ABSTRACT
The circularity argument threatens to strip the theory of natural selection of its explanatory power. The theory would be useless in explaining the dynamics of the world because literally nothing is conveyed by adding “by natural selection” to the claim that has evolved. The various versions of the circularity argument are certainly valid; if the premises are true, then the conclusion must also be true. But are the premises true? Were the premises of the circularity argument true and unavoidable, it would mean that Darwin’s theory would not be able to play the role he sought for it in explaining both the variety of organic life and its manifest adaptedness to its environments. This is a very serious threat to the theory, which plays such a central role in our understanding of the world. This is the worry to which we turn our attention. In this chapter, we find ways to define the key concepts of fitness and natural selection, which respect the aims Darwin had for his theory. Moreover, there is some reason to think that the way we define the concepts is very much in keeping with Darwin’s own understanding and intentions. If this is right, it would go to show that Darwin was very sensitive to the way the theory of natural selection figured in explanations of the biological world. His presentation of the theory, his arguments and explanations, all point toward a solution to the objection presented by the circularity argument.
