Biodiversity is usually defended on the ground that humans are part of nature – that they are tied to nature instrumentally. This argument is about prudence, not ethics. It is designed to counter the arrogant claim that because humans technologically and culturally are no longer part of nature, nonhuman nature is expendable. In contrast, an ethical argument depends on the view that the special characteristics of humans that separate them from other parts of nature provide the foundations for their ethical obligations to protect it. Both kinds of arguments (prudential and ethical) and both views of the human-nature relationship (that humans are part and not part of nature) are needed if biodiversity is to be preserved. Moreover, the ethical argument needs to be supported by an aesthetic argument analogous to arguments for preserving artistic beauty.

Humans as part of nature

In terms of the general arguments given for and against the preservation of nature and biodiversity, there is considerable disagreement about the relationship of humans and nature – whether humans are part of nature or not. In the modern period, pride about human achievements has frequently turned into an arrogant disregard of nature. Many humans have come to think of themselves as godlike beings who have gone beyond nature and no longer have any need for it. They are confident that, whatever might occur, science and technology will find solutions and provide artificial environments for them.