in the image of God.” We were also given a job: to rule the animals and tend a garden. And to this day, our love of gardening and especially of zoos bears witness to this original human vocation. 

How can mere evolutionism explain why we love to stand outside the glass and look at lions and tigers, and more than that, how our hearts yearn to be inside the glass, and run our hands through the lion's mane, and feel the tiger's soft fur? Reason knows that, with the glass to protect us, we're safe enough. But instinct, which knows nothing of glass, ought to be screaming, “Get away!” Sometimes, no doubt, it does. I've known young children who feared the zoo because of all the dangerous animals. But there is nonetheless something that attracts us to the zoo. Why? We feel instinctive disgust and hatred for spiders and snakes and many insects and sometimes mice, and that's understandable. But why do we feel so much love for animals that will never profit us? Why do we even prefer not to profit from them, so that we are sorry to have to kill for food the deer that ran free with such grace? Why, unless it's because God wrote on the human heart a love for our first vocation? And isn't that also why most children's books are about anthropomorphized animals, and why we keep so many economically useless pets?

Above all, Genesis highlights, even if it hardly explains, perhaps the single oddest and most mysterious feature of the human race: clothing. All adult humans feel an extreme, nonnegotiable need to keep certain body parts hidden from strangers of the opposite sex. There are plenty of secondary reasons to wear clothes too, of course: for warmth, for safety, to carry tools, etc. But we still wear clothes when none of these apply. It's a high price to pay for being human! Clothes are often uncomfortable and usually expensive. Before the Industrial Revolution, every shirt or pair of trousers represented a lot of work. Not only is it hard to see how our shame at being naked could ever have evolved, it's hard to see how such an obviously maladaptive trait could have survived. Why didn't people burdened with an irrational obsession to drape themselves in weeds or animal hides lose out in the gene pool, relative to people free of these inconvenient hang-ups? And yet no one is free of them, not in the poorest cultures where clothing is hardest to come by, not in the rationalist West which prides itself on having discarded so many taboos and inhibitions. Genesis tells a tale of how the shame of nakedness is a kind of curse on mankind, a consequence of sin and alienation from God. That explanation hardly explains, but at least it seems commensurate with the weirdness of clothing.

The truest and most profound thing that can be said of the past is that we weren't there, so, with a few slight and patchy exceptions, we don't know what happened. But the human mind doesn't like blank spaces. That's why mapmakers in the old days drew dragons in the edges of the map, and the theory of evolution is the same kind of story, scrawled by ideological fancy on the parchment of ignorance. Darwin the analyst of adaptation is a very useful thinker, but Darwin the historian is only the latest panderer to the human credulity that once peopled Mount Olympus with Zeus and Hera and the rest of them.