This chapter is about the singular nature of natural selection as an explanatory principle. This chapter is also about clear thinking, particularly the need for intentional consideration of several factors which affect adaptive explanation. It explains how several classic puzzles can be resolved. Some of the issues addressed in this chapter are emphasized in creationist attacks on evolutionary theory. Other issues are of greater concern for contemporary biologists.
Natural selection is the only known explanation for adaptation.
In this section, Ridley tries to celebrate the effectiveness of evolutionary explanation while dismissing opposing explanations. There are several important points in this section. Natural selection can explain adaptation, given well-known facts or widely accepted assumptions about biology. Alternative explanations are famously less successful. That is, it is not so much an explanation as an assertion that further scientific explanation is unnecessary.