On the Origin of Species is one of the most persuasive texts in the history of western thought. Analogous to Descartes' Discourse on Method, the Origin changed almost overnight the way europeans understood the natural world and humanity's place within it. Central to understanding the Origin's epochal character and continuing subversive vitality is close examination of its rhetorical structure. How was it possible for Darwin to convince a lay and expert audience accustomed to viewing life as a product of wise design that organic structures were the unintended outcomes of undirected mindless forces? As Aristotle observed--thought alone moves nothing (Nicomachean Ethics VI.2.1139a35--36). Darwin's Origin moved readers in his own time and continues to provoke them now because it is a profoundly "ethical" work in the sense in which Aristotle in his Rhetoric identified "ethos" as the most important "artistic" mode of proof (Rhetoric I.2.1356a3--5). Character is revealed in discourse when a rhetor so speaks as to be worthy of belief--and character is important as proof in direct proportion as scientific demonstration, is thin, ambiguous or is unavailable.
My essay argues that Darwin's "ethical proof" is manifest in his ability to use the familiar maxims and commonplaces of the industrial order to convert the reader's commitment to methodological naturalism into a metaphysical naturalism. In his anticipation of the reader's skepticism, in the variety of plausible reasons he offers for how complex structures might have been formed according to his theory, and for why the positive evidence for them is not found in the geological record, Darwin deliberated well. Through sheer mastery of scientific decorum Darwin lent dignity to an argument which, on occasion, he himself "freely confessed" seemed "absurd in the highest possible degree." (Origin, 186). On reading the Origin Huxley--who remained committed to a very different research program, and despite doubts about the adequacy of natural selection--was persuaded that Darwin's theory, or something like it, simply had to be true.
Not only did Darwin appeal to scientific afficionados through his novel deployment of the maxims of scientific reason "to bring many facts under a single point of view" but he simultaneously appealed to a broader reading public through his ability to identify his theory with the shared world-picture of his time. Updating Paley's watchmaker Darwin used the analogy of domestic breeding and the imagery of technological power to reread nature's "designs" as the unintended side effects of nature's productive self-sufficiency. When in his conclusion (itself a stirring peroration) Darwin declares that with acceptance of his theory "we [will] no longer look at an organic being as a savage looks at a ship" (Origin, 485) design becomes a synonym for barbarism and anti-science. The victory of the Origin is coincident with the victory of Darwin's metaphysical naturalism--now made coextensive with science. Darwin's rhetoric makes possible the success of his philosophy of science and his philosophy of science insures the triumph of his materialist vision of nature by requiring it as a premise.
Copyright © John Angus Campbell