According to classical utilitarianism, the only intrinsic good is happiness; the only intrinsic bad is pain. That implies no intrinsic value in preserving nature, that preserving an endangered plant is valuable only if it benefits humans or other animals. Intuitively, that seems wrong but perhaps I shouldn't trust my intuition here.
Peter SingerDolphins are social mammals, capable of enjoying their lives. They form close bonds with other members of their group.
Peter SingerSo why don't we make ourselves the last generation on earth? If we would all agree to have ourselves sterilized then no sacrifices would be required - we could party our way into extinction!
Peter SingerTo protest about bullfighting in Spain, the eating of dogs in South Korea, or the slaughter of baby seals in Canada, while continuing to eat eggs from hens who have spent their lives crammed into cages, or veal from calves who have been deprived of their mothers, their proper diet, and the freedom to lie down with their legs extended, is like denouncing apertheid in South Africa while asking your neighbors not to sell their houses to blacks.
Peter Singer