Editor’s note: We are delighted to present an excerpt from the new book by Dr. Shedinger, Darwin’s Bluff: The Mystery of the Book Darwin Never Finished. This article is adapted from Chapter 3.

Aside from proposing a naturalistic explanation for the mechanism driving evolution, it is clear that one of Charles Darwin’s main goals in his species work was to put the final nail in the coffin of creationist approaches to the diversity of life. Natural selection was actually subordinated to this latter goal. Darwin wrote to Asa Gray on May 11, 1863, “Personally, of course, I care much about Natural Selection; but that seems to me utterly unimportant compared to [the] question of Creation or Modification.” As a result, a book widely hailed as proposing a true mechanism for evolution actually reads more like an anti-creationist polemic.

In contrast to the view that species represent ideal types in the mind of God that were created in the form we see them today and placed in the locations where we encounter them today, Darwin argued that the geographical distribution of species in the world represented evidence for a long history of evolutionary development from common ancestors. There are many places in the Origin of Species where Darwin makes explicit that the evidence he is describing makes little sense on the assumption that species were each specially created.

On Oceanic Islands

For example, when discussing the lack of certain species of animals and plants on oceanic islands, Darwin writes, “He who admits the doctrine of the creation of each separate species, will have to admit that a sufficient number of the best adapted plants and animals were not created for oceanic islands.”¹ Here Darwin seems to assume that a creator would have no reason to leave oceanic islands devoid of these “best adapted plants and animals,” so their absence stands as evidence against creationism. A few pages later Darwin argues:

As the amount of modification which animals of all kinds undergo partly depends on the lapse of time, and as islands which are separated from each other or from the mainland by shallow channels, are more likely to have been continuously united within a recent period than the islands separated by deeper channels, we can understand how it is that a relation exists between the depth of the sea separating two mammalian faunas, and the degree of their affinity, — a relation which is quite inexplicable on the theory of independent acts of creation.²

That is, because the mammalian fauna on islands close to continents is more like the continental fauna than that found on oceanic islands much farther away from continents, it is reasonable to believe there is a relationship between continental and island fauna rather than to believe that a creator decided to make the fauna of oceanic islands more different from continental fauna.

Doubling Down

Darwin doubles down on this line of argument when discussing the way in which closely allied species can often be found in separate but nearby locations, suggesting a common ancestor that inhabited both places that then diverged into two new species. To illustrate, he again invokes the island/continent relationship. “We see this in the striking relation of nearly all plants and animals of the Galápagos archipelago, of Juan Fernandez, and of the other American islands, to the plants and animals of the neighboring American mainland; and of those of the Cape de Verde archipelago, and of the other African islands to the African mainland,” he writes. “It must be admitted that these facts receive no explanation on the theory of creation.”³

Time after time Darwin discusses some specific observation about the distribution of living organisms and then insists that a theory of independent creation of each species is powerless to explain it. Yet surely it is hazardous to assume one knows what a creator of the natural world would or would not do.

There is also the fact that many of Darwin’s best examples of geographical distribution pointing to evolutionary change involve rather less than dramatic modifications. In light of this, perhaps natural selection can diversify a species into a family of species and no further. The Darwin skeptic could thus contend, why not the special creation of types that then diverged into families of species via natural processes? Or perhaps the diversification fueled by natural selection reaches another rung or two up the taxonomic ladder, to orders or classes. Or perhaps universal common descent is the case, but it proceeded from intelligent input rather than by a purely blind mechanism.

A Classic Fallacy

One searches the Origin in vain for a thoughtful engagement with these other options. Darwin’s theory of descent with modification may indeed be a better explanation than independent creation of each species, but Darwin does not merely declare his explanation better than this one alternative; he implies it is the only possible explanation. Thus one could be forgiven for seeing in Darwin’s argumentation the classic either/or fallacy, wherein the person knocks down one option and declares a second option the clear winner, never mind that there are other live options available.

In Darwin’s defense, he does invoke a more sweeping defeater for any theory of biological origins invoking a creator. We find this in a passage where he is discussing the phenomenon of typology — the structural similarity between many organisms such as the four-limbed pattern found in mammals, birds, and reptiles: “On the ordinary view of the independent creation of each being, we can only say that it is so; — that it has pleased the Creator to construct all the animals and plants in each great class on a uniform plan; but this is not a scientific explanation.”⁴

Darwin’s Wider Goal

Darwin’s problem with creationist explanations is not that they are demonstrably false or impossible; it is that they are not, in his view, scientific. Here we find one of Darwin’s wider goals for the Origin: to stamp out creationist explanations and put natural history on a firmly naturalistic (by his lights, scientific) foundation. But it never seems to have occurred to him that his “God wouldn’t do it this way” argument was itself theologically driven, and therefore, on his own accounting, itself not a particularly scientific mode of argument.⁴

Of course, Darwin knew he would be on firmer ground if he could produce empirical evidence to support his view and overcome various difficulties confronting it. One such difficulty: If all organisms had descended from one or a few common ancestors, how had life spread all over the planet? Certain animals like birds and fish can move over long distances, but what about stationary organisms like plants? How could plants travel over long oceanic distances to colonize islands? Trying to answer this question sent Darwin into a series of experiments related to seed dispersal.

Notes

1. Darwin, Origin, 305.
2. Darwin, Origin, 308.
3. Darwin, Origin, 365.
4. Darwin, Origin, 334.
5. See Cornelius G. Hunter, Darwin’s God: Evolution and the Problem of Evil (Eugene, OR: Wipf & Stock, 2019). Hunter shows that Darwin’s God-wouldn’t-have-done-it-that-way argument is central to his theory. Darwin’s theory, according to Hunter, is more theological than scientific.