``Every ethical theory must provide principles that describe which objects matter for their own sakes and which do not'' [4, p. 188]. So how do we determine that species, to take one example, ``matter for their own sake?'' In particular, how do we determine that causing a species to go extinct is ``bad'' and that preventing its extinction is ``good,'' especially when we remember that the eventual fate of every species is extinction?12 Part of the response I gave in one of the first lectures in this class was that the current rate of extinction is much higher than it has been at any time in the recent geological past. But why is a high extinction rate bad?
One response might be that it isn't a ``natural'' rate of extinction. It's a ``human-caused'' rate of extinction. We've seen repeatedly that distinguishing between ``human-caused'' and ``natural'' states of a system is problematic because it's very difficult, if not impossible to identify an objective baseline for comparison. Think about our discussion of how past land use history affects the current structure and composition communities or about how the structure and composition of the Pisgah forest in New Hampshire has changed over the last three centuries. But there's an even more fundamental issue associated with trying to define a ``good'' or ``desirable'' state of a system with its ``natural'' state:
If we are part of nature, then everything we do is part of nature, and is natural in the primary sense. When we domesticate organisms and bring them into a state of dependence on us, this is simply an example of one species exerting a selection pressure on another. If one calls this ``unnatural,'' one might just as well say the same of parasitism or symbiosis (compare human domestication of animals and plants and ``slave-making'' in the social insects).[4, p. 180]Similarly, if humans are causing a higher rate of extinction and we are part of nature, how can we say that human-caused extinctions are unnatural?
As Callicott et al. point out  whether we regard humans as part of the system or not goes well beyond simply noting that we are evolutionarily related to all other living things on this planet. The answer depends on whether we take a more compositionalist view of ecosystems or a more functionalist view.
Callicott et al. suggest that terms like biological diversity, biological integrity, and ecological restoration are values typically associated with a compositionalist approach, while terms like ecosystem health, ecological services, adaptive management, ecosystem management, sustainable development, ecological sustainability, and ecological rehabilitation are values typically associated with a functionalist approach. They argue that a synthetic approach combining insights of both is needed.