Where does life come from, and why is it what it is? These are great mysteries. Even so, Darwinian theorists tell us it is nothing but a mechanical process that in principle is entirely explicable by reference to biochemistry, and thus to well-known properties of matter.
The key, they say, is random variation and natural selection. Parents and offspring differ in random ways because of mutation and shuffling of DNA molecules. As one generation follows another, variations that happen to facilitate survival and reproduction accumulate, since offspring that possess them live longer and have more descendants. As the process goes on, and more favorable variations become fixed, distant descendants diverge more and more from the ancestral type.
There is no evident limit to the process, and it has been going on for billions of years. With that in mind, it becomes imaginable that a single-celled organism that started sticking together with others in clusters, because that somehow helped it survive, should eventually develop into something like a primitive worm, the worm into a fish, and the fish ultimately, after hundreds of millions of years, into you and me.
The story is a compelling one, a great deal of biological evidence is consistent with it, the mechanisms it relies on undoubtedly exist, and scientists like to explain complex things by reference to simple mechanical causes. As a result, the account has given rise to a very widely accepted framework for understanding living things.
Even so, it’s evidently incomplete as an account of life, since you, I, and Richard Dawkins have features mechanical processes don’t: sensations, intentions, reflective thought, decisionmaking capacity, and so on. These features are important, even from the standpoint of the observable behavior modern natural science wants to explain, so the story must leave out something that matters a great deal.
But we also have physical features that work mechanically, some of which—neurological processes—seem intimately connected to mental states and events, and such is the prestige of science that enthusiasts can claim that a mechanistic account fully explains the latter as well.
The claim is nonsensical, the sort of thing best described as not even wrong. What could people possibly mean by saying that when they present arguments for Darwinian evolution their action is a mechanical physical process and nothing more? Can a mechanical process be rational or irrational, right or wrong? Many nonetheless make such claims, and form a very influential school of thought, philosophical naturalism. The proponents of that view simply won’t allow anything but mechanical physical processes to exist: Anything else is too spooky to contemplate and would exclude part of reality from the scope of modern natural science.
Hence the intensity and intractability of arguments over Darwinian evolution, which are really arguments over the ultimate nature of life and the world. Such arguments are rendered yet more intractable by differences in styles of thought. Darwinian theory pleases those who demand clear, simple accounts that seem adapted to scientific methods of investigation, and therefore offer hope of comprehensive explanations, while Darwinian skepticism appeals more to people who want accounts to be more open-ended, and more adequate to life as we find it. As a result, each side considers the other irrational.
Tom Bethell, an independent-minded journalist with an interest in unorthodox scientific theories, has written an account of recent disputes over the fundamental validity of Darwinian theory. His book breaks little new ground, but brings the story up to date and presents its various aspects in a clear and lively way.
So he covers a broad array of topics. Some of them are not closely relevant to biological science as such—for example, the failure of efforts to simulate human thought through computers, and the unpopular political implications and frequent vacuousness of attempts to explain all aspects of human life by reference to Darwinian evolution. Others seem relevant but of comparatively minor importance, such as whether life began just once or multiple times, or the frequent presence of very similar structures in organisms thought to be only distantly related.
The heart of the book is its coverage of several issues that seem to raise real difficulties for the theory. These include the destructive effect of almost all mutations; the necessity for every step in the development of a new bodily organ or appendage—the wing, for example—to favor survival and reproduction; and the great stability of species in the fossil record and world around us, as shown by the absence of examples of one species imperceptibly turning into another as required by the theory.
But the strongest argument against Darwinian evolution as a comprehensive explanation for life on earth is the stupefying complexity of all life forms, a complexity revealed by modern biochemistry itself, and the consequent difficulty of conceiving how even the simplest of them could have originated by chance and begun to reproduce so that random variation and natural selection could have something to work with. As the British astronomer Fred Hoyle noted, we might as well expect that a tornado in a junkyard would assemble a Boeing 747.
The author also discusses more general issues regarding the status of the theory. “Survival of the fittest” is a tautology, for example, since “fitness” can be determined only by reference to actual survival. The result is that Darwinian theory offers few explanations or predictions that are not speculative or couched in the most general terms. The ancestors of today’s life forms evidently did what it took to survive, but knowing that tells us very little when neither ancestry nor the conditions that led to survival can be determined with any specificity. He cites prominent biologists who take that problem to heart, for example the “transformed cladists,” who ignore speculative ancestral connections in favor of observable current similarities in classifying living organisms.
He also quotes with approval the Harvard biologist Richard C. Lewontin, who asserts that Darwinian theory is accepted, in spite of implausibilities, for political and metaphysical reasons. The author’s own view is that dogmatic attachment to the theory has been owing to a combination of philosophical naturalism and belief in progress, and that declining faith in progress is gradually leading to its abandonment. I have my doubts: Progressive politics are more extreme than ever before, which must count for something, and the commitment to naturalism, which requires something like Darwinian evolution to work, maintains its strength in scientific and philosophical circles, and seems to be spreading in the population at large.
The strongest arguments against Darwinian evolution as a physical theory are based on the extreme improbability of events such as the origin of life and development of complex new organs and functions through chance mutation and natural selection. It ought to be possible to evaluate that line of thought mathematically. The author mentions some work in that direction that has been done, and more will no doubt be forthcoming.
However such studies turn out, they are unlikely to settle the issue, because we have run into similar arguments elsewhere. Astronomers and physicists tell us that an astonishing degree of fine-tuning of the position and structure of the solar system, and of physical constants such as the charge of the electron, is necessary to make complex life on earth possible. So it seems that criticisms of Darwinian evolution as a physical theory at most add another layer of improbability to those layers already present.
But philosophical naturalists have responses to such arguments, notably the proposal that numerous universes exist, each with different characteristics, and it is only in those comparatively very few that happen to be propitious for life, and in which intelligent life has actually evolved, that anti-Darwinian arguments can be made. So they might say that the improbability that fundamental physical law, the layout and position of the solar system, and the history of biochemical reactions, genetic mutations, and natural selection on earth should lead to intelligent life is of a piece with the improbability that you and I should be located in one of the vanishingly few places in the universe that have air to breathe and stable temperatures that make life possible.
It seems, then, that fascinating and important though the issues covered in this book undoubtedly are, they will not finally be dispositive. If someone wants to be a Darwinian and a philosophical naturalist he will find a way to be so.
With that in mind, the question as to the nature of the world and human life that is at the root of these disputes must be decided by reference to considerations outside the scope of the modern natural sciences. These include whether philosophical naturalism can account for existence as such, and in particular for the existence of sensations, intentions, knowledge, and the like. If not—as seems obvious—we must ask whether some other view gives us a more adequate understanding and should therefore be preferred. Such a change in perspective would reduce Darwinian evolution to a physical theory like other theories, one that explains whatever it explains, rather than a total account of man and the world. And that would enable the issues Bethell discusses to be considered more calmly and rationally, an outcome that, in view of their interest, is greatly to be desired.
[Darwin’s House of Cards: A Journalist’s Odyssey Through the Darwin Debates, by Tom Bethell (Seattle: Discovery Institute Press) 294 pp., $21.95]