On the Origin of Species

Throughout the book, Darwin uses a two-pronged style of argument to support natural selection, or the theory of evolution. He not only directly and repeatedly demonstrates the power of his theory but also consistently shows how the predominant theory of the time—that of independent/instantaneous creation—fails to adequately address the same issues. Thus, in his ambitious attempt to invoke a change of thinking in biology, Darwin consistently criticizes the prevailing view and shows how his theory explains the same problems with greater conceptual clarity. In doing so, he effectively demonstrates the scientific need for a new paradigm in natural history and addresses the resistance he predicts.

Independent creation theory, as the name implies, is the view that separate species were created independently of one another, that they share no common ancestors, and (implicitly) that they were instantaneously brought into being by the divine intervention of God. The variety of independent creation theory that people are now most familiar is “spontaneous generation.” Although this theory has little scientific basis, it still holds some cultural influence and has required consistent rebuttal from evolutionary biology. Darwin, keenly aware of the strength and preponderance of this view during his own lifetime, generally criticizes it with a light hand, sensitive to the personal attachments of his readership. Here, in one of his most forceful rebuttals, Darwin takes off his metaphorical gloves:

But do they really believe that at innumerable periods in the earth’s history certain elemental atoms have been commanded suddenly to flash into living tissues? Do they believe that at each supposed act of creation one individual or many were produced? Were all the infinitely numerous kinds of animals and plants created as eggs or seed, or as full grown? And in the case of mammals, were they created bearing the false marks of nourishment from the mother’s womb? Although naturalists very properly demand a full explanation of every difficulty from those who believe in the mutability of species, on their own side they ignore the whole subject of the first appearance of species in what they consider reverent silence” (908).

Here, with rhetorical flourish, Darwin not only attacks the legitimacy of the theory but criticizes the lack of rigor with which proponents of this theory defend it. He exposes the scientific inadequacy of the view by reducing it to an absurdity directly opposed to efficient causality. No natural explanation of the occurrence of spontaneously generated species is possible. An appeal is made to divine commandment—which is, by definition, supernatural rather than natural. Thus, the battle in natural history between natural selection and independent creation indicates a more fundamental epistemological and metaphysical dispute.

Darwin’s naturalist approach explains natural phenomena solely through other natural phenomena. His opponents, conversely, appeal to a source beyond the natural world. The “reverent silence” with which proponents of independent creation glide over these questions, according to Darwin, belies a tacitly held religious conviction, not a scientifically justifiable view. Although Darwin prudently avoids explicit confrontation on the metaphysical level, natural selection theory has ramifications beyond its incontestable impact on evolutionary biology because it challenges an entire metaphysical perspective, a religious tradition, and an uncritical anthropocentric assumption of humanity’s place in the cosmos.

Darwin’s use of the scientific method is multifaceted. In general, he applies his thesis—that the principle of natural selection can explain the origin and diversity of species—to innumerable problems and situations. To test his principles, he uses various personal experiments (on ant colonies, seeds, flowers, etc.) as well as empirical data collected from personal observations and those of other scientists (including geologists). He uses speculative histories to account for potential problems with his theory. His process entails the systematic attempt to explain his theory by applying it to a wide variety of issues within biology, such as domestication, instinct, hybridism, and embryology.

Darwin’s methodology isn’t one-dimensional. As a scientist, he attempts rigor, thoroughness, and detail in advocating for natural selection theory. However, he permits his philosophical views to afford him some creative leeway in explaining his theory. Darwin’s philosophy allowed for stricter adherence to scientific methodology and conclusions than many of his contemporaries. He held that natural laws inherent to the physical world could purely explain the processes, events, and organisms of the natural world. Simply assuming that species development was naturally explicable put him philosophically ahead of his peers, who assumed that independent creation was divinely commanded—that is, explained by a force outside the normal, natural forms of explanation. Darwin needed no recourse to divine intervention, and his philosophical premise permitted him to attend to the implication of data and look for patterns in ways that his more fundamentalist religious colleagues couldn’t.

More than anything, Darwin’s argument for natural selection relies on its vast explanatory power—the degree to which a theory or idea can explain various problems and curiosities in a given field. Whenever Darwin encounters a supposedly “grave” challenge to natural selection theory, he invariably attempts to explain the issue via natural selection instead of admitting defeat. For instance, when considering the intricately complex instinctual actions of ants or honeybees, Darwin attempts to explain how those instincts, though too complex to be developed in a single generation, could have been selected for in incremental stages over many generations. Although his answers, at times, may seem deeply unintuitive or hard to imagine, he strives to demonstrate their rationality. This doesn’t mean that Darwin incontrovertibly proves the steps by which these instincts develop but that he has the means to explain them through the conceptual power of natural selection. Darwin doesn’t prove that rudimentary organs are explained by evolutionary lineage, for example, but can explain them through natural selection theory, whereas independent creation theory can’t explain them. In using explanatory power to advance natural selection theory, Darwin attempts to show that it’s the most likely explanation for a wide array of strange natural occurrences.