If we all think only of our own interests, we are headed for collective disaster - just look at what we are doing to our planet's climate.

Sci-fi is often a metaphor. I think it's more the themes and questions that science fiction raises rather than the exact predictions that should guide us.

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.

One thing is certain: you will find plenty of worthwhile things to do. You will not be bored, or lack fulfillment in your life. Most important of all, you will know that you have not lived and died for nothing, because you will have become part of the great tradition of those who have responded to the amount of pain and suffering in the universe by trying to make the world a better place.

If governments did not mislead their citizens so often, there would be less need for secrecy, and if leaders knew they could not rely on keeping the public in the dark about what they are doing, they would have a powerful incentive to behave better.

To turn the other cheek is to teach would-be cheats that cheating pays.

It is a mistake to assume that the law should always enforce morality.