Origin’s Chapter III: The Two Faces of Natural Selection

Abstract

Chapter III contains several puzzles and unexpected features. The first puzzle regards the chapter’s relationship to Chapter IV: Natural Selection. Both chapters treat of natural selection, so what distinguishes them? Is it that Chapter IV indicates the intelligence behind nature’s selections and Chapter III introduces the analog of intelligence? And is it that Chapter III suggests that natural selection performs an eliminative function, while Chapter IV shows the positive impact of selection? In Chapter IV, and in many subsequent chapters, natural selection, Darwin says, operates only for the good of each individual creature, though Chapter III suggests it destroys most individuals. Darwin asserts that he uses the term “struggle” metaphorically, which raises the question of the explanatory weight his metaphors carry, such metaphors as "the face of nature.” There are a number of unexpected features of Darwin’s analysis displayed in the chapter: for example, his introduction of a new concept of the selective environment and the several experiments he performs to establish his theory, e.g., from mathematical and thought experiments to controlled empirical experiments. Chapter III is a rich though puzzling chapter.