Metaphors and Models in Evolutionary Biology (Greg Priest, Jessica Riskin, Ehud Lamm)

From “natural selection” to the “war of nature” to the “tree of life,” Darwin's On the Origin of Species teems with metaphors. There are, no doubt, many reasons Darwin was so free with metaphorical figures in the Origin. They served a rhetorical function, assisting him to persuade his audience of the truth of his theory. In many cases, the metaphors had been central to how Darwin had developed his own ideas about evolutionary change, and so came naturally to hand as he sought to articulate his ideas. Without denying the importance of these uses of metaphor, I want to explore a different use to which Darwin put metaphor in the Origin. Darwin believed that human mental capacities were evolved traits. In consequence, the human mind is not a perfect engine of deductive logic or inductive inference but an evolved bodily system with characteristic capacities and infirmities. Just as human eyes can perceive certain wavelengths of light and not others, human minds are good at dealing with and understanding certain kinds of facts about the world but are apt to misperceive others. Darwin believed that the limitations and weaknesses in evolved human mental capacities make complete comprehension of evolutionary processes unachievable. In this paper, I explore how Darwin's understood those limitations and weaknesses, and how he deployed his metaphor of the “tree of life” to provide his audience with what he believed to be a limited and imperfect, and yet meaningful, understanding of evolutionary processes.