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.

There are a lot of weapons that we've developed which we've pulled back from - biological weapons, chemical weapons, etc. This may be the case with armed autonomous robotics, where we ultimately pull back from them.

With the eventual acceptance of Darwin's theory we reach a modern understanding of nature, one which has since then changed in detail rather than in fundamentals. Only those who prefer religious faith to beliefs based on reasoning and evidence can still maintain that the human species is the special darling of the entire universe, or that other animals were created to provide us with food, or that we have divine authority over them, and divine permission to kill them.

I would like us to think about it more explicitly, and not take our intuitions as the given of ethics, but rather to reflect on it, and be more open about the fact that something is an ethical issues and think what we ought to do about it.

I don't see how anyone could really think that if you have a choice between saving the life of one person and saving the lives of a million people, to say - well, I've saved the one - can you really take that seriously? I can't.

There are many cases in which gifted children have done great things without special school programs. There are also gifted kids who have been to special schools and achieved nothing that has benefited the world as a whole. Without solid evidence, I have no confidence that funding school programs for the intellectually gifted would do more good than the most cost-effective programs to help people in extreme poverty.

We don't usually think of what we eat as a matter of ethics. Stealing, lying, hurting people - these acts are obviously relevant to our moral character. In ancient Greece and Rome, ethical choices about food were considered at least as significant as ethical choices about sex.