This chapter is about biological diversity, or biodiversity – one of those things everyone is in favor of. A rough definition of biological diversity is the diversity of living things at a number of levels: genetic, between and within species, and between and within habitats and ecosystems. The rest of this chapter could be spent exploring the adequacy or otherwise of this definition and the conceptual issues that arise in relation to it. I am not going to do that. Instead, I want to raise three questions about the role of biological diversity in the formation of conservation policy.

The first question arises in the context of conflict between conservationists and animal welfarists over issues like culling. The question is, does the aim of preserving biological diversity justify conservation policies that involve killing sentient animals?

Conservation aims are increasingly formulated in terms of the preservation of biological diversity. My second question is, does the aim of preserving biological diversity fully capture what conservationists actually do? I suggest that it does not. There is an aspect of conservation irreducibly concerned with the dubious concept of nativeness.

Third, I want to ask whether the preservation of biological diversity is what conservationists should be trying to achieve.