Environmental issues raise a host of difficult ethical questions, including the ancient one of the nature of intrinsic value. Whereas many philosophers in the past have agreed that human experiences have intrinsic value and the utilitarians at least have always accepted that the pleasures and pains of nonhuman animals are of some intrinsic significance, this does not show why it is so bad if dodos become extinct or a rain forest is cut down. Are these things to be regretted only because of the loss to humans or other sentient creatures? Or is there more to it than that? Some philosophers are now prepared to defend the view that trees, rivers, species (considered apart from the individual animals of which they consist), and perhaps ecological systems as a whole have a value independent of the instrumental value they may have for humans or other sentient creatures.

　　Our concern for the environment also raises the question of our obligations to future generations. How much do we owe to the future? From a social contract view of ethics or for the ethical egoist, the answer would seem to be: nothing. For we can benefit them, but they are unable to reciprocate. Most other ethical theories, however, do give weight to the interests of coming generations. Utilitarians, for one, would not think that the fact that members of future generations do not exist yet is any reason for giving less consideration to their interests than we give to our own, provided only that we are certain that they will exist and will have interests that will be affected by what we do. In the case of, say, the storage of radioactive wastes, it seems clear that what we do will indeed affect the interests of generations to come.

　　The question becomes much more complex, however, when we consider that we can affect the size of future generations by the population policies we choose and the extent to which we encourage large or small families. Most environmentalists believe that the world is already dangerously overcrowded. This may well be so, but the notion of overpopulation conceals a philosophical issue that is ingeniously explored by Derek Parfit in Reasons and Persons (1984). What is optimum population? Is it that population size at which the average level of welfare will be as high as possible? Or is it the size at which the total amount of welfare—the average multiplied by the number of people—is as great as possible? Both answers lead to counterintuitive outcomes, and the question remains one of the most baffling mysteries in applied ethics.

　　31. The first paragraph is mainly about .

　　［A］ the intrinsic value of human experiences

　　［B］ the intrinsic value of the experiences of nonhuman animals

　　［C］ the intrinsic value of ecological system as a whole

　　［D］ an ancient ethical question about the nature of intrinsic value

　　32. , we owe nothing to the future generations.

　　［A］ In the author’s opinion

　　［B］ From a social contrast view of ethics

　　［C］ For a utilitarian

　　［D］ For most environmentalists

　　33. Population policy we take should be considered .

　　［A］ positive［B］ negative［C］ complex［D］ reasonable

　　34. According to this passage, optimum population .

　　［A］ refers to the population size at which the average level of welfare will be as high as possible

　　［B］ refers to the population size at which the total amount of welfare will be as great as possible

　　［C］ is a difficult philosophical issue which remains to be resolved in the future

　　［D］ is a difficult philosophical issue which Derek Parfit has successfully settled in Reasons and Persons

　　35. The proper title for this passage should be .

　　［A］ A Mystery in Applied Ethics

　　［B］ Our Obligations to Future Generations

　　［C］ Environmental Ethics

　　［D］ Environmental issues