ABSTRACT
One should think of natural selection as a family of related modes of explanation, which have changed gradually over the years as the theories in which they are embedded have been reformulated in order to address different problems. In other words, understanding of natural selection itself has been subject to a process of 'descent with modification'. This chapter uses some of these transformations in our thinking to reflect on conceptual puzzles about what natural selection is, and how it works. In the introduction to the Origin of Species, Darwin (1859) pointed out how much strong evidence there is in favor of 'transformism'. By considering the explanatory task that Darwin intends natural selection to discharge, one can also understand why he describes natural selection in a way that makes it an essentially gradual process. The pragmatic focus on 'Darwin's Question' also helps us understand why Darwin is so often at pains to distinguish natural selection from sexual selection.
