Of all the arguments against voluntary euthanasia, the most influential is the slippery slope: once we allow doctors to kill patients, we will not be able to limit the killing to those who want to die.

In my world of the people who study war and defense issues, we simply did not talk about robotics. We do not talk about it because it's seen as mere science fiction. It's cold, hard, metallic reality.

If it is in our power to prevent something bad from happening, without thereby sacrificing anything of comparable moral importance, we ought, morally, to do it.

Unfortunately for ethical egoism, the claim that we will all be better off if every one of us does what is in his or her own interest is incorrect. This is shown by what are known as "prisoner's dilemma" situations, which are playing an increasingly important role in discussions of ethical theory... At least on the collective level, therefore, egoism is self-defeating - a conclusion well brought out by Parfit in his aforementioned Reasons and Persons.

For most humans, especially for those in modern urban and suburban communities, the most direct form of contact with nonhuman animals is at meal time: we eat them.... The use and abuse of animals raised for food far exceeds, in sheer numbers of animals affected, any other kind of mistreatment.

The traditional view of the sanctity of human life will collapse under pressure from scientific, technological and demographic developments.

If zoos are like arks, then rare animals are like passengers on a voyage of the damned, never to find a port that will let them dock or a land in which they can live in peace. The real solution, of course, is to preserve the wild nature that created these animals and has the power to sustain them. But if it is really true that we are inevitably moving towards a world in which mountain gorillas can survive only in zoos, then we must ask whether it is really better for them to live in artificial environments of our design than not to be born at all.