Environmentalists are concerned with the protection of nature, but (as has often been noted) nature may already have ended. The “environment” – the world that environs us -- seems to be a built one, and environmentalism ought to focus on that. It ought to drop the concept of "nature," both because there may no longer be such a thing (if there ever was), but also because the concept is so ambiguous as to be practically useless. Are humans part of nature or not? If they are, then the built world is natural too, so nature is in no danger. If they're not, how did that happen? Mill pointed out years ago that the word “nature” has at least two meanings, but on neither one does it make sense to talk of human actions as harming nature. The distinction between the natural and the human (or the artificial) does not stand up to analysis: it depends on an unjustified metaphysical dualism that seems at bottom both Cartesian and anthropocentric.