Faith Versus Fact : Why Science and Religion Are Incompatible (9780698195516) (23 page)

Theistic evolution and human exceptionalism aren't just the views of garden-variety believers, but are espoused today by some science-friendly theologians. Here are two modern theologians—first John Haught and then Alvin Plantinga—arguing that naturalistic evolution is both unpalatable and un-Christian:

Religions can put up with all kinds
of particular scientific ideas so long as these ideas do not contradict the sense that the whole scheme of things is meaningful. Religions can survive the news that Earth is not the center of the universe, that humans are descended from simian ancestors and even that the universe is fifteen billion years old. What they cannot abide, however, is the conviction that the universe and life are pointless.

What is
not
consistent with Christian belief
, however, is the claim that evolution and Darwinism are
unguided
—where I'll take that to include
being unplanned and unintended
. What is not consistent with Christian belief is the claim that no personal agent, not even God, has guided, planned, intended, directed, orchestrated, or shaped this whole process. Yet precisely this claim is made by a large number of contemporary scientists and philosophers who write on this topic.

As an evolutionary biologist, I'd respond that all the evidence points to unguided evolution, and even if that's distressing, it's the best inference we have. After all, we have to accept lots of things we don't like, including our own mortality.

Why is theistic evolution a failure of accommodationism? Before I explain, we should realize that “theistic evolution” is a semantic umbrella covering diverse and sometimes conflicting views differing in the assumed amount and nature of God's intervention. The least intrusive of these is a “let it roll” brand of deism, one that sees evolution as simply operating according to the physical laws created by God. (Advocates of this view differ in whether the origin of life required God's intervention.) Once the process is under way, God no longer interferes.

A more teleological interpretation sees evolution as
inherently progressive
. This was expressed by the theologian and former physicist Ian Barbour:
“
The world of molecules
evidently has an inherent tendency to move toward emergent complexity, life, and consciousness.”
The process driving evolution in this direction is often unspecified, but is somehow directed by God.

Barbour's view, one that is widespread, implies that humans were a built-in feature of evolution, one envisioned by God when he set up the process. In other words, big-brained humans, or similar humanoid creatures, were a
planned
result of evolution, and were therefore inevitable. Others also see the evolution of humans as inevitable, but argue that divine intervention wasn't needed—that there simply existed an open ecological niche for a conscious and rational animal, one capable of apprehending and worshipping the divine. And in time, one of the endlessly ramifying products of evolution would fill this niche.

Still others see God as having to interfere
sporadically
in evolution, guiding it in various ways we'll discuss below. Divine interventions are deemed necessary to ensure both the initial appearance of life and the eventual appearance of humans, for such matters simply couldn't be left to naturalism. And this view shades insensibly into intelligent design (ID), the modern version of creationism that, while accepting a limited amount of evolution within species, insists that garden-variety Darwinian evolution simply can't explain some “irreducibly complex” features like the blood clotting system of vertebrates or the complicated whiplike tails (flagella) that propel some bacteria.

While ID arguments
have been refuted by scientists,
versions of theistic evolution keep popping up like heads on the Lernaean Hydra, for believers are tenacious. Yet all of these versions come perilously close to ID creationism. One of them is the Catholic Church's insistence that God intervened at least once in the human lineage to insert a soul. This remains church dogma, expressed by Pope John Paul II in his famous 1996 message to the Pontifical Academy of Sciences:

With man, we find ourselves
facing a different ontological order—an ontological leap, we could say. But in posing such a great ontological discontinuity, are we not breaking up the physical continuity which seems to be the main line of research about evolution in the fields of physics and chemistry? . . . But the experience of metaphysical knowledge, of
self-consciousness and self-awareness, of moral conscience, of liberty, or of aesthetic and religious experience—these must be analyzed through philosophical reflection, while theology seeks to clarify the ultimate meaning of the Creator's designs.

It's hard to see this “ontological discontinuity”—the endowment of humans with a metaphysical soul—as anything other than creationism. Granted, it may have been a one-time intervention, but it still mixes science with religion, weakening the claim that Catholicism is compatible with evolution. With respect to evolution, the position of the Catholic Church differs from biblical creationism only in the amount of God's intervention.

Finally, some theistic evolutionists hold a “constant tweaking” model: God interferes frequently in evolution, tugging it, like an errant dog that won't take to its leash, in prescribed directions. These could involve preserving endangered species, creating new mutations, or tinkering with genes or environments. These interventions have two features: they are undetectable, rendering them immune to scientific investigation, and they are invariably used to give God a way to ensure the evolution of humans. Kenneth Miller suggested that this could occur if God simply fiddled with the movement of electrons:

Fortunately, in scientific terms
, if there is a God, He has left himself plenty of material to work with. To pick just one example, the indeterminate nature of quantum events would allow a clever and subtle God to influence events in ways that are profound, but scientifically undetectable to us. Those events could include the appearance of mutations, the activation of individual neurons in the brain, and even the survival of individual cells and organisms affected by the chance processes of radioactive decay.

It's ironic that Miller, who has produced some of the most compelling and convincing arguments against intelligent design, finally winds up touting God as using quantum mechanics to guide evolution. In this way he's camping on the outskirts of creationism. And why would God want to act in a “clever and subtle” (i.e., sneaky) way? Why is that better than creating
humans de novo? The only advantage of Miller's theory is that God's interventions are conveniently undetectable.

Theistic evolution fails to harmonize science with religion because it pollutes evolution with creationism, positing interventions by God that are either scientifically refuted or untestable—and therefore superfluous. That is why, though eagerly embraced by the American public, theistic evolution has been completely rejected by scientists. Imagine if we had equivalents in other fields, like “theistic chemistry,” proposing that God undetectably forges bonds between molecules, or “theistic gravity,” claiming that the attraction between objects is maintained by a Ground of Being. Nobody, even believers, would take this seriously. The only reason why theistic
evolution
has gained traction is because it's politically expedient (scientists don't mind it because it gives religious people a foot in the evolution camp), and because for believers it removes some of the sting from naturalistic evolution. Believers don't propose the notions of theistic chemistry and physics only because those fields don't conflict with scripture. Only biology has theories that strike down the human exceptionalism touted in sacred texts.

But theistic evolution is also riddled with scientific problems. The big one is that despite adherents' claims that mutations in our DNA are biased in a given direction (i.e., are “nonrandom”), there is no evidence that useful mutations crop up more often when the organism “needs” them. Mutation would, for instance, be nonrandom if mammals moving to a colder environment experienced relatively more mutations producing longer fur. But there's no evidence for that. As far as we know, the mutational process appears to be “indifferent” (a term I prefer over “random”): errors occur in an organism's DNA regardless of whether they'd be good or bad for its survival and reproduction. While one could save theistic evolution by arguing that God-created mutations are undetectably rare—in effect, miracles—that's not a testable hypothesis.
What we
have
shown
, in experiments with microorganisms, is that no external force seems to be producing mutations in an adaptively useful way.

Further, evolution doesn't show the signs of teleological guidance or directionality proposed by theistic evolutionists. Evolutionary biologists long ago abandoned the notion that there is an inevitable evolutionary march
toward greater complexity, a march culminating in humans. If one considers all species together, the
average
complexity of organisms has certainly increased over the 3.5 billion years of evolution, but that's just because life began as a simple replicating molecule, and the only way to go from there is to become more complex.

Contrary to popular wisdom, complexity isn't always favored by natural selection. If you are a parasite, for instance, natural selection may make you
less
complex, for you can live largely off the exertions of another species. Tapeworms evolved from free-living worms, and during their evolution have lost their digestive system, their nervous system, and much of their reproductive apparatus. Yet tapeworms are superbly adapted for a parasitic way of life: they simply pump out eggs and let their host do much of the metabolic work.

It doesn't always pay to be smarter, either. For some years I had a pet skunk, who was lovable but didn't seem very bright: in fact, sometimes he seemed to be unaware of anything but food. I mentioned this to my vet, who put me in my place with a sharp retort: “Stupid? Hell, he's perfectly adapted for being a skunk!” Intelligence comes with a cost: you need to produce and carry that extra brain matter, and crank up your metabolism to support it. When this cost exceeds the genetic payoff, the brain won't get larger. A smarter skunk might not be a fitter skunk. There are many cases in which organisms have lost features, becoming simpler because such loss was favored by natural selection. Organisms that invade caves often lose their eyes, for it's no advantage to have a useless organ that, besides being easily injured, can divert resources from other parts of the body that are useful. Remember that the currency of natural selection is
reproductive output,
and sometimes reproduction is enhanced by evolution's removal of features that aren't useful.

Finally, we know of no natural or supernatural process that drives evolution in certain directions; in fact, sometimes natural selection can drive species extinct, by adapting them to environments that are vanishing. I suspect that polar bears will go this route as global warming proceeds.

When thinking about evolutionary “direction,” we should remember that there are just two important evolutionary mechanisms, natural selection and genetic drift. Drift is simply random changes in the proportions of
genes caused by the vagaries of reproduction: it's the genetic equivalent of flipping coins. If different forms of genes (say, those producing blue versus brown eyes) made no difference to your number of offspring, the proportions of those genes in a population would simply fluctuate at random. This process is nondirectional by definition, and cannot produce adaptation.

The other mechanism, of course, is natural selection, which
is
nonrandom and does promote adaptation. Selection produces changes in traits that give an organism a reproductive advantage in its
current
environment. Although that process can occasionally be directional, as in an evolutionary “arms race” when predators and prey evolve higher efficiency in killing and avoiding each other respectively, the directionality is due not to God but to environments in which there's only a single way to improve. When the climate becomes colder—and major glacial cycles occur every hundred thousand years or so—organisms must adapt to low temperature or face extinction. When things warm up, the evolutionary direction is reversed. If theistic evolution is to be a truly coherent theory, its proponents must do more than raise it as a theoretical possibility: they must explain what mechanism makes evolution directional, guiding it toward humans, and show us how and where God intervened in that process.

An important claim of many theistic evolutionists, whether or not they invoke God's intervention, is that the evolutionary appearance of humans on Earth was inevitable. But that argument also dissolves under scrutiny.

If science can make a plausible case that the naturalistic evolution of humans, or of creatures with similar mental faculties, was inevitable, then theistic evolutionists get a big break. In that case we'd no longer need to invoke supernatural intervention to produce our species, for humans, or something like them, would always appear after sufficient evolutionary time. This would produce, through a purely material process, just what theists need: a complex and rational creature who apprehends and worships God. (Let's call such creatures “humanoids.”) That leaves the naturalism in
biology but still produces the outcome theists want. It's important, then, to see how far science supports the notion of human inevitability. Indeed, if we can't show that humanoid evolution was inevitable, then the reconciliation of evolution and Christianity collapses, for if we're really the special objects of God's creation, our appearance must have been guaranteed by either God or nature.