Richard Dawkins famously asserted that "Darwin made it possible to be an intellectually fulfilled atheist." Prior to Darwin, all an atheist could do was to repeat with Hume that in an infinite amount of time anything is possible, including the complex design we see in nature. The Edge of Evolution makes it much more difficult for an atheist to find fulfillment in Darwin.
Michael Behe's new book begins by distinguishing three issues that are commonly subsumed under the banner of "Darwinism." One is common descent. A second is natural selection. And the third is random mutation. Behe argues that though there is very strong evidence for common descent, and though natural selection certainly has an important place in the biological explanation of organic diversity, random mutations by themselves cannot explain the molecular foundation of life on earth. It is hard to think of a group in the current controversy over evolution that will not be angered by something Behe writes. This is good; no one can legitimately dismiss The Edge of Evolution as propaganda.
The subtitle of Behe's book is "The Search for the Limits of Darwinism." Again, Behe's conclusion is not that evolution by means of natural selection is a myth, but only that its domain is limited. Of course, almost everyone will grant that "micro-evolution" occurs. Yes, moths gain or lose spots, and finches evolve new and improved beaks. But macro-evolution—turning a mouse into a whale—Never! Or so many creationists say.
Behe disagrees: "Evolution from a common ancestor, via changes in the DNA, is very well supported." After summing up the argument from the genetic similarity of all life, Behe writes that "It's hard to imagine how there could be stronger evidence for common ancestry of chimps and humans." And again, "Let's acknowledge that genetics has yielded yet more terrific (and totally unanticipated) evidence of common descent." Finally (though many more examples could be cited), "The purposeful design of life is also fully compatible with the idea of universal common descent, one important facet of Darwin's theory" [emphasis added]. Behe is quite clear that he has no objection to the idea that species as distinct as mice and whales evolved from common ancestors.
Behe would also be quite sympathetic to Darwin's suggestion that perhaps life was "originally breathed by a Creator into a few forms or into one." We shouldn't forget that Darwin never claimed to have provided a scientific explanation of life's origin. Instead his great insight was to demonstrate observationally how the origin of different species can be traced back to just a few primitive "life forms." Behe would agree: if it's alive and if it's big enough to be seen by the human eye, then it evolved.
And finally, Behe agrees with Darwin that "it accords better with what we know of the laws impressed on matter by a Creator that the production and extinction of past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual." Or, as Behe puts it, "Those who worry about 'interference' should relax. The purposeful design of life to any degree is easily compatible with the idea that, after its initiation, the universe unfolded exclusively by the intended playing out of natural laws."
What Behe will not countenance is the "just-so stories" and question-begging mathematical models of someone like Richard Dawkins. Dawkins' argument goes like this: There are countless examples in nature where the appearance of design is overwhelming. And while anything is possible given enough time, atheism is no longer dependent on philosophers' hand waving. After Darwin, nature's complex "designs" are fully explainable in terms of natural selection. The problem is that natural selection is typically misunderstood. Most non-scientists think about evolution in terms of chance. Yet nothing could be further from the truth, says Dawkins. Nothing as complex as a human eye could evolve by mere chance except in some vacuous philosophical sense. Darwin's theory is not powered by chance selection; it's powered by cumulative selection.
Consider Yahtzee. It's a game played with six dice. While there are many ways to score points, the highest score is awarded for rolling six of a kind, called a "Yahtzee." Yet this is not a game of pure chance. On each turn, a player gets three throws of the dice, and after each throw he can select which dice he will re-throw. If, for example, after the first throw there are two threes on the table, the player can elect to re-throw the other four dice; if after the second throw there are now four threes on the table, the player has one more throw to produce a Yahtzee.
The example has a single point. Speaking from a purely statistical point of view, the odds of rolling six of a kind on any single throw is only one in 66—a very small number. However, the odds of throwing six of a kind given the provision for cumulative selection are very much better. Yahtzees are typically rolled once or twice a game. That's the kind of power which drives evolution to create organisms with the appearance of exquisite design, but without a designer. Now there are many critics who argue that this sort of analogy begs all sorts of crucial questions, the most common being, "Who's doing the selection if not an intelligent designer?" But this is not Behe's objection.
There is, however, one catch. The dice analogy only works if we assume the existence of what Dawkins calls "replicators" (i.e., living organisms which are capable of reproduction). Without something to accumulate the benefits of chance after each roll (in biological terms, after each generation), the process of cumulative selection can't begin and we are back to pure chance.
Dawkins never tries to hide this point of simple logic—no accumulation without an accumulator. Nor does he hide the fact that it would be question-begging to give a "Darwinian" explanation for the origin of the first replicators. Again, cumulative selection only works if we assume the existence of organisms that can benefit from small acts of random kindness. Here the intellectually fulfilled atheist must rely on pure luck. Obviously, one's "fulfillment" will vary inversely with the amount of luck required. So how much luck does it take for the original replicators to simply "poof" into existence? And is there enough luck in the atheists' account from which to draw?
Before looking at the numbers, it is important to emphasize that Dawkins and Behe agree on the proper method for answering these questions. First, questions about the amount of pure luck required to biologically account for the origins of life both can and must be quantified. Second, science gives us a pretty good idea of how much quantifiable luck is available.
Yet, given these shared assumptions, Behe and Dawkins come to radically different conclusions. Dawkins' argument in The Blind Watchmaker goes like this: "There are probably more than a billion billion available planets in the universe. If each of them lasts as long as Earth, that gives us about a billion billion billion planet-years to play with." He then adds with obvious satisfaction, "That will do nicely!" However, he also warns that "we haven't the faintest hope of duplicating such a fantastically lucky, miraculous event as the origin of life in our laboratory experiments." Thus, he argues that purely theoretical arguments become scientifically justifiable.
Perhaps, but what for Dawkins is a scientifically justifiable piece of theoretical reasoning is a "just-so story" for Behe. Why? Because Behe doesn't share Dawkins' pessimism about what can be demonstrated in the laboratory. While scientists cannot be expected to carry out a billion billion billion years' worth of experiments, nature can and has.
The logic of Behe's argument is simple (though the details are not). He admits that humans will never be able to reproduce experimentally the huge spans of time available to evolution. But this is not a good reason for ignoring the laboratory and venturing into the realm of speculation. Indeed, the careful study of nature below the cellular level produces calculable results comparable to the extremely long periods of time assumed by evolution.
It would be foolish for me to attempt a summary of Behe's essentially statistical premises. His whole point is to warn science popularizers (and their readers) against glossing over the complexity of molecular biology. Besides, Behe himself acknowledges that "Darwinian evolution has a number of tricks up its sleeve, tricks that can easily be overlooked if you're not careful." So the odds of leaving out some important detail are great. Nonetheless, it is worth tasting the sort of mathematical odds with which molecular biologists work. (For those whose last biology class was long ago and far away, Behe includes an extremely helpful appendix reviewing the basic facts about the structure of protein and DNA and how they work. It is worth reading first!)
Most of Behe's book is a case study of the evolutionary history (or lack thereof) of malaria cells, hiv viruses, and E. coli. Since all of life is a story of the chased and the chasers, the prey and the preyed upon, according to Dawkins, all organisms are perpetually engaged in a kind of arms race. Gazelles who (as the result of a lucky gene) run faster than average gazelles win in the struggle for existence. Their "fast genes" are passed on to the next generation. But the genes of faster than average lions are also being passed on to the next generation. Like the "Red Queen" in Alice in Wonderland, everyone has to run faster just to stay the same. The important point for Dawkins is that even though "arms races" do not improve one's relative advantage, it is nonetheless true that in absolute terms succeeding generations of the chased and chasers are more sophisticated runners than the previous generations.
But what happens when we make use of the extremely sophisticated instruments of x-ray crystallography to survey the relentless contest between malarial cells and human beings? Do we see an arms race where each side is evolving—in absolute terms—superior weapons and defenses, or do we see a kind of trench warfare where desperate circumstances lead to desperate means, like destroying one's own bridges to slow down the advancing enemy?
Chloroquine is a cheap, easily synthesized drug that for a while appeared capable of eliminating the malarial scourge. Of course, it didn't. Though malaria required a few decades to muster its defenses, it evolved a defense against the new drug (about which we'll say more in a moment). But did this defensive maneuver constitute an improvement (from malaria's point of view, of course) in the machinery of the cell? No—because when chloroquine lost it effectiveness and its use was reduced, the cellular machinery of malaria reverted back to its previous plan. In other words, when the enemy is coming (chloroquine) we'll burn bridges; but when the enemy is no longer threatening, we rebuild the bridges. Why? Because all things being equal, a city with bridges is better than one without bridges.
Behe acknowledges that it would be legitimate to wonder if he was "just countering Dawkins' suppositions" with his own. After all, comparing malarial cells with or without resistance to chloroquine to cities with or without bridges is quite a stretch. So we must go to the numbers, since that's ultimately where the battle is to be fought.
It took two chance mutations for malaria to develop a resistance to chloroquine. The protein in the malarial cell that provides resistance has 424 amino acids. The two changes required were at the 76th and 220th positions. So how long did it take for malaria to develop such a defense against modern science? Between thirty to forty years. Score one for evolution. But how many cells had to be sorted through before evolution stumbled upon this defense? 100,000,000,000,000,000,000. In scientific notation that's 1020. (For comparison, the number of seconds that have elapsed since the Big Bang 15 billion years ago is about 1019!) Let's call this round a draw.
But now consider the construction, not the destruction, of protein machinery. "Generating a single new cellular protein-protein binding site is of the same order of difficulty or worse than the developmentof chloroquine resistance in the malarial parasite." Now simple math demonstrates that if the odds of rolling a single 6 on a six-sided die are one in 6, then the odds of rolling two 6's in a row are 6 squared or one in 36. So if the odds of a single protein binding site are 1020, then the odds of having two binding sites (i.e., a three-protein bond), where all three proteins are necessary to do what they were intended to do, are 1040.
How should we score this round? Before answering, consider this: the sum total of bacterial cells that have existed on earth during its entire history has yet to reach 1040. Here's Behe's conclusion: "Admittedly, statistics are all about averages, so some freak event like this might happen—it's not ruled out by force of logic. But it is not biologically reasonable to expect it … . In short, complexes of just three or more different proteins are beyond the edge of evolution." In other words, if it's alive and smaller than a cell, then science is pretty much clueless concerning its origin.
(Before we move on, let me quibble just a bit with the phrase "edge of evolution." While I too enjoy a catchy title, I'm afraid Behe's phrase might actually obscure the power of his argument. His argument is about how much pure chance is tolerable in biological explanations. But as Dawkins continually—and correctly—repeats, evolution is not about chance, it is about cumulative selection. Behe's title obscures the fact that his topic is the molecular foundations of life, where there is no cumulative selection to improve the odds.)
So far, Behe has offended those who believe that macro-evolution is a myth and those who believe that Darwin refutes any and all arguments for an intelligent designer (we'll call them metaphysical Darwinists). But Behe also gives offense to those who believe philosophy can stand on its own feet and doesn't require "scientific" support for its conclusions. Crudely put, this last group argues that metaphysical Darwinism both can and should be refuted with metaphysical arguments.
Here's the problem. Philosophical realists like Aristotle have been in a 2,500-year dispute with philosophical materialists. In this dispute, metaphysical Darwinists are simply the brash and somewhat naïve youngsters. The materialists have consistently argued that since we have an infinite amount of time, chance and necessity explain everything. Now obviously anyone can short-circuit this honorable dispute by placing philosophically arbitrary limits on the amount of time available. Sure, the best science of the day places the Big Bang about 15 billion years ago. But unless science becomes philosophical (or theological), it has nothing to say about whether this was merely the most recent of an infinite series of Big Bangs or if it was truly the beginning of the universe. And the currently fashionable infinite multiverse interpretation of quantum mechanics simply stacks up "universes" spatially instead of temporally.
So what's a philosopher to make of Behe's claim that "Infinite Multiverse scenarios are no different from 'Brain-in-Vat' scenarios. If they were true, you would have no reason to trust your reason. So anyone who wants to do any kind of productive thinking must summarily reject infinite multiverse scenarios for intelligent life and assume that what we sense generally reflects the reality we know exists"? Behe's argument goes like this: In a multiverse, everything that is logically self-consistent exists someplace, so we might be the brain-in-a-vat. It is not rational to believe anything that might be false; therefore, it is not rational to believe that reality exists pretty much as we perceive it to exist. Since this conclusion is absurd, Behe believes that we must reject multiverse scenarios.
The problem with Behe's reductio is that it simply assumes materialists will adopt Descartes' "rule to trust only what is completely known and incapable of being doubted." But there is no reason to think that philosophical materialists will or must adopt such a rule. Behe's philosophical argument knocks down a straw man. (In contrast, Stanley Jaki's Science and Creation constitutes a powerful historical argument for something similar to Behe's conclusion, namely, that the quantitative methods of modern science cannot flourish in "a pantheistic and animistic view of nature caught in the treadmill of perennial, inexorable returns.")
That's not to say that metaphysical Darwinism is immune to criticism. For example, the self-refuting nature of full-blown materialism that Alvin Plantinga has dubbed "Darwin's Doubt" is ancient and yet to be answered. In Darwin's own words it goes like this: "With me the horrid doubt always arises whether the convictions of man's mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey's mind, if there are any convictions in such a mind?"
But in a context where so much of the argument has been statistical, the ancient Aristotelian argument that "quantity is itself a quality" deserves mention. Suppose that as a prelude to some sort of statistical argument you are given the assignment of counting the number of "things" in a relatively small, well-defined, finite space. Do you begin by obtaining the most sophisticated scientific instruments money can buy? Hardly. Everyone must begin philosophically. Until we know what counts as one thing, no statistical argument is possible. Do we count individual cells as one thing or as literally thousands of individual protein machines? Do we count individual protein machines as one thing or as a half-dozen or more individual proteins? Do we count individual proteins as one thing or … ? Anyone who reads Behe can continue this series at least five or six levels deeper.
The point is this. There is nothing "empirically detectable" in a wholly "scientific" sense that one protein, one cell, one table, one game, one essay, one corporation, one basketball team, one language, one nation, one philosophical refutation, or one pair of pliers have in common except the rationally perceived quality of being a unified whole.
Now Behe frequently introduces, quite legitimately, the notion of coherence or "fit" in his description of how protein machines work. Design, he says, is nothing more then "a purposeful arrangement of parts." In this regard he has reproduced Aristotle's distinction between the heterogeneous and homogeneous ordering of parts. Heaps and aggregates are homogeneously ordered. They can be measured and weighed. But whenever a number of distinct parts "fit together" to perform a single function, we have a qualitatively distinct heterogeneous ordering.
So far, so good. But design and heterogeneous ordering are necessarily invisible to the most sophisticated scientific instruments, which can only measure quantities. If you limit your reasoning to what is quantifiable, you'll never find design in nature. No matter how long the odds, materialists will simply demand more time or tries. But if you don't limit your reasoning to what is quantifiable, you can't miss the design implicit in even so simple a truth as: The first pair of claws on a lobster are pincers.
Metaphysical Darwinism attempts to ground its atheism in the "assured results of modern science." Behe casts serious doubt on its premise. Yet Behe's scientific objections are not the sole defense against the pretensions of metaphysical Darwinism. "Darwin's doubt" and the fact that all scientifically measurable quantities are ultimately rationally understood qualities suggest an equally potent counterattack. But that's a story for another day.
Ric Machuga is professor of philosophy at Butte College. He is the author of In Defense of the Soul: What It Means to Be Human (Brazos Press).
Copyright © 2007 by the author or Christianity Today/Books & Culture magazine.
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